Insanely Cold Thermal Test Chamber for High Altitude Flight

So, you decided you want to launch something into near space. Awesome, but will your electronic components hold up, or will they crack under the pressure of sub zero temperatures? Build a thermal test chamber for pre-launch electronics testing.

Basic concept:
Getting stuff *really* cold is difficult, dangerous, and lots of fun. Our group is preparing to send an autonomous glider up to about 100,000 feet, so we needed a way to chill our electronics to -70c to test their use before these edge-of-space flights.

Just using dry ice in a cooler will result in about 0c air. In order to chill air much colder, a fan is used to circulate the air to reach -42c. In order to hit -70c or colder, liquid nitrogen and a heat exchange (coil) is used.