Description
The main difference with MSP-1 resides in the tracking system. I got the technical radio operator license in order to get a HAM radio call sign. My call sign is KJ6MUD. I was then able to use an APRS tracking system. I chose the Byonics Micro-Trak 8000 FA for its simplicity and light weight. The radio transmitter was connected to the Byonics GPS4 which does not have the 60k ft altitude limit.
Tracking the payload after the launch was very easy and accurate. It was set to send its position every minute.
Flight Path from launch to landing
MSP-2 at its highest altitude
All trackers worked very well, each showing the same data.
Hardware
| Sensors | Internal and External Temperature Sensors DS1620 Photo Resistor VT935G-B |
| Cameras | Canon PowerShot SD1200IS + 4Gb SD Card (photo script w/CHDK) Canon PowerShot SD880IS + 8Gb SD Card (video mode) |
| Batteries | (SD880IS) Canon Battery Pack NB-5L (Battery Life 36min-ish) (SD1200IS) Canon Battery Pack NB-6L (Battery Life 4h10-ish) |
| Camera Shots | 1314 pictures (3648*2736) (1.84Gb) |
| Video Camera | Go Pro HD Hero + 32GB SD Card + Battery Backpack |
| Computer System | Parallax HomeWork Board |
| Trackers | Byonics Micro-Trak 8000 FA + Byonics GPS4 SPOT Personal Tracker Motorola i296 + accutracking application |
| Parachute | 6ft Parachute |
Flight Data
| Launch Date | 4/9/2011 |
| Launch Point | 38.494923,-121.75044 near Davis, CA |
| Retrieval Date | 4/10/2011 |
| Landing Point | 37.720520, -121.615260 |
| Balloon Lift | ~3.5 kg Gross Lift |
| Total weight | ~1.7 kg |
| Highest Altitude | 95,581ft (29,133m) |
| Distance traveled | 54 miles (87km) |
| Flight Duration | 2h10min |
| Average ascent rate | 1125ft/min (343m/min) |
| Average descent rate | 2254 ft/min (687m/min) |
| Max fall rate | 128.3 mph (206.4 km/h) at 76,245ft (23,239.5m) |
| Landing speed | 14 mph (22.4km/h) |
Sensors
The computer system did not work as planned. The data from the external temperature sensor and photo resistor does not make any sense. It could be due to a bad mounting (no protection against the wind and the sun…).
The micro-controller had an operating temperature of -40 to +185 °F (-40 to +85 °C) but the internal temperature sensor stopped working at -4°F (-20°C ). It had been thoroughly tested at low temperatures. It could be due to hardware failure (wire disconnection?).
The internal temperature sensor stopped working during the descent.
The camera sensors worked the whole time.
(Temperature in °C)
Battery Voltage (in mV)
This is actually quite surprising. I thought that 3600mV was the hard deck for Canon cameras. But I wrote an intervalometer script in ubasic to disable the LCD and take pictures every 10 seconds. Disabling the LCD had a substantial impact on the battery life.
The camera battery lasted 4h20min and took 1314 pictures. The standard battery life was 260 pictures!
Pictures
The ascent:
Travis AFB
The San Francisco Bay Area from 95500 ft:
South Bay
San Francisco (You can guess the Golden Gate and the Bay Bridge)
North Bay
Sacramento Valley
Recovery
MSP-2 landed after a 2h10min flight. It landed in a wind farm, east of Livermore, CA.
Despite having the GPS coordinates, when typed into the Google maps application, it did not return the location entered but the location of the closest road, several hundred yards away. We couldn’t find it the first day, I had to come back the next day.
When it landed, the winds got so strong (40+mph), the payload got dragged about 200 yards uphill.
What is left from the balloon. It never completely bursts:
The lines are twisted all the way down and the GoPro Camera is gone:
Despite the scotch tape and the super-lock strips, most of the devices are now moving free.
Conclusions
- Tracking MSP-2 was easy and reliable. (Using APRS was definitely the way to go)
- Recovering a Near Space Balloon is always hard; Start your pursuit as soon as possible. Do not trust your smartphone. You need a laptop with Internet connection.
- The descent is a very rough ride. You need to secure the critical devices very well (trackers, tracker batteries, Gopro…). Since the capsule can land in any position, it is necessary to set the Spot tracker in a gimbal system.
- The computer system and sensors need to be soldered all together
- You definitely need to be at least 2 people to launch a high altitude balloon
My most sincere thanks to my friend TJ without whom I would not have been able to make it.
