Balloon Research Launch Requires Teamwork, Early Start
November 20, 2012 — A small facility, located at the end of a lonely, washboard dirt road off State Highway 130, is visible in the dark due only to a few lights that emanate inside, while a faint glow cast from nearby Laramie Regional Airport illuminates the shape of the building.
Inside, University of Wyoming scientists quietly prepare to launch a balloon that will record stratospheric aerosol.
Terry Deshler, a professor in the UW Department of Atmospheric Science, works with Shane Murphy, a new assistant professor of atmospheric science, and doctoral student Patrick Campbell, who tinker with and batten down aerosol-measuring equipment they will send skyward in a few short hours.
The wee-hour ritual begins inside the facility, where the team reviews the instrument gondola, which includes two aerosol-measuring instruments; two instruments to measure ozone; a GPS tracking device and a camera, Campbell says.
The equipment is encased in Styrofoam for cushioning and insulation, and is attached to an aluminum frame that uses nylon and fiber straps. For the antenna, designed to break free on impact, tape is administered. It all sits on two paper crash pads designed to help brace the impact when the equipment parachutes back to Earth, Campbell says.
Murphy relays information -- including the current temperature and radio frequency -- to the telemetry center, where other team members monitored receivers and computers that would later collect the aerosol data in real time after the balloon was launched.
Campbell checks the transponder, which “paints” the instruments so they are visible to aircraft, he says.
Catch the wind
Obtaining the measurements isn’t just a matter of inflating a balloon and sending it on its way. Executing an actual balloon launch can be tricky, relying on such factors as wind speed and direction to gauge a balloon’s trajectory, as well as a requirement of less than 50 percent cloud cover.
For example, winds from the northwest push instruments to the southwest, which is not ideal as such winds push the balloons into airspace over Denver International Airport. If winds originate from the east, balloons are pushed west and into the mountains, also an unwanted outcome.
“Wind direction is critical,” Deshler says. “Generally, we want winds from the west-northwest or southwest. That’s ideal for a balloon trajectory that does not interfere with air traffic and allows the instruments to be easily recovered.”
In addition to the wind moving in the proper direction, wind speeds must be less than 10 knots at the ground level to ensure the measuring instruments can be lifted off the ground without incurring damage, Deshler says.
Deshler and his team -- which includes an engineer and technician from UW’s Atmospheric Science Department and three graduate students -- rise two to three hours before dawn to check and ready the measuring equipment at UW’s balloon launch facility, located approximately two miles east of Laramie Regional Airport.
The team originally planned to launch the research balloon Nov. 12 to be in concert with the next satellite overpass. However, multiple days of delays nixed that goal. Due to wind speeds being too high, blowing in the wrong direction, and even a light snow one morning, plans were scrapped daily until Nov. 16, when weather conditions were favorable.
To ensure a successful launch, experiments are conducted at dawn -- when winds typically are calmest and before air traffic begins to fill the skies, Deshler says.
After checks inside the facility were completed, the measuring equipment was then wheeled out onto the tarmac, where other team members slowly inflated the balloon, but only partially. Other team members laid out cloth tarps on which the parachute was laid out, connected first to the balloon and then to the measuring equipment.
Up, up and away
Even with all of the precise preparation, surprises happen. Just when it looked like the crew had everything in place for a launch, the surface wind suddenly changed direction. Deshler’s team quickly had to reposition the balloon, parachute and measuring equipment.
The balloons, which resemble giant jellyfish at the surface, are released partially inflated and carry the measuring instruments, which, all told, weighed 123 pounds (including the load line and parachute).
In flight, instruments collect measurements every 10 seconds. In real time, the instruments transmit measurements of particles of various sizes back to the facility.
“The balloon sends us back data that need to be converted after flight into ozone and particle counts, for the older instruments,” Murphy says. “For our new instrument, the tracking software provides preliminary ozone and aerosol levels, but these are also only finally analyzed after flight.”
The balloon fully expands to a diameter of approximately 120 feet when it reaches its ceiling above 30 kilometers (roughly 100,000 feet), Deshler says.
When the balloon reaches its ceiling, a weak seam on the balloon tears open. In turn, a tension switch device releases the measuring package, which, aided by a parachute, falls back to Earth to its forecast destination, Campbell says.
“It was a good launch. Everything went smoothly,” Deshler says. “But I don’t relax until the instruments have safely separated and are on their way back.”
A retrieval team left shortly after the balloon release and was en route east to just north of Bushnell, Neb., approximately 83 miles away (the forecast impact point) to pick up the package.
Terry Deshler (right) and Patrick Campbell, a UW doctoral student in atmospheric science, carry the instrument package into position moments before the balloon launch.