NASA awards $9.3 million to Dartmouth researcher for radiation study using
balloons
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. The flotilla of balloons will carry instrumentation
that may allow scientists to better understand and predict how the belts
release radiation into the near-Earth space.
 Members of the Balloon Array for
Radiation-belt Relativistic Electron Losses (BARREL) team launch a balloon from
the South African Antarctic station during a previous campaign. Dartmouth’s
Robyn Millan is principal investigator of a NASA study that will use balloons
to better understand the Earth’s Van Allen Belts.
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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.
Robyn Millan
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“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,” says Millan.
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 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.”
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