This is the high altitude balloon mission that my colleges and I are preparing for Global Space Balloon Challenge. We are team from Ventspils University and we decided this would great opportunity as we are somewhat involved in some space related projects. Our objective is to launch a near-space probe that will take beautiful video of near-space scenery and take pictures in near-infrared light. The infrared pictures will be used to determine NDVI (Normalized Difference Vegetation Index). This basically indicates how well the plant life is doing. We will use a SJ4000 cmera to capture video of near space and an modified canon camera to take pictures in near-infrared. Additionally we will have a pressure sensor, accelerometer, gyro, magnetometer and several temperature sensors on-board.
This is the first near-space probe any of us have worked and launched, so we will be glad to hear advice from any experienced balloonist :)
Must be able to measure -50 C
Our project IRBE-1 got 2nd place in nomination for best science experiment! We also got the prize - it's a balloon and parachute form High Altitude Science. That means more ballooning, right?! Anyways, first place went to team JADE from Poland who had a really cool bio-experiment. If anyone of the team JADE is reading this, good job guys and congratulations! :)
We did it! We have launched and recovered our high altitude balloon IRBE-1! I can not say it was very easy because we had several problems that might have ruined our little near-space mission, but in the end everything went well! We are very excited that we got to launch our first HAB and also to participate in the GSBC. I finally found some time to sit down and write about the launch and I hope you will enjoy reading it and most importantly learn from our mistakes.
So we had the launched planned for 10th of april, but with just couple weeks to go we had a lot of programming and testing to do. We designed the boards three circuit boards for our payload:
Data Logger board - SD card, RTC and temperature sensors
Comunication board - RTTY transmitter, GPS and GSM module
Here is a picture of complete stack that was planned for launch.
Since these boards were basically home made, they did not have solder mask. This in turn caused several problems when soldering the SMD components. In fact these problems made us ditch the sensor board. In the end we got it working but because we had little time left before launch we decided not to take risk. Also the GSM module was removed from payload after we tested it and found that it randomly locks up the program. Again, we had little time to solve this problem and we decided to not use it. This was a quite bad thing. It meant that we had to rely only on RTTY transmitter and GPS when tracking the balloon and I do not recommend using only one wireless link for transmitting balloon coordinates, because you double the possibility of loosing your payload. We did it anyway, because we are crazy, but seriously don't do this.
So at the end we had only stellaris launchpad, data logger and communication boards, but without GSM module. This is very basic configuration for a HAB and we decided to stick with it because wanted to avoid any glitches caused by untested hardware or software. On the stellaris board we had to remove the reset management IC which did not allow the VBUS voltage to be lower than 4.38V. Since we had Li-ion batteries with voltage ranging from 3.7V to 4.2V, we removed U4 and connected batteries to VBUS. Thus we could run stellaris launchpad with li-ion batteries while using the original voltage regulator on the board. Please not that if you try to recreate this small hack with your stellaris launchpad, DO NOT leave the power switch on the ICD mode while connecting to PC via ICD usb. We did not try it, but it will probably set something on fire.
We had arranged the balloon launch from an Ventspils airport which gladly supported us in our activities. We also got a generous donation from a company AGA, that gave us 50l of 99% helium. Ventspils University College covered most of the expenses related to electronics. Combining all this made our project super cheep.
Soon enough came the launch day. When we arrived at the airfield, we discovered a problem that we had not paid much attention and it was the conductive material presence near the GPS antenna. And it turned out that we needed to rise the GPS module about 5cm above capsules cover, because the tin foil thermal insulation and other conductive bits made GPS loose the coordinates. We had the tin foiled cover and GPS tested earlier and it was fine, but as soon as we inserted it into capsule with cover on top, GPS went bananas.
Of course we did not know that in the beginning and so starts the spiral of problems that arose from this one. At the beginning we turned to software and ran a test code. Guess what happened after we found that it was physical problem? Off course we forgot to upload the flight code. This did not have catastrophic coincidences, but the GPS did not have flight mode enabled. So GPS would stopped transmitting coordinates after reaching altitudes above 12 km. Next chain-linked problem was the camera batteries. While we were trying different things...
The capsule is now covered with tinfoil and it has the holes for each camera. Here is pictures of both cameras we will be using and capsule.
By removing the IR filter in canon A490 and adding adding infrablue or red filter, this camera will be able to take pictures with infrared in red channel and visible light in blue channel.
SJ4000 will capture full HD video of the flight. SJ4000 angle of view is quite wide (140 deg) and capsules walls are about 3cm thick, so if we were going to fit it inside capsule, it would require ridiculusly large lense hole. Instead camera was moved inside capsules wall. Also a plastic cover was made to prevent it from falling out of the payload. Now it fits inside nicely.
We will have a custom made parachute, because it is more cheap and more fun. We did some tests with material of our choosing, threads and ropes.
At this moment we have assembled capsule and fitted the IR camera inside of it. The capsule is made from extruded styrofoam panel. Several screws and tape holds styrofoam together. Here you can see the capsule and rope mounts.
We teared down a laptop battery and extracted the li-ion cells. After recharging and discharging each of three battery pairs it appears that all three pairs still have about 70% of original capacity (2600mAh).
We got an GSM module for back-up tracking. It can be used to communicate with base station, as well as to determine coordinates of balloon.
Also we tried out 10DOF board, works good, but we will not be using this on the payload.
This is the quick overview of what we have been doing. We plan to make PCBs for sensors and com's. Follow us to get more frequent and detailed updates.