July 17, 2011 | HAO’s HiWind, a balloon-borne instrument that measures winds in the thermosphere, was launched from Esrange, Sweden. It ascended about 26 miles (43 kilometers) into the atmosphere and headed west across the Atlantic Ocean, passing above Greenland on its way to Canada in round-the-clock sunlight. The flight was terminated on June 17 and the payload landed with a parachute descent 300 miles northeast of Cambridge Bay, Nunavut.
A team of researchers in HAO has been working on HiWind for the past three years. Qian Wu, Alice Lecinski, and Greg Card spent five weeks at Esrange building, testing, launching, and monitoring HiWind. Launch services were provided by the NASA Columbia Scientific Balloon Facility, with the help of Swedish colleagues at the Esrange facility.
“It was very rewarding to see HiWind leave the launch vehicle and silently drift into the early morning sky,” says Greg, who served as project engineer and traveled to Canada to retrieve instrument data from the recovery site. “I was also relieved to see that HiWind received minimal damage when it touched down on a snow field and gently rolled onto its back side.”
A NASA-sponsored mission, HiWind is a balloon-borne Fabry-Perot interferometer that measures thermospheric winds, which are important for understanding Earth’s upper atmosphere. Data from the mission will help scientists study the impact of heating in high-latitude regions on thermosphere global circulation, the interaction between the thermosphere and ionosphere above the polar cap during the summer, and how energy is transferred from the solar wind to Earth’s upper atmosphere. The data will be used to validate two key NCAR community models: TIEGCM (Thermosphere Ionosphere Electrodynamic General Circulation Model) and WACCM (Whole Atmosphere Community Climate Model).
HiWind is especially significant as the first balloon-borne Fabry-Perot interferometer to measure the daytime thermospheric winds. Positioned near the top of the stratosphere, the upward-pointing instrument was able to measure winds in the high, thin thermosphere.
“The mission has opened a new window to explore the daytime thermosphere and ionosphere,” says Qian, principal investigator for the project. “There have been many attempts to measure daytime thermospheric winds from ground-based and satellite-borne instruments, but many have only obtained mixed results. I’m very excited about HiWind as it will make a big difference.”
The instrument measures 164 inches (417 centimeters) and weighs about 1,600 pounds (726 kilograms). Solar panels on its body were continuously positioned to face the Sun during flight to provide power and shade critical areas of the instrument from intense solar radiation. A large radiator at the rear allowed precise thermal control of sensitive components inside the payload.
The team has submitted a proposal to NASA to re-fly HiWind in 2013 and 2014.