Robyn Millan, Assistant Professor of Physics and Astronomy, will lead a NASA project to launch more than 40 high altitude balloons from Antarctica to study the Earth's Van Allen Belts. The type of radiation in the belts can be hazardous to astronauts, orbiting satellites and aircraft flying in high altitude polar routes, and the flotilla of balloons will carry instrumentation that may allow scientists to better understand and predict how the belts release radiation into the into near-Earth space.
Millan and her team responded to a call for project proposals from NASA in the area of geospace science. After more than a year of review and a study of how the project would work, NASA awarded a $9.3 million contract to fund Millan’s proposal for the Balloon Array for Radiation-belt Relativistic Electron Losses, or BARREL. Over the next several years, Millan and her team, which includes Dartmouth students and Professor of Physics and Astronomy Mary Hudson, will conduct test flights of the balloons and their instrumentation, and in early 2013, Millan and her team will launch roughly 20 balloons from the South African and British Antarctic research stations. A year later, they will repeat the procedure.
The balloons, filled with helium, are roughly spherical and will expand to a diameter of 90 feet as they reach the very edge of Earth’s atmosphere, 21 miles above the ground. Millan and her team will launch a new balloon about once a day, and polar winds will carry them around the South Pole, separated by about 620 miles, for a duration of approximately two weeks. The instruments carried by the balloons will provide answers to how and where the Van Allen Belts, discovered in 1958, periodically release electrons into Earth's upper atmosphere. BARREL will fly in conjunction with NASA's Radiation Belt Storm Probes satellites, due to launch in 2011, allowing Millan’s team to measure both particles in the belts and the particles released from the belts.
“We’re interested in understanding how particles trapped in the radiation belt get lost into the atmosphere,’ said Millan. Charged particles from the Van Allen Belts can cause damage to satellite instrumentation, destroying electronics and causing memory loss. Outbursts from the sun can pump additional energy and particles into the radiation belts, allowing them to drain into the atmosphere in a matter of days or weeks. These fluctuations are poorly understood and highly unpredictable. “Ultimately, people would like to be able to predict that variability so that satellites can protect themselves from big increases in radiation,” said Millan.
Martin Wybourne, Vice-Provost for Research, said “understanding space weather is critically important because it can disrupt many of the technological systems on which society relies. Professor Millan’s multi-balloon based experiments to probe the complex processes that particles undergo in the atmosphere will add important new elements to the understanding. The work will bring new opportunities for Dartmouth students and will strengthen the College’s position as one of the leading institutions for space weather research.”