Launching CRISIS: recounting a cosmic ray research balloon launch

These are excerpts from an article describing a scientific balloon launch from Aberdeen, South Dakota in 1977 by researchers at the University of Minnesota. The full story, including the challenges and setbacks encountered, is linked below the article.

While attending the University, one of my part-time jobs was as a lab assistant in the School. I worked in a laboratory dedicated to the cosmic ray research group led by professors Phyllis Freier and C J (Jake) Waddington.  In the group were lab manager Chuck Gilman and graduate student Bob Scarlett who were preparing an instrument to be launched and held aloft by a balloon to gather data about cosmic rays, a (still) mysterious radiation of high energy particles from deep outer space.

This was an experiment to identify isotopes in the population of cosmic rays. It is not easy to detect cosmic rays, and it is even harder to distinguish their isotopes. But this is what the experiment aimed to do, and so it acquired the title “Cosmic Ray Isotope Separation Instrumentation System,” or "CRISIS."

There were several constraints on this experiment. It had to be conducted at or above latitude 45, or the Earth’s magnetic field would deflect the particles we sought to measure. The instrument needed to stay aloft long enough to gather a useful amount of data. This required low stratospheric wind speeds which only occurred in short time-windows in the spring and fall.  

And finally, since balloons sometimes fail, we needed to launch over low-density population areas to minimize the risk of thousands of pounds of scientific gear falling on something or someone. Minneapolis did not qualify. The National Center for Atmospheric Research had a balloon launching facility in Texas, but it was too far south. Instead, we would be operating from makeshift facilities in a town of modest population that offered enough infrastructure to meet our launch requirements.

Magnetic fields, wind patterns, and the need to avoid people: this is why in April of 1977, we were in the town of Aberdeen, South Dakota.

There was a regional airport outside of town, and an airplane hangar was provided to house our laboratory field station.  It took several days to set up our equipment and prepare our experiment, and we now waited for its launch.  We would be waiting for weeks because a balloon launch requires low surface winds, but in South Dakota the winds flowing across the prairie were incessantly too high.  We heard stories from the visiting Texas crew of launches gone wrong, where the weather was perfect right up until it wasn’t, with balloons twisting into self-damaging knots, or shearing to the side, unable to break free of the release spool, or splitting away from its helium filling tubes.  A balloon is a specialized and expensive item, and no one wanted to be risking their career-critical instrument package.  We waited for the right launch conditions.

Launch at Last

Finally one day, the meteorologist declared that the winds would diminish in the late afternoon.  We were skeptical, because it seemed like a day like every other—winds blowing across the prairie as usual.  But sure enough, at around 5:00 the digital anemometer I had jury-rigged showed a leading zero for the first time in weeks.  The launch crew set to work.

The launch sequence, with photographs, is described in the full story at https://thorolson.com/launching-crisis/launch-at-last/

The launch was exciting, but now the serious business of monitoring began. A data stream was radioed back that gave altitude and position information. When the balloon reached the target height of about 20 miles, data collection could begin in earnest. It was important to stay as high as possible for as long as possible. The balloon drifted with the high-altitude winds, which we had no control over, and rose up and down with temperature variations, over which we did have some control. The payload included ballast, containers of metal shot that had radio-controlled valves. When the temperature dropped, as it did during the darkness of night, the balloon would shrink, become less buoyant and drop in altitude. To compensate, we could lighten the load by releasing some ballast. As the first night progressed, numerous ballast drops were made to maintain height.

The Mission Ends

I would not stay around to see the mission end. Once the instrument was airborne, there was no further purpose for our lab in the airplane hangar, and my job title became moving man and trucker to bring everything back to the labs in Tate Hall.

I learned later that the balloon carrying our instrument had drifted west, accumulating 56 hours of data. It eventually was radio-commanded to cut its cables and release the payload, which descended by parachute and was retrieved in the high plateau of central Washington. 

The data gathered from our CRISIS project was reported over the next years in scientific journals and conferences. Our results, along with other similar experiments, contributed to early understandings of the makeup of cosmic rays.

Afternotes

It has been nearly 50 years since that eventful spring. In gathering my memories for this story I relied on indirect clues from the photos I took. I also was able to track down Chuck Gilman, now retired after a fascinating career in high energy physics. Our reconnection and reminiscences surfaced additional background information. There are still a few questions which could be resolved by a few key people. Sadly, our professor mentors, Phyllis Freier and Jake Waddington have passed away.

It had been a remarkable experience for me, a young physics and engineering student starting his career. It reinforced my growing suspicion that experiments and measurements in physics required proficiency in electronics and instrumentation. I pursued that course, combining the disciplines of physics and electronics, and was rewarded with a fascinating and satisfying career. It had many highlights, but nothing as unique as what I experienced waiting six weeks for the wind to die down in Aberdeen, South Dakota, to launch a cosmic ray research balloon.  

Thor Olson
November 2024