The edge of space / Part two
In my last post, I talked about the challenges I would be facing and the micro controller I would use. In this post, I'll get into the nitty-gritty of my High Altitude Balloon project as well as show off some progress.
The GPS unit is perhaps one of the most important parts of my HAB payload since, obviously, it will enable recovery. The model I settled on was the UBlox Neo-6M; it was cheap, readily available, and capable of functioning above 60,000 feet.
In addition to the GPS, I also got an altimeter (BMP180), temperature/humidity sensor (DHT22), and UV sensor. The altimeter will assist with telemetry — since I don't entirely trust the altitude readings of the GPS — and the other sensors will provide interesting environmental data for no other purpose than to satisfy my curiosity.
Transmitting all of this data to the ground will be the Rockblock module from Rock7. The Rockblock runs off of the Arduino's 5V out, can communicate over simple serial commands, doesn't require a license to operate, and essentially has unlimited range (it can transmit from anywhere in the world as long as it can see the sky). It relies on a constellation of 66 Iridium satellites to send messages to and from online servers. It's expensive, though, and I don't plan on purchasing it until I've figured out the rest of the HAB payload.
The hardest part was getting the GPS unit to give me sensical readings. As it turned out, I made a weird wiring error, and I needed to be outside for the GPS to get a lock on some satellites. Below is a video of all the sensors giving me readings over USB — finally!
Getting all of the sensors soldered onto a development shield and running it all off of a small, single cell lithium polymer battery will be my first next step. Sending a rickety breadboard into the upper atmosphere is probably unwise.
Then, getting the damn expensive Rockblock module and hooking it up will be my next priority. There's a lot of guides online, so I'm not too concerned about making it work.
Finally, the last step will be getting the airframe printed. This is probably the most exciting part of the project, since it'll be where the payload comes together and takes on its final form. As a nod to my spacefaring brethren, I intend to make the airframe per CubeSat specifications (one can dream).