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PowerPoint-Präsentation - Solar System Exploration

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Low Ballistic Coefficient
Re-Entry Probe
K. Ramus (kevinramus@vandals.uidaho.edu)1, B. Holmes1, A. Camery1, D. Eld1, R. Riggs1, R. Gunn1,
D.H. Atkinson1, M. Murbach2, and the Univ. Idaho RISE Student Launch Team1
1University
of Idaho, 2 NASA Ames Research Center
Abstract: There are regions of the Earth’s atmosphere that are especially difficult to study. One of these is between 30km and 100km. NASA Ames has
been developing scientific payloads to fly on sounding rockets to reach this region. Since 2007, the University of Idaho Near Space Engineering
program has worked with the SOAREX program at NASA Ames to develop low-ballistic coefficient descent systems for slow descent through the 30100 km region. The current project comprises a small 2.2 kg probe beneath a parachute with an area of about 1.35 square meters. This system allows
the probe to descend very slowly and allows for large amounts of data to be gathered in the upper atmosphere. The probe, equipped with a PCB board
that includes 3 temperature sensors, 2 pressure sensors, an accelerometer, a Geiger counter, a GPS unit and a beacon for tracking, and an SD card for
data acquisition and storage, will be deployed at about 85-90 km. The data is recorded as a function of altitude, and the pressure and temperature
sensors are used to determine the elevation and descent speed. Since a GPS is being used for tracking, the accuracy of the calculated descent trajectory
profile can be determined. Measurements of atmospheric pressure and temperatures will characterize the atmospheric structure along the descent
path. The probe will be sent to Ames for vibration, shock, and thermal/vacuum testing prior to launch from NASA Wallops Flight Facility in Virginia.
Background: In 2008 the SOAREX program at NASA Ames Research Center provided funding for a University of Idaho senior engineering project to design, build, and fly a low ballistic coefficient
descent probe. The probe is to be launched aboard a sounding rocket from NASA Wallops Flight Facility. The Idaho Vandal Atmospheric Science Team (VAST), the University of Idaho chapter of the
Idaho Space Grant Consortium (ISGC) RISE student launch program, continued work on the capsule following the completion of the senior design program. VAST is a student led class that consists of
around 20 graduates and undergraduates from many disciplines, including electrical, mechanical, and computer engineering and physics. The main purpose of this project is to improve the physical
design of the probe, and to achieve a ballistic coefficient of 1. The probe carries temperature and pressure sensors, accelerometers, and a radiation detector. Data is stored on board, so all data is recorded
for later retrieval and analysis after the probe is recovered. The probe payload uses a redundant tracking system that includes a tracking beacon and a GPS receiver/transmitter. The tracking beacon will
assist with locating the probe after reaching the surface, while the GPS receiver/transmitter will allow the probe flight path to be tracked.
Flight Plan
Instrumentation
Capsule Design
The structural design is based on a preliminary design as part of a
engineering senior design project, but many improvements have been
made. In particular, the body length has been extended, an improved seal
and end cap system were designed to better seal the probe and to make
the interior more accessible. The structure is sufficiently buoyant so that
the antennas will remain above the water line. To protect the capsule
from the mild descent heating, Teflon was chosen for a simple, lightweight and low cost TPS system.
The University of Idaho capsule
will be launched from Wallops
Flight Facility on an Improved
Orion Sounding Rocket. Launch
is tentatively planned for late
2010 or early 2011.
The data logger was designed by the VAST team. An existing set of
cubesat boards has been flown successfully on many previous high
altitude balloon launches. A new data logger was needed that would fit
into the 4” diameter probe body. This new design copied the old boards
as much as possible for reliabilities sake. The board has the following
important features:
• Arm – 7 Microprocessor
• SD Card for storing data from the following sensors:
The Body
The Nose Cone
- Pressure
• 13” Long Aluminum Body
• 4” diameter
• Machined Aluminum End Caps
• O-Ring seals
• 3” Long
• Machined Teflon
• Houses large pressure sensors
- Temperature
- 3 Axis Accelerometer
- Radiation
• Gravity-Switch activated power circuit (Allows power flow when the
launch is detected)
• 10 Hz Sampling Rate
• GPS Receiver
Power
Tracking
Accurate and reliable tracking is an essential part of the probe launch system, since the probe must be recovered to analyze the gathered
data. For redundancy, the probe carries two independent tracking systems. The first is the Microtrak 8000FA. This is a commercial
product that has a GPS receiver and transmitter, and provides the probe location and elevation. This will allow the path of the probe to
be known, and will help determine the approximate location of the probe when it enters the ocean. The probe will also have a radio
beacon, and with the use of a directional antenna, the beacon should lead the recovery boat straight to the probe.
How the Microtrak works with the
GPS to determine the probe’s
location.
Due to the nature of launches, which are highly dependent on
weather, a design was needed to power the instrumentation at
launch, and also have it in standby for an extended period of
time. An 11.1V battery pack is attached to a latching relay
circuit. The latching relay is routed through a 2 parallel gswitches, which will trigger on launch, and the latching relay
will move power to the rest of the electronics for the duration of
the flight. The batteries are located near the nosecone to help
the capsule float nose-down in the water. The battery pack is a
Lithium battery, due to the power required.
Timeline
Fall 2009 / Spring 2010
The VAST team picked up the project, and began to work on
improving the design. Accomplishments for the semester include:
• Lengthening the probe body for improved buoyancy and payload
volume with a small impact on probe mass.
• Redesigning the data logging board to record temperature,
pressure, accelerometry, and radiation versus elevation.
• Chose a reliable, previously used, tracking system and the
beacon.
The Microtrak GPS Unit
Summary
The goals of this project are to demonstrate that a low-cost, low
ballistic coefficient capsule to study the upper atmosphere can be
developed at low cost, and to introduce undergraduate and
graduate science and engineering students to aerospace design.
Acknowledgments
The University of Idaho VAST team would like to acknowledge
the support provided by the Marc Murbach and the NASA Ames
SOAREX program, Dr. David Atkinson and the NASA Idaho
Space Grant Consortium.
Fall 2010 / Spring 2011
Final testing of the data logging board will be completed, followed
by system integration and integration testing. The fully integrated
flight probe will be sent to NASA Ames for thermal-vac, vibration,
centrifugal (g), and shock testing. Launch is anticipated in Spring,
2011.
Univ. Idaho RISE Student Launch Team: G. Wilson, S. Wagoner, C. Abraham, K. Baird, S. Rainsdon, M. Zarate, J. Brubaker, G. Korbel,
W. Taresh, G. Gallagher, T. Lenberg D. Rickford, C. Lawrence, C. Birkinbine, C. Gonzalez, B. Kisling, J.Henry, J. Law, D. Taylor, C. Booth
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