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A new NASA project will use more than 40 high-altitude balloons to return new scientific insights about the Earth's Van Allen Belts. Research using the balloons can be carried out at a fraction of the cost of using an orbiting satellite. The radiation in the Van Allen Belts can be hazardous to astronauts, orbiting satellites and aircraft flying in high-altitude polar routes.

NASA's Science Mission Directorate, Washington, has awarded $9.3 million to Dartmouth College of Hanover, N.H., for the study.

The new mission is called the Balloon Array for Radiation-belt Relativistic Electron Losses — or Barrel. The mission's principal investigator is Robyn Millan of Dartmouth. Barrel will fly in 2013 and 2014, and will provide answers to how and where the Van Allen Belts, discovered in 1958, periodically drain into Earth's upper atmosphere.

The Van Allen Belts are a ring of energetic, charged particles that encircle the Earth and are constrained by the Earth's magnetic field. Outbursts from the sun can pump additional energy and particles into the radiation belts, allowing them to drain again in a matter of days or weeks.

Barrel will fly in conjunction with NASA's Radiation Belt Storm Probes satellites, due to launch in 2011. The balloons will be launched from Antarctica. They will expand to roughly the size of a large blimp when they reach the near-space research altitude. A single balloon of this type will hover at an altitude of approximately 21 miles for as long as two weeks. By carefully timing the launch of a series of balloons, about one per day, Millan and her group of researchers can form a ring of balloons encircling the South Pole to study the total influx of radiation from the belts into Earth's atmosphere.

The Radiation Belt Storm Probes satellites are part of NASA's Living with a Star Program that is designed to understand how and why the sun varies, how planetary systems respond and how human activities are affected. NASA's Goddard Space Flight Center, Greenbelt, Md., manages the program for the Science Mission Directorate.