Sven Bilén, associate professor of engineering design, electrical engineering and aerospace engineering, and John "Jack" Mitchell, professor of electrical engineering, spent three weeks in Fairbanks, Alaska, preparing and launching NASA rockets into the upper atmosphere.
The purpose of the experiment was to collect information about the Turbopause, the layer of atmosphere that exists at an altitude of about 100 km — an area too high for balloons and too low for satellites to measure.
"The region between 50 and 250 kilometers altitude is sometimes referred to as the "ignore-osphere" because it is very difficult to make measurements," said Bilén. "By understanding what happens in that region, we get a better understanding of how the earth couples to the sun."
"All the models on global warming make certain assumptions of what that coupling process is. Getting better data is important — you'd like to have more accurate numbers so you don't make wild assumptions."
In order to collect the data, Bilén, Mitchell and scientists from all over the country traveled to the Poker Flat Research Range earlier this semester, which is located 30 miles north of Fairbanks. During the course of their stay, they assembled, tested and launched four rockets — 35-foot, two-stage Terrior Orions — that traveled 87 miles into the sky.
All four rockets were equipped with a mechanism that released a fluorescing gas into the atmosphere to measure high altitude winds. Two rockets were equipped with an instrument designed by the Leibniz-Institute for Atmospheric Physics containing a filament that was used to ionize gases in the atmosphere, allowing the neutral gases to be measured on grids. In addition, a highly sensitive nose-tip probe sensor element had the ability to measure electric current in femtoamps — the equivalent of one amp (the amount of electric current in a standard light bulb) to the negative 15th power. Charles "Charlie" Croskey, professor emeritus of electrical engineering, designed and built the instrument.
The rockets were launched in a series to observe trending. The first three rockets were launched within 30 minutes of each other, and the last rocket was launched within 50 minutes after the third rocket.
Gerald Lehmacher of Clemson University, who is the principal investigator for the experiment, noted that the "instruments worked well."
The "Turbopause team" is now in the analysis phase, interpreting data and writing journal articles over the next year. Bilén has been sharing his rocket-launching experience with his graduate systems design class.