Spaceblimp test launch writeup, part one.

Aug 07, 2010

A couple of months back I mentioned that HacDC had thrown its hat into the ring of the Hackerspaces In Space competition held by Workshop88. The past few months have been a whirlwind of activity designing and fabricating circuitry, running simulations, carving a number of chassis out of high density foam, installing hacked camera firmware and writing code for the microcontroller. Folks with much better engineering skills than I put together all of the interesting stuff - the microcontroller board, the transmitter, the camera controller, and stuff like that. Aside from helping wherever I could I spent most of my time studying to get my ham radio license (which wound up not happening on time) and trying to figure out how to get my Bayonics TinyTrak 4 TNC picking up traffic on the air (note to self: set NODISP configuration variable to FALSE).

Anyway, I'm rambling. Today was the first test launch of the project Spaceblimp. Earlier this week data were collected, simulations were run and re-run and final preparations were made for the launch this morning. I got out of bed at the bright and shiny time of 0730 EST5EDT and after bringing myself online as fast as I could I piled the TARDIS' trunk full of gear and set a course for rural western Virginia (different from West Virginia) to meet up with the rest of the launch and chase team. Last minute calculations carried out with today's meteorological data showed that there was an excellent chance that our probe would come down somewhere in downtown Washington, DC, which necessitated changing the launch site to a new one about 15 miles farther south. While we'd probably get style points if our weather balloon was shot down by an F-18 for violating a no-fly zone, chances are we'd be disqualified for winding up in federal prison and nobody wants that. So, I got there a little late, just in time to see everyone setting up the balloon inflation kit, readying tools, and testing circuitry. As I got out of the TARDIS I saw a few people huddled in the back of an SUV around the instrument package's microcontroller board doing a little last minute soldering with a gas-powered soldering iron.

Yeah, whoa. Right?

I made myself useful where I could, bringing out tools from my physician's bag/toolbox, cutting static line, taking pictures to document the first launch of our near-space probe, and getting Windbringer set up with a hand-held transceiver and TNC (FCC regs state that it's illegal to transmit if you don't have a ham license but it's legal to receive because it doesn't interfere with radio traffic), and the commlink with the Spaceblimp was one-way (we would only be receiving telemetry from the instrument package via APRS). It was at this time that Bokunenjin and I were able to copy, or successfully receive test telemetry from the instrument package. At last it came time to inflate the weather balloon from a tank of compressed helium and a home-made balloon inflater which was quite an experience. First, when filling an 800 gram weather balloon it's frickin' loud because the gas expands inside the balloon and then rubs along the inside of the latex rubber, making an awful shrieking sound. Second, it's amazing how big a ballon has to be to get a decent amount of lift. Our weather balloon reached a bit over six feet in diameter before we got eight and a half pounds of lift out of it. Also, it took three of us clinging to the balloon for dear life to tie it off and rig the parachute (and thus the instrument package) to the balloon.

The launch seemed to go smoothly. I let go, R. Mark Adams let go, and then his wife let go at the very end of the tether. All of us - there had to be about fifteen of us in the parking lot of a small community church in the middle of rural Virginia - watched it float silently into the air and away... and then sprint for our cars, carring tools and radio equipment the whole way as we started setting up our laptops and radio rigs to track the balloon's telemetry. The simulations run earlier today gave us an idea of where the balloon would go, how fast it would go, and roughly where we could expect it to land under optimal conditions.

Somewhere in Culpeper, Virginia, after spending the afternoon driving back toward DC and then back toward the launch site in the hope of getting somewhere near the Spaceblimp's projected LZ a few of us got tired and hungry and stopped off at a little pizza place on the side of the highway to get a bite to eat, plug our laptops in, and figure out what was going on. The staff of the place was not only friendly and helpful, they were very interested in what we were doing and why. The guy behind the counter used to be a climatologist and we kicked around ideas about what could have happened while our pizzas baked. No sooner had we sat down to eat than Elliott called - they had a fix on the Spaceblimp and had calculated a likely LZ. We gulped our slices of pizza, threw the rest into the boxes, and scurried back to our cars to meet up with the rest of the chase teams.

Unfortunately, somewhere around 60,000 feet things seem to have gone a little wonky; the last time we heard from the Spaceblimp it reported that it was at an altitude of 57,831 feet, though the last good data packet we got from it said 38,228 feet and climbing, timestamped a few hours before that. The entire chase team of ten people wound up at the same pizza joint as before to recharge our kit, mull over the raw telemetry data and try to figure out what happened. The APRS data reported by the digipeaters that picked up the signal looks like a dog's breakfast; the packets are out of order, there are duplicates all over the place, and we weren't able to make much sense out of it. A few of us fear that the Spaceblimp Mark I is lost. By early evening three of us were pretty much out of spoons and wanted nothing more than to head for home and rest. This necessitated a little re-jiggering of driving arrangements and equipment but we left the remaining chase teams to either find where the Spaceblimp went down or figure out what had happened to it.

We ran into significant problems with our radio net. For most of the day we could barely hear one another over the radio; text messaging and cellphones were a more reliable means of communication even that far in the back country. We got a lot of use out of the website to track the Spaceblimp's position, and Nate (my navigator/radio operator) was even able to use my Android smartphone and the Dolphin web browser to monitor its progress and relay information to other people. Unfortunately, when rearranging magmounted antennae on the roof of the TARDIS I scratched the finish up pretty good, so I'll have to get her to an auto detailing place soon to get that taken care of.

For the judges of the competition, while we had fifteen people present for the assembly and release of the Spaceblimp we had only ten people across six chase teams (a few went solo) and will stick to the maximum number for the judged launch.

I put out word on a couple of different services earlier today but I don't think that it's going to be all that helpful. We'll see what the next couple of days bring, and when we put the data together and draw conclusions I'll post them in a followup.