Mission to study plasma around Earth

GREENBELT, Md., July 19 (UPI) -- NASA says its next science mission, to study two giant donuts of electrified gas known as plasma that surround Earth, will launch in August.

The Radiation Belt Storm Probes will improve understanding of what makes the plasma move in and out of a region known as the Van Allen Radiation Belts, the space agency said in a release Thursday.

There are two such belts. The inner belt stays largely stable, but the number of particles in the outer one can swell 100 times or more, easily encompassing a horde of communications satellites and research instruments orbiting Earth.

"We discovered the radiation belts in observations from the very first spacecraft, Explorer 1, in 1958," David Sibeck at NASA's Goddard Space Flight Center in Greenbelt, Md., said. "Characterizing these belts filled with dangerous particles was a great success of the early space age, but those observations led to as many questions as answers. These are fascinating science questions, but also practical questions, since we need to protect satellites from the radiation in the belts."

Figuring out what drives the changes in the belts requires understanding what drives the plasma, scientists say.

"We know examples where a storm of incoming particles from the sun can cause the two belts to swell so much that they merge and appear to form a single belt," Shri Kanekal, deputy project scientist at Goddard, said. "Then there are other examples where a large storm from the sun didn't affect the belts at all, and even cases where the belts shrank. Since the effects can be so different, there is a joke within the community that 'If you've seen one storm ... You've seen one storm.' We need to figure out what causes the differences."