Van Allen Probes: Giant Electric Fields Supercharge Particles In Radiation Belts

Huge electric fields in the radiation belts around Earth may help explain how electrons surrounding the planet can be accelerated to speeds near that of light, researchers have found in a new study.

These findings, detailed Dec. 2 in the journal Physical Review Letters, could help shed light on the radiation belts of planets such as Jupiter, Saturn, Uranus and Neptune, as well as the behaviour of the sun during flares and of bodies beyond the solar system, such as stellar nurseries, neutron stars and incredibly energetic black holes known as quasars.

After humanity began exploring space, the first major find made there were the Van Allen radiation belts, zones of magnetically trapped, highly energetic charged particles discovered in 1958.

The Van Allen Probes aka Radiation Belt Storm Probes (RBSP) Mission, part of NASA's Living With a Star program, will provide unprecedented insight into the physical dynamics of the radiation belts. 

Credit: NASA

These belts generally consist of two rings: 

• an inner zone with both high-energy electrons and very energetic positive ions that remains stable in intensity over the course of years to decades; and
• an outer zone made up mostly of high-energy electrons whose intensity swings over the course of hours to days, primarily depending on the influence from the solar wind, the deluge of radiation streaming from the sun. 

Earlier this year, scientists also detected a third radiation belt temporarily surrounding Earth.

The gigantic amounts of radiation the Van Allen belts generate can pose serious risks for satellites. To learn more about them, NASA launched twin spacecraft, the Van Allen probes, in the summer of 2012.

The satellites are armed with a host of sensors to comprehensively analyze the plasma, energetic particles, magnetic fields and plasma waves in these belts with unprecedented sensitivity and resolution.

Two giant swaths of radiation, known as the Van Allen Belts, surrounding Earth were discovered in 1958. In 2012, observations from the Van Allen Probes showed that a third belt can sometimes appear. 

The radiation is shown here in yellow, with green representing the spaces between the belts. 

Credit: NASA/Van Allen Probes/Goddard Space Flight Center.

Now, using the Van Allen probes, scientists have detected structures that pop in and out of existence in the outer belt that could help explain the high-energy electrons seen in that zone.

The structures in question are known as "double layers." They are each made up of a pair of parallel layers of particles with opposite electrical charge that move along Earth's magnetic field.

The probes saw huge numbers of double layers in the outer belt —7,000 in the course of a minute, each lasting on the order of seconds.

These double layers were discovered "sort of by accident as the Van Allen probes passed through this region of space, and only captured a snapshot," said study lead author Forrest Mozer, a physicist at the University of California, Berkeley.

"The spacecraft will get back to this region maybe eight months, maybe 10 months from now, and we're setting up our instruments to do what we now know they should — to collect data at that site then with a continuous view, to really get definitive information on what is going on there."

Mysterious electron Cluster found hidden among Van Allen belts

This NASA rendering depicts Earth's Van Allen radiation belts and the path of the Van Allen Probe spacecraft, which were launched in August 2012. 

Data from the spacecraft have confirmed a never-before-seen phenomenon-a long-lived zone of high-energy electrons residing between the inner and outer radiation belts. (Credit: NASA illustration)

U.S. researchers, including a trio from Los Alamos National Laboratory, have witnessed the mysterious appearance of a relatively long-lived zone of high-energy electrons stored between Earth's Van Allen radiation belts.

The surprising findings, discovered by NASA's Van Allen Probes (formerly known as the Radiation Belt Storm Probes), were outlined Thursday in Science Express and during a press conference at NASA headquarters in Washington, D.C.

The research was led by Dan Baker of the University of Colorado, Boulder, Laboratory for Atmospheric and Space Physics.

"Nature keeps on surprising us by producing long-lived harsh environments in space in regions not previously considered," said Los Alamos plasma physicist Reiner Friedel of LANL's Intelligence and Space Research Division. "This finding may impact the planning of future space missions."

The Van Allen radiation belts - named in honor James Van Allen, who discovered them nearly 50 years ago - are a pair of donut shaped zones of charged particles that surround Earth and occupy the inner region of our planet's Magnetosphere.

The outer belt contains extremely high-energy electrons, while the inner belt is comprised of energetic protons and electrons.

The belts have been studied extensively since the dawn of the Space Age, because the high-energy particles in the outer ring can cripple or disrupt spacecraft. Long-term observation of the belts have hinted that the belts can act as efficient and powerful particle accelerators; the recent observations by the Van Allen Probes-a pair of spacecraft launched in August 2012-now seem to confirm this.

Shortly after launch, the spacecraft activated their Relativistic Electron-Proton Telescope (REPT) instruments to measure particles within the belts and their immediate environs.

The instrument immediately detected on September 1, 2012, the presence of a stable zone of high-energy electrons residing between the belts. This donut-shaped third ring nestled between the belts existed for nearly a month before being obliterated by a powerful shockwave of particles emanating from center of the solar system.

Such a distinct, long-lasting ring of high-energy electrons had never before been seen by any prior instrument in space or on Earth.

The findings suggest that the Van Allen Belts somehow capture and store energetic electrons in a circular path around our home planet, perhaps in much the same way as a cyclotron can capture and store charged particles here on Earth.

"One of the main reasons the Van Allen Probe instruments are seeing these new features are their unprecedented sensitivity and rejection of backgrounds," Friedel said.

"As the mission proceeds, we expect further surprises that will challenge our conventional wisdom on the transport, loss and energization processes in these highly energetic electron radiation regions."

RBSP Launch - Multiple camera angles - YouTube

Video from several different cameras of the Aug. 30 4:05 a.m. EDT launch of NASA's Radiation Belt Storm Probes.

NASA Space Weather: RBSP Successful Launch Today

The countdown was holding at the T-4 minute mark for 25 minutes but the launch went ahead as planned.

The Atlas V first stage and Centaur upper stage had been fueled for the planned launch at 4:05 a.m. EDT of NASA’s Radiation Belt Storm Probes (RBSP). 

The Atlas V burns refined kerosene fuel, known as RP-1, mixed with liquid oxygen.

There are no technical problems and weather has improved to 90 percent “go.”

NASA RBSP Moves to Kennedy Space Centre

NASA RBSP took a 15-mile trip from Astrotech to Kennedy Space Centre.

It took 3.5 hrs at an average speed of 7mph. 

Credit: NASA

Space Weather: RBSP - Twin NASA probes around our Earth

Spectacular events on Mars are making most of the space headlines, but NASA is getting ready to launch an upcoming mission to explore the environment of our own planet Earth.

Twin Radiation Belt Storm Probes (RBSP) are due to lift off aboard a United Launch Alliance Atlas V rocket on August 23 from Cape Canaveral, Florida.

They were placed, in their nose cone, atop the rocket on August 10. 

The two satellites will travel in orbits that take them through two extreme and dynamic regions of space surrounding the Earth called the Van Allen Radiation Belt.

They will probe space weather, the direct effects of activity on the Sun, which can in extreme cases damage satellite electronics, GPS services and cause power grids to fail.

Barry Mauk, RBSP project scientist at the Johns Hopkins University, in Maryland, said: "The dramatic dynamics of Earth's radiation belts caused by space weather are highly unpredictable.

"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 radiation belts, named after their discoverer, James Van Allen, are two concentric, donut-shaped rings filled with high-energy particles that dance about, bounce and drift through the region.

Sometimes these particles shoot down to Earth's atmosphere, sometimes they escape into space.

The radiation belts swell and shrink over time, a change that is part of a much larger space weather system that is driven by solar activity as material from the Sun spreads through space.

NASA says that the RBSP probes, the second mission in NASA's Living With a Star program, will help scientists to understand this radiation zone better and to design spacecraft that can survive such environments better.

The spacecraft carrying out such research may eventually help scientists predict space weather before it hits the Earth's neighbourhood.

Follow the RBSP team on Twitter with #RBSP and on their account @RBstormProbes