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Category: 2004
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Our seventh flight of 2004 was on a typical November morning - clear and calm with temperatures in the low 20s. Most of us arrived at about 0730 and began setting up. Shortly after 8 we started filling the balloon and checking out the payloads. Everything proceeded normally and we released the balloon at 0829 CST.

After release, I went to my APRS laptop to check out the early ascent data. Immediately it was apparent something was wrong - the balloon's position showed no direction, speed, or altitude information. This is typical for a poor or non-existent GPS fix. I immediately switched to our backup beacon to get an idea of the ascent rate and to verify its operation - we had good data from it and a nominal ascent rate. The simplex repeater checked out OK and we prepared to leave the launch site.

Once we were on the road, I switched back to the main beacon and saw that it was once again reporting good altitude/course/speed information. The GPS fix quality was poorer than usual, but usable. At the time, I speculated that the GPS antenna had slipped out of position within the payload and was no longer pointing vertically.

We continued on the chase, heading for Massena, IA and our usual mid-chase gas station stop. The simplex repeater continued to work well, with stations near Des Moines, Omaha, Topeka, and Kansas City checking in. However, the main payload's GPS showed signs of having poor fixes, and finally at about 70,000 ft became too unreliable to use. We switched to the backup payload for tracking the remainder of the flight.

After we stopped in Massena, chase team members could spot the balloon without much difficulty owing to the clear skies and a favorable orientation relative to the sun. Nearing burst, the balloon was only three miles or so to our west, but 14 miles up. Burst occurred at 0951 CST and 90,273 ft.

Soon after burst, one of the team member said he could see the payloads and parachute even though they were still above 60,000 ft. I was skeptical, since the highest altitude we had ever been able to see a parachute was at less than half that altitude. But sure enough, with a little help I could see them too. Using binoculars I could see a large chunk of balloon along with the payloads - I think this is why we could see it so well. We watched the parachute for a while longer, then left the gas station to head north.

Based on the burst location, I expected the landing to happen about 3 miles north of Massena. We went about two miles north and pulled off the road to watch more of the descent. Below 20,000 ft the payload began drifting north and then northwest. It passed almost directly overhead, then landed in a field about a half-mile to our west at 1027 CST. Someone headed south on the highway had seen the payload and stopped to ask us if we were tracking it.

It appeared the landing was closer to the road one mile west than to the road we were on, so we drove around the section and onto a minimum-maintenance road. Fortunately it had dried some from the recent rains and was in good shape. We hopped the fence and headed towards the landing site - the parachute and payloads could be seen in the open field.

Upon inspecting the payloads, the GPS in the main payload was in its proper location. The other payloads were undamaged, but there was quite a bit of fouling by the balloon shards on the load lines.

The videotape ran from launch to landing and was one of the better tapes we have collected to date. The video camera landed face-first into the ground and provided a neat clip. On the way down, the balloon remnants could be seen hanging freely below the payloads, so the fouling may have occurred in the last few minutes of flight. I've theorized that the digital camera may have interfered with the GPS-18 - this will be tested over the winter hiatus. Because the GPS did not function correctly, not all the scheduled pictures were taken. Even so, over 90 were taken and yielded some good ones. It appears that the way to get good balloon pictures is to take lots of them, and the digital camera allows this without the expense of more cameras and film processing. The humidity sensor appears to be stuck on 75% and may be broken - I was not as careful as I should have been with a last-minute wiring job.

Follow-up:  It appears the digital camera desenses the GPS-18 by 10-15 dB - this is enough to cause the GPS to lose its position fix if the geometry or number of satellites is unfavorable.  There is a similar but lesser effect on the GPS-35.  I will switch back to the GPS-35 and increase the physical separation until a permanent solution is found (probably involving some method of shielding the camera).