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Millan Leads Balloon-Based Study of Earth's Van Allen Belts

Undergraduate improves design of equipment

Robyn Millan, assistant professor of physics and astronomy, was recently awarded $9.3 million by NASA to fund her study of the Earth's Van Allen Belts using high-altitude balloons launched from Antarctica. When the balloons are sent up in a series of launches over the next five years, the payload, which carries the instrumentation used to take readings from the outer atmosphere, will have been designed by Dartmouth undergraduate Robin Meyers '10.

Group photo
From left: Robin Meyers '10; Robyn Millan, assistant professor of physics and astronomy; and Mary Hudson, the Eleanor and Kelvin Smith Distinguished Professor in Physics. (photo by Joseph Mehling '69)

Meyers was a sophomore interested in engineering when he saw Millan's job posting on an engineering career services bulletin at Thayer School of Engineering. The posting called for someone with computer-aided design (CAD) experience, something Meyers had been working with since high school. Although he had no background in astronomy or physics, he and another undergraduate (a visiting student from Middlebury) were asked to use their CAD skills to design the placement of the instruments in the payload.

According to Meyers, in earlier balloon launches, "the components were just put in a box, and it was hard to access if anything went wrong in them. We were asked to come up with a new design where everything will be secured in the box and easily accessible."

Meyers' design was part of the presentation Millan made to NASA that secured the funding for the project. After more than a year of review and a study of how the project would work, NASA awarded the 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 Mary Hudson, the Eleanor and Kelvin Smith Distinguished Professor in Physics, will conduct test flights of the balloons and their instrumentation, and in early 2013, they will launch roughly 20 balloons from South African and British Antarctic research stations. A year later, they will repeat the procedure.

Balloon launch
Members of the BARREL team launch a balloon from South Africa's Antarctic station during a previous campaign. (photo by John Sample/U.C. Berkeley)

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 Probe 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," says 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," she explains.

Martin Wybourne, vice-provost for research, says, "Understanding space weather is critically important because it can disrupt many of the technological systems on which society relies. Professor Millan's multiballoon-based experiments to probe the complex processes that particles undergo in the atmosphere will add important new elements to the understanding. The work will also bring new opportunities for Dartmouth students and will strengthen the College's position as one of the leading institutions for space weather research."

By GENEVIEVE HAAS

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Last Updated: 5/30/08