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Science Illustrated Australia - May 17, 2018

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SPACE CRASH! POND MONSTERS
Nightmare in a puddle
AU STR ALI AN
Destroying probes, for science
CRASHING
TO SAFETY
CAN SCIENCE READ
YOUR MIND?
We know what
you’re thinking
How engineers
learn from
disaster
HUNTING
SUBMARINES
With really big
magnets
NUCLEAR
ERUPTION
SCIENCEILLUSTRATED.COM.AU
9 771836 517000
ISSUE #59 $9.99 NZ $10.99
59
HOW NORTH KOREA COULD ACCIDENTALLY END
THE WORLD, WITHOUT FIRING A SINGLE MISSILE
THE HUNT FOR DARK ENERGY GOES ON / BUILD A LASER MICROSCOPE AT HOME / ALL YOU
NEED TO KNOW ABOUT RAINBOWS / SAND IS FILTHY / TINY AIRSHIPS EXPLORE THE PYRAMIDS?
EDITORIAL
Issue #59 (17th May 2018)
EDITORIAL
Editor Anthony Fordham
afordham@nextmedia.com.au
DESIGN
Art Director Malcolm Campbell
ADVERTISING ENQUIRIES
Advertising Manager
Di Preece
dpreece@nextmedia.com.au
ph: 02 9901 6151
Production Manager Peter Ryman
Circulation Director Carole Jones
INTERNATIONAL EDITION
Editor-in-Chief Sebastian Relster
International Editor Lotte Juul Nielsen
BONNIER INTERNATIONAL
MAGAZINES
International Licensing Director
Julie Smartz
Art Director Hanne Bo
Picture Editors Allan Baggesø,
Lisbeth Brünnich, Peter Eberhardt
NEXTMEDIA
Chief Executive Officer David Gardiner
Commercial Director Bruce Duncan
Science Illustrated is published
7 times a year by nextmedia Pty Ltd
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Magazines. © 2018 Bonnier Corporation
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Reproduction in whole or part without
written permission is prohibited. Science
Illustrated is a trademark of Bonnier Corporation and is used under limited license.
The Australian edition contains material
originally published in the US and UK editions reprinted with permission of Bonnier
Corporation. Articles express the opinions
of the authors and are not necessarily those
of the Publisher, Editor or nextmedia Pty
Ltd. ISSN 1836-5175.
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THE SCIENCE ILLUSTRATED CREDO We
share with our readers a fascination with
science, technology, nature, culture and
archaeology, and believe that through
education about our past, present and future,
we can make the world a better place.
Extremely Dangerous Toys
T
he concern that North
Korea’s nuclear testing
could accidentally set off a
supervolcano isn’t the first
time scientists have been
worried that merely playing
around with these things nevermind fighting a war
with them - could destroy the world.
There’s even a legend that the scientists on the
Manhattan Project in 1945 were worried that the
first nuclear test could cause a “chain reaction”
that could set fire to the entire atmosphere.
Of course, the legend isn’t exactly true. Enrico
Fermi jokingly offered to take bets from the top
physicists and military leaders, on whether the
20 kiloton explosion would ignite the air around
it and destroy just the state of New Mexico, or the
entire planet.
In fact, he never thought this was possible, and
he copped a bit of criticism for scaring the guards
and other base personnel who hadn’t been part of
the ongoing concerns about whether The Gadget
(the first nuclear bomb), would work.
Far from destroying the whole world, the
Manhattan Project scientists were much more
concerned with the Gadget going half-off, producing
what’s called a “fizzle”. In this case, probably nuclear
criticality isn’t achieved. The bomb explodes,
sure, but rather than a huge release of energy and
a moderate amount of radioactive fallout, instead
just the conventional explosives inside go off, and
scatter plutonium across the immediate area.
Despite The Gadget’s history-changing success,
as a nuclear weapon it was a fairly modest
device. At only 20 kilotons, it’s a mere firecracker
compared to today’s weapons, which are mostly
in the megaton range.
Indeed, the advent of thermonuclear devices
- which start with a fission reaction that leads to
a much more powerful fusion reaction - became
so enormous that testing them really did start to
pose a risk to the planet.
One of the most shocking examples was the
detonation of a device called Castle Bravo at
Bikini Atoll, on 1st March 1954. The US military
expected the bomb to yield six megatons. But
because this was the first thermonuclear device
the US had tested, Castle Bravo unexpectedly
yielded a massive 15 megatons.
While detectable levels of fallout from this test
spread around the whole world, the people living
on nearby islands received a heavy dose and
suffered radiation sickness. And 23 members of a
Japanese fishing vessel operating legally outside
the declared “danger zone” also suffered acute
radiation sickness.
In fact so much radioactive pulverised coral fell
on the boat as ash, the fishermen had to scoop it
off using buckets.
Castle Bravo accelerated growing international
concern about the safety of nuclear testing.
Six years later, on the 9th of July 1962, the US
detonated Starfish Prime, a 1.4 megaton device,
at an altitude of 400 kilometres (similar to where
the ISS orbits today).
While this time they got the yield right,
they massively underestimated the size of
the associated electromagnetic pulse, or EMP.
The EMP was so big it ruined many of the
instruments watching the test, and knocked out
300 streetlights in Hawaii, 1450 kilometres away.
So it should be no surprise that recent reports
out of North Korea say the country’s not exactly
state-of-the-art testing facility suffered some kind
of collapse after the sixth test in September 2017.
And that was just from a bomb with a yield of
100-200 kilotons at best.
The history of nuclear testing has shown
how difficult and impractical these weapons of
unthinkable destruction really are. Remember:
it’s not the size of your button, but whether
pressing it accidentally causes the Earth to open
up and swallow you whole.
Anthony Fordham
afordham@nextmedia.com.au
THINGS WE LEARNED IN THIS ISSUE
+ There’s MORE THAN ONE KIND OF RAINBOW
including fog- and moonbows.
+ Setting off nuclear bombs near a SUPERVOLCANO
might be a bad idea (who knew?).
+ There are TERRIFYING MONSTERS living in your
pond, but luckily they’re really small.
+ The best way to dispose of an UNWANTED SPACE
PROBE is to crash it into a planet, for science!
+ You can make a 1000X POWER MICROSCOPE with
just a laser pointer and a drop of water.
scienceillustrated.com.au
|
3
CONTENTS
ISSUE #59
SCIENCE ILLUSTRATED AUSTRALIAN EDITION
PUBLISHED 17TH MAY 2017
24
SPACE CRAFT DOWN
When a space probe comes to the end of its
mission, we can’t go and pick it up. So these
machines go out in a more spectacular style...
62
THE HUNT FOR DARK ENERGY
A new experiment aboard the International
Space Station could take us one step closer
to understanding the weird universe.
32
COVER
STORY
NUCLEAR SUPERVOLCANO
No it’s not a new blockbuster disaster
movie, it’s a real risk. North Korea’s
nuclear tests could cause a massive
eruption. So what would that mean?
4
|
SCIENCE ILLUSTRATED
REGULARS
AND OTHER
FEATURES
42 50
CRASHED PLANES SAVE LIVES
Travelling by air remains the safest way to
go. Why? Because every disaster showed us
how to stop it happening again.
6
MEGAPIXEL
How many birds am I holding up?
FRESHWATER KILLERS
Beneath the silvery surface of a pretty creek or
pond lurk a nightmare bestiary of true horrors.
Just when you thought it was safe...
10
SCIENCE UPDATE
This is a grain of sand. And you won’t
believe how absolutely filthy it is.
18
ASK US
Is all this prescription medicine I
found at the tip REALLY expired?
62 66
SCIENCE WANTS TO READ YOUR MIND
Sure, they always say it’s not REAL mindreading, but look at all these machines and
electrodes and whatnot...
MAGNETS VS SUBMARINES
Today’s submarines are stealthy and almost
silent. They’re all-but-invisible to sonar, but
they’re still made of metal. That’s a problem.
74
INSTANT EXPERT: RAINBOWS
Find out how a double-rainbow forms
and why people are so amazed.
78
INSTANT EXPERT: POLAR OCEANS
They are, in many ways, the planet’s
climate generators. Here’s how.
80
TRIVIA
Now even harder!
82
BIODIVERSITY
Why Satin Bowerbird chicks probably
don’t need your help...
SUBSCRIBE
70
NOW!
Get Australian Science
Illustrated delivered to
your door and save $$$!
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5
MEGAPIXEL
6
|
SCIENCE ILLUSTRATED
BIRDS
New technique captures
birds’ flight patterns
If birds left visible evidence in the sky, it
would look like Spanish photographer Xavi
Bous’ photos. He records birds with a high-speed
video camera, combining single images, which are
united into one picture of a bird’s flight patterns. This
is a yellow-legged gull captured in flight. Each wing
stroke consists of two stages: the downward motion
ensures propulsion, whereas the upward wing stroke
motion and the bird’s speed contribute to the lift.
Photo // Xavi Bou
scienceillustrated.com.au
|
7
MEGAPIXEL
PREGNANCY
A baby’s first organ is
the least explored
At the same time as an embryo’s own
organs are developing, the placenta
removes waste products and supplies the baby
with oxygen and nourishment. But a child’s first
organ is one of those about which we know the
least. The placenta is closely linked with blood
vessels in the womb wall, but we do not know how
it is dislodged immediately after birth. The cause of
many common pregnancy complications such as
very premature delivery, is probably to be found in
the close interaction between placenta and womb.
Photo // Monet Nicole
8
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SCIENCE ILLUSTRATED
scienceillustrated.com.au
|
9
A small, intelligent balloon is to explore
archaeological treasures without doing any harm.
TECHNOLOGY Archaeologists
are facing a difficult dilemma,
when they find hidden chambers in
pre-historic structures. Should they
break through the wall or is it too
risky? That was the case, when
Egyptian archaeologists recently
used a muon detector to find a
hidden chamber in the Great
Pyramid of Giza. Muons are tiny
particles produced, when the
atmosphere is struck by space
radiation. Rock stops more muons
than air, and the scientists used
that to scan the pyramid. The scan
revealed the existence of one or
more unexplored cavities in the
ancient Egyptian structure.
French robotics engineers from
the Inria and CNRS institutes, who
aim to make the exploration easier,
are developing a remote-controlled
robot, which can search the cavity
without causing any other harm
than a hole with a 3.8 cm diameter.
The robot is pushed through the
hole, inflating the miniature airship
above it. Supported by helium, the
robot will subsequently fly about
the cavity to explore it with its
instruments such as different
sensors, lamps, and cameras. The
robot and its equipment cannot
weigh any more than 50 g,
engineers have calculated.
The flying robot is not limited by
obstacles such as steps, ramps, and
loose stones. It can record video
from many angles, and if it hits
something, the helium
balloon functions as a
soft buffer, protecting
both the robot and
the prehistoric
premises.
Helium balloon
makes robot fly
Archaeologists study the
pyramids with cameras, tracking
equipment, and a large balloon.
TUBE
ROBOT
HOLE
ROBOT IS INTRODUCED
In the future, archaeologists
1 only need to drill a hole with a
diameter of 3.8 cm in pyramid walls.
Subsequently, they introduce a tube,
in which they have placed a folded
robot, that includes cameras, light,
and an inflatable balloon.
Scientists Create Low-Fat Pigs
GENETICS Low-fat bacon may one day join the
ranks of other tasty meats at your local supermarket
or deli. Chinese scientists have used the CRISPR-Cas9
genome editing method to create slender pigs, which
are also better at keeping warm.
Normally, pigs develop fat to insulate and protect
themselves against the cold, as – unlike other animals
and humans – they lack a special protein, which
regulates body temperature.
In the experiment, the
scientists took DNA from
ENCYCLOPEDIA
mice, which makes cells
produce the protein, and
CRISPR-Cas9 consists of
inserted it into pig embryos.
three molecules. One finds
Twelve edited boars were the DNA to be edited, one
edits, and one unites the
born with 24% less body fat
DNA again.
than ordinary pigs.
NORMAL
GENOME EDITED
JIANGUO ZHAO
Science Update
THE LATEST
FINDINGS AND
DISCOVERIES
Miniature airship may find
hidden pyramid treasures
1° C
30° C
Infrared images show that the low-fat pig with an inserted mouse
gene – bottom – is better at keeping warm than ordinary pigs.
Editor: Rikke Jeppesen
The robot’s balloon
takes up a lot of
space, when it is full
of gas, but it can be
folded up.
SHUTTERSTOCK & INRIA/CNRS
CLAUS LUNAU
ROBOT
LANDS.
HOLE WITH A 3.8
CM DIAMETER
LIGHT
TUBE IS UNFOLDED.
LAMP
BALLOON IS
INFLATED
ROBOT ROUTE
BAR
HELIUM ESCAPES.
CAMERA
INFLATION
Inside the pyramid, the pipe opens,
2 exposing the robot and inflating
the helium balloon with an 80 cm
diameter. The balloon is either inflated
via a small hose or from a container
carried by the robot.
THE WHOLE ROOM IS EXPLORED
The robot illuminates the room,
3 filming it from all angles. It must avoid
to collide with obstacles, but GPS does not
function in a sealed-off room, so technicians
use optical sensors, which function with
very little light.
ROBOT LANDS AND FOLDS UP
The robot releases gas from the
4 balloon and folds up, so it will fit into
the tube again. The robot is controlled by
radio signals from the operator outside, but
it must be able to find its way back via
optical sensors and tracking gear.
Cancer cells push through the body
SKIN CANCER CELLS
PENN STATE
laboratory experiments with real cells.
MEDICINE Cancer cells live longer and
In order to make the model fit, the
divide faster than normal cells. But scientists
scientists had to encode the cancer cells with
have long suspected that the aggressive cells
a much better ability to spread, even when
also have other ways to spread fast.
they were crammed and lacked space.
Scientists from Pennsylvania State
Normal cells were not able to
University in the US have used
Cancer cells do not
obtain space in the same way as
mathematics to find the secret
listen to body signals,
cancer cells. Consequently,
tricks of cancer cells. They have
rather they divide more
scientists have found a possible
developed a mathematical model often and out of control
explanation of why cancer cells can
to predict how much space cancer than other body cells.
divide and produce tumours – even
cells and normal cells need to
in very dense tissue. In the longer term, the
propagate. Subsequently, they combined the
discovery could help scientists develop
model with computer simulations that
medication that is directly aimed at
demonstrate how the two types of cells
eliminating this very characteristic of cancer
spread in the body. Finally, the
cells, hence preventing the most lethal
mathematicians adjusted their model by
tumours from reappearing.
incorporating accurate results from
Cancer cells can divide, although they are
located in very dense body tissue. Scientists
aim to eliminate this ability.
S C I E N C E U P DAT E
BY THE WAY
SAND GRAIN
BACTERIA
MAX-PLANCK-INSTITUT FÜR MARINE MIKROBIOLOGIE
BRIGHT PLANT SAVES POWER
Future lamps need no power, but you must
remember to water them. American scientists have
used nanotechnology to place the light-generating
luciferase enzyme in the leaves of watercress, so
the plant emits sufficient light for you to read. Now,
they aim to create plants that can light up a table,
and trees which can replace street lights.
100 MICROMETRES
The tiny nooks and crannies of sand grains are the homes of countless
bacterium colonies, which appear green in a microscope.
Sand is covered in bacteria
SEONYEONG KWAK/MIT
AND SPEAKING OF LIGHT ...
GENE THERAPY PRODUCES
BRIGHT CATS
Scientists create glowing
mice, rats, and cats by supplying them with jellyfish genes. They
do not aim to make the animals light
up, but to study other genes. The
glow-cat was created by the Mayo
Clinic in the US, where scientists are
searching for a cure against FIV – the
virus that causes AIDS in cats.
MAYO CLINIC
PHOSPHORESCENCE MAKES
THE OCEAN LIGHT UP
The phosphorescence
phenomenon is caused by
small plankton known as dinoflagellates. The creatures unite in
surface water, often in near-shore
areas, and if there is motion in the
water, the creatures light up. The
light show is probably a defence
mechanism to confuse enemies.
WAN RU CHEN/GETTY IMAGES
12
|
SCIENCE ILLUSTRATED
DAVID SHALE/NATURE PICTURE LIBRARY
TERRIFYING TOADFISH
USES LIGHT AS BAIT
In the deep sea, where there
is no sunlight, light is an
efficient tool to attract mates,
deceive enemies, or make prey
come closer. The deep sea toadfish
waves a “fishing rod” equipped
with a bright organ in front of it to
attract prey. The largest toadfish
species grow up to 120 cm long.
BIOLOGY The next time you
are on a beach, letting a
handful of sand slip through
your fingers, think about how
you hold about 500 billion
bacteria in your hands.
Scientists from the Max
Planck Institute of Bremen,
Germany, have examined how
many different bacteria they
could find in sand from an area
off the small island of
Heligoland in the North Sea.
They were not surprised that the
sand was full of bacteria, but
they were amazed that it was so
diverse. On one single sand
grain, they found thousands of
different species, but the
distribution was not the same
on all grains. Some species were
present on almost all sand
grains, whereas others only
rarely existed. According to the
head of the studies, marine
biologist David Probandt, the
species that exist on all sand
grains probably also play the
same role in the local eco system.
Bacteria’s conversion of
carbon, nitrogen, and sulphur is
an important part of Earth’s
cycle of those very elements; a
cycle that all life on our planet
forms part of.
The scientists’ microscopes
also showed that the bacterium
colonies are not evenly
distributed on the tiny pieces of
quartz. The smooth areas on the
surface are almost deserted,
whereas bacteria thrive in the
tiny nooks and crannies, which
protect them against friction
from other sand grains and
hungry enemies.
100,000
Number of bacteria on one sand grain,
more or less. The thousands of species
contribute to the conversion of carbon,
nitrogen, and sulphur.
S C I E N C E U P DAT E
Gas cloud
makes star
flash
ASTRONOMY The most
mysterious star in the universe.
That is what astronomers have
nicknamed KIC 8462852. Located
1,000 light years away, it's about
50% larger than the Sun and
1,000 degrees hotter. And it
appears to turn its light up and
down in a way that we haven't
seen in any other stars.
More than 200 astronomers
have cooperated to find out why.
Headed by Tabetha Boyajian from
Louisiana State University in the
US, they have collected
observations from telescopes
throughout the world over a
period of 1.5 years. In this way,
they have obtained detailed data,
which demonstrates exactly how
and when the light from the star
increases and decreases in
different wavelengths.
If a solid, impenetrable
object were orbiting the star,
blocking out its light, the
astronomers expected that all
wavelengths would be equally
affected, but that was not the
case. The light decreased more
in some wavelengths than
others, suggesting a cloud of
gas was orbiting the star.
The mystery has not yet
been completely solved.
According to the astronomers,
comets around the star might
also play a role, whereas other
scientists still believe that it is
the star itself which is getting
brighter and dimmer.
Patch With Needles
Holds Diabetes at Bay
An intelligent patch, which monitors and regulates the blood
sugar level, could make life much easier for diabetics in the future.
MEDICINE Pills every day, frequent
blood sugar level measurements, and
insulin injections. That's life for 257 million
people with type 2 diabetes. But life could
be much easier in the future.
Instead, they will only need to replace an
upper arm patch once a week. The patch
includes microscopic needles that measure
the blood sugar level. If it is too high, the
needles release the exendin-4 hormone that
makes the pancreas release insulin. Insulin
ensures that the sugar of the blood is broken
down and absorbed by body cells as energy.
When the blood sugar level has once again
been reduced, the patch releases no more
hormones. The patch takes advantage of the
fact that the pancreas of many diabetics can
produce some insulin, although it is not
enough. The ability to regulate the release
of hormones makes the patch unique. The
mechanism was created by filling the
needles with copper phos-phate, which
combines with the blood sugar.
When the blood sugar level rises, the pH
value of the blood falls. The needles include
exendin-4 deposits bound to calcium
phosphate. Low pH makes calcium phosphate
release exendin-4 to the blood. When the
blood sugar reaches a normal level, the pH
value of the blood rises again, and the patch
halts the release of exendin-4. Tests on mice at
the National Institute of Biomedical Imaging
and Bioengineering in the US, saw blood sugar
levels regulated for up to one week.
MICRONEEDLES
Long needles
inject drugs
PATCH
BLOOD SUGAR
COPPER PHOSPHATE
EXENDIN-4
BLOOD VESSELS
LOW BLOOD SUGAR LEVEL
SKIN
HIGH BLOOD SUGAR LEVEL
EXENDIN- 4 IS
RELEASED.
MICRONEEDLE
CHEMICAL
REACTION
BLOOD SUGAR
SPITZER/NASA
BLOOD VESSEL
GAS CLOUD
14
|
SCIENCE ILLUSTRATED
Sugar sets hormones free
When the blood sugar level rises, it reacts with
copper phosphate, and exendin-4 is released into the
blood. The hormones head for the pancreas, where
they stimulate the organ's production of insulin.
CLAUS LUNAU
A skew gas cloud around the KIC
8462852 star makes its light flash
irregularly.
Microneedles are full of hormones
The long thin needles penetrate the blood vessels.
As long as the blood sugar level is low, it has no
effect on the needles' deposits. The exendin-4
hormone is bound in copper phosphate pockets.
+RZZLOO\RXVFLHQFH
WKLV1DWLRQDO6FLHQFH:HHN"
11–19 AUGUST 2018
)LQGHYHQWVQHDU\RXDWVFLHQFHZHHNQHWDX
S C I E N C E U P DAT E
Baumgartner’s suit broke the sound barrier
wrinkled suit surface surprisingly did not slow him
down, on the contrary. Whereas the brake block
effect would double, if a smooth body fell in the
same way, the effect remained almost unchanged
in Baumgartner's case. The astonished scientists
had to acknowledge that a surface with many
indentations and bumps is useful, if you wish to
fly at the speed of sound or faster.
The irregular surface is probably responsible
for Baumgartner reaching the speed of sound
much earlier than expected. The results are
relevant to engineers working on future
passenger planes, which will also be travelling
at speeds close to that of sound.
ANATOMOGRAPHY
PHYSICS Felix Baumgartner was the first to
break the sound barrier in a free fall in 2012, when
he jumped from a balloon at an altitude of almost
29 km. Now, scientists from the Technical
University of Munich, Germany, have calculated
how he could obtain such a falling velocity.
Baumgartner’s suit was a customised, tightfitting pressure suit, which was not particularly
aerodynamic. Its surface was wrinkled just like
an ordinary boiler suit.
It is complicated to predict what happens to
the air currents around a falling body, when it
approaches the speed of sound. The air behaves
differently, and shock waves and turbulence
develop, which function as an
aerodynamic brake block. But
according to the scientists’
calculations, Baumgartner’s
INFERIOR FRONTAL GYRUS
Two brain centres control our
speech. If their cooperation fails,
we begin to stutter.
Hyperactive
centre makes
us stutter
A FALL OF 42 KM
The speed of sound is some
1,200 km/h.
Baumgartner's top speed
was 1,357.64 km/h.
RED BULL
He kept his record for two
years. It was beaten in 2014
by Alan Eustace, who
jumped from an altitude of
42 km.
The wrinkled suit that Baumgartner wore during his free fall made him
break the sound barrier much earlier than expected.
SHOOTING STAR · Spiral galaxies
NGC 4039
ESA/NASA
NGC 4038
Cosmic lanterns shed light on space time
Two galaxies have merged, and their colliding gas clouds form many new stars, making the
galaxies easier to see. They can help us understand how dark matter and energy affect the
space time of the universe. We can calculate the exact distance to them in order to understand
how mass bends space time.
16
|
SCIENCE ILLUSTRATED
MEDICINE About 1 % of all
adults stutter, and now, scientists
are trying to find out why. Several
studies indicate that stuttering is
caused by interruption of the
cooperation between two brain
centres located on either side of
the frontal lobe. In the left
cerebral hemisphere, the centre
controls our speech motions,
whereas the same centre in the
right cerebral hemisphere
impedes speech.
Scientists from the Max
Planck Institute in Germany
have scanned the brains of
stutterers, as they imagined
that they were stating the
names of months. A control
group was asked to do the same
thing. The results showed
hyperactivity in the right brain
centre of stutterers, impeding
the activity in the left one. In
non-stutterers, the activity was
much more balanced.
The explanation of
stuttering is probably to be
found in the right cerebral
hemisphere. The scans also
revealed that the stutterers had
a particularly active bundle of
nerve threads that originates
from the right brain centre. The
more a test subject stuttered,
the higher the activity of the
nerve bundle. It is probably
those very nerve threads that
carry impairing signals from the
right to the left cerebral
hemisphere, causing stuttering.
WATCH HAGFISH MAKE
SHARKS COUGH
A meeting between a shark and a hagfish: 1 The shark spots the apparently
attractive prey, enters its teeth into the
hagfish, 3 but has to let go again –
overwhelmed by convulsive coughing.
Stop Shark Attacks
With Vomit!
UNIVERSITY OF WASHINGTON
SHARK
HAGFISH
The hagfish has developed a slimy substance that it uses to
defend itself against sharks and other predators. The slime
blocks the gills, making sharks cough and struggle to breathe.
ZOOLOGY The hagfish belongs to a
group of animals that biologists consider
the most primitive among vertebrates.
But when they must protect themselves
against enemies, they turn out to be
rather sophisticated.
The hagfish releases a slimy
substance that makes larger predatory
fish gasp for breath. The slime swiftly
blocks the predatory fish’s gills, so it
cannot absorb oxygen. When a hungry
shark dares to enter its teeth into a
hagfish, it will hence very quickly let go
of its prey again, allowing the hagfish to
escape unharmed.
Biologists from three US universities
have studied the scenario via several
video recordings and were inspired to take
a closer look at the skin of the hagfish to
LOOSE SKIN
CLAUS LUNAU
SHARK TOOTH
find out how it can escape the attacks so
easily. The scientists assumed that the
skin was very sturdy and hence difficult to
penetrate for the teeth of the predatory
fish. So, they tested the breaking strength
of hagfish skin, comparing it to the skin of
21 other fish species. However, the study
showed that hagfish skin is not any
sturdier than that of other species.
When the hagfish escapes predator fish
teeth almost unharmed, it is instead due
to the fact that the skin is very loose.
Not only the scientists’ video
recordings, but also other observations
demonstrate the efficiency of hagfish
defence mechanisms. When biologists
study the stomach contents of other
large predatory fish, they very rarely
come across hagfish remains.
Watch the video at youtu.be/Bta18FdkVcA
HAGFISH
ANDRA ZOMMERS/CHAPMAN UNIVERSITY
MUSCLES
Loose skin protects
hagfish's smooth body
Hagfish skin is almost not
fastened to the underlying
muscles, so the body escapes,
although the skin is penetrated
by the sharp teeth of a shark.
LOOSE SKIN
The hagfish belongs to the
cyclostomes – the most primitive
group of modern vertebrates.
scienceillustrated.com.au
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17
Ask Us
Is the amount
of water on
Earth constant?
I wonder if the total quantity of water on Earth is
always the same? Or can the water “leak” into space?
NATIONAL WEATHER SERVICE
SCIENTISTS ANSWER
QUESTIONS FROM
OUR READERS
The total quantity of water on
Earth has varied throughout our
planet's geological history and it
still does, but the changes are much
more insignificant now than when
the Earth was newly formed.
Earth’s water forms part of a
cycle, in which there is a constant
exchange between different
reservoirs – rivers, lakes, oceans,
atmosphere, glaciers, and ground
water. Though the water changes
state from solid to liquid and
gaseous, it has no effect on the total
quantity of water.
On the other hand, volcanoes
continuously bring new water to the
surface. Water from depths of 50+
km is not considered part of the
water cycle, so when this water is
forced towards the surface, the
quantity of water on Earth is
suddenly increased. The water could
HOW LARGE CAN
HAILSTONES BECOME?
The world’s biggest
hailstone had a diameter
of 20.3 cm – about the
size of a grapefruit – and
it weighed 878 grams.
The huge hailstone fell
near the town of Vivian
in South Dakota, USA,
during a thunderstorm
on 23 July 2010.
both have been inside the planet,
since Earth was formed, or it could
have come from underneath the
continental plates. When continental
drift pulls the plates into the abyss,
they melt, and water is released.
Moreover, Earth is supplied
with water from space via meteors
that contain water. Just like Earth
receives material from space, the
planet also loses particles which
escape Earth’s atmosphere;
primarily hydrogen, of which we
lose 3 kg per second. The particle
loss influences the quantity of
water on Earth, as water consists
of one oxygen atom and two
hydrogen atoms. So, every time the
atmosphere sheds hydrogen, we
lose one of the building blocks of
water. At the existing rate, Earth
will run out of water in three
billion years.
INCREASE
REDUCTION
HYDROGEN
PARTICLE
Particles
escape
A particle can
become "too hot",
and obtain so much energy - and speed - that
it can escape Earth's
gravity.
Strike removes
molecules
A meteor that
speeds into the atmosphere can push water
molecules or hydrogen atoms into space.
Meteors
bring water
to Earth
Earth is supplied
with water, when it is
struck by meteors
containing water ice.
In the planet's youth,
the process meant that
Earth ended up as a
blue planet. Now,
Earth is only supplied
with very little water
from meteors.
METEOR
Editor: Morten Kjerside Poulsen
TOP 5
Space gives and takes our water
Which body cells
live the longest?
ROBERT MCNEIL/SCIENCE PHOTO LIBRARY
We can thank space and Earth’s interior geology for the fact that
the planet is a wet one. Meteors, volcanoes, and Earth's magnetic
field influence how much water there is on Earth.
EARTH'S
INTERIOR
1
Volcanoes bring hidden
water to the surface
TECTONIC
PLATES
Water that has been in Earth's
interior since the planet was
formed can be forced to the
surface by volcanic eruptions.
BRAIN CELLS
Possibly 200 years
Experiments have shown that neurons from old mice can easily go
on living in a young mouse brain.
EYE LENS CELLS
2 AllThelife
lens is only clear, because
cells that are as old as the owner
exist in permanent patterns.
Underneath the tectonic plates,
there is both mud and a series of
hydrated minerals, which also
include water. When the plates
sink into Earth's interior and melt,
the water molecules are
liberated, and they can be brought
to the surface by volcanoes.
EGG CELLS
50 years
3 From she is still in her own
mother's womb, all the eggs that a
woman ever has are formed.
HEART MUSLCE CELLS
4 40Heartyearscells are static cells, ie.
Magnetic field
is escape route
E L E C T R I C A L LY
CHARGED IONS
only half of them will be
renewed throughout life.
INTESTINE CELLS
MAGNETIC FIELD
MIKKEL JUUL JENSEN
Electrically charged
hydrogen ions can
accelerate along
magnetic field lines
and disappear into
space above the poles.
years
5 15.9
Intestinal wall cells are replaced
every few days, but the intestinal
exterior has a longer life span.
What is superfetation?
BODY-SAVVY?
?
What happened to
my penis bone?
JUAN CARLOS MUNOZ/GETTY IMAGES
The "baculum", or penis bone
found in many mammals,
prolongs intercourse and
increases the chance of
fertilisation. Humans lost this
trait, instead using monogamy
and faster, more frequent mating
as our main reproductive strategy.
Superfetation involves the simultaneous
occurrence of more than one stage of developing
offspring in the same animal. In other words two
pregnancies at the same time, but where the
babies are different ages.
Some animals such as rabbits and hares have
two wombs or bipartite wombs, allowing them
to expect two different litters at the same time.
Superfetation is also known from rodents,
horses, sheep, cats, and some marsupials. The
existence of superfetation differs from breed to
breed and from species to species, but it is not
the normal state of any mammal.
A rabbit womb might include two different
litters at the same time.
scienceillustrated.com.au
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19
ASK US
Does medicine really expire?
DRUGS CAN REMAIN
EFFICIENT FOR DECADES
Studies have shown that
painkillers, antihistamines,
and sedatives can remain
efficient for 30-40 years.
The durability of liquid
mixtures, ointments, and
cream is shorter than “dry”
drugs like aspirin.
In the US, hospitals scrap
nearly a billion dollars
worth of drugs each year.
SHUTTERSTOCK
The health authorities require
pharmaceuticals to label their drugs with an
expiry date, so consumers can be sure that
the medication is still efficient and has not
been converted into toxic substances.
Consequently, drugmakers test the
durability of the medication by storing it as
required and checking its effect regularly. The
experiments rarely go on for more than two
years. If so, drugmakers indicate a duration
of two years on the packaging, although the
contents might be durable for much longer.
Pills are usually much more
durable than the expiry date indicates.
NATURE
?
Why can some trees endure
being covered in water?
To most trees, it is not healthy to have their roots
covered in water. Roots need oxygen, or they will die.
However, mangroves thrive in water thanks to their
special roots, which can endure being flooded in
salt water for long periods of time.
Mangroves cannot only survive
flooding – they can grow in salt
water. When the water enters the
roots, 90 % of the salt is filtered
out. The remaining salt is
secreted through glands in the
leaves, drying up to form crystals.
The roots grow vertical
structures known as
pneumatophores, which rise
above the water surface,
functioning as snorkels.
TIM LAMAN & JOUAN & RIUS/NATUREPL & CZESHOP & SHUTTERSTOCK
PNEUMATOPHORE
LENTICEL
20
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SCIENCE ILLUSTRATED
At the top of the
roots, you will find
lenticels, i.e. areas
with porous tissue,
where gases can
enter and exit
the plant.
Puzzles, etc., improve
both your ability to learn
and your memory.
SHUTTERSTOCK
Why are some people better
at remembering things?
Why do some people find it difficult to
remember already at an early age?
The memory is one of the brain’s most
basic functions and one of the most
complex to understand. First of all,
memory is not just memory, it comes in
different types such as working, shortterm, and long-term. Secondly, the
different types of memory function
differently, operating in different areas of
the brain. Hence, the memory is a highly
integral part of the entire brain, and it is
considered an important element of
overall intelligence. In other words, you
generally stand a better chance of being
smart, if you have an excellent memory.
The memory
is controlled
by about 70
billion cerebral
cortex cells
As all brains are different, and all
people are not equally intelligent, it is
only natural that we are not equally
good at remembering. Moreover, it is
important to sleep well, because the
long-term memory repeats all its
knowledge and secures memories
during sleep.
WORLD RECORDS
What is the longest battery life?
Two brass bells connected with two
different voltaic piles make up the
Oxford Electric Bell, which requires so
little power that it has operated for
COUNTRY
Where: Oxford, England
What: The Oxford Electric
Bell, whose voltaic piles
have lasted since 1840
BATTERIES
176 years
YOUTUBE
scienceillustrated.com.au
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21
ASK US
Cold tap water is colder in the winter than in the
summer. It is not the temperature of the ground water
that is affected by seasonal change,but rather the
temperature of the water pipes that carry drinking
water to our water taps.
Water pipes are typically located at a depth of a few
metres, where summer and winter temperatures differ
by 8-10 °C. However, the temperature of the cold water
does not vary as much, as the water from the
waterworks is the same temperature all year, and the
pipes are insulated. So, the temperature of the water
will vary no more than 6 °C in the course of a year.
SHUTTERSTOCK
Is ground water affected
by summer and winter?
In the winter, water pipes in the ground
are cooled, resulting in up to 6 degrees colder water in our taps.
How many asteroids does the asteroid belt include? Millions of asteroids orbit in the
asteroid belt. Scientists estimate that the number of asteroids with diameters 1+km is
1.9 million
The picture shows the
prototype of a new,
customised pacemaker
on the surface of a model
of the heart of a rabbit.
WHAT IS THIS?
By means of MRI and CT
scans, scientists have
produced a 3D computer model
of a rabbit heart, 3D printing it
in plastic.
1
A thin membrane with
30 electrodes connected
to a network of flexible cords
is customised using the plastic
heart as a guide.
2
The network of electrodes
is a pacemaker, which is
placed on the rabbit’s real
heart. The pacemaker records
the heart’s electric signals and
mechanical work. Based on this
data, scientists calculate which
electrodes are to affect the heart
by a weak shock.
3
UNIVERSITY OF ILLINOIS & WASHINGTON UNIVERSITY
THIN MEMBRANE
WITH ELECTRODES
RABBIT HEART
22
|
SCIENCE ILLUSTRATED
BLACKOUT
In about 1 billion years,
the
constant expansion of the
universe will mean that
even
the closest galaxies will
be
travelling so fast away from
us
that we cannot see them.
By
then, any astronomers
can only
study our own galaxy –
everything around it is a
void.
C E N TAU RU S A
Is it really true that ...
Are galaxies travelling so fast that the
distance between them is expanded
faster than at the speed of light?
Two galaxies can move away from each
other so rapidly that it looks as if they are
travelling faster than light. But it is not
the galaxies that are in a hurry, it is the
expanding universe which is increasing
the distance between galaxies.
The space in between these (and
every) galaxy is expanding like the rest
of the universe. If two galaxies are
located more than about 14 billion light
years from each other, the distance
between them is growing so rapidly that
light cannot follow suit.
Such galaxies can no longer be
observed. The light that they emit will
never reach us, because space is
expanding too fast for the light to keep up.
GALAXY
ACCELERATING
UNIVERSE
DISTANCE BETWEEN
GALAXIES: 14 MILLION
LIGHT YEARS
Future
Accelerating
expansion
Not only has the universe
been expanding ever since
the Big Bang, the expansion
is also accelerating.
Physicists explain the
phenomenon with dark
energy, which functions as
a type of inverted gravity,
making everything diverge.
Present
MIKKEL JUUL JENSEN & NASA
... two galaxies can move away from
each other at the speed of light?
DISTANCE
BETWEEN
GALAXIES:
4 MILLION
LIGHT
YEARS.
Past
BIG BANG
scienceillustrated.com.au
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23
S PA C E
SOLAR SYSTEM
TAKING THE
PLUNGE
Intended crashes, deliberate
fires, and pure bad luck have
killed countless spacecrafts.
However, the expensive
equipment has not died in vain.
Struggling for their lives, the
crafts pick up new knowledge
and test bold manoeuvres. The
next in line is Juno, that will
die in Jupiter's atmosphere.
her worlds
42 probes are 'buried' on ot
cosmic cemeteries,
PROBE
tem include
Planets throughout the Solar Sys
rovers are buried.
and
ts,
in which probes, landing craf
LANDING CRAFT
ROVER
NASA
MERCURY
VENUS
MARS
JUPITER
SATURN
By Mikkel Meister
The testing of new,
bold manoeuvres has
killed several spacecraft.
CLAUS LUNAU
scienceillustrated.com.au
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25
MERCURY
CASUALTIES:
1 PROBE
A
NASA
Crash stops
stray pioneer
In 2011, NASA’s MESSENGER probe
is the first to enter into an orbit
around the innermost and smallest
planet of the Solar System, Mercury.
Over a period of four years, the
probe reveals that the small rocky
planet has a large, partly liquid
core and that cooling makes the
planet slowly shrink. Based on data
from the probe, scientists conclude
that Mercury – as the only Solar
System planet apart from Earth – is
still geologically active.
In April 2015, after 11 years in
space, MESSENGER runs out of
power and dies in a dramatic
finale. In order that MESSENGER
does not end up as a stray craft
with empty fuel tanks, NASA
chooses to crash the probe against
Mercury’s pockmarked surface.
REST IN PEACE
MESSENGER
3 August 2004
30 April 2015
CAUSE OF DEATH:
Skydiving
GREATEST
ACHIEVEMENT:
The probe was the first
to pay Mercury a visit.
26
|
SCIENCE ILLUSTRATED
t a speed of 200,000
km/h, the Juno probe is
roaring into Jupiter’s
atmosphere, where
gases make the small
craft vibrate out of control and catch
fire. In the course of a few minutes, the
craft succumbs and explodes. This is what
is going to happen in July 2018, when
NASA’s Juno probe ends its two year mission
around the Solar System’s greatest planet in a
scheduled suicide mission.
Juno is not by far the only one to end its life
on another planet far away from Earth. So far, 42
probes, landers, and rovers have died on other
Solar System planets.
The crafts have burned up in boiling
atmospheres, b e en devastate d b eyond
recognition in vertical crashes, or simply gone
missing. But fortunately, none of them have died
in vain, as their last words have made up
invaluable data, which astronomers could not
otherwise obtain, and they have provided us
with more ac curate insight into our
neighbouring planets.
MANY VICTIMS ON VENUS
Since the first probe left the close vicinity of Earth
in 1956, an army of probes, rovers, and landers
have been sent to other Solar System planets and
their moons to take a closer look at them.
The distances to other planets are vast, and
even our closest neighbour, Venus, is 40+ million
km away. This requires large quantities of
energy, so even though it often cost millions of
dollars to build the crafts, they will never return
to Earth. Some of the crafts enter into eternal
orbits. That is true for the Pioneer 6 probe, which
was launched into an orbit around the Sun in
1956 and is the probe that has been functional
for the longest time. In 1995, its transmitter
failed, but NASA engineers managed to make
the probe use its emergency transmitter, which
was still functional, when NASA tried to make
contact in December 2000.
A craft in an eternal orbit will rarely
c o n t r i b ut e n e w k n o w l e d g e . I n s t e a d ,
astronomers kill off the crafts, using their last
resources to test bold technical manoeuvres and
collect new knowledge about otherwise
inaccessible places such as extremely hot
atmospheres.
The Solar System’s planetary cemeteries are
located on Mercury, Venus, Mars, Saturn, and
Jupiter, where 42 crafts have so far been buried.
Of those, by far the most are to be found on our
two neighbouring planets of Venus and Mars.
Venus includes 24 landers and probes, which
were killed in the atmosphere and on the surface
after more or less successful landings.
The first spacecraft to end up on a foreign
planet was the Soviet Venera 3. With a small
landing module aboard, the probe was launched
towards Venus in November 1965. Having
arrived safely, Venera 3 let go of its landing
module on 1 March 1966, so it could land to
measure temperature, pressure, and the makeup of the planet’s atmosphere. Russia lost contact
with Venera 3, which was to have collected and
sent back data to Earth from its orbit around the
planet, so no data exists from the module’s
descent through the atmosphere. Nevertheless,
Venera 3 was the first craft ever to reach – and
die on – the surface of another planet.
Its successor, Venera 7, reached Venus in
1970, becoming the first spacecraft to send data
back from the surface of another planet.
The craft managed to record 22 minutes and
58 seconds of data from the surface, revealing a
temperature of about 475 degrees C and a pressure
of some 90 times the conditions on Earth. The
measurements came close to the results of
astronomers' previous calculations concerning
the conditions on Venus, but Venera 7's career
was a short one. Immediately after the brief
report to Earth, the module fell over following a
hard landing, making data transmission
impossible.
In 2009, NASA’s Spirit
rover got stuck in the
Gusev Crater near Mars’
equator.
NASA
Braking Test Ends
in a Sea of Flames
Over a period of 9 years, Venus Express carries out a thorough
investigation of Venus, before burning up in the atmosphere.
E
quipped with brand new
instruments such as magnetometers, spectrometers, etc., ESA's
Venus Express probe is launched from
Earth on 9 November 2005, heading for
Venus, to study climate, cloud cover,
and the chemistry of the atmosphere.
The probe discovers an atmosphere
that contains water – in spite of a
temperature of 465 °C on the planet’s
surface. The water molecules are
shattered by UV radiation and blow into
space. Based on data from the probe,
astronomers calculate that Venus was
probably covered in water 3 billion years
ago and might have included life.
Last, the probe dives to an altitude
of 130 km in 2015 to test slowing itself
down by skating across the atmosphere.
VenusExpress is lost in the manoeuvre.
GOODBYE
VENUS EXPRESS
9 November 2005
18 January 2015
CAUSE OF DEATH:
Cremation
GREATEST ACHIEVEMENT:
The probe discovers that Venus’
atmosphere contains water.
ESA & NASA
VENUS
CASUALTIES:
14 LANDERS
10 PROBES
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27
S PA C E
SOLAR SYSTEM
Miscalculation
Destroys Lander
In 2016, erroneous height measurement makes the
Schiaparelli lander collide with Mars at a speed of 540 km/h.
W
hen the Eurpoean Space Agency, ESA, launches
the Trace Gas probe towards Mars on 14 March
2016, the aims are high. The probe brings the Schiaparelli landing module, and together, the two make
up the first part of the ExoMars mission, which is to
find out whether there is life on the Red Planet.
Everything goes according to plan, when, three
days before its arrival to Mars, the probe lets go of its
lander. Whereas the probe is to orbit Mars, searching
for molecular evidence of life in the atmosphere, Schiaparelli is a test craft, which is to test the landing
technologies that will be necessary in 2020, when ExoMars is to land a sophisticated rover on Mars.
On 19 October, following three days in a state of
hibernation, Schiaparelli is reactivated, starting to
slow down at an altitude of 122.5 km. At an altitude of
11 km, the speed has been reduced from 21,000 to
1,650 km/h, and the parachute is activated. When it
is shed at an altitude of 1.3 km, the craft’s motors are
to reduce the speed to 7 km/h. But a negative altitude
measurement makes the craft shed it parachute too
early, crashing onto the red surface of Mars.
Craft hits Mars at 540 km/h
The Schiaparelli lander is in a free fall, when the parachute
is disconnected by mistake at an altitude of some 4 km.
SCHIAPARELLI
14 March 2016
19 October 2016
CAUSE OF DEATH:
Unscheduled disassembly
GREATEST ACHIEVEMENT:
The craft paves the way for
the ExoMars rover in 2020.
PARACHUTE
UNFOLDS
Schiaparelli enters the Martian
1 atmosphere as planned, activating
its parachute at an altitude of 11 km.
HEAT SHIELD
DISCONNECTED
At an altitude of 7 km, the
2 bottom heat shield is
disconnected as scheduled.
SENSOR CALCULATES
WRONG ALTITUDE
The craft miscalculates its altitude,
3 disconnecting the top heat shield
and the parachute at an altitude of 3.7 km.
CRAFT IN A FREE FALL
FOR 37 SECONDS
At a speed of 540 km/h,
4 Schiaparelli strikes Mars’ surface
after a free fall of 37 seconds.
CLAUS LUNAU
have taken
Probes orbiting Mars
s impact site.
lli'
photos of Schiapare
ESA
MUCH TOO EARLY
NASA
MARS
CASUALTIES:
MISSING:
1 PROBE
2 ROVERS
11 LANDERS
3 PROBES
Scientists find
the error
The first part
of the ExoMars mission
consisted of a probe and a
landing module.
ESA & NASA
Rover stuck in Martian soil
With a radiation-scorched, barren surface and
an atmosphere that is almost only made up of
carbon dioxide, Mars is not a friendly place. As
compared to Venus, the Red Planet – with its
lower temperatures and tolerable pressure – is
nevertheless a world that astronomers consider
an obvious place to colonize in the future.
In an effort to research the conditions on the
surface, NASA and other organizations have
over the years sent landers, probes, and rovers to
the planet. Of those, 14 have ended their lives on
the Red Planet. That is true for the six-wheeled
Spirit rover, which has been stuck since 2009.
The rover arrived after a six month journey
to Mars in January 2004 – three weeks before its
twin, Opportunity. According to plan, the rover
was to move about for 92 days to collect
geological and chemical data, but the mission
was prolonged over and over again. The small
rover managed to work on the planet 24 times
longer than planned and cover at total of 7.73
km – i.e. 12 times longer than the 600 m, which
were originally the aim.
On 1 May 2009, the rover got stuck in a sandy
area of the Gusev Crater near Mars’ equator. It
continued to send data back until March 2010,
when it failed, probably because it had spent the
winter in a too cold place. For nine months,
engineers of NASA’s Jet Propulsion Laboratory
tried to wake the rover up, but in vain, so the
Spirit mission officially ended on 11 May 2011.
Since then, NASA engineers have been
working hard to invent new wheels, which are
not only suited for both soft and hard surfaces,
but can also handle more weight. The wheels will
probably be introduced on NASA’s 2020 rover.
The first NASA mission to Mars in
17 years ends as a total failure,
when the American space agency
loses contact with the Mars
Observer craft on 21 August 1993.
After a 725 million km journey,
and only three days before the
probe was to enter into an orbit
around Mars, NASA no longer
receives any signals from it. The
connection is never restored, so
the craft does not make any of the
measurements which were the aim
of the USD 813 million mission.
NASA sets up a commission,
which analyses 60 accident
scenarios. Engineers conclude that
the error was due to a fuel pipe
leak that might have harmed the
craft’s electronics and forced it
into an uncontrolled spin,
entering into an eternal orbit
around the Sun.
Missing probe reemerges
Although astronomers generally know where
their spacecraft are, a few have gone missing.
That is true for the two Soviet Phobos 1 and 2
probes, which disappeared as a result of a
computer error and an incorrect command from
the control centre.
Sometimes, engineers find spacecraft again
after years without contact. In August 2009, the
Indian space agency lost contact with the small
Chandrayaan-1 moon craft. Astronomers
thought that the craft might have been drawn
close to the Moon by its gravity and had crashed
onto the surface.
In 2016, NASA invents a new method for
finding even small craft such as Chandray-aan-1
orbiting around the Moon. So far, it has been
difficult, as the light from the Moon can easily
prevent telescopes from spotting the small
objects. But with the help of two radio telescopes
located in California and West Virginia, USA,
OUR BELOVED
MARS OBSERVER
25 September 1992
21 August 1993
CAUSE OF DEATH:
Lost in space
GREATEST
ACHIEVEMENT:
Engineers “calculate”
the error made.
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29
S PA C E
SOLAR SYSTEM
Suicide mission
reveals age of rings
SATURN
CASUALTIES:
1 PROBE
THANKS FOR EVERYTHING
CASSINI
15 October 1997
15 September 2017
CAUSE OF DEATH:
Scuttled
CLAUS LUNAU & NASA
GREATEST ACHIEVEMENT:
The probe is the first
to visit Saturn.
NASA was able to spot the small Indian craft.
One telescope emitted a powerful microwave
signal, after which the other telescope received
the reflected signal from Chandrayaan-1, as it
passed over the Moon’s north pole at an
altitude of about 160 km. The telescopes
followed up with observations for the next
three months, mapping out the probe’s
accurate orbit. Even though the craft has now
been found, there is no contact.
So far, engineers must consequently be
happy that the probe is not included in the vast
quantities of wreckage on Earth’s loyal
follower. A total of 59 crafts, including manned
Apollo missions carried out by NASA and a
series of unmanned craft launched by the
space agencies of the world have over time left
a mixture of old landing stages, worn-out upper
rocket stages, and other hardware on the
surface of the Moon.
Burning protects worlds with life
On the two gas giants of the Solar System,
Jupiter and Saturn, burials do not take place as
a result of computer or engine errors, they are
carried out on purpose. The planets are huge
balls of gas without solid surfaces to land on,
but the reason for the scheduled suicides is to
30
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SCIENCE ILLUSTRATED
The Cassini probe makes the headlines
throughout the world on 15 September 2017,
when the probe ends its 13 year mission
around Saturn and its largest moons.
Over the years, the Cassini probe has
ensured a series of magnificent recordings
including up to 500-km-high geysers on the
Enceladus ice moon, severe storms in
Saturn’s atmosphere, and surging methane
oceans on Titan. Cassini brings the Huygens
lander, which in 2005 lands on Titan as the
first – and so far only – craft to land on a
world in the outer Solar System.
In a grand finale, Cassini in April 2017 dives
under Saturn’s innermost rings. Over the next
five months, the probe makes 22 hazardous
moves in between the planet and the rings,
before finally diving into the atmosphere,
burning up like a meteor. The scientific aim of
the scheduled suicide is to finally find the
answers that will solve decades of disputes
concerning the age of Saturn’s rings. Scientists
are currently analysing all the data that
Cassini has sent back during its grand finale.
be found in a different place, i.e. on the moons
orbiting the gas giants.
Moons such as Jupiter’s Europa and
Saturn’s Enceladus are at the top of
astronomers’ list of other Solar System worlds
that could include biological life. Even though
the surfaces of the moons are barren and icy,
large oceans with liquid water could exist
under the thick ice sheets. The tremendous
gravitational pull of Jupiter and Saturn leaves
It can't be ruled out that
a spacecraft could bring
microbes from Earth.
enough energy in the moons to create a tidal
effect that heats the water, making it liquid. If
there is also volcanic activity on the ocean
floor, astrobiologists suddenly have all the
elements of the equation that – at least on Earth
– are synonymous with life.
If astronomers do one day find life on one of
the Moons, they want to make sure that the
organisms are not really from Earth.
Cons e quently, the spac e craft are
laboriously assembled in clean rooms, in which
the quantity of dust, bacteria, and other sources
of contamination are minimal. Still, it cannot be
completely ruled out that a spacecraft could
bring microbes from Earth. As scientists lose
control of spacecraft, when they run out of fuel,
they do not wish to risk that a stray craft strikes
one of the moons, leaving life from Earth.
When the Juno probe enters Jupiter’s
atmosphere in July 2018 after seven years in
space, burning up in the course of a few
minutes, the burial is completely intentional.
Such cremation will not only bring the probe
close to Jupiter’s atmosphere, it will also
prevent the probe from striking one of Jupiter’s
five moons at some point in the future, leaving
microbes from Earth.
Only in this way, NASA can make sure that
any future discovery of life on another world
is surely a sensation.
Whereas Juno will be sacrificed, scientists
have other plans with another guest of the
outer Solar System, New Horizons. After a
successful mission near Pluto, the probe is now
on its way towards the next destination in the
Kuiper Belt, before it will finally end its life in
interstellar space.
NASA
JUPITER
CASUALTIES:
2 PROBES
XT
THE NE
VICTIM
As the first ever, the Galileo craft
visits Jupiter after six years of
travelling hrough space with an
arsenal of instruments and a small
atmospheric probe.
In December 1995, Galileo lets go
of the atmospheric probe, which slowly
descends through the atmosphere. The
small probe reveals wind speeds of 700+
km/h, which is more than expected.
The probe manages to send data to
Galileo for 59 minutes, before it burns
up in the atmosphere. Galileo continues
its scientific research of the gas giant,
discovering volcanic activity on the Io
moon and possibility of primitive life
on the ice moon of Europa. After eight
years of research, Galileo in 2003
suffers the same fate as the probe,
burning up in the atmosphere.
NASA
Close encounter
ends in flames
Cremation to
Kill Bacteria
The Juno craft is to burn up in Jupiter’s thick cloud cover
to avoid polluting the moons around the gas giant.
A
fter two years of observations of
Jupiter, the Juno probe will be
sent down into the gas planet’s
atmosphere in 2018.
The probe, which NASA launched in
2011, is only 4,200 km from Jupiter’s
surface in the closest section of its
orbit. From there, Juno has revealed
that the core is large and frayed, that
the atmosphere is layered, and that
extreme hurricanes cause havoc by the
gas giant’s poles.
The powerful radiation belts around
Jupiter are gradually destroying Juno’s
instruments, and it is unknown how long
they can endure the rough treatment.
Originally, the probe was supposed to
have completed 37 orbits, but due to a
rocket engine error, NASA has changed
its plans, so it will instead complete 12
slightly more remote orbits. Hence, the
probe is subjected to less radiation,
which could extend the mission beyond
its scheduled end in July 2018. No matter
the final deadline, Juno will be sent into
Jupiter’s atmosphere in the end, so the
craft – which might be contaminated
with bacteria from Earth – does not
collide with the moon Europa, etc.,
which could support life.
CLAUS LUNAU
ALWAYS IN OUR HEARTS
GALILEO
18 October 1989
21 September 2003
CAUSE OF DEATH:
Scuttled
GREATEST ACHIEVEMENT:
The probe was the first
to visit Jupiter.
After two years of
constant observations
of Jupiter, the Juno probe in
July 2018 heads towards the
gas giant’s red-hot atmosphere to end its mission.
1
At a speed of 208,000
2 km/h, the craft enters
the gases of the atmosphere.
The encounter sets fire to
the probe, which vibrates
out of control.
Like a meteor, the
3 burning craft will
burst, and Juno ends its
mission to Jupiter as a
shooting star high up in the
gas giant’s atmosphere.
scienceillustrated.com.au
|
31
N AT U R E
SUPERVOLCANOES
This Sci-Fi Sounding
Danger is Very Real:
NUCLEAR
TESTS
COULD WAKE
A SLEEPING
DRAGON
The Paektu supervolcano could bury
half of Asia in ash, and North Korean
nuclear tests threaten to wake the
volcano from its sleep. Two British
geologists have been granted
extraordinary permission to observe
Paektu, and they are worried.
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SCIENCE ILLUSTRATED
By Niels Hansen
The hardened lava and ash layers
are up to 80 m deep, bearing
witness of Paektu’s eruption in 946.
SEOUL ARTS CENTER
N AT U R E
SUPERVOLCANOES
KOSIMA WEBER LIU
James Hammond
and North Korean
geologists are
ready to install
seismometers on
Mount Paektu.
“
H
i James, this is Clive. Have you ever
thought about going to North Korea
for a brief visit?”
The call is made in 2011, and one
week later, two British geologists,
James Hammond and Clive Oppenheimer, are in one of the
world’s most unapproachable countries – after an almost
unprecedented invitation from the Communist
government itself. The underground has begun to stir,
threatening North Korea as a nation.
Due to the short run-up, Hammond and Oppenheimer
do not have much time to think about what they are doing,
but when Hammond steps out of the plane in Pyongyang,
he is both curious and anxious.
PAEKTU
CHINA
NORTH KOREA
SOUTH KOREA
The border between China
and North Korea winds
across Mount Paektu.
The top of the crater and
Heaven Lake are located
on the North Korean side.
The two geologists' stay in the North Korean capital is a
short one. Immediately upon arrival, they join about 30
North Korean ge ophysicists, s eismologists, and
volcanologists to fly north to the impressive mountain
range of Changbai, which makes up the border between
North Korea and China. It is also the location of the volcano
of Mount Paektu.
If you do not know Mount Paektu, you are not the only
one. The volcano is probably the one of the 25-30 sleeping
supervolcanoes in the world about which we know the
34
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SCIENCE ILLUSTRATED
least. Supervolcanoes are volcanoes that have the potential
to eject more than 1,000 km3 of magma, causing an ash
cloud to rise 25 km into the air.
Mount Paektu has not produced a severe eruption since
946 AD, and the historic sources are very limited. However,
2,744-m-high Mount Paektu makes most other volcanoes
seem like, well, fizzers. The North Korean volcano is a
monster with sufficient explosive force to blanket half of
Asia in ash and trigger a climate disaster that could cause a
severe winter lasting several years across the whole of the
Northern Hemisphere.
James Hammond and Clive Oppenheimer are the first
Western geoscience researchers to visit Mount Paektu,
which rises barren and scarred on the horizon.
Once on the volcano, the two scientists inspect the
scarce and outdated scientific equipment, which North
Korea has already erected, and learn the extent of the
eruptions, the volcano could produce.
Subsequently, a long discussion follows between the
Western scientists and their North Korean colleagues
concerning future cooperation. When Hammond and
Oppenheimer go home after one week, they have a welldefined mission. They are going to find time and money for
exploring North Korea’s secret supervolcano to understand
Mount Paektu’s full "potential".
Ash rained down over Japan and Greenland
In 2013, Hammond and Oppenheimer return to research all
the evidence of the eruption in 946 AD, they can get close
to along with their Korean colleagues. They study the
extent and thickness of ash and lava, taking geochemical
samples to determine the make-up of the magma and how
it escaped the volcano.
According to Clive Oppenheimer, Mount Paektu's
eruption in 946 was like "a million nuclear bombs
Underground short cut supplies the fuel
Most volcanoes get their magma directly from subduction zones, where crust plates
disappear underneath each other and melt. Mount Paektu is located far away from
the closest subduction zone, receiving its magma via an underground short cut.
CRUST PLATE SINKS
Under Japan, the oceananic
crust is heading down into
Earth’s mantle, where it
melts, producing magma, which
turns into Japan’s volcanoes, etc.
MOUNT PAEKTU, NORTH KOREA
JAPAN
1
JAPAN
TRENCH
About 600 km under Mount
Paektu, the crust plate
cracks. Moulten material
underneath the crust plate is now
able to escape, flowing up through
the crack.
3
4
U P WA R D F L OW
The crust “strands” at
depths of 410-660 km, as
the density of the lower
mantle is too high for the crust to
sink any deeper. So, the crust plate
levels out.
660 KM
1
SINKING IS
SLOWED DOWN
MAGMA FINDS
SHORT CUT
MAGMA CHAMBER
FILLS UP
3
2
2
OCEANIC
CRUST
The material is light and
warm enough to rise like a
bubble towards the surface,
supplying new fuel to the large
magma chamber under Mount Paektu.
4
CRATER
Exceptional
quantity of magma
under Mount Paektu
Seismic surveys have revealed that Mount
Paektu’s magma chamber is extremely
spacious and full of magma.
LIQUID MAGMA
VOLCANIC
SLURRY
S P O N G Y L AY E R
CHAMBER DEPTH:
65 KM
FEED PIPE
CLAUS LUNAU
Right under the crater, there is a
major quantity of liquid magma, which is
ready for the next eruption. The magma
is of a kind that causes particularly
explosive eruptions.
Under the magma, there is a layer of
volcanic slurry with 50 % crystals and 50
% magma, which is sufficiently liquid to
be ejected in case of an eruption.
At the bottom of the chamber, there
is a stiff, spongy layer that consists of 65
% crystals and 35 % liquid magma.
Feed pipes supply new magma.
N AT U R E
SUPERVOLCANOES
Supervolcanoes
located in clusters
Ye llo w st on e
The world includes six groups of a total of 27
supervolcanoes, which could cause eruptions
with global consequences. Unlike smaller volcanoes, they often lack the distinctive coneshape. That is due to the fact that they
have blown themselves to bits and pieces.
Eruption zone: The area is bombarded
with large rocks and flooded in red-hot
avalanches. Few or no survivors.
Primary ash zone: Lots of ash fall, quickly
accumulating into a layer of several metres.
Many die immediately.
Secondary ash zone: The ash slowly
accumulates into a thick layer, slowing down
traffic and making roofs collapse. Few casualties.
VEI 7
VEI 8
ASTERS
TO GLOBAL DIS the VEI (volcano explosivity
S
ER
K
A
LE
T
d according to
FROM QUIE
des.
eruption is estimate
the world for deca
volcanic
I 8 darkens
The strength of a
gma, whereas VE
w upwelling of ma
slo
a
is
0
I
VE
).
ex
ind
ASH CLOUD
FREQUENCY
EXAMPLE
< 100 m
Continuous
Mauna Loa
100-1,000 m
Daily
Stromboli
1-5 km
Weekly
Galeras (1993)
Annually
> 10,000,000 m³
3-15 km
Cordón Caulle (1921)
Severe
≥ 10 yrs
> 0.1 km³
10-25 km
Eyjafjallajökull (2010)
Cataclysmic
≥ 50 yrs
5
> 1 km³
> 25 km
Vesuvius (79)
Paroxsysmal
Laki (1783)
6
Colossal
≥ 100 yrs
> 10 km³
> 25 km
≥ 1,000 yrs
> 100 km³
> 25 km
Tambora (1815)
Super-colossal
≥ 10,000 yrs
> 1,000 km³
> 25 km
Taupo (26.500 BC)
Mega-colossal
DESCRIPTION
VEI MAGMA VOLUME
Non-explosive
< 10,000 m³
0
Minor
> 10,000 m³
1
Explosive
> 1,000,000 m³
2
3
4
7
8
exploding at the same time” and probably the most severe
that the world had seen in 2,000+ years. The eruption
eliminated the entire mountain peak, leaving a hole with a
four kilometre diameter, which is now called Heaven Lake. A
thick layer of volcanic ash was spread across an area of 1.5
million km2, reaching as far as Japan 1,000+ km away. Even in
Greenlandic ice core drillings 7,000 km away, you can see
evidence of Mount Paektu’s ash.
Closer to the volcano, the eruption was a maelstrom of fire,
rock, gas and ash, which eliminated all life. In a 40 km radius
around Mount Paektu, the layer of slag, ash, and hardened lava
averages eight metres thick, and in hollows in the terrain, the
thickness of the layer is 70-80 m. It is the remains of glowing
36
|
SCIENCE ILLUSTRATED
North America
Yellowstone in the US is the
most famous of North America's
supervolcanoes, and it is
seething with volcanic gases.
Yellowstone's most recent super
eruption happened 639,000
years ago. In case of a new one,
major parts of central North
America will be devastated.
avalanches, which, according to the scientists’
calculations, flowed down the volcano at speeds of up
to 600 km/h. Glowing avalanches occur, when an
eruption is briefly losing momentum – perhaps only
for a few hours. When it happens, the energy source
that keeps the 25-30-km-high eruption column of
magma drops, ash, and volcanic gases in the air is
turned off. The column collapses, falling towards the cone, and
continuing down the sides and further across the landscape as
a 400-degree-hot avalanche.
Seismographs monitor the volcano
Hammond and Oppenheimer’s stay has exc eeded all
expectations, and the scientists install seismographs or
earthquake meters, which they use for passive seismic
tomography purposes. The method takes advantage of
earthquake vibrations spread through the ground like 3D
ripples in a pond.
Around the volcano, minor earthquakes constantly occur,
sending microscopic vibrations in all directions. The type of
i
Ca m pi Fl eg re
Pa ek tu
Europe
East Asia
Close to Naples, you will find Campi Flegrei,
whose eruption 39,000 years ago blast away
the volcano, which is now almost invisible
in the landscape. The Greek Archipelago
also includes a sleeping supervolcano
(Santorini), which erupted 3,600 years ago.
Where the Pacific plate dives
beneath Asia, there is a series of
supervolcanoes: Mount Paektu,
Japan's Aso-san, Aira, and Kikai,
which could bury the island realm
in ash, and Karymshina and Kurile
on the densely populated Russian
peninsula of Kamtchatka.
La ke Ta up o
a
Vi la m a Ca ld er
To ba
South East Asia
In Chile, Bolivia, and Argentina,
several volcanoes have had super
eruptions in the past 6 million
years. The extreme volcanic
activity is caused by the Pacific
plate, which sinks below South
America. The collision between
the two plates has also produced
the Andes.
75,000 years ago, Toba on
Sumatra was responsible for the
most severe eruption in the
history of man. Genetic data
indicate that the eruption
reduced the number of people to
3,000, threatening our species.
Further east is Tambora, which
had a VEI 7 eruption in 1815.
rock determines, how fast the vibrations travel to reach the
seismic monitoring stations. The seismographs record all
motion in Earth’s crust, saving the data, and after about two
years of measurements, they can be united into a 3D image of
what is going on under the volcano, providing us with an idea
of how imminent the next eruption is.
Climate change could reach Europe
An eruption such as Mount Paektu’s in 946 AD sends large
quantities of climate-changing chemicals into the atmosphere.
Historic sources from East Asia describe, how the weather was
markedly colder during the years following the eruption with
snow in the summer and thick ice on the lakes.
Luckily for the rest of the world, the eruption was in early
winter, when the climate effect of a volcano with Paektu’s
geographical location remains local instead of spreading to the
entire Northern Hemisphere. If the eruption had taken place
in the spring or summer, when winds spread fine particles
more efficiently, the effect could have been much more
marked – also in Europe.
SHUTTERSTOCK & PANORAMIO & CARLO HERMANN/GETTY IMAGES
South America
Oceania
26,500 years ago, Taupo on New Zealand's
North Island had the most recent VEI 8
eruption with a total quantity of ash and
magma of 1,170 km3. The volcano is still
very active with frequent, minor outbreaks.
Taupo is one of the most probable candidates
for Earth's next colossal eruption.
The Indonesian Tambora volcano showed how such
chemicals can spread on a global scale in 1815. An eruption of
the same dimensions as Mount Paektu’s made temperatures
fall markedly in many parts of the world, resulting in the
famous "year without a summer" in 1816.
Today, a similar eruption would have much more severe
consequences, reducing the production of grain such as wheat
and rice from the world’s breadbaskets in Europe, the US, and
China by 75%. Global food production would collapse, billions
could starve, and our civilisation would be put to a serious test.
Faimine is, however, the least of North Korea's worries. In
case of an eruption like the one in 946 AD, the entire northern
part of the country would be buried in lava and the rest
smothered under massive quantities of ash, ruling out any
relief and feeding of survivors.
It is probably bearing such a destructive disaster in mind
that the government in Pyongyang has begun to take an
interest in Mount Paektu. Worries grew in 2002-2005, as the
volcano became ever more active. The ground rose, gas leaks
became more frequent, and earthquakes in the area became
scienceillustrated.com.au
|
37
N AT U R E
SUPERVOLCANOES
Ash and sulphur darken the world
The most insidious threats from volcanoes are ash and sulphur, which cause
massive harm to climate, environment, and communities. And the more severe
the eruption, the more ash and sulphur are produced.
An ash cloud rises and
spreads with the wind.
The ash blocks out the light,
grounding planes, whereas sulphur
particles make the cloud cover thicker,
blocking out even more sunlight.
Sulphur particles react with water
molecules in the stratosphere at altitudes
of 15-25 km. The reaction produces
droplets of sulphuric acid, some of which fall as
acid rain, while others remain in aerosol-form.
1
2
STRATOSPHERE
The aerosols absorb
solar energy, reflecting
the light back into space.
The reduced quantity of sunlight
cools Earth's surface, and in
some places, average
temperatures are reduced by up
to 17 degrees.
3
2
ASH AND DUST
SUNLIGHT IS
REFLECTED.
(SULPHUR DIOXIDE)
H 2O
SO 2
SO 2
H 2 SO 4
AEROSOL
3
ERUPTION
1
4
ACID RAIN
6
CLAUS LUNAU
LAVA
5
Ash and major volcanic
fragments bury homes
and traffic. Electricity
and sewerage collapse, allowing
disease to spread.
6
38
|
SCIENCE ILLUSTRATED
Mega eruption
makes the world
slowly freeze
An angry supervolcano could have
fatal consequences for the world’s
climate. UK scientists have simulated
a massive eruption near the Equator,
where the sensitive parts of the
atmosphere are filled with energyreflecting sulphur particles, causing
temperatures to fall dramatically for
years. As a consequence, the sea ice
grows markedly, the winter snow
remains in major regions, and in some
places, it almost stops raining.
-9
-8
-13
NSOON
THE MO
,
RUPTED
R
E
IS INT
T
S
A
E
H
UT
AND SO
.
IES OUT
R
D
IA
S
A
-16
-8
-17
-8
-15
-14
-8
-8
Precipitation is reduced
by 80 % or more.
Snow remains
all year.
Increasing
precipitation.
A sea ice layer of
at least 10 cm.
Sulphur in the
atmosphere makes
the rain acid,
polluting soil and water
resources for 20-50 years.
Ash, acid rain, and cold kill
plants and animals, causing
all food production to stop.
- Maximum
reductions of
annual average
temperatures.
4
LLER/GETTY IMAGES
Fine ash particles enter
the tissue and harms
our
airways, eyes, and ea
rs.
PHILIPPE BOURSEI
Falling temperatures spread to
the oceans, causing the sea ice to
spread and ocean currents to slow.
Cold, nutrient-rich bottom water no longer
rises, and ocean food chains collapse.
5
Tiny ash particle
s
enter directly in
to
the lungs, caus
ing
diseases such as
asthma and
bronchitis, and
the
ash damages ey
es
and ears mildly.
In
case of prolong
ed
exposure, very
fine
ash particles ca
use
silicosis, also kn
own
as grinders' dis
ease,
and perhaps lun
g
cancer.
scienceillustrated.com.au
|
39
N AT U R E
SUPERVOLCANOES
Seismographs registered
North Korea's most recent
nuclear testing in
September 2017.
The artificial earthquakes
were up to 6.3 Richter.
more powerful. The danger signals finally made North
Korea reach out to the outside world and the two British
geologists.
Paektu is ready for its next eruption
Hammond and Oppenheimer’s work showed that the active
magma chamber reaches at least 35 km into the ground,
which is unusually deep. The same conclusion has been
reached by Chinese scientists, who estimate that the unstable
period in 2002-2005 was due to the fact that magma flowed
up into the magma chamber from deep below.
Previous studies have also shown that the magma is only
very briefly in Mount Paektu’s magma chamber, before the
volcano starts to erupt. Moreover, Paektu is a sensitive
volcano, in which minor exterior influences could trigger an
eruption. The eruption in 946 probably began, when small
quantities of easy-flowing magma arrived to the bottom of
the magma chamber.
In 2012, scientists even concluded that the next major
eruption would naturally come in the next few decades. In
other words, the volcano is ready to pop.
Testing speeds up eruption
Though the relationship between the British geologists and
their North Korean colleagues is improving, they are
constantly challenged by political tension.
The project has to use mostly North Korean or Chinese
technology, because international sanctions against the
North Korea’s nuclear weapons
program might be on hold
RUSSIA
Since North Korea tested its first
nuclear weapons more than 10
years ago, the bombs have grown
much more powerful. All six
nuclear tests took place at
Punggye-ri only 100 km from
MOUNT
PAEKTU
PUNGGYE-RI
TEST SITE
CHINA
country prevents the foreign scientists from bringing
sophisticated equipment. One of the tools that Hammond and
Oppenheimer would like to use measures microscopic
variation in Earth’s magnetic field. However, the method is
too much like the equipment that ships and planes use to
detect submarines, so they are not allowed to bring it.
The highly Communist government is an enemy of about
all other nations in the world, so the poor and starved country
spends huge resources on its military and not least its nuclear
arms programme, which has so far carried out six successful
underground test explosions of still more powerful bombs.
A nuclear bomb, which detonates under the ground, is
not by far innocent in a geological perspective. The
explosion sends shock waves in all directions, and as Mount
Paektu is just 100 km from the test site, the volcano very
much feels the artificial, but powerful earthquakes of
magnitudes of 6+ Richter.
So, the underground test explosions make up a direct
menace to Paektu, four American and South Korean geologists
concluded in 2016.
The problem arises, because the vibrations cause pressure
changes in the magma chamber. Pressure changes can make
dissolved gases change state and produce air bubbles like the
carbon dioxide of sodapop. In a state of bubbles, gas takes up
much more space than when it is dissolved, increasing the
pressure in the magma chamber explosively – perhaps even
enough to kickstart an eruption.
In 2017, Hammond and Oppenheimer visited North
Korea for the ninth time to study Mount Paektu, but also to
celebrate that the first scientific articles about the
exc eptional c o op eration have b e en publishe d in
international journals; a cooperation that contributes slightly
to improving difficult international relations that diplomats
have almost given up on.
There might be good new though. Reports in April 2018,
after North Korea's sixth test, suggest the underground site
suffered collapse and cannot be used anymore.
NORTH KOREA
Paektu. But reports of the site's
destruction due to some kind of
collapse, come as North Korean
Leader Kim Jong-un pledged not to
do any more tests... for now. Have
we dodged another bullet?
SEPT 2017
THE HIROSHIMA
BOMB IN
COMPARISON
SEPT 2016
Korea Bay
2006
FORCE
(KILOTONNES)
EARTHQUAKE
(RICHTER SCALE)
SOUTH KOREA
0.48
4.3
2013
JAN 2016
11.3
17.8
120.0
7.0
12.2
4.7
5.1
5.1
5.3
6.3
2009
15
Automatic ther
mostat
Normally, the
"greenhouse ef
fect" is a good
thing that keep
s temperature
s stable. The
laws of physics
keep the climat
e from
fluctuating wi
ldly.
Volcanoes Make
the Land Fertile
When the world
cools, less
water evaporate
s. Rain removes
less CO from th
e atmosphere.
2
The greenhouse
effect
intensifies, and
it gets warmer.
Major volcanic eruptions cause acute chaos in the
world, but without them, the planet would end up
as a cold snowball. The eruptions keep the carbon
cycle – Earth’s integrated thermostat – going.
Volcanoes emit gaseous
carbon, CO2, to the
atmosphere. The carbon
dioxide heats the world via its
greenhouse gas qualities.
1
When the world
warms, the
evaporation of
ocean water
intensifies, and
rain removes
more CO . The gr
eenhouse effec
2
t
is reduced, and
the world cools
.
In a warm world, more
rain will fall. The rain
absorbs CO2, which
combines with the water,
producing carbonic acid – H2CO3.
2
CO 2
H 2 CO 3
The acid rainwater
dissolves rock minerals.
The carbon is bound in
bicarbonate ions – HCO3.
3
HCO 3
Bicarbonate is a basic
building block, when
marine organisms produce
shells of calcium – CaCO3. The
shells end up on the ocean floor.
CO 2
Continental drift pulls the
ocean floor into Earth's
mantle, where some of it
melts, releasing CO2, which forms
part of magma. Finally, the magma
ends up in a volcanic eruption.
4
CaCO 3
5
CLAUS LUNAU
scienceillustrated.com.au
|
41
TECHNOLOGY
PLANE CRASHES
2018
FLYING IS 40
AN
TIMES SAFER TH
DRIVING A CAR.
Relax:
CRASHES
HAVE MADE
FLYING
SAFE
Just a few decades ago, plane
crashes were common, and killed
thousands of people. But after each
crash, the causes were carefully
analysed to improve safety.
The next step is a new system that
prevents planes from disappearing.
SHUTTERSTOCK & NICOLAI AARØE
Air traffic growth (billions of
nts
Decline in the number of accide
42
|
SCIENCE ILLUSTRATED
5,000
100
In 2016, the number of
crashes was 25 % of
the number in 1950.
90
80
4,500
4,000
3,500
From 1950 to 2010,
air traffic grew by
a factor of 5,000.
70
3,000
60
2,500
50
2,000
40
1,500
30
1,000
2010
1990
1980
1970
1960
1950
2016
2000
1990
1970
1960
1980
500
10
2000
20
1950
FLYING BECOMES SAFER
YEAR BY YEAR
When a plane crashes, it is all over
the media, but in fact, flying is the
safest of all means of transport.
Every year, more than three billion
t
passengers survive flying, and fligh
ry
histo
the
in
ever
best
the
is
y
safet
of aviation. US Flight Safety
Foundation statistics illustrate
how safe it is to fly: a person who flies
,
once a day must fly for 19,000 years
.
crash
a
in
dying
of
to be guaranteed
passenger km)
By Stine Overbye
1956
ISION
THE PLANE COLL
D
OVER THE GRAN
ONE
CANYON IS ONLY
AT YEAR.
TH
L
RA
VE
SE
OF
TECHNOLOGY
PLANE CRASHES
From accident to improvement
The light on the aisle floor is only one example of safety features
that have become obligatory in all airliners as a result of a crash.
1983: LAVATORY FIRE HAS
FATAL CONSEQUENCES
1985: FLEEING PASSENGERS
TRAPPED BY EMERGENCY EXIT
Accident: At an altitude of 750 m, a
Boeing 727 approaching the Juneau
Airport in Alaska strikes a mountain side
and is destroyed. Because of dense fog
and clouds, the pilots weren't able to
see anything.
Accident: During a flight from Dallas,
Texas, to Toronto, Canada, a Douglas
DC-9 must force-land due to fire. The
smoke makes it difficult for passengers
to find the emergency exits, and 23
people die.
Accident: A Boeing 737 abandons
take-off in Manchester Airport due to
fire, immediately landing again. During
the evacuation, an emergency exit
"traffic jam" makes 55 people die of
smoke inhalation.
Result: All major planes are equipped
with the Ground Proximity Warning
system. Objects that rise above the flying
altitude are marked in red on a display.
Result: The floors of all airliners include
shining stripes that guide passengers to
the emergency exits in the dark. Smoke
alarms become mandatory in lavatories.
Result: At the emergency exits above
the wings, seats are removed to allow
more space for evacuation, and standard
evacuation procedures are introduced.
“Salt Lake, United 718 ... Ohhh,
we're crashing,” is the last radio
message from the co-pilot of the
DC-7 over the Grand Canyon.
LOST FLIGHTS ARCHIVE
1956 HEAVEN IS A LAWLESS PLACE
41-year-old plane captain Jack Gandy is heading directly into the
last storm of his life. With 64 passengers and six crew members
aboard, his Trans World Airlines plane took off from the airport in
Los Angeles at 9.01 AM, and apart from a delay of about 30 minutes
before take-off, Saturday 30 June 1956 seems to be just another
day at the office in the Lockheed Super Constellation cockpit.
On its way to Kansas City, Missouri, the plane will fly over
the Grand Canyon, and the experienced pilot has taken the trip
more than 170 times before. But this morning, dark thunder
clouds begin to develop above the sunny Californian landscape
immediately following take-off. So over the radio, Grady
routinely requests the control tower's permission to climb higher
44
|
SHUTTERSTOCK
SHUTTERSTOCK
HONEYWELL AERO
1971: PLANE HITS MOUNTAIN
SIDE IN DENSE FOG
SCIENCE ILLUSTRATED
than the instructed cruising altitude of 5,800 metres, allowing
him to avoid the intense turbulence caused by the thunderstorm.
Gandy gets his permission, and as he makes his craft climb,
he leaves the city of Los Angeles behind, heading into unmonitored airspace. In 1956, planes are only guided and
monitored by control towers in the busy airspace above
airports. Otherwise, just about all the sky over the US is no
man’s land, where pilots are completely left to themselves. No
radar keeps an eye on them, and no control tower monitors
their whereabouts.
After 1.5 hours of quiet flight, the Trans World Airlines
plane is over the Grand Canyon in Arizona, cruising at an
altitude of 6,400 m. A few kilometres away, United Airlines
Flight 718 with 58 people aboard is on its way towards Chicago,
Illinois. The Douglas DC-7, which took off from the airport in
Los Angeles only three minutes after Grady’s flight, is flown by
Captain Robert Shirley, who is cruising at an altitude of 6,400
metres, as instructed.
In the cockpits of both aircraft, the pilots are focused on
navigating through the dense clouds. The visibility is very poor,
and Gandy and Shirley stand no chance of spotting each other’s
planes, which are heading towards each other at a speed of
more than 500 km/h.
At 10:31, radio operators in Salt Lake City, Utah, pick up a
vague message from the United plane.
“Salt Lake, United 718 … Ohhh, we're crashing,” says co-pilot
Robert Harm. In the background, the radio operators can hear a
Air traffic exploded in the 1950s.
In the photo, passengers in Los
Angeles board a plane of the type that
collided with another one in 1956.
LOST FLIGHTS ARCHIVE
high-pitched voice. “Pull up! Pull up,” Captain Shirley orders.
But it's too late. At an angle of 25 degrees, his plane has
collided with the Trans World Airlines craft, and the two flights
fall almost vertically to the ground like wing-shot birds. Smoking
pieces of wreckage are spread across a huge area of the Grand
Canyon, and when the rescue team reaches the disaster site, the
scenario is a gloomy one. All 128 passengers and crew members
of the two planes have been killed, and not one single body is
found in one piece.
INVESTIGATOR INVENTS BLACK BOX
The mid-air collision is not by any means the first one in aviation history. In 1950-1955, 65 planes collided over American
soil. But the Grand Canyon collision is the by far most deadly,
and in the weeks and months that follow, the American people is outraged. Every day, there are newspaper reports about
the primitive flight control service, which has not at all
moved with the times, about the rapidly rising number of airliners, and the state of complete anarchy in the skies.
“Did Outdated System Kill 128?”, the Detroit Free Press
newspaper rhetorically asks in the wake of the disaster.
The public and politicians demand a thorough modernization of air traffic control, and the request is heard. As a direct
consequence of the collision, the US government headed by
President Eisenhower in 1958 establishes the first modern
aviation authority, the Federal Aviation Agency, now the Federal Aviation Administration, FAA.
The organization, which will in the future become a model for the aviation of other nations, is given the task of regulating all aspects of civil and military aviation in the US. The FAA
is assigned responsibility for establishing an air traffic control
service, which guides, layers, and tracks down all planes
throughout American air-space. In other words, the service is
to handle all flights, right from the moment the planes are
ready for take-off until they have landed again.
In the case of the accident above the Grand Canyon, there
is no doubt about the cause of the disaster, but that is a rare
example. Crashes are common in the era, and once tragedy
has struck, crash investigators often only have a wreckage
heap to search, when they are to find out what went wrong.
But already in the 1950s, Australian scientist David
Warren thought of something that would revolutionise
aviation over time, improving air safety considerably.
Warren participated in the investigations of a number of
inexplicable crashes involving the world’s first jet airliner,
the British De Havilland Comet, which was entered into
regular service in May 1952.
After a thorough investigation, investigators established
that the disasters were caused by metal fatigue, and the
primary culprit was the plane’s rectangular windows. When
the cabin was pressurised, the pressure on the corners of the
windows was so intense that the metal cracked. The
discovery meant goodbye to rectangular plane windows and
hello to rounded ones.
scienceillustrated.com.au
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45
TECHNOLOGY
PLANE CRASHES
Clever
inventions
to protect air
passengers
in the future
Engineers are constantly
trying to improve flight
safety by means of new
inventions. An aircraft
can be equipped with
parachutes for
emergencies.
“Damn, the son of a bitch is
heading right towards us,”
says Captajn Grubbs, as the KLM
Jumbo emerges from the fog.
CLIPPERARCTIC
1
The cabin is
detached
A Ukrainian aircraft
engineer has patented an
invention that separates
the passenger cabin from
the rest of the plane.
In case of engine
failure, etc., the pilot
detaches the cabin from
the rest of the plane.
1
As the cabin is
2 detached, two large
parachutes are released,
ensuring a soft landing.
2
Inflatable air cushions
3 under the cabin make
sure that it lands sofly and
is able to float on water.
V. TATARENKO/RUMBLE
3
have provided experts has meant that aircraft makers have
continuously been able to correct errors for the benefit of
safety. But when it comes to the most frequent cause of crashes
– the human factor – technical improvements are no help.
About 3 in 4 crashes are caused by errors made by pilots or air
traffic controllers – and that percentage is likely to climb.
As for the cost in human lives, the worst day in aviation
history tells the story about how bad things can go.
1977 IMPATIENCE BECOMES FATAL
David Warren was convinced that the investigative work
would have been very much easier, if he and his colleagues
had had access to sound recordings of the pilots’ conversation,
before things went wrong. If so, it would have been possible
to accurately reconstruct what happened before the accidents, said Warren, who in 1954 wrote a report about his
voice recorder. Three years later, he developed a prototype of
the device, which is now known as the black box and is standard equipment in all major commercial aircraft.
Today, there is not just one, but two black boxes on the
planes. Whereas the first one, the cockpit voice recorder,
records all conversation and sounds in the cockpit, the second
one, the flight data recorder, stores information about cruising
altitude, course, speed, etc.
To crash investigators, the black boxes are invaluable tools,
which mean that they have been able to solve lots of different
aviation crash mysteries. The knowledge with which the boxes
46
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SCIENCE ILLUSTRATED
In the afternoon of Sunday 27 March, two Boeing 747s are
waiting for permission to take off from the Los Rodeos Airport
on the Spanish island of Tenerife. In the cockpit of the one Jumbo
from Dutch KLM, Captain Jacob van Zanten is happy, when the
control tower finally allows him to take off at 4:30 PM. Due to a
bomb in the airport of the neighbouring island of Gran Canaria,
all planes have been re-directed to the airport of Tenerife, which
is densely crowded. Now, Amsterdam is finally waiting ahead,
and in dense fog, van Zanten makes his plane taxi to the end of
the runway, where it is to make a 180 degree turn and take off in
the opposite direction.
Somewhere behind him on the same runway, another Jumbo
from American Pan Am is taxiing. Captain Victor Grubbs has
been told by air traffic controllers to get off the runway and wait
until the KLM flight has taken off. But in the fog, he cannot find
his stop, so he does not move his plane out of the way.
At the end of the runway, Captain van Zanten is ready for
IAN HASKELL
Rear-facing seats
provide better
support in a crash
BRS AEROSPACE
As a plane hits the
ground, passengers are
subjected to tremendous
force, and according to a
study, they stand a 10 times
better chance of surviving,
if seated in rear-facing
seats. The UK air force has
this type of seats in several
of its transport aircraft.
Huge parachute
ensures soft landing
About 1 in 10 of the
world’s sports planes are
already equipped with a
huge parachute that
unfolds in an emergency.
Ballistic Recovery Systems,
which manufactures
parachutes for four seat
Cessna planes, is
developing parachutes for
planes seating up to 20
passengers.
583 people die, when two
Boeing 747s collide at the
airport in Tenerife. The
worst accident in
aviation history was due
to a human error.
TONY COMITI/SYGMA/GETTY IMAGES
take-off. He is impatient, and consequently, he does not wait for
permission from the air traffic controllers to take off, rather he
chooses to accelerate his aircraft at full throttle.
“We are taking off,” he says over the radio.
“Okay. Standby for takeoff. We will be back,” the control
tower answers.
“We are still taxiing down the runway,” the captain of the
Pam Am flight warns, but Captain van Zanten does not get his
message. His huge steel bird is already roaring down the runway
at a speed of 260 km/h, and only too late, he spots the Pan Am
Jumbo ahead of him.
“Oh shit,” van Zanten says, realizing that a collision is
inevitable. He tries to climb sharply, as the Pan Am pilots struggle
to get off the runway.
“Damn, the son of a bitch is heading right towards us,”
Captain Grubbs says, as the KLM flight appears from the
dense fog.
“Get off, get off,” his co-pilot, Robert Bragg, shouts,
desperately hoping their own plane will clear the runway in time.
But the fates of the planes are sealed. As the KLM Jumbo
takes off, its undercarriage and engines cut through the Pan Am
plane’s roof, and the Dutch plane only flies 200 m, before it falls
to the ground, exploding in a sea of fire. All 248 passengers and
crew members are killed.
The Pan Am plane catches fire, and only 61 of the 396 people
aboard it survive. With a total of 583 casualties, the disaster is
the worst in aviation history.
“OKAY” IS NO LONGER ON THE LIST
After the tragedy, an army of Spanish, American, and Dutch
experts struggled to shed light on the full cause of the disaster.
The conclusion is that it was primarily due to the fact that the
impatient Captain van Zanten had taken off without
permission. The poor vision of less than 300 metres
contributed, but the triggering factor was several fatal
communication misunderstandings between the Dutch
captain and the control tower. Van Zanten considered the air
traffic controller’s “okay” as confirmation that the plane could
take off. But really, the air traffic controller only
acknowledged that he had received the message.
The Tenerife disaster made it clear that air traffic needed
a standard language. As a direct consequence of the accident,
aviation authorities throughout the world introduced a series
of standard expressions that are now used in all
communication between air traffic controllers and pilots. The
world “okay” is not on the list.
In order to reduce the risk of communication errors and
misunderstandings even more, both parties must speak an
oddly stilted formal language. When the air traffic controller
says something over the radio, the pilot is to repeat the
message to confirm that he has understood the words.
The recordings from the black boxes allowed investigators
to establish the course of events leading up to the collision in
Tenerife in details – right up until the cry of horror that was
the last to be heard in the cockpit of the KLM plane.
scienceillustrated.com.au
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47
TECHNOLOGY
PLANE CRASHES
Satellites to monitor all planes
SATELLITE
In 70 % of the airspace, planes are now outside air traffic control
radar screens. That will change with the Aireon system.
SHUTTERSTOCK
COVERAGE
SATELLITES
COVER EARTH
The Aireon system works by
1 means of 66 satellites that
cover all of the world, including
oceans, deserts, and poles.
AIRCRAFT
TRANSMIT DATA
All planes automatically
2 transmit information about
position, speed, altitude, etc.,
which is received by the satellites.
“We deeply regret not being able
to locate the plane,” says the last
search report concerning
Malaysia Airlines 370.
LAURENT ERRERA
However, investigators do not always have access to the
black boxes of a crashed plane. The boxes are extremely
sturdy and designed to resist a crash, but if a plane crashes
into the sea, they could disappear for good in the dark abyss.
In early April 2014, the very fear of this scenario causes the
employment of a fleet of planes and ships in the Indian Ocean
to search for the black boxes of Malaysia Airlines Flight 370.
2014 PLANE CHANGES COURSE
On 8 March at 12:41 PM local time, the plane, a Boeing 777,
took off from Kuala Lumpur, Malaysia, heading for the
Chinese capital of Beijing. About 45 minutes after take-off, at
1:19 AM, one of the pilots contacts the control centre in Kuala
Lumpur over the radio.
“Good night – Malaysian three seven zero,” the pilot says,
as the plane with 239 people aboard passes from Malaysian
48
|
SCIENCE ILLUSTRATED
CONTROL SERVICES
MONITOR PLANES
Twice a second, the
3 data is sent to earth
stations, allowing planes to
be observed in real time.
into Vietnamese airspace, as planned.
The plane is to land in Beijing at 6.30 AM, and a few hours
before arrival, several of the Chinese passengers’ family
members arrive to the airport. But Malaysia Airlines Flight
370 never lands. According to advertisement boards in the
arrivals hall, the plane is delayed, and the family members
anxiously wait to hear any news. But as minutes and hours
pass, desperation and uneasiness grow in the airport.
“We have been here for more than 20 hours. How many
hours are we supposed to wait?” a crying man asks one of the
police officers, who have been summoned to maintain peace
and order.
“Don’t worry,” the officer says.
“My whole family is on that plane, and we have been
waiting since six o’clock this morning,” the man replies.
At this point, nobody knows that the impossible has
happened: the modern airliner has disappeared without a trace,
making up the greatest mystery in the history of civil aviation.
When the pilot said good night, there was no indication
that the plane was in trouble, but the MH370 pilots never
contacted the control tower in Ho Chi Minh City, Vietnam, as
they were supposed to. However, the plane’s communication
system kept showing signs of life via satellite for hours. The
signals only indicate the distance between satellite and plane,
not its accurate position, but investigators can still calculate
that the plane suddenly switched course, flying south for four
hours instead of continuing towards Beijing.
AIRBUS
New black box
to float on the water
PLANES MONITORED ANYWEHRE
The disappearance of MH370 triggered an intensive search,
to which 26 nations contributed, and as ships, planes, and
underwater robots tried to find the black boxes and plane
wreckage in the southern part of the Indian Ocean for more
than two years, all sorts of theories concerning the plane’s
fate prevailed. The pilots had died, and the plane crashed,
when it ran out of fuel, the plane had caught fire, or it had
landed on a secret military base.
However, very few facts existed, and no physical evidence
was discovered until July 2015, when a wing flap fragment
was found on the island of Réunion in the Indian Ocean. Since
then, more wreckage washed up on the shores of Mauritius
and Tanzania without causing any significant breakthroughs
in the investigation.
In January 2017, the search for the plane was, much to the
regret and frustration of the victims' families, called off, and in
October, the Australian Transport Safety Bureau, which had
coordinated the search, published its final report.
“We would like to express our deepest sympathy with the
families of the passengers and crew members of the MH370.
We share your immense sorrow and deeply regret not being
able to locate neither the plane nor the 239 people aboard,
who are still missing,” it says in the 440 page report.
“It is almost unthinkable and socially unacceptable in
modern aviation, with 10 million commercial plane
passengers a day, that a large aircraft disappears, and the
The disappeared Malaysia
Airlines plane is searched
for in the South China Sea
and the Indian Ocean,
but the black boxes
are still missing.
world does not learn the fate of neither the plane nor the
people aboard it,” the report states. How do we make sure that
a tragedy such as the MH370 will never be repeated?
The answer is the new global satellite monitoring system
Aireon, which is to monitor all planes in real time, so their
positions, directions, altitudes, and speeds are always known.
Today, air traffic is monitored by means of radar and the
ADS-B system, which sends signals about position, speed, etc.,
consisting of plane and earth station transmission and
receiving equipment. However, the monitoring only includes
30 % of the airspace. With the Aireon system, 100 % of the
airspace will be monitored by satellites, and so, aviation enters
into a new and even safer era. According to plan, the system
will be introduced in the second half of 2018.
Aireon also means that the airspace will be used much
more efficiently, as the accurate information about plane
positions and the constantly updated data mean that the safety
distance between planes can be halved, allowing more traffic
at altitudes with plenty of tailwind, saving both fuel and flying
time for the benefit of the environment and passengers.
In April 2017, Malaysia Airlines was the first to buy the
Aireon system, which was developed as a direct consequence
of the MH370 disappearance. In this way, the wheel has come
full circle. Like in the collision over the Grand Canyon in 1956
and numerous other times in aviation history, a disaster has
proved very educative, paving the way for advances and
improved safety.
scienceillustrated.com.au
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49
HOW FOO YEEN/GETTY IMAGES
As a result of the fruitless search for Malaysia
Airlines Flight 370, Airbus has developed a new
type of black box, which will be standard
equipment in all new Airbus long distance planes
from 2019. Over time, the box will be installed in
all the European plane manufacturer's aircraft. If
a plane crashes into water, the box will
automatically be ejected from the tail fin to float
on the water. All existing black boxes sink to the
bottom. From the water surface, the box will
send signals about its position for up to 90 days,
which is three times the existing capacity.
N AT U R E
HUNTING
The water spider is
ready to dive for fish
or other prey, which it kills
with its poison.
MYN/NIALL BENVIE/NATUREPL & SHUTTERSTOCK
MEET YOUR LOCAL MONSTERS
DEATH LURKS RIGHT
BENEATH THE SURFACE
A few metres from your home, a drama much like
the one taking place on the African savannah is
unfolding. In lakes and waterholes, dragon fly
larvae spike prey with their long lower jaws,
as leeches crawl into duck nostrils to start sucking.
50
|
SCIENCE ILLUSTRATED
By Xxxxxx xxxxxxxx
AML
NPNTOIB
CA
5
4- C
IZE: U
S
Big Tadpoles Eat the Little Ones
If food is scarce, tadpoles use extreme methods. Large tadpoles will eat their smaller siblings,
growing even bigger. Biologically speaking, the cannibalism makes sense.
It looks idyllic in the spring, when ponds and lakes
start to fill with tadpoles, which swim about
eating algae and other tiny creatures. But in
reality, tadpoles participate in a merciless race for
life and death.
All tadpoles hatch within a few days, and from
that very moment, everything is about eating as
much as possible as quickly as possible, so they
can be converted into frogs or toads and climb
ashore – preferably before any of their siblings,
as tadpoles are not afraid of using dirty tricks,
particularly not if times are rough, because the
pond is drying up, etc. Under such
circumstances, they forget that they love their
siblings, turning into cannibals. Some tadpoles are
lucky enough to be in slightly bigger eggs and are
hence larger than the rest, and they mercilessly take
advantage of the situation, consuming their smaller
peers. This makes them grow still bigger, affecting
the rest of the family even more adversely.
However, the brutal behaviour makes
sense, as it ensures that at least
some individuals of the
family survive to
reproduce
themselves.
Large tadpoles
will not refrain
from consuming
smaller siblings.
WILD HORIZON/GETTY IMAGES &
RMI MASSON/GETTY IMAGES
N AT U R E
HUNTING
ER
DIV
2
:
E CM
SIZ
Spider Lives Its Whole
Life Underwater
The water spider uses its swimming capacity to
capture prey. Its web is used in other ways.
The spider collects air
with the hairs on its
abdomen, creating a
diving bell with its web.
GERHARD SCHULZ/GETTY IMAGES
T
he water spider is the only spider that lives its entire
life under water, although it needs to breathe just
like other spiders. And instead of catching prey in a
web, it uses its excellent swimming capacity to
catch up on and kill its prey with poison. The web,
which its spins between aquatic plants, is
used to hide behind, when it is hunting.
The water spider’s life would be very
troublesome, if it were to move to the
surface to breathe all the time, but by
means of the water-repellent hairs
covering its abdomen, it can collect a
layer of air at the surface and use it as
an oxygen bottle. Moreover, it spins a
web that it fills with air bubbles, moving
into it like a diving bell.
CO2
O2
Spins its own diving bell
MYN/NIALL BENVIE/NATUREPL
HAKAN SODERHOLM/ALAMY/ALL OVER PRESS
STEPHEN DALTON/MINDEN PICTURES/GETTY IMAGES
The water spider’s diving bell can capture oxygen from the water,
so the hunter only needs to go to the surface 2-3 times a day.
COLLECTS AIR BUBBLES
When the water spider makes
1 its abdomen protrude above
the water, an air bubble is produced
around the water-repellent hairs.
52
|
SCIENCE ILLUSTRATED
CRAWLS DOWN A THREAD
The bubble causes so much
2 lift that it is difficult to swim
with it. Instead, the spider crawls
down a thread that it has spun.
FILLS THE WEB WITH AIR
The spider spins a web
3 between aquatic plants,
filling it with air bubbles by
brushing its abdomen with its legs.
BELL ABSORBS OXYGEN
The web stretches into a bell.
4 The air is gets dissolved oxygen
from the water, while CO2 from the
creature's expiration escapes.
GLUTTON
SIZE: 10 CM
Leech is a Ducks’
Worst Nightmare
Leeches, which are common in all
waterholes and lakes, specialise in
sucking blood from larger animals.
They bite a hole using three sharp
jaws placed in a triangle. Once they
have gnawed a hole, they spit specific
substances into the wound, which kill
the pain, so the victim does not
realize that it has been attacked, and
have an anti-coagulating effect on the
blood, which remains flowing out for
as long as possible.
One of the more horrifying of the
numerous leech species is the duck
leech, which specialises in ducks.
When a duck puts its head under the
water, the leech swims in through its
nostrils or mouth, settling in the
nasal cavity or the throat. Finally,
there may be so many leeches in the
bird’s airways that it suffocates.
Diving beetles spread fear and dread
in any waterhole during the summer.
The streamlined, fast-swimming
beetles are proper eating machines,
which will consume almost anything
– but their larvae are even worse.
Adult diving beetles grow up to 4 cm
long, but their larvae often measure
up to 10 cm. The larvae are equipped
with a pair of large, curved jaws,
that they sink into anything they
can get to – even prey larger than
themselves. The meal is dissolved
and sucked out via two channels,
and once the larvae have grown
fat, they crawl onto the shore
to pupate. The next year,
adults emerge to mate and
lay new eggs.
Diving beetles descend
from terrestrial ground
beetles, but they still need to
breathe. The larvae have a
volume of air inside their
bodies, which they replenish
by the surface of the water,
whereas the adults collect
air under their wings, so
they can remain under the
water for a longer period of
time. A total of 4,200
different diving beetle
species exist, making
them the largest family
of aquatic beetles.
Diving beetle larvae try
to take hold of
everything that
flows by.
Copepods hatch
all at once to
confuse hunters.
The Prey
is No Pushover
Prey which is on the menus of
countless predators must use
drastic methods to produce
offspring in waterhole jungles.
EXPLODING NUMBERS
Copepods are one of the species,
whose offspring hatches at the
same time in a brief
population explosion. The
loads of prey confuse
predators, ensuring that as
many individuals as possible
survive to breed new
generations.
HIGHER SPEED
Apart from hiding, they prey’s
only way of surviving is to be
faster than the predators.
Some insect larvae can shoot
water out of their anuses
with such force that they
speed through the water.
STRONGER ARMOUR
Water fleas, of which most
lakes include millions, can
immediately adapt, if the
hunt for them intensifies. In
a few days, they will start
having offspring with longer
spikes, making it harder for
predators to swallow them.
scienceillustrated.com.au
|
53
ALEX HYDE/NATUREPL
UP
SIZE:
Diving Beetles
Gobble Their Food
ALAMY/IMAGESELECT
IRE M
VAMP
C
TO 20
ALAMY/IMAGESELECT
The duck leech swims into the nostrils
of ducks to feed on blood from the
nose and throat.
N AT U R E
HUNTING
ARTERRA/GETTY IMAGES
SIZE
Raft spider uses the
surface as a net
With a leg span of up to 10 cm, a raft
spider can scare most people. The
spider, which is one of the largest in
Denmark measured by body weight,
can often be observed on a lakeshore
with its front legs resting on the water
surface, while the hind legs stick to the
plants on the shore. The water surface
is used as a type of replacement for a
real web. If a small creature falls into
the water from above or approaches
the surface from below, perhaps
penetrating it, the raft spider’s
sensitive front legs will immediately
feel the slight vibrations of the water.
In spite of its size, a raft spider can
walk, or rather run, on the water, as it
speeds forwards to catch the prey,
which might be as large as a stickleback
or another small fish. The agile hunter
gives its victim a lethal toxic injection,
bringing it back to the shore, where it
sucks all nourishment out of it.
Frogs lay their eggs
in lumps (below).
Toads lay them in a
long string (top).
Borrow the Bugs,
Leave the Frogs
Freshwater bugs are easy to catch,
but challenging to keep. As for
tadpoles, declining frog numbers
mean they are now protected.
CAPTURE:
USE A NET AND A BUCKET
Use a net and a white
bucket to see what you
have caught. You must
return any tadpoles to
the water-source where
you found them. No
stocking your pond!
JAN HAMRSKY/NATUREPL
NNER
WATER :R10UCM
KILLER JAW
SIZE: 15 CM
Dragonfly larva
hunts wearing mask
Dragon fly larvae are just as efficient
hunters as their parents, although they
do not fly, but rather swim or crawl
about lakes and streams. With their
large eyes, they can easily spot the prey
– i.e. almost anything that moves
under the water surface – capturing it
with their “secret” weapon, the mask.
In spite of the name, it is not a disguise,
but rather a particularly well-developed
lower jaw, which the dragon fly larva
can jut out to capture its unsuspecting
prey from a distance of several cm.
CARE:
TEMPORARY PETS
Why aren't water insects
super popular pets? Because
they are hard to keep... not
alive, actually in the tank!
Because unlike crabs,
yabbies etc, most aquatic
insects can fly away!
54
|
SCIENCE ILLUSTRATED
The raft spider makes
a rush at the victim,
as soon as it feels any water
surface vibrations.
THE JAW JUTS OUT
In attacks, the mask is rapidly jutted
2 forwards, and the curved spikes at
the end of it capture the prey like pincers.
KEN IKEDA MADSEN
A smartphone with an
extra macro lens worth a
few hundred DKK is
sufficient to take excellent
pictures of the creatures. A
small, narrow fish tank will
limit distortion via refraction.
STEPHEN DALTON/MINDEN PICTURES/GETTY IMAGES
PHOTOGRAPHY:
USE A MACRO LENS
THE JAW REMAINS FOLDED
The dragon fly larva’s well-developed
1 lower jaw (the mask) can be bent in
two joints and is folded under its body.
RS
BIT: E
1-2 CM
SIZE
Water Bugs
Bite and Suck
With its inverted swimming
style, a water-boatman
attacks the prey from
an unexpected angle.
IMAGESELECT
PREY
Water bugs come in many species, which all
have trunk-shaped mouths, that inject toxin
into the prey and suck out the contents.
Murderous boatman
attacks from below
BACKSWIMMER
One of the most common water bugs is the waterboatman, or backswimmer, which spends most of its life on
its back. Whereas most aquatic insects are light on their
bellies and dark or patterned on their backs to be as invisible
as possible, the backswimmer has it the other way around.
The special inverted swimming style makes the prey believe
that the creature has turned its back, when it attacks.
Backswimmers will happily attack larger creatures and can even
kill a frog, when hunting in groups.
SUCTION PIPE
Creeping water bugs
can penetrate skin
Water scorpion breathes
through a snorkel
Creeping water bugs are very common in small ponds and
waterholes, where they are easy to catch. But please do not do so,
unless you treat them very carefully. The small and rather square
insects, which are almost as wide as they are long, will attack in
case of even the least provocation, and with their short, but very
powerful suction pipes, they can easily penetrate
human skin. The sting is very unpleasant, but
to insects, small fish, and tadpoles,
which are the hungry bug’s usual
victims, the toxin will
surely mean death.
Whereas many other water bugs are gifted swimmers, the
water scorpion swims so poorly that it might drown, if it cannot
rest its feet on solid ground. So, the species will remain in shallow
waters, and it is equipped with a 1-cm-long respiratory
tube, which it places above the water to
breathe. The snorkel might
resemble a scorpion tail, and
the front legs look like
pincers, but the water
scorpion is only hazardous
for crustaceans, insects,
and small fish.
The creeping water
bug looks harmless,
but its suction pipe
leaves a painful sting.
Respiratory tube
(bottom) and front
legs make the bug
resemble a scorpion.
BLICKWINKEL/ALAMY/ALL OVER PRESS
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MA/SI59
ABSOLUTE ZERO
CAL/JPL/NASA
TECHNOLOGY
SCIENTIS
S USE
ULTRA-COT
L
ATOMS FORD
:
A cloud of ultra-cold atoms
is let loose from a chip in
the International Space
Station, ISS. The cloud
expands and is cooled to
100 billionths of a degree
above absolute zero
(-273.15 °C).
FROM VISION
TO REALITY IN
58
|
SCIENCE ILLUSTRATED
DET
ECTING theo
retical
particles, which
produce dark en
ergy
1924
1985
1995
EINSTEIN PREDICTS QUANTUM WAVE
LASER COOLING
IS INVENTED
Laser beams can
slow down atoms,
hence cooling them.
The method allows
the cooling of a gas
of atoms to less than
one thousandth of
a degree above
absolute zero.
CONDENSATES
ARE PRODUCED
The first BoseEinstein condensates are
produced at temperatures
of a few billionths of a
degree above zero. In
2001, three US physicists
are rewarded with a
Nobel Prize in physics for
their results.
Physicists S. Bose and A. Einstein predict that
ultra-cold atoms will behave like a collective
wave – a Bose-Einstein condensate.
NIST
100
YEARS
DEVE
LOPING extre
mely
sensitive sensor
s, which can m
easure
gravity unprec
edentedly accu
rately.
An ordinary gas is
made up of separate,
individual particles.
Near absolute zero,
atoms collect into
one quantum wave.
By Rolf Haugaard Nielsen
Ultra-Cold Atoms Harnessed
to Hunt For Dark Energy
Just 0.0000000001 degrees above absolute zero. That is how
deeply an atom cloud will be chilled, in a new ISS experiment. In a state of
weightlessness, the atoms remain for 10 seconds, so physicists can study
them and perhaps solve one of the major astronomy mysteries.
I
n 1995, when three US physicists
cooled a gas of atoms to a few billionths
of a degree above absolute zero,
producing the first Bose-Einstein
condensate, it was a sensation. Still, the
physicists were not perfectly content. They
dreamed of carrying out the experiment at the
international Space Station, ISS, because in a
state of weightlessness, an ultra-cold gas cloud
will live much longer than on Earth, where
scientists barely have time to study it. Back
then, the vision was pure science fiction, as the
cooling required large, heavy lasers, which
could neither be launched nor fitted into the
cramped space station.
Now, things are different. The large lasers of
the past have been packed into a small chip, and
the entire experiment set-up has been fitted
into a box the size of a microwave oven. Named
the Cold Atom Laboratory (CAL), the box will
now be launched and mounted outside the
space station by a team of NASA scientists, and
subsequently, the experiments can be remote-
controlled from Earth via radio signals.
Physicists throughout the world have
already lined up to make experiments in the
distant lab, as the ultra-cold atoms are almost
completely unexplored. In a state of
weightlessness, the gas will live for 10-20
seconds, so physicists have time to study and
manipulate the cold atoms. According to
scientists, the ultra-cold atoms can be
converted into extremely sensitive sensors
that can measure the strength of gravity with
unprecedented accuracy, allowing the
scientists to measure the extent of ice cap
melting. Perhaps, the sensors can even find the
unknown particles that produce the repellent
black energy which makes the expansion of
the universe accelerate.
Cold atoms converted into wave
particles at the same time, but close to absolute
zero, the atoms lose their individual identities
as particles, instead becoming a collective
wave. The state, which is produced in gases at
temperatures of a few billionths of a degrees
above absolute zero, is known as a BoseEinstein condensate, as the phenomenon was
predicted in 1924 by physicists Satyendra Nath
Bose and Albert Einstein.
For years, scientists have dreamt of
studying the ultra-cold atoms, but so far, Earth’s
gravity has prevented it. Only 10 milliseconds
after the production of a Bose-Einstein
condensate, the atoms fall to the bottom of the
experimental chamber, where the chamber
wall heats the atoms, making the collective
quantum state cease. However, the state of
weightlessness of the space station will allow
scientists time to make
Close to absolute zero, atoms behave very
differently than they usually do. Under normal
circumstances, according to the laws of
quantum mechanics, atoms are both waves and
2001
2007
2017
2018
BOSE-EINSTEIN
IN ATOM CHIPS
Bose-Einstein
condensates can be
produced in atom chips,
but they are hard to
study. When the atom
cloud is let loose,
physicists have 10ms,
before the quantum
state collapses.
UNIVERSAL COLD
RECORD
Scientists make a
chip-based chamber
fall down through a
146-m-high tower in a
state of weightlessness. En route, the
condensate is cooled to
50 billionths of a
degree above zero.
FIRST SPACE
EXPERIMENT
An chamber is
launched into space for
the first time from
Kiruna, Sweden. Over a
period of six minutes of
weightlessness,
physicists make 85
different condensate
measurements.
100 BILLIONTHS
ABOVE ZERO
The Cold Atom
Laboratory is launched to
the ISS, to study
condensates for 10-20
seconds, as they expand
and cool. The chamber
Satyendra Bose and Albert Einstein
cools below 100
predicted that ultra-cold particles are
billionths of a degree
converted into a quantum wave.
above absolute zero.
SCIENCE SOURCE/IMAGESELECT, F. SCHMUTZER
TECHNOLOGY
ABSOLUTE ZERO
measurements. Moreover, the state can be
used to cool the atoms to even lower
temperatures than on Earth. In the space lab,
the Bose-Einstein condensate is produced by
laser cooling, while the gas is captured in a
magnetic field by ultra-cold atoms. When the
magnetic field is "switched off", the gas spreads
in the vacuum chamber.
The spread cools the atoms even more, as
the longer the distance in between atoms, the
more rarely they collide, and the colder they
get. The principle is the same as when a spray
bottle becomes ice-cold after the gas has been
released and the pressure inside the container
has been reduced. The longer the cloud
develops, the colder the atoms.
Physicists hope to beat the cold record on
Earth of 50 billionths of a degree above
absolute zero, which was set by dumping a
version of the experiment down a 146-m-high
tower in Germany. The free fall produced five
seconds of weightlessness, during which the
gas expanded and was cooled, before the
experimental chamber landed in plastic balls at
the bottom of the tower.
In the space lab, the gas will expand and
cool for 10-20 seconds, and the atoms will
become even colder. If the cold record is beaten,
the atom cloud at the space station will be the
coolest spot in the universe – about 100 million
times colder than empty space, in which the
temperature is 2.725 degrees above absolute
zero anywhere.
The space experiments also involve
another major advantage: whereas scientists
can only make three experiments a day in the
tower, CAL will be available to physicists 24/7,
and the remote-controlled experiments can
be carried out over and over again from
anywhere on Earth.
100
million times colder than
empty space is what the
ISS atom cloud will be.
Highly accurate measurements
First, physicists aim to study the properties of
Bose-Einstein condensates and manipulate
the collective quantum wave, into which the
cloud of ultra-cold atoms is converted, in
order to see, if they can shake the wave or
make it produce a circle.
When an improved version of the lab is
launched no later than in 2021, it will be possible
to carry out atomic interferometry, by which a
laser beam splits the quantum wave in two, one
half moving a little further away from Earth
than the other, causing a tiny difference of the
weak gravity acceleration from Earth, which
the top and bottom waves are subjected to.
When the two quantum waves are reunited,
they produce a grooved pattern, that can be used
to calculate the tiny difference and the strength
of the gravity acceleration very accurately.
The ultra-cold atomic interferometer can
make the world’s most accurate gravity
measurements and is able to measure small
changes in Earth’ field of gravity, as they are
produced. Apart from observing melting ice
caps, scientists will also be able to say to which
extent the ground water deposits of an area
are emptied of water for drinking and
irrigation purposes.
Intense search for dark energy
An atom chip from the American company
ColdQuanta is the heart of the space station
experiment. The Bose-Einstein condensate is
produced at the centre of the chip.
D SCOTT CLARK
60
|
SCIENCE ILLUSTRATED
An atomic interferometer will be sensitive to
all types of fields and so, it could also reveal the
physical mechanism behind dark energy,
which, according to astronomers, makes the
universe expand ever faster. The key is that the
detector is located in empty space, where the
particles’ rejection cannot be out-competed by
the attraction of gravity.
The dominant theory involves that dark
energy originates from empty space and has a
constant strength – i.e. any given volume of
empty space always contains the same
quantity of dark energy. A competing theory
says that dark energy is mediated by particles
that change their masses and forces depending
on their location. Near compact masses such as
Earth, the particles have so much mass that not
even CERN’s LHC accelerator can produce
them. But at the ISS, a highly sensitive atomic
interferometer might be able to detect the force
fields produced by the particles. So, scientists
hope that the ultra-cold atoms in space can
soon solve the major mystery of astronomy
once and for all, explaining dark energy.
NASA
Coolest Spot In the
Universe on the ISS
Scientists will equip the space station with a vacuum
chamber with an atom chip, lasers, and magnetic coils
in order to cool atoms, so particles are converted into
quantum waves.
ISS
CAL
The Cold Atom Laboratory (CAL)
is the size of a microwave oven. It is
complete with lasers, magnetic coils,
and a vacuum chamber, in which the
Bose-Einstein condensates are produced.
The lab is mounted on the outside
of the space station. Scientists
working in shifts remote-control the
experiments from Earth.
VACUUM CHAMBER
MAGNETIC TRAP CAPTURES ATOMS
RADIO WAVES
ATOM CHIP
CLAUS LUNAU
MAGNETIZED
ATOM CHIP
MAGNETIC COIL
FULLY COOLED BOSEEINSTEIN CONDENSATE
BOSE-EIN STEIN
CON DEN SA TE
COLD
ATOMS
LASER
BEAM
FIRST, LASERS COOL ATOMS
Laser beams coming from
six directions slow down
a cloud of millions of atoms. A magnetic trap captures
the atoms, cooling them to 100
millionths of a degree above absolute zero.
1
WARMEST
ATOMS
VACUUM
CHAMBER
ATOM CLOUD TRANSFERRED TO CHIP
After the introductory
cooling in the vacuum
chamber, the atom cloud
moves to the centre of an atom
chip. The magnetized atom chip
maintains the atom cloud in a
magnetic field.
2
RADIO WAVES REMOVE
WARM ATOMS.
Radio waves deflect hot
atoms out of the cloud, just
like hot tea is cooled, when
you blow on it. The cloud becomes
so cold that the atoms produce a
Bose-Einstein condensate at a few
billionths of a degree above zero.
3
EXPANSION COOLS ATOM
CLOUD ONCE AGAIN
The trap weakens, and
weightlessness ensures a
life time of 10-20 seconds,
so the cloud expands, and the
atoms are cooled even more, to a
record of 50 billionths of a degree
above zero.
4
scienceillustrated.com.au
|
61
HUMANS
THE BRAIN
Thoughts consist
of more than words
When we think about familiar objects
such as a hammer, the thought does not
only cause activity in the language
centres of the brain. It produces a
specific activity pattern in several brain
regions, which process actions related to
the object. The word hammer discharges
neurons in the frontal lobes, which have
to do with motor functions, as the
word makes us think about how to
hold a hammer, etc. By decoding
the pattern, scientists can
read our minds.
MARCEL JUST/CLAUS LUNAU
62
|
SCIENCE ILLUSTRATED
By Andreas Ebbesen Jensen
Scientists Can Read
Your Mind... Almost
A brain scanner and newly developed artificial intelligence have allowed
American scientists to decode complex thoughts. Soon, the method can be
used to control computers only by the power of thought.
“
T
he young girl was playing
s o c c er.” Paus e. “The
lawyer was drinking
c offe e.” Paus e. “The
witness shouts in the
court room.” Pause. A young man slowly and
methodically reads out 240 short sentences, as
a large fMRI device scans his brain activity.
The scanner data is converted into detailed
scan images with coloured 3D spots that
indicate the exact brain activity. Scientists
upload all the s can images and the
accompanying sentences but one set to a
computer, which is to analyse the relations
between the sentences and the activated parts
of the brain. The computer is artificial
intelligence, which can learn from data
without having been explicitly programmed to
do so – also known as machine learning. The
computer has two tasks: it is to predict the
brain activity of the left out scan No. 240 only
based on the sentence, and it is to decode the
missing sentence only based on the detailed
scan image of the brain activity.
Based on four days of scans from seven
different test subjects, scientists have gone
through the test 240 times, leaving out a new
sentence every time. And the results of their
efforts are ground-breaking. With a success rate
of 87 %, the AR has decoded complex thoughts
in a human brain for the very first time.
Hammer paved the way
The scientists behind the 2017 breakthrough
are Marcel Adam Just, Jing Wang, and
Vladimir L. Cherkassky from the Carnegie
Mellon University in the US. The team has
carried out mind reading experiments before.
The three scientists have shown that when we
think of objects, we already know – such as a
hammer – the brain does not only treat
hammer as a word. The word also causes
activity in areas at the centre of the brain’s
frontal lobe, which are related to visual
representations of motor functions, etc. When
we think about the word hammer, we hence
also associate specific actions or concepts with
the object, such as how we hold it or use a
hammer to build things.
The building blocks that the brain uses to
think about individual words can be identified
in specific regions of the brain. And that was
the discovery that made the scientists develop
the new mind reading AR. If the brain links
specific words with specific brain areas, it will
theoretically be possible to decode all thoughts,
no matter how complex the sentences, only
based on the activity patterns that the
thoughts cause.
Thoughts are invisible waves
The new scientific result is a milestone in more
than 100 years of efforts to develop a
technology that can disclose people’s
innermost thoughts. The first test was made in
the late 1800s by US scientist Julius Emmner.
Mind reading takes over
from the classic polygraph
scienceillustrated.com.au
TEK IMAGE/SPL
Sky-high blood pressure, a thumping pulse rate, and rapid
breathing are physical reactions which have been used to
disclose lies, since the classic polygraph was invented in 1921.
But now, scientists can use brain activity scans to identify the lie,
where it is produced: in the brain. The brain consumes extra
energy in specific areas, when we tell a lie, such as in the frontal
lobe, the front part of the brain, which is involved in problem
solving and planning. Generally, the brain areas that handle
language, analysis, and logic are working overtime, when we
tell lies. According to experiments by the Perelman School of
The polygraph has been criticised, because the challenging
Medicine in the US, brain scans are 24 % better at spotting lies
situation of the test can easily cause an erroneous, positive result.
than the good old polygraph.
|
63
HUMANS
THE BRAIN
He was inspired by a new invention, the
phonograph, that demonstrated what sound
waves looked like on paper. According to
Emmner, thoughts – just like sound – emit
invisible waves, and he tried to build a machine
that c ould measure them. Emmner’s
experiment never left his lab, but it triggered a
wave of similar experiments.
In 1924, German scientist Hans Berger
was responsible for the very first EEG
re a d i n g . E E G i s s h o r t fo r e l e c t ro
encephalography and measures the brain’s
electric activity via electrodes located in
central areas of the cerebral cortex. 50 years
later, scientist Lawrence Pinneo tried to use
the method for mind reading. In 1973, he
designed a mind reading helmet with lots of
electrodes, which transmitted the brain’s
electric activity to a computer, indicating a
small dot in the display. If the computer
recognized the words “up”, “down”, "left", and
“right” in the test subject’s thoughts, the dot
moved accordingly across the display.
Pinneo’s helmet involved major limitations,
but it paved the way for a fusion of brain and
computer – known as a brain-computer
interface. In 2010, scientists from the
University of Utah translated brain signals into
words by means of electrodes on the speech
centre of a patient with locked-in syndrome, by
which the aware patient is totally paralysed.
During the experiment, scientists read out 10
words such as “yes” and “no” to the patient, as
they measured the brain activity. A computer
linked the brain activity pattern measurements
with the words, matching activity and words
with a success rate of up to 90 %.
Brain to control computer
Carnegie Mellon University’s mind reading
experiments prove that an envisaged word is
not just made up of the activity that individual
words such as yes and no cause in the brain’s
language centres. Thoughts consist of more
complex mental concepts, which are linked
with the words.
Based on the experiment, the scientists
identified 42 building blocks involving all 240
sentences. The 42 Neurally Plausible Semantic
Features – NPSFs – are basically divided into
four main groups: people, places, emotions, and
actions. The sentence “the witness shouted
during the trial” activates 9 NPSFs, “the
witness” accounting for four of the mental
building blocks: social norms, knowledge,
person, and communication.
The experiment also showed that the
sentences triggered the same brain activity in
all test subjects, i.e. the mind reading model is
universal – and that is useful for technology
companies such as Intel. In 2009, the company
began to develop computer chips that rest on
the same principle as the scientists’ mind
reading experiment and can control computers
and smartphones by the power of thought. The
computer chip is to be implanted in the user’s
brain to function as a sensor, registering brain
activity and converting the thoughts into
control signals. If the user thinks “delete
document” or “call mother”, the computer or
smart-phone carries out the task. Other
companies aim to make the technology control
small private aircraft and cars.
In spite of the major breakthrough, the
Carnegie Mellon University researchers are
not yet satisfied with the mind reading
technology, so they are still developing the AR.
The next step is to learn how to decode brain
activity in connection with abstract concepts
such as skateboarding or geology, but chief
researcher Marcel Adam Just hopes that in the
long term, the technology can result in a
complete mapping out of what all knowledge
looks like in the brain.
Marcel Just (left) heads a team of
brain researchers, who have
developed a new, accurate mind
reading technology.
MARCEL JUST/CARNEGIE MELLON UNIVERSITY
A coil aims
radio waves at
the person.
The magnetic field
is 50,000 times
more powerful
than Earth's.
Magnets
affect
the body.
EXECUTION
Oxygen reveals activity
The test subjects read out
sentences, as a fMRI scanner
measures the blood flow of the brain.
Active brain regions consume more oxygen
and energy as they receive more blood.
1
ANALYSIS
The brain is divided into
tiny building blocks
The data is analysed by a computer,
which produces scan images by dividing
the brain into tiny voxels – a combination
of pixels and volume. One voxel includes
about 100,000 neurons.
100,000
NEURONS
SHUTTERSTOCK
Self-Taught AR Reads Your Mind
With brain scans as the only knowledge, artificial intelligence has learned how to read
the minds of test subjects – and predict the brain activity caused by thoughts.
computer was fed 239 scan images and accompanying
sentences, and via machine learning, the artificial intelligence
learned how to link brain activity and thoughts. Finally, the AR
was able to guess the wording/predict the brain activity of the
left out sentence:
With a success rate of 87 %, newly developed artificial
intelligence can read the minds of test subjects. The scientists
behind the experiment used 240 sentences, which were made
up of 242 different words. The test subjects read out the
sentences, as their brain activity was scanned. The
“The witness shouted during the trial.”
AFTER
BEFORE
Magnetic field
AFTER
BEFORE
AFTER
Energy
Radio waves
N
S
BEFORE
N
N
N
S
N
S
S
S
S
CLAUS LUNAU
S
The body is magnetic
Nuclei absorb energy
The body's hydrogen nuclei rotate
2 themselves, hence functioning as
tiny magnets. Normally, they are
pointing in random directions, but the
scanner's magnetic field aligns them.
Under the effect of the magnetic
3 field, the nuclei are bombarded
with radio waves. The nuclei absorb
the waves' energy, entering into an
energy state, in which they vibrate.
RESULT
N
N
S
N
S
N
N
S
Signal reveals activity
When the radio impulse is
4 deactivated, the nuclei emit
energy. Oxygen rich and oxygen poor
blood react to this, allowing scientists
to measure the activity.
Predicted brain activity
Computer predicts the
missing sentence
The scientists feed the computer all scans but
one along with the sentences. The data teaches
the artificial intelligence how to link the words
of the sentences with the brain's activity
patterns, and the computer discovers that the
sentences are made up of four general
concepts: people, actions, places, and
emotions. The computer can predict the missing
sentence with a success rate of 87 %.
Actual brain activity
MARCEL JUST/CARNEGIE MELLON UNIVERSITY
FACTORS
PEOPLE
ACTIONS
PLACES
EMOTIONS
POSITIVE REACTION
NEGATIVE REACTION
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65
TECHNOLOGY
SUBMARINES
A NEW
DEVELOPED
CHINA HAS
SPOT
N
NT, THAT CA
INSTRUME
D
L FROM
GNETIC FIE
A WEAK MA
P BELOW
E HULL DEE
A SUBMARIN
SURFACE.
THE OCEAN
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By Esben Schouboe
China has developed a
quantum magnetometer, from
which even stealth subs
cannot hide.
Super Magnets
Will Spot Silent
Sea Warriors
Modern spy submarines are hard to spot with sonar,
so a network of sensitive magnets are to make it
impossible to sneak into foreign waters undetected.
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67
TECHNOLOGY
SUBMARINES
P
ing ... Ping .. Ping. The time
lapse between the highfrequency sonar signals
and the resulting echoes
becomes ever briefer. The
submarine is approaching a rock
formation, trying to avoid an enemy
torpedo. The captain listens intently to
the pauses between ping and echo,
which indicate the distance between
the submarine and the rocks. Finally,
the sounds are almost heard as one,
and at the very last moment, he gives
his order, so the submarine steers
clear. The torpedo continues into the
rocks and explodes.
The scene, which is from the Hunt
for Red October film from 1990
illustrates how much sound means in
submarine warfare. In the abyss, there
is zero visibility, and radio waves from
radar, are slowed down in water. Sound
waves, on the other hand, travel faster
under the water than through air, and
so, sonar with the familiar ping sounds
has been the primary method for
navigating under the water, tracking
down enemy vessels in the abyss. But as
the sense of hearing is the only way to
size up the situation below the surface,
a silent submarine is impossible to spot.
Today, military stealth submarines have
become so silent that they are almost
impossible to detect with sonar, and so,
Four silent tricks
keep subs hidden
MIKKEL JUUL JENSEN
With sound-deadening
lining and electromagnetic
engines, submarines are
now so silent that they are
difficult to spot using sonar.
LESS FRICTION
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they play an ever more important role
in nations’ efforts to keep and gain
control of the waters of the world.
One of the most controversial
waters is the South China Sea, where
several nations claim the right of the
same territories. The tense situation has
made the Chinese navy initiate the
Great Underwater Wall, which will
consist of sonar on the ocean floor,
patrolling submarine drones, and buoys
with s ensitive underwater
microphones, that will make it difficult
for vessels to pass undetected into
Chinese waters.
China has even developed a brand
new sup er weap on, which no
submarine can hide from: a quantum
magnetometer. Instead of listening for
weak noise signals from submarine
mechanics, it can detect the magnetic
field of the metal hull at depths of
several hundred metres.
Wi-Fi on the Ocean Floor
Sonar remains the most reliable method
for detecting stealth submarines, and it
comes in two versions: active and
passive. Active sonar is the method that
is often seen in films such as the Hunt
for Red October. If the characteristic
pings strike large objects, the sound
waves will be reflected back to their
starting points. Based on the number of
sound waves reflected and the speed, it
is possible to figure out which objects
have been hit. However, active sonar is
not so efficient, when it comes to
searching for uninvited guests. The
technology is directional, so it is vital to
know in which direction to send the
ping sound. Moreover, the enemy
submarine’s own sonar systems will
immediately detect the ping, reducing
the tactical advantage of monitoring the
enemy. So, China will particularly use
passive sonar.
Passive sonar does not involve any
pings. Instead, the sensor listens for
deviating sounds in the ocean. The
weakness is that background noise from
marine animals, waves, and vibrations
on the ocean floor can easily interrupt,
increasing the risk of false positives, by
which the system believes it has
detected an enemy submarine, which
turns out to be an innocent marine
animal. Passive sonar is also directional,
and for the same reason, the Chinese
navy is going to use hundreds of meters,
which will each cover a small area in all
directions. They are to sit on the ocean
floor, be fastened to buoys 400-500 m
under the surface, and be mounted on
ships and Chinese submarines, so all
ocean depths are covered. With a finemeshed sonar network, which will
continuously collect data, the
HULL FLOWS SILENTLY
THROUGH THE WATER
HOLLOW MATERIAL
SILENCES ECHO
Friction between the sub hull
and the water causes noise.
Subs are designed to be as
hydrodynamic as possible. The water
resistance of new models is measured
by hauling hulls through large basins.
The hull can be lined with
tiles made of a type of
rubber that only reflects 3 % of
the sound. Small cavities in the
material capture sound waves,
as they are cast back and forth,
until they have shed almost all
their energy.
NOISE-ABSORBING TILES
PROPELLER NOISE IS
ENCLOSED
NEW ENGINE TYPE IS
ALMOST SILENT
The pressure falls right
behind and around the
propeller, producing air bubbles,
which make noise, as they burst.
By placing a cylinder around the
propeller, a higher pressure is
maintained, so fewer bubbles are
produced in the wake of the sub.
Engineers have developed
the pump jet engine, in
which the propeller sits in an
electromagnetic ring that forces
the propeller to move. Without
a mechanical shaft, the noise is
dramatically reduced.
PROPELLER
ENGINE SCREEN
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69
SUBMARINES
ROYAL NAVY/AFP/RITZAU SCANPIX
TECHNOLOGY
A stealth sub is often lined with noise-absorbing tiles, which deaden noise from the inside, reducing the
echo, when a ping sound from a sonar hits the hull from the outside.
calculations of what is noise in any given
area will be much more accurate. Passive sonar
can listen for weaker, deviating sounds without
risking a false positive, making it harder for
enemy submarines to pass undetected.
In order for the network to be efficient, all
permanent and mobile sonar units must be
able to exchange data quickly and flexibly via
a wireless network. Wireless communication is
challenging under the water, as it usually uses
radio waves, i.e. electromagnetic radiation. The
salty ocean water conducts electricity, which
will slow down all radio waves across even
short distances. But with sound, it is the other
way around. Sound waves are mechanical
waves, which push through a material in the
shape of pressure variations. As the molecules
of ocean water are located closer together than
those of the air, the sound waves can push
ahead more efficiently, and so, they travel four
times faster in salt water than in air.
Silent submarines are detected
But even a sensitive and sophisticated sonar
network is rather inefficient, when it comes to
the most recent generations of military
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submarines, which have been developed to
cause the least possible noise, when they enter
into stealth mode.
Approaching enemy territory, they will
switch to electric propulsion, which is much
more silent than mechanics. Many military
submarines are powered by small nuclear
reactors and will often deactivate the cooling
of their reactors temporarily and slow down –
SQUID magnetometers
are more vulnerable to
false positives
both reduces the noise of the vessel
considerably. Modern submarines are also
typically lined with anechoic tiles made of
rubber or plastic with thousands of microscopic
cavities, which ensure that sound waves are
absorbed and cast about the cavities, until they
have shed all their energy. In this way, sound
from inside the submarine has more difficulties
escaping, and a ping from an active sonar does
not cause a marked echo.
No matter how silent a submarine is, it
will not be able to travel through the water
without leav ing magnetic ev idenc e.
Submarines are made of ferrugineous metal,
which contains unpaired electrons. This
makes the material magnetic, and so, the
submarine’s metal hull will bend the field
lines of Earth’s magnetic field slightly towards
itself. Salt water is also full of electrically
charged sodium and chlorine ions, and when
the submarine pushes through the water, they
are set in motion, producing small magnetic
fields in the wake of the submarine.
For decades, submarine hunters have used
magnetometers to detect submarines – often
mounted on the tails of planes, which can
quickly search large areas. But as the
electromagnetic waves emitted by the
submarine are slowed down in salt water, a
submarine needs not dive very low, before an
ordinary magnetometer cannot detect it. So,
China has developed one of the world’s first
S QU I D ( s u p e r c o n d u c t i n g q u a n t u m
interference device) magnetometers, which
take advantage of the qualities of
superconductive materials, which are
characterized by the fact that they can conduct
an electric current without any resistance.
SQUID magnetometers are so sensitive that
microscopic variations in Earth’s magnetic field
will make a current pass trough them,
destroying their superconductivity. The result
is electric reistance, which can be read very
accurately. According to experts, SQUID
magnetometers can detect a fridge magnet
interrupting Earth’s magnetic field by moving
slightly from a distance of 6 km.
However, the extreme sensitivity makes
SQUID magnetometers more vulnerable to
erroneous measurements and false positives.
China aims to solve the problem by installing
many quantum magnetometers on planes, so
background noise measurements become
more accurate – like with the network of
passive sonars. If China succeeds in extending
the “SQUID net”, it will be the first nation to
take advantage of the sensitive technology to
detect submarines.
In the Hunt for Red October, the
submarine’s ultimate stealth technology is a
worm drive, which uses magnetism for silent
propulsion. The fictive technology has never
b e en realize d, but even if it were,
magnetometers would still be efficient. So,
engineers must be very creative, if the
submarines of the future are to be able to sneak
past the Great Underwater Wall.
Sensors Make the Ocean
a Bad Hiding Place
Small submarine drones, permanent sensors on the
ocean floor, and planes equipped with quantum
magnetometers are to make sure that no submarines
can move undetected about the South China Sea.
Super magnet
reveals even
silent subs
ELECTRONS GET NO
RESISTANCE
A quantum magnet1 ometer consists of a
ring made of a superconductive material – i.e. it
has no electrical resistance.
POWER GENERATION
In a superconductive
2 material, electrons
will pair up instead of being
repelled. They move about,
generating electricity
without any resistance.
MIKKEL JUUL JENSEN
DRONES SENT ON
PATROL
If a submarine is visible
to sonar, submarine drones
can be used to find the
submarine with optical
sensors. They can also
patrol the waters for
months.
SONAR SEARCHES
THE OCEAN FLOOR
A fine-meshed network
of passive sonar sensors
will be placed on the
ocean floor. They can emit
sound, using the echo to
spot, if the sound has
struck objects.
BUOYS LISTEN
TO THE OCEAN
Hydrophones –
micro-phones for
underwater use – are
anchored at different
depths. The mikes’
transducer converts sound
waves into electric signals.
FLUCTUATIONS
CAUSE RESISTANCE
Fluctuations of Earth’s
3 magnetic field accelerate the electrons, destroying
the superconductivity. So,
electric resistance arises.
VOLTAGE MEASURED
According to Ohm’s
4 law, electric resistance
also produces voltage, which
can be measured very
accurately. The voltage reveals if
a submarine lurks below.
MEGAPIXEL
THE SUN
6,000 °C
50,000 °C
The Sun is warmest far
away from its surface
GSFC/NASA
The Sun’s surface, the photosphere, is a toasty
6,000°C, but its outer atmosphere, the corona,
can get 10+ million °C, particularly when solar
eruptions occur. The Solar Dynamics Observatory
(SDO) space telescope studies the Sun in several
wavelengths, which capture the radiation from
specific layers of its atmosphere. These are SDO
recordings from the Sun’s surface to the upper layer of
its atmosphere. Scientists do not yet fully understand
why the temperature rises in the Sun’s atmosphere,
but magnetic forces probably play a role.
Photo // Solar Dynamics Observatory
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600,000 °C
1,000,000 °C
2,000,000 °C
2,500,000 °C
6,000,000 °C
10,000,000 °C
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73
N AT U R E
CIRCUMPOLAR OCEAN
Instant Expert: Polar Oceans
Ice and Salt Keep
Arctic Ocean Alive
T
he circumpolar oceans are primarily
characterised by temperatures of
around zero degrees, so they involve
large quantities of sea ice . Some of the
sea ice melts during the summer, and
when the ocean surface freezes up again
in the autumn, quite a lot of salt is shed
from the new ice. The water right below
this ice is consequently very salty and so
also very heavy, sinking to the bottom.
The heaviest water that exists anywhere
in the oceans is the result of this process,
and it is part of the global abyssal
circulation. Unlike the more well-known
surface currents such as the Gulf Stream,
the abyssal circulation is particularly
"fuelled" by specific weight differences
between volumes of water.
Because of the huge ice masses, the
circumpolar oceans are still the most
unknown ocean regions, as genuine
exploration was not initiated until after
World War II. Today, there is much focus
on these ocean regions, because they
are expected to include major natural
resources such as oil and minerals
beneath the ocean floor. Today, oil and
raw material producers are engaged in
tapping into the resources.
Around the ice front, the ocean is
productive. The formation of ice
produces heavy water, and so, a
circulation results which carries
nutritious water to the sur-face. In
combination with the large quantity of
sunlight in the summer, the result is a
major primary production in the shape
of plant plankton. The tiny organisms
form the basis of a food chain for fish,
birds, and mammals that is adapted to
the special polar conditions.
The circumpolar oceans are among
the regions where climate change is
most obvious. Changes of sea ice
extension and thickness are clear. The
sea ice plays a central role ice albedo
feedback. Albedo is a measure of a
surface’s ability to reflect visible light.
When the extension of the ice is reduced
due to heating, the reflection ability is
reduced, resulting in absorption of more
sunlight and so in more heating.
MARSCHALL H/ARCO
The circumpolar oceans – the Arctic Ocean and the Southern
Ocean – are still not well understood. Yet it's here, in the interaction
of ice, water and sunlight, where our future could be determined.
The Polarstern is one of the customised and icestrengthened research vessels which can handle the
difficult conditions in Antarctica.
Difficult conditions
for scientists
Rough and hostile conditions involving cold,
high winds, and huge quantities of sea ice are
the reason why the circumpolar oceans were not
seriously explored until the 20th century. During
the Cold War, the Arctic Ocean was strategically
important in the conflict between the two
superpowers. Both American and Soviet
submarines operated under the polar ice,
sometimes making observations of sea ice
thickness, etc. The measurements from the
1950s onwards are very important for the
assessment of ice cover changes. The ice masses
mean that it is necessary to use customized
vessels, making the exploration very expensive
and limited to summers.
A R C T I C C I R C U L AT I O N
In the Arctic, there is a constant flow of cold water and sea ice from
Siberia across the North Pole to Greenland. East of Greenland, the
cold, fresh water is located beneath the warm, salty water from the
Atlantic. The water layer in between the two water volumes is
known as the cold halocline, i.e. the prerequisite for the permanent
existence of 3-m-thick ice on the Arctic Ocean.
SIBERIA
Warm
surface current
Warm downward
current
NORTH
AMERICA
NORTH POLE
GREENLAND
ATLANTIC
OCEAN
Cold
surface current
The Arctic Ocean
Covering 14,056,000 km2,
the Arctic Ocean is the smallest
ocean in the world, and almost
totally surrounded by the
landmasses of Siberia and
Canada, but linked with the
Pacific Ocean via the Bering
Strait and the Atlantic via the
Fram Strait and the Bering Sea.
This causes a characteristic
layering of the water.
Precipitation falling on Siberia
and Canada is carried by
Siberian and Canadian rivers
into the Arctic Ocean. This
supply of fresh water and fresh
water from melting ice in the
summer result in a layer of
relatively fresh water with
temperatures below 0 degrees
in the upper 100-200 m. Below
this water and separated by a
stable layer – the cold halocline
– there is a salty water volume,
which is heavier, but warmer,
with temperatures of 0-3
degrees. Further below, at
depths of 1+ km, you will find
the most salty – and
consequently heaviest – water.
SHUTTERSTOCK
EASTERN
ANTARCTICA
NASA/SPL
BRITISH ANTARCTIC SURVEY/SPL & MIKKEL JUUL JENSEN
SOUTH POLE
WESTERN
ANTARCTICA
In the Southern Ocean
around Antarctica, icebergs
can occur all year. They are
the results of calving from
the major ice shelves.
Near the coast, huge ice volumes are produced in the winter.
When the ocean water freezes, salt is shed, making the water under the ice salty and heavy.
A 3,000 km2 iceberg drifted along the coast of Eastern
Antarctica, before shattering in 2005.
The Southern Ocean
Icebergs
The Southern Ocean surrounds
Antarctica, linking the Atlantic, the
Pacific, and the Indian Oceans. So, it is
central to the global ocean circulation.
The Southern Ocean, which covers
an area of 20,327,000 km2, includes
typical depths of 4-5,000 m. The
Southern Ocean is dominated by the
Antarctic Circumpolar Current, which is
a cold, easterly current flowing 21,000
km around the world. The ocean
current is the most powerful in the
world – carrying a water volume of 130
million m3 per second, i.e. 130 times
the water flow of all rivers of the
world, and it is about four times as
powerful as the Gulf Stream. The
circumpolar current is fuelled by the
powerful zone of prevailing westerlies,
which also encircles the world. It is a
belt of stormy low pressures like the
one that we know from the North
Atlantic – only much more violent,
providing the region with names such
as the “Roaring Forties”, the “Furious
Fifties”, and the “Shrieking Sixties”.
Icebergs occur all year in the Southern Ocean
off Antarctica, including table- shaped icebergs,
made by calving from the large ice shelves, which
flow from the continent onto the ocean. They can
be huge – the B-15 iceberg by the Ross Ice Shelf
near Eastern Antarctica was some 11,000 km2. In
2000, parts of B-15 broke loose, drifting off for
several years. Particularly the B-15A, which NASA
scientists observed for years via satellite images,
was famous. En route, the iceberg cut off
penguins’ access to food in open sea several times,
so for two years, they were forced to migrate 180
km for food. In 2005, the iceberg disintegrated.
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N AT U R E
RAINBOWS
Instant Expert: Rainbows
More Than Just
a Trick of the Light
Rainbow colours
Even children know a rainbow is created by the interaction between
sunlight and raindrops. Today, we know a lot about the phenomenon, but
previously, it was the subject of myths, tales, and superstition, and
scholars have obsessed over rainbows for thousands of years.
I
n Nordic mythology, Bifröst is a burning
rainbow bridge that reaches between
Midgard (Earth) and Asgard (the realm of the
gods). The bridge is guarded by the god
Heimdall. Indigenous Australian cultures see
the rainbow as a creative force, and the
Abrahamic religion, a covenant.
With the advent of the Greek
philosophers, people started to prefer
scientific methods over the world of myths.
Aristotle (384-322 BC) imagined that the
rainbow was an incomplete reflection of the
Sun in an irregular “mirror” on the surface
of a cloud – made up of myriads of droplets
and located in a hemisphere known as the
“meteorological hemisphere”. According to
Aristotle, the Sun was also located in this
hemisphere. The light was reflected by the
hemisphere to produce the rainbow. This
explanation comes quite close to the correct
one, only people did not understand the
raindrops' function, and they thought that
we get visual impressions via light beams
radiating from the eye – hence the
expression “cast a glance at something.”
Aristotle’s explanation was not questioned
until the early 1300s, when Dominican scholar
Theodoric (approximately 1250-1310) realized
the relation between a rainbow and the shape
of raindrops by experimenting with ballshaped bottles filled with water. He
discovered that a rainbow was the result of
light refracted and reflected in the interior of
raindrops, hitting the eye at a specific angle.
However, his discovery was forgotten,
and not until René Descartes (1596-1650) of
France, who undoubtedly knew Theodoric’s
work, made the same experiments did we
get an explanation of the rainbow in 1637.
The explanation was so good that it largely
holds water today. It was the culmination of
a thousand years of trying to understand and
explain the phenomenon. Nevertheless,
some nature philosophers still preferred
Aristotle's model as late as in the second
half of the 17th century.
Red, orange, yellow, green, blue, indigo
blue, and purple are the colours of the
rainbow, and they always appear in this
sequence, except from double rainbows, in
which the sequence is inverted.
In 1669, physicist Isaac Newton (16421727) explained how white sunlight could
produce colours. He directed light through a
glass prism and watched, as it was refracted
into a colour spectrum. White light contains
all colours, and you can split it up, like when
it is refracted in a prism or produces a
rainbow. The sequence is due to light being
refracted differently – purple light is
refracted the most, red the least.
Double rainbow
Sometimes, you might observe a
weaker rainbow on the outside of the
primary arc. Known as a secondary
rainbow, this arc is the result of light
having been subjected to extra reflection
inside the water drops before reaching our
eyes. The secondary rainbow can be
observed about 9 degrees above the
primary arc (i.e. 51 degrees from the
position of the sun). Its colour sequence is
inverted, and its colours are not as clear as
those of the primary rainbow. In rare cases,
there will also be a third rainbow, in which
the colours have once again been inverted.
R A I N B O W F O R M AT I O N
A rainbow is produced
as a result of refraction,
reflection, and so colour
dispersion of sunrays in
millions of water drops.
The drops are circular
rather than dropshaped, as you might
have thought. The
rainbow appears as a
shining circle in the sky,
when we observe falling
rain with the Sun behind
us. The observer’s line
of sight to a random
point on the rainbow
produces a 42 degree
angle with the direction
of the sunlight.
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The observer only
sees the light
reflected at a
specific angle from
the raindrops.
You see the rainbow, if you
stand with the Sun behind
you, looking at a dense quantity
of drops such as a shower.
1
As the colours are refracted differently, drops
of different altitudes produce
light of different colours.
2
The refraction takes place
3 inside a raindrop. The light
is refracted at an angle of 42 degrees, i.e. the same as the arc.
FOUR TYPES OF RAINBOWS
Dark sky on the outside
PIERRE LESAGE
When the sunlight hits the raindrops, it is refracted
and reflected to produce a rainbow. The light is sent back
at an angle of 42 degrees or less, never more. So, the
area on the inside of the rainbow will seem lighter than
on the outside.
In the case of a double rainbow, you can sometimes
observe a similar dark area between the two arcs. The
sunlight that is reflected twice to make up the exterior
rainbow will be sent back at an angle of 51 degrees or
more, but never less. The area on the outside of the
exterior rainbow will hence be lighter than on the
inside. All in all, the result is consequently a dark band
between the two rainbows – also known as Alexander’s
dark band or Alexander of Aphrodisias, who described
the phenomenon around 200 AD.
We are used to seeing rainbows on rainy
days, but the phenomenon occurs anywhere in the presence of water drops and
light. Depending on the size of the drops,
the light source, and the observer’s
position, the rainbow might seem different,
although the principle is the same.
MOONBOW: Rainbows are most frequently
associated with sunlight, but bright moonlight
can also cause rainbows. However, the colours
are weak or nonexistent, as our colour vision is
poor at night. The moonbow will hence very
often seem whitish.
SUE FLOOD/GETTY
FOG BOW: Fog consists of water drops that are
so small that individual colours will be dispersed
and mixed to such an extent that a wide, whitish
rainbow results. So, this rainbow will not always
be associated with ordinary rainbows.
SHUTTERSTOCK
SUPERNUMERARY BOWS: On the inside of the
primary rainbow, you can very rarely observe a
series of extra arcs that do not form in the same
way as the rainbow itself. These arcs are due to
the fact that the light beams in a raindrop can
intensify or weaken each other (interference),
and to make them visible, it is necessary that
the raindrops be very similar in size.
A rainbow at sunset is high
in the sky, because the Sun
is close to the horizon.
SHUTTERSTOCK
SHUTTERSTOCK
RAINBOWS IN WATERFALLS: A rainbow is
often produced in the drops from the turbulent
water volumes of a waterfall. There, you might
see the entire circular rainbow, if you are above
the waterfall, looking down at the water drops.
scienceillustrated.com.au
|
77
HOME CHEMISTRY LAB
HOME CHEMISTRY LAB
YOU WILL NEED:
A green laser pen
of at least 5
milliwatts
A syringe
Build Your Own
Laser Microscope
GUIDE:
IT WILL TAKE 5 MINUTES TO
COMPLETE THE EXPERIMENT.
Select the liquid that you
would like to
study. You could use
your own saliva or
water from a puddle.
Place the sample in
one of the glasses.
1
Two glasses of the
same size – not
made of plastic
A sample (beer,
saliva, or water
from a puddle)
A chopping board
Suck a little
liquid up into
the syringe.
Place the two glasses
on a chopping board,
and make the syringe
rest on both of them.
Make sure that there
are a few centimetres
between them.
2
Lasers could cause permanent eye
injury, so do not point the laser
beam at your eyes nor at other
people’s faces.
Carefully
press the
syringe to
produce a drop. The
drop should reach as
far as possible without
actually falling from
the syringe.
3
Point the
laser at the
syringe and
move it slowly
towards the drop.
When the light hits
the drop, the sample
is enlarged on the
wall behind it. Use
the difference of
height between the
board and table to
stabilise the laser pen.
4
78
|
SCIENCE ILLUSTRATED
By Babak Arvanaghi
The Round Drop Shape Takes
You Into an Invisible World
BODY CELLS
IBLE.
BECOME VIS
Almost all liquids are full of bacteria, cells, and impurities. By using the curved
surface of a drop, you can zoom in on organisms, which are normally hidden.
W
e can see the largest body cells such
as egg cells with the naked eye, but if
we use the round shape of a drop, we will be
able to see much smaller ones such as skin
cells of 30 micrometers or 0.03 mm. In the
experiment, otherwise invisible organisms
are enlarged, so that we can see them.
The laser light is unidirectional - all the
light particles are directed in the same
way, and the light appears as a focused
beam. When the focused light hits the
drop, the convex shape of the water
surface functions as a zoom lens, which
focuses the light even more. At the back of
Liquid turns everything
upside down
the drop, the light will once again hit a
convex surface, which focuses the light
once more, before it escapes on the other
side of the drop. There, the laser light
collects in a focal point close to the drop,
after which the light is spread and
inverted. The further away from the
experiment the wall is, the more the light
is spread, enlarging your zoom.
The image on the wall shows the
particles hit by the laser in the water drop.
The particles block out the light and are
seen as shadows. Apart from cells, you can
see bacteria and tiny creatures.
FOCAL POINT
Like a spherical zoom lens, the drop
focuses all the light. But when the
image is enlarged, it's flipped.
S A L I VA
LASER LIGHT
SAMPLE
COLA
ENLARGED
IMAGE
LASER LIGHT
CLAUS LUNAU
LASER PEN
MIRRORS FOCUS THE LIGHT
DROP FUNCTIONS AS LENS
LASER REVEALS CELLS
Two mirrors in the laser pen make sure
that all light particles flow parallel to each
other by sending them back and forth in
between them. A small hole in one mirror
lets the focused light escape as a laser beam.
The liquid sample’s drop shape functions
as a ball lens, accumulating the light and
spreading it again. The laser strikes a small
point in the sample, enlarging it onto the
wall. The drop inverts the image.
The combination of the laser’s focused
light and the drop’s lens effect results in major
enlargement. At a distance of 1.5 m between
sample and wall, the home-made laser
microscope enlarges by a factor of 1,000+.
scienceillustrated.com.au
|
79
Trivia
PUT YOUR KNOWLEDGE
TO THE TEST
1. On 29th April 1899, Belgian racecar
driver Camille Jenatzy set a new land
speed record, the first time a car went
faster than what speed?
2. When the 5G mobile data
network is rolled out, it should
potentially offer download
speeds how much faster than 4G?
3. For the torture and murder
of Elisabeth Bousquet, on 10th
September 1977, Tunisian
agricultural worker Hamida
Djandoubi became the last
person in the Western world to
be legally what?
4. Which common, often
weedy, flower has a name that
means ”lion’s tooth”?
5. In the Mercury program,
first a chimpanzee and
eventually the first
US astronauts, were
carried to orbit on
a rocket that was a
converted what?
6. Because of the
the specific genes
involved, teeth
probably evolved as a
modification of which
part of the body still
found on fish?
q. 8
7. Which type of sail has a name that
might mean ”to drive before a strong
wind”, ”spanker”, ”Sphinx’s Acre”
or ”spin maker”? (But no one really
knows.)
8. Marie Curie’s daughter Irène
Joliot-Curie also won a Nobel Prize for
chemistry, in 1935. Marie
q. 5
Curie famously died as a
result of radiation exposure. What did
Irène die from?
9. The ”Three Body Problem” is most
closely associated with which branch
of science?
10. This sentence is grammatically
correct: “The old man the boat.” Which
word is the verb?
Trivia Countdown (use fewer clues, get a higher score!)
5 POINTS
1. SPACE
Name this
machine
2. GASTRONOMY
Name this
ingredient
3. HISTORY
Name this
scientific
model
4 POINTS
3 POINTS
2 POINTS
1 POINT
NASA launched the
machine into space
from Cape
Canaveral Air Force
Station in Florida on
26 November 2011.
Its destination was
reached on 6 August
2012. Meant to last
one year, the mission
was prolonged
indefinitely.
Today, it is still
carrying out
research. In the
years to come, it
will be joined by
similar machines.
The machine, which
weighs 899 kg, is 2.9
m long, 2.7 m wide,
and 2.2 m high – the
size of a large car. It
has six wheels.
Technically classed
as a rover, this
machine was named
in a contest. The
name is another
word for nosiness.
The ingredient
comes from a plant
that is a member of
a family wellknown as a source
of poison.
Use of the leaves of
the plant in herbal
tea has killed at
least one person.
Yet the fruit is
universally popular.
The botanical
definition of the
ingredient is a fruit,
but most people
consider it a
vegetable
When this
ingredient is still
green, it is only ever
fried or pickled.
When ripe, it has a
wider range of uses.
The name of this
red fruit has an
Aztec origin, and it
contains the
insecticidal alkaloid
called ”tomatine”.
Particularly one
work, which is a
scientific classic, was
epoch-making for the
realization. It was
published in 1543.
The work was
written by an
astronomer, who
did, however, not
mention astronomy
in his book.
The title is “De revolutionibus orbium
coelestium”, or “On
the Revolutions of
the Heavenly
Spheres”.
Nicolaus
Copernicus of
Poland introduced
the theory, which is
also known as the
Copernican model.
According to the
new view of the
world, rather than
Earth, the Sun is the
centre of the
universe.
ANSWERS ON p82!
80
|
SCIENCE ILLUSTRATED
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BIODIVERSITY
ORNITHOLOGY
AN INDEPENDENT
YOUNG FELLOW
T
he distinctive bowers, decorated with
all your blue pegs that the local male
bowerbirds stole off your clothesline, are
of course the best-known feature of these
iconic Aussie birds.
But along with its unique and complex
courtship behaviours, the satin bowerbird
has a few other notable quirks.
Given their apparent intelligence,
ability to select objects and arrange them
with some sense of aesthetics, perhaps it’s
not surprising that even young bowerbird
chicks and be unexpectedly independent.
This chick, sitting in a wicker basket
provided by a WIRES volunteer, was
found hopping around in a carport.
Concerned it would be taken by a cat, the
chick was “saved”, WIRES called, and an
ersatz nest set up in a nearby tree.
Satisfied the mother was still feeding the
chick, the helpful humans went about
their business.
A couple of hours later, the chick
jumped out of the basket. A helpful
human who happened to be passing,
popped it back in. It jumped out again,
and could not be found. The poor humans
feared the worst, but that’s nature.
Over the course of the next month
though, it became apparent this little
chick was absolutely fine. It was spotted
in various locations around the garden,
including several metres up a pine tree.
While it quickly grew to more or less the
same size as its mother, that distinctive
“crazy hairdo” remained for some weeks.
Before they can fly, bowerbirds are fed
mainly large insects, such as cicadas, by
their mothers. But mature bowerbirds
mostly prefer fruit. Unfortunately, despite
being a native bird, their lack of fussiness
when it comes to food means they do play
a role in spreading weeds like privet.
Is this chick a male or female? It’s not
really possible to tell just from looking.
Male satin bowerbirds don’t develop their
signature dark feathers until they are
about seven years old.
Indeed, along with those elaborate
bowers, the satin bowerbird’s other claim
to fame is that it is the longest-lived
“passerine” bird. While most are estimated
to live eight to nine years, one wild bird
that had been banded with an identifying
tag, lived 26 years.
SPECIES:
Satin Bowerbird
SCIENTIFIC NAME:
Ptilonorhynchus violaceus
DISTRIBUTION: Eastern
Australian from southern
Queensland down to Victoria.
ICUN CONSERVATION STATUS:
Least Concern
TRIVIA ANSWERS 1. 100 km/h 2. 10 x 3. Beheaded (via guillotine) 4. Dandelion 5. ICBM 6. Scales 7. Spinnaker 8. Also radiation exposure 9. Physics 10. Man Trivia Countdown – Name this spacecraft: Curiosity
Name this ingredient: Tomato Name this scientific model: Heliocentrism or heliocentric theory
82
|
SCIENCE ILLUSTRATED
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