NSTAR 11-C was our UNO Aerospace Education Workshop BalloonSat flight, which we have done annually for the last several years. This one was a little more exciting than most. Once again we teamed up with Paul KD4STH of NearSys on a joint flight.
This was the first time we flew from this launch site, a park on the northwest side of Carson IA. Our usual launch sites, including Treynor, were not suitable giving that we were unsure what our burst altitude would be and the proximity of several rivers. Our biggest water hazard was the Missouri, which was substantially flooded in the region.
The morning didn’t start auspiciously at all. It was raining at my house when I awoke at 0545. Fortunately the radar showed only spotty showers, so we pressed ahead. We arrived at the launch site shortly before 0730 and immediately had problems setting up our chase equipment. The Street Atlas USA program I use for maps and real-time vehicle plots stopped working, so I was dependent on my Garmin Street Pilot maps and whatever I could get from my mobile Internet connection.
Another complication was the wind, which was from the south at 10-15 mph. The wind was steady rather than gusty, and with the teachers’ help we were able to steady the balloon easily through the fill process. Our 1600g Hwoyee balloon from Scientific Sales was launched at 0818 CDT (1318 UTC).
Right away we noticed that the backup beacon signal was not being received, despite a last-minute ground check. At that time I realized the reason it passed its bench checks after the last flight where it failed was that it probably had a very short range instead of an intermittent failure. Our main beacon had been OK so I wasn’t too concerned at that point.
With a short chase expected, we drove to Oakland and waited at a convenience store for well over an hour while the flight continued its ascent. As the flight approached the 100,000-foot mark our excitement grew – would the flight make it into six digits? Our balloon sailed right past the 100,000 with ease, continuing to drift to the west at 40-50 mph. Next was the highest NSTAR flight to date at about 111,000 feet – could we match that? It did, surpassing that and reaching 112,949 ft at 1015 CDT (1515 UTC).
After burst, we heard a couple of packets with a lot of flutter in the signal. This is not too unusual, as the initial fall is often chaotic until the flight train stabilizes. However, this packet caused me a chill:
N9XTN-11>GPSPO,WIDE2-1,qAR,N9XTN-9:T000 Baro 12 mb 3 logs
The “T000” was the telemetry frame counter, which starts at zero and counts upward through the entire mission. The fact that this reset to zero after burst indicated the program had started over, possibly due to a power glitch.
After that, no signal was heard at all, not even a faint or distorted packet burst. No signal at all. This was serious – we now had no signals coming from the payload at all. The simplex repeater was taken off the manifest to save weight for the BalloonSats. I calculated a revised landing prediction based on the higher burst altitude, which was about 6 miles ENE of Underwood IA. We set off for that location, hoping to hear a weak signal before landing.
After we arrived, and the expecting landing time of 1100 came and went with no signals and no visual sightings, I broke the bad news to the UNO BalloonSat crew. With maturing corn and beans all around the area, it would be unlikely we could spot the parachute from the road if it landed in a field. I was not at all optimistic we would see the payloads before harvest, but we would make our best effort at a search given the very hot conditions upon us (temps into the mid 90s and high humidity). I told the crew they could choose to head back to UNO while Doug, Wayne, and I performed the search. Paul KD4STH from NearSys had also contributed a payload, but he needed to return to Topeka.
Our plan was to perform a grid search of the area to a radius of about five miles, driving down the roads and hoping to hear a signal. On a 2010 flight, the BasicStamp 2p stopped functioning for about an hour, but then was able to restart itself and we got a good location from its landing site. With the increasing heat and humidity I told the crew they could choose to head back to UNO while Doug, Wayne, and I performed the search.
The UNO crew left, and we finalized our search plan and started off. I checked my phone and saw a Twitter message addressed to me.
@N9XTN Mark, someone retrieved the payloads near Underwood, IA and called me. Have Mitchell call me!
I couldn’t believe it! Less than a half hour after our expected landing, and before we could even start searching, someone found them for us! I got Doug on the radio to let him know, then we headed to Underwood. After a couple of missed connections I was able to reach Dr Mitchell (UNO professor and workshop leader) and passed the information to her.
A while later Dr Mitchell called me back and said she had picked up the payloads from the finders and was on her way to us waiting in Underwood. They were all still connected and intact! When she arrived we started to examine the payloads.
The load line from the chute to the balloon and all the parachute shroud lines were thoroughly twisted. The lines below the main beacon to the BalloonSats and backup beacon were also very snarled. We had never had such a badly fouled flight train. The parachute must have offered some wind resistance as it took 20 minutes to fall from 113,000 ft. The landing was at about 1035 CDT and from the video aboard Paul’s BalloonSat I estimated the landing to be along Magnolia Road about a mile west of Underwood.
As of July 17, I have not been able to determine the cause of failure of the main beacon, other than to observe symptoms. The main payload’s electronics are almost all from our rebuild in early 2002 after the power line landing in September 2001 destroyed the first NSTAR main payload. This make the main payload electronics over nine years old and forty flights of use and abuse. I have been wanting to do a redesign of the main payload for two years but have not found the time or incentive. The backup beacon also needs to be made more robust. At this point I think we will take a hiatus from flying until we have a new main payload ready to go, which will probably be in spring 2012.
Below is a video from the NearSys BalloonSat payload by Paul KD4STH