High-Altitude Ballooning



Balloon horizon

The TigerSats Lab has developed expertise in high-altitude ballooning.  We are interested in providing tech support, discounted balloon/gondola hardware, and even (occasionally) full launch management services (when lab resources allow) to enable other Princeton groups and research labs to conduct their own high-altitude balloon missions to "the edge of space"! 

High-altitude balloon missions can be useful for:

1. Atmospheric experiments requiring sensor readings across a wide range of altitudes.  We've achieved peak (burst) altitudes of ~100,000 ft (~30,000 meters) and have successfully taken data continuously during the full ~2.5hr ascent (and ~1hr parachute descent!).  

2. Proof-of-concept astronomical observation missions that might benefit from an observing "perch" above the turbulence of most of Earth's lower atmosphere (i.e., balloon-borne astronomy, etc.).

3. Proof-of-concept Earth observation missions. Our ~3hr flight paths typically traverse 50-100 miles laterally above NJ or PA farmland.

4. Qualification of new hardware to a cold (-40C) thermal "vacuum" (0.01 atm), while perhaps actively operating in some functional, observational, or sensor readout mode. 

For example: the reason we are developing ballooning capability is because we want to test our own upcoming custom Earth horizon sensor on a real, "black-edged" Earth horizon scene (characteristic of what our CubeSats might see from orbit), and we don't think a simulated image would be sufficient proof-of-concept.  (Update: we did it!)

Our early launches

Over summer 2021, we (especially SPRE intern Alexander Haywood, '24) conducted our first 2 test launches.  Launch #1 burst at ~86,000 ft (~26,000 m) after a 2hr ascent, collecting temp/pressure sensor data continuously throughout, but our camera (GoPro Hero Session) battery died after only ~1hr in the cold (-30C) temps, at only ~40,000 ft (see photo at the bottom of this page, and video here).  

Launch #2 burst at ~100,000 ft (~30,000 m) after a 2.5hr ascent, while its now-extended camera battery died after 1hr45min in cold (-20 to -30C) temps at ~70,000 ft (see photo above, and video here).  Our next step is to try to add battery heaters.  A heavy oncoming storm system that day prevented much Earth observation, but we got some promising views of a "black-edged" Earth horizon!

Some notes about our current favorite ballooning kit:

1. We use the Eagle Pro kit from High Altitude Science.  Their standard 350g balloon is usually sufficient for a modest payload. Our latest ~4 lb horizon sensor suite payload demanded their 600g balloon. 

2. A size 55 (37 cu ft) cylinder of balloon-grade helium from Linde fills the 350g balloon quite nicely, and is small and easy to transport safely. 

3. Our flight camera is the lightweight GoPro Hero Session (4 or 5) with the EcstaPro GP-KT5S battery extender (Hero4 version extender is occasionally in stock as well). 

4. The Eagle kit includes a Spot Trace for near-continuous downlinking of the balloon's GPS position (during flight and post-landing) via the Globalstar satellite network.  This tracking is crucial for end-of-mission gondola recovery, since continuous sensor readout data is only recorded onboard (not downlinked live). 

5. The Eagle Flight Computer includes an altitude-unlocked GPS that logs (onboard) continuous GPS coordinates throughout the flight, to help fill in the gaps of the Spot Trace position log later (after gondola recovery). 

6. To predict flight path (and landing zone), we use HabHub's balloon landing predictor (based on Cambridge University's landing predictor and NOAA GFS models).  We were shocked at how accurate the predicted trajectory proved (even with slightly misestimated ascent and descent rates).  Below shows a coarse overlay of predicted (black) flight path versus actual (red) for our first launch.  After a meandering ~50 mile flight path, the actual landing zone was only ~8 miles from the prediction (and even this divergence was largely due to our misestimation of predicted ascent rate).  Our 2nd launch actually landed <5 miles from the prediction, even after a longer ~100 mile meandering fight path! And, in both cases, we were already waiting patiently in the landing zone, with the help of live descent updates from the Spot Trace!



Trajectory overlight flight #1



Balloon launch #1 view