GAGA-1 flew on Sunday, April 10, 2011 and took more than 1,800 pictures of its adventure. The flight and recovery computers worked well right up until impact and the capsule landed safely in a field to the west of Cambridge.
Before giving details of the flight, I need to thank all the people who helped make it possible. Most importantly, Ed Moore of CUSF who helped on the day with balloon filling, expertise, a good place for coffee and a snack, and the chase. He was even the one that saw the little yellow square lying on the ground through a line of trees.
Also, very important were the radio amateurs and other enthusiasts who listened to the RTTY telemetry transmitted from the capsule and uploaded to the tracker. In particular G3VZV (and M0LEP) who followed the balloon almost to the ground enabled us to find it.
And lastly thanks to the denizens of #highaltitude for advice and encouragement, and who jumped in at the 11th hour and fixed some bad XML so that the tracker would accept the telemetry transmitted by GAGA-1.
GAGA-1 flew to 32,086m altitude and spent 2h12m in the air. The first telemetry in the air came at 09:48:54 UTC and the final telemetry was received at 12:01:09 UTC. The camera took 1,856 photographs including capturing the Thames estuary, the moon and the black sky. The complete photograph set (editing out tedious repetition) can be found here. Here's the first in flight photo showing Churchill College, Cambridge:
map. The blue markers indicate where SMS messages were sent. Two were sent on ascent (the recovery computer that sent them was programmed to go quiet at 2,000m) and one was sent close to the ground.
The final moments of the flight are here. The yellow marker shows the rough landing spot, the two blue markers show where the recovery computer sent SMS messages (the second one failed) and the yellow track is telemetry received.
Here's a shot taken very high up looking down on the Thames estuary; to the bottom right there's a U bend in the river at Greenwich. The south coast is clearly visible.
And more of space:
1. The flight computer worked flawlessly throughout and the signal from the 10mW transmitter was audible across the UK. It was picked up 542 km away in Northern Ireland and also in Scotland (as well as around England). A triumph for the coat hanger antenna and line-of-sight. Here's a video of the transmission being received in Northern Ireland:
2. The recovery computer followed a preset state machine. Initially it transmitted its location on early ascent, and then went into a quiet mode while above GSM access level. Once above the ballistic missile height the GPS shutdown and the built in program performed a cold reset. It successfully restarted and once below 4,000m started trying to SMS its position.
It managed to send one SMS reading T+12126: 5208.8703N 00001.9362W 785m 298.92deg 26.71kph 11sats (3810mv, -1000C, RECOVERY). The -1000C indicates a temporary error reading the built in temperature sensor. RECOVERY indicates that it knew it was landing. The altitude is 785m and it was traveling (across the ground) at 26.71 kph.
3. The camera worked and took many fantastic photographs.
4. Painting the capsule fluorescent yellow turned out to important as it was spotted on the ground from a few hundred meters and through a line of trees.
5. During the flight the recovery computer dealt with unexpected errors from the GSM module (indicating no access to the GSM network) and managed to carry on.
6. All my knots held and the rigging through the capsule walls worked. The UHF antenna was badly damaged on impact as expected. Unexpected was the fact that the capsule was upside down in the field meaning that the GPS antennas would likely have been completely shielded from the sky.
Things that didn't work
1. Both computers cut out on landing. Opening the box revealed that the two battery packs (that I had hot glued in place) had come loose, the six battery pack used for the flight computer had lost a battery when it hit the ground. The batteries were in place for the recovery computer, and it had power, but it had stopped operation.
Camera removed showing battery packs unglued. The red light is the recovery computer power LED.
4. I couldn't access the tracker using my laptop in the car because O2 Internet Tethering was blocking maps.google.com for some reason.
5. The temperature values are surprising. The minimum external temperature measured was -20C and then the temperature rose with altitude. Although this is expected in the stratosphere it should have been much colder. This may indicate that the sun was warming the external temperature sensor which was encased in a small black plastic straw. Also on descent the internal temperature dropped. I suspect that this was caused by cold air being forced into the capsule around the camera lens.
6. There are a couple of unexplained erroneous bits of telemetry corresponding to spikes in temperature and altitude at the same time (see the above chart).
7. On booting the camera it failed to turn on twice resulting in me changing the batteries and finding that it would only boot with the SD card missing. Putting the SD card back in would then work. I saw this twice.
1. The complete log of telemetry received is log.
2. The log kept by the recovery computer is here.
3. The log kept by the camera is here.
4. The source code used for the camera and both computers is here.
The camera has three temperature sensors in it covering the lens, the electronics and the battery compartment. Here's a graph showing its temperatures. Note that the front of the lens is exposed to the air with no protection. The heating at the end seems to be because the capsule sat around on the ground in full sunlight in a lovely afternoon while I searched for it.
A handy complete history of the GAGA-1 project from its inception in July, 2010 to the flight itself.
July 8, 2010: GAGA-1
July 17, 2010: Some initial investigations
September 5, 2010: Camera Hacking
September 8, 2010: Redundancy and Independence
September 9, 2010: Honey, there's a camera in the freezer
September 12, 2010: 2,766 tedious photographs and a log file
September 13, 2010: Weight Budget and The Capsule
September 19, 2010: Capsule paint job
September 20, 2010: Source Code Repository
October 4, 2010: Computer Mounting
November 5, 2010: Recovery Computer
November 20, 2010: Recovery Computer Ground Test
November 27, 2010: Capsule insulation and antenna mounting
November 28, 2010: CoCom limit for GPS
December 6, 2010: The Camera Hole
January 22, 2011: Getting close to completion
January 26, 2011: Flight Computer radio's first transmission
January 27, 2011: Voltage divider calculator for Radiometrix NTX2
January 28, 2011: Calculating, rather than experimenting to find, resistor values for the NTX2 voltage divider
February 5, 2011: Voiding the warranty (for great justice!)
February 8, 2011: Batteries
February 10, 2011: Temperature Measurement
February 18, 2011: Parachute
February 19, 2011: Working flight computer and The lovely sound of RTTY
February 25, 2011: Another little freeze test
February 28, 2011: Flight computer testing
March 13, 2011: The Stack
March 24, 2011: Parachute test
March 31, 2011: Tentative launch date: April 10, 2011
April 5, 2011: Integration testing
April 8, 2011: Looking good for Sunday
April 10, 2011: Quick post-flight update
In my original post on GAGA-1 in July, 2010 I said I hoped to launch in time for the 50th anniversary of Yuri Gagarin's Vostok 1 flight. It occurred at 0607 UTC on April 12, 1961. This post comes exactly 50 years later.
GAGA-1: The Movie
My friend Eric Melski suggested while I was working on GAGA-1 that the appropriate soundtrack for the work would be Europe's The Final Countdown.
And so, for Eric and for everyone else, here are all 979 photographs taken during the flight set to epic Swedish 1980s synth rock.