Solar unmanned balloon launch
July 21, 2015
On July 21, 2015, faculty and students from the Computer Science department
launched a solar balloon. This balloon was a 16' diameter tetroon, made from
36 black plastic trash bags of 30 gallon capacity and 0.5 mil thickness, bound together with
masking tape.
The balloon carried a payload weighing just short of 1 pound, consisting of a Raspberry Pi,
Pi cam camera, Arduino Uno, and SainSonic AP510 APRS tracker. The Pi was programmed to run
the camera and take images of the ground through the Pi cam. The Arduino was used to
power the Pi system and to run a servo, which controlled the cutdown mechanism. Cutdown
was set for one hour and 15 minutes after launch.
The balloon was filled and launched in nearly perfect weather conditions, from the road
next to the UND Space Studies Observatory west of Grand Forks. The balloon ascended to
an altitude of approximately 26,000 feet when the cutdown triggered. Unlike helium
balloons, the cutdown on this system releases the open nozzle end of the balloon, but a
second line still connects the payload to an upper corner of the envelope. This caused
the balloon envelope to invert, allowing the hot air to escape, and to serve as a
recovery streamer to slow the payloads' descent.
The balloon system worked perfectly and the envelope and payload were recovered. Unfortunately,
the Pi system rebooted during flight, and wrote over all of the image files, making the
science mission a failure.
The AP510 tracker sent APRS packets that did not I-gate properly, though they were logged by
a local I-gate system (text file, KML file).
The flight path is the one on the left:
