Every semester, students in the AE325/326 "Experimental Space Systems Engineering Labortory" course build gondolas that are launched
into the upper atmosphere on a latex weather balloon. Along with taking photographs of the upper atmosphere, students also determine
the attitude of their gondolas throughout the flight and they collect data to verify whether or not a dynamic heat-transfer model that
they develop for their gondola is correct. The flights are conducted with the support of Arizona Near Space Research,
ANSR, who provide flight predictions and assist with the recovery upon landing.
For the first few flights, a commonly available data-logger that writes data to a microSD card, was utilized. These data-loggers were very prone to failure, most likely due to electro-static discharges, and had to be replaced every semester. In order to gain more control of this, I developed a 23 channel data-logger based around the relatively low-cost PIC18LF46K22 microcontroller. This data-logger, which is pictured below, also writes data to a microSD card but does so with a 10 Hz sampling period.
This was followed with the development of a flight package consisting of an IMU, temperature and pressure measurement circuit, an analog sun-sensor cicrcuit, and a power supply. These are pictured below. More details are on these circuits are here.
At the start of the Fall 2017 semester, I developed a new flight package based around the BeagleBone Green development board. Specifically, I designed a BeagleBone cape that multiplexed voltages derived from 8 thermistors, a pressure sensor, the battery, and a 6 solar panel sun-sensor array into one of the BeagleBone's analog to digital converters. I also provided screw terminal access to the I2C bus and a UART through which the Adafruit breakout for the Bosch BNO055 and breakout for the MTK3339 GPS module are connected. The cape and BeagleBone Green are pictured below. The schematic drawing is here. The cape printed circuit boards were fabricated by Oshpark and populated in the ERAU Space Robotics Laboratory. I have also written a Python library to provide access to the various sensors via simple function calls.
Typical Balloon Launch:
Typical High-Altitude Photographs:
Earth's horizon from approximately 100000 ft:
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