Probes To Study Van Allen Radiation Belts
August 20, 2012

Twin Probes To Study Space Weather Extremes In The Van Allen Radiation Belts

Video: The Radiation Belt Storm Probe

Lee Rannals for - Your Universe Online

NASA will be launching its Radiation Belt Storm Probes (RBSP) mission from Kennedy Space Center in Florida this Friday, August 24.

The launch was delayed by 24 hours overnight Sunday due to an anomalous engine condition that was identified during testing of another Atlas vehicle at the Factory in Decatur, Ala. According to NASA's website, "the delay will allow additional time for engineers to complete their assessments and verify that a similar condition does not exist on the RBSP launch vehicle engine."

The mission will send two spacecraft into Earth's harsh radiation belts in order to collect crucial data to help scientists have a better understanding of the most hazardous regions of near-Earth space.

The two Van Allen radiation belts have very high energy electrons and protons that can pose hazards to human and robotic explorers.

"We discovered the radiation belts in observations from the very first spacecraft, Explorer 1, in 1958" David Sibeck, a space scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., and the mission scientist for RBSP, said in a prepared statement. "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."

The RBSP mission will help scientists understand how the belts behave and react to changes in the sun, which contributes to Earth's space weather.

"The dramatic dynamics of Earth's radiation belts caused by space weather are highly unpredictable," Barry Mauk, RBSP project scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md, said. "One of the fundamental objectives of the RBSP mission is to use Earth's magnetosphere as a natural laboratory to understand generally how radiation is created and evolves throughout the universe. There are many mysteries that need to be resolved."

The spacecraft will be launching aboard a United Launch Alliance Atlas V rocket from Cape Canaveral.

"Everything is ready and prepared for RBSP to launch as scheduled," Richard Fitzgerald, RBSP project manager at APL, said. "Both the twin spacecraft and the entire RBSP team are eager to begin their exploration of one of the most dangerous parts of space near our planet."

The two spacecraft will have nearly identical eccentric orbits that will cover the entire radiation belt region. They will be lapping each other several times over the course of the mission.

Scientists want to not only understand the origins of electrified particles, but also what mechanisms gives the particles their speed and energy. Electrified particles, also known as plasma, make up 99% of the universe.

"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, RBSP's 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."

RBSP will also be measuring a range of energies from the coldest particles in the ionosphere to the most energetic. NASA said information about how the radiation belts swell and shrink will help improve models of Earth's magnetosphere as a whole.

"Particles from the radiation belts can penetrate into spacecraft and disrupt electronics, short circuits or upset memory on computers," Sibeck said. "The particles are also dangerous to astronauts traveling through the region. We need models to help predict hazardous events in the belts and right now we are aren´t very good at that. RBSP will help solve that problem."

Image 2 (below):  An artist's rendition of what the two Radiation Belt Storm Probe spacecraft will look like in space. Credit: NASA/Goddard Space Flight Center