July 18, 2012
NASA Mission Set To Study Plasma
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Lee Rannals for redOrbit.com - Your Universe Online
Ninety-nine percent of the universe is made of this electrified gas, but when it comes to the Earth it is more absent than present.
There are two giant donuts of plasma surrounding Earth trapped within a region known as the Van Allen Radiation Belts. The belts are close to Earth, sandwiched between satellites in geostationary orbit above. Satellites in low Earth orbit (LEO) are generally below the belts.
RBSP is set up to help improve our understanding of what makes plasma move in and out of these electrified belts wrapped around our planet, NASA said.
"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. "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 inner radiation belt is essentially stable, but the number of particles in the outer belt can jump 100 times or more, which could encompass a horde of communication satellites and research instruments orbiting Earth.
In order to understand more about what is driving these changes in the belts, scientists must have a better understanding about what drives the plasma.
Plasmas generally flow along a skeletal structure made of invisible magnetic field lines, while simultaneously creating more magnetic fields as they move.
Understanding the rules that help dictate the environment will help scientists also have a deeper grasp about the range of events that make up space weather.
RBSP scientists have designed a suite of instruments to answer three broad questions, including: Where do the extra energy and particles come from?; Where do they disappear to, and what sends them on their way?; and How do these changes affect the rest of Earth's magnetic environment, the magnetosphere?
The mission will also use two spacecraft in order to better map out the full spatial dimensions of a particular event and how it changes over time.
Scientists want to understand not only the origins of electrified particles, but also what mechanisms gives the particles their extreme speed and energy.
"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 be able to measure a wide range of energies from the coldest particles in the ionosphere to the most energetic, most dangerous particles. Having information about how the radiation belt swells and shrinks 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."
Another reason scientists are interested in studying the belts is because it is the closest place to study plasma. NASA said that understanding this environment so foreign to our own is crucial in understanding the make-up of the universe.