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RBSP space


An artist's depiction of the two RBSP satellites in orbit around Earth.

NASA launches twin satellites to probe Earth's radiation belts

by Joanna Carver
Aug 22, 2012

RBSP preparations


NASA technicians checking out solar energy arrays on the satellites prior to Thursday's launch from Kennedy Space Center in Orlando.

RBSP logo


The nose cone for the Atlas V rocket that carried the radiation belt storm probes into space.

RBSP storm


An artist's interpretation of a solar storm striking the Earth's magnetic field.

Van Allen belts


An artist's interpretation of the Van Allen radiation belts.

NASA launched twin satellites into the Earth’s massive Van Allen radiation belts Thursday morning to explore an environment that can cripple satellites when a solar storm blasts past Earth.

And that’s just the point. The Radiation Belt Storm Probes will measure the impact of space storms and the activity of the belts on the Earth and on communications and weather satellites.

The mission draws on a legacy of exploration of the belts as astrophysicist James Van Allen and his graduate students helped cradle the space program 60 years ago in the basement of the 1910 physics building at the University of Iowa in Iowa City.

Van Allen headed the physics and astronomy department, pioneered space exploration and found the radiation belts with America’s earliest satellites, making the first discovery of the space age.

The mission launched on an Atlas V rocket from the Kennedy Space Center in Orlando early Thursday morning.

“I think Van Allen would be delighted that there are still mysteries to be discovered that are important mysteries,” said John Wygant, one of the principle investigators on the Radiation Belt Storm Probes mission.

Wygant’s Electric Field and Wave instrument, as the name suggests, will measure electric fields in the belts that can disrupt weather and communications satellites. He said he wasn’t very interested in the radiation belts until a 1992 spacecraft mission he was involved in was suddenly destroyed by a giant shock wave in outer space.

“That kinda told me everything we know about the radiation belts previously was up for grabs,” he said. “The mission is gonna discover new stuff. It’s gonna discover stuff we never even imagined.”


"We live in the atmosphere of the sun. So when the sun sneezes, the Earth catches a cold," said Nicky Fox, deputy project scientist at Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. "So whatever is happening on the sun, the Earth will feel an effect and will respond to that changing space weather."

This is the first time NASA will send dual satellites directly into the radiation belts that surround the planet. The belts are two zones of intense radiation where charged particles from cosmic rays and the solar wind are trapped by the Earth’s powerful magnetic field. The zones can damage and destroy satellites, such as communications satellites. The radiation levels are so intense that spacecraft have to be careful to avoid them.

“The radiation belts for some time were thought to be a solved problem. The scientists in the field kind of moved on to other problems,” said Craig Kletzing, a principle investigator on the mission from the University of Iowa. “It wasn’t until we returned with better measurements that we realized it wasn’t quite so simple.”

The reason for sending two satellites instead of one is so that scientists on the ground can track behavior in the radiation belts at different points simultaneously, which can lend a wider perspective and help in predicting space weather and understanding its impact on Earth.

“We don’t do so well with weather from the surface of the Earth,” Kletzing said. “Space is a lot bigger and there are a lot fewer measurements.”

The spacecraft measure about six feet in diameter, each with cables the length of a football field that anchor spin plane booms on their tips. These act as sensors that can collect better measurements of radiation belt conditions far away from the satellites themselves.

In the past, spacecraft have had to navigate around the radiation belts to avoid being damaged or destroyed. The RBSP satellites have been heavily shielded with a thick layer of aluminum to allow them to collect data in the belts.

“There’s a tremendous intellectual reach for a mission like this,” said John Wygant of the University of Minnesota, principle investigator for RBSP’s EFW (Electric Field and Wave) Instrument.

There are five sets of instruments carried by RBSP. Kletzing is the principle investigator on EMFISIS (Electric and Magnetic Field Instrument Suite and Integrated Science), which will measure a range of radio waves in the belts.

Kletzing said the mission has enduring connections with Van Allen's work. “It’s quite amazing that 50 years later the University of Iowa is actively involved with this mission,” he said.

Van Allen discovered the first hints of the radiation belts after firing “rockoons,” economy-model surplus rockets that could nonetheless reach into space because they were launched several miles above the earth by gas-filled balloons. Van Allen launched rockoons in the Arctic and Antarctic circles in the 1950s before the launch of satellites officially ignited the space race with Sputnik in 1957.

For the next 50 years, until his death in 2006, he was involved in the Pioneer, Mariner, Voyager and Galileo missions, which flew unmanned spacecraft across the solar system.

Lou Lanzerotti of the New Jersey Institute of Technology is the principle investigator on the RBSPICE (Radiation Belt Storm Probes Ion Composition Experiment) instrument, which will measure electrons and energy ranges in the Van Allen Belts.

Lanzerotti has been involved with the space program since 1969, when he decided to pursue a career that combined physics and engineering. After working on close to a dozen NASA missions, including Voyager and Cassini, RBSP will be his last mission.

“It’s certainly back to the future for me,” he said.

Lanzerotti said he is looking forward to the data coming in and to having a rest after a long career.

“After 50 years it’s about time to let the younger generation take over,” he said. “I think it’s really important to let the younger people take a leadership role.”

But Lanzerotti said the mission touches very well on Van Allen’s legacy as a scientist.

“We know a lot more about the kinds of measurements we should be making to understand the space environment in more depth,” he said. “The two spacecraft are better instrumented than anything that has been done since the discovery of the Van Allen Belts.”

Harlan Spence of the University of New Hampshire is the principle investigator on the ECT (Energetic Particle, Composition and Thermal) instrument suite, the largest of the instruments, which will measure the energies of charged particles.

“It’s hard not to be mindful of the past when you’re working with the first generation of explorers,” he said. “They were really the pioneers of that 50 years ago and many of them are still working.”

But while the launch itself is exhilarating, he’s most excited about making new discoveries in the radiation belts, even more than five decades after they were discovered. After finishing graduate school, he worked with Van Allen on the Journal of Geophysical Research.

“He was just a remarkable scientist, a remarkable individual,” he said. “You’d never know talking to him [about] his great accomplishments, because he was a very humble man. He had strong opinions but he expressed them in a very humble manner.”

One of those strong opinions, Spence said, was that Van Allen was a strong proponent for basic scientific exploration and robotic missions, rather than human space flight, a point of view that didn’t always win him favor.

“That he had the imagination to put scientific instruments into space is just phenomenal,” he said. “There’s a kind of basic wonder, basic amazement of being able to do science from space. I think you can trace a lot of that history of space exploration back to Jim Van Allen.”