Space

July 26, 2013

NASA mission discovers particle accelerator in heart of Van Allen Radiation Belts

Using data from a NASA satellite, scientists have discovered a massive particle accelerator in the heart of one of the harshest regions of near-Earth space, a region of super-energetic, charged particles surrounding the globe and known as the Van Allen radiation belts.

New results from NASA’s Van Allen Probes show the acceleration energy is in the belts themselves. Local bumps of energy kick particles inside the belts to ever-faster speeds, much like a well-timed push on a moving swing. Knowing the location of the acceleration within the radiation belts will help scientists improve predictions of space weather, which can be hazardous to satellites near Earth. The results were published Thursday in the journal Science.

“Until the 1990s, we thought  the Van Allen belts were pretty well-behaved and changed slowly,” says Geoff Reeves, lead author on the paper and a radiation belt scientist at Los Alamos National Laboratory in Los Alamos, N.M. “With more and more measurements, however, we realized how quickly and unpredictably the radiation belts change. They are basically never in equilibrium, but in a constant state of change.”

In order for scientists to understand such changes better, the twin Van Allen Probes fly straight through this intense area of space. One of the top priorities for the mission, launched in August, is to understand how particles in the belts are accelerated to ultra-high energies.

By taking simultaneous measurements with advanced technology instruments, the Van Allen Probes were able to distinguish between two broad possibilities on what accelerates the particles to such amazing speeds. The possibilities are radial acceleration or local acceleration. In radial acceleration, particles are transported perpendicular to the magnetic fields that surround Earth, from areas of low magnetic strength far from Earth to areas of high magnetic strength closer to Earth. Physics dictates particle speeds in this scenario will increase as the magnetic field strength increases. The speed of the particles would increase as they move toward Earth, much the way a rock rolling down a hill gathers speed due to gravity.

The local acceleration theory proposes the particles gain energy from a local energy source, similar to the way warm ocean water can fuel a hurricane above it.

Reeves and his team found they could distinguish between these two theories when they observed a rapid energy increase in the radiation belts Oct. 9. The observations did not show an intensification in particle energy starting at high altitude and moving gradually toward Earth, as would be expected in a radial acceleration scenario. Instead, the data showed an increase in energy that started right in the middle of the radiation belts and gradually spread both inward and outward, implying a local acceleration source. The research shows this local energy comes from electromagnetic waves coursing through the belts, tapping energy from other particles residing in the same region of space.

“These new results go a long way toward answering the questions of where and how particles are accelerated to high energy,” said Mona Kessel, Van Allen Probes program scientist in Washington. “One mission goal has been substantially addressed.”

The challenge for scientists now is to determine which waves are at work. The Van Allen Probes, which are designed to measure and distinguish between many types of electromagnetic waves, will tackle this task, too.

The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., built and operates the twin Van Allen Probes for NASA’s Science Mission Directorate. The Van Allen Probes are the second mission in NASA’s Living With a Star program, managed by NASA’s Goddard Space Flight Center in Greenbelt, Md. The program explores aspects of the connected sun-Earth system that directly affect life and society.

 




All of this week's top headlines to your email every Friday.


 
 

 

News Briefs August 18, 2014

New U.S. strikes in Iraq include land-based bombers The latest round of U.S. airstrikes in Iraq against the Islamic State extremist group includes the first reported use of land-based bombers in the military campaign. U.S. Central Command says a combination of bombers, fighter jets, attack planes and unmanned drones hit targets near Iraq’s largest dam...
 
 

Headlines August 18, 2014

News NATO would respond militarily to Crimea-style infiltration: general If Russia tries to infiltrate troops into a NATO country, even out of official military uniform as it did before it annexed Ukraine’s Crimea, NATO will respond militarily, the alliance’s top commander said in an interview published Aug. 17. http://www.reuters.com/article/2014/08/17/us-ukraine-crisis-breedlove-i...
 
 

U.S. Navy to test, evaluate Lockheed Martin industrial exoskeletons

Lockheed Martin has received a contract through the National Center for Manufacturing Sciences for the U.S. Navy to evaluate and test two FORTIS exoskeletons. This marks the first procurement of Lockheed Martin’s exoskeletons for industrial use. Terms of the contract were not disclosed. The FORTIS exoskeleton is an unpowered, lightweight exoskeleton that increases an operator’s...
 

 

Orbital completes third cargo delivery mission to ISS

Orbital Sciences Corporation, one of the world’s leading space technology companies, announced Aug. 18 the successful completion of its third cargo delivery mission to the International Space Station in the past 10 months, including the initial demonstration flight completed in October 2013 and the first two operational missions under the company’s $1.9 billion Commercial Resupply...
 
 

Brown extends tax credit to Northrop Grumman

California Gov. Jerry Brown has signed legislation that extends a $420 million state tax credit to aerospace giant Northrop Grumman after approving a similar deal for its competitor, Lockheed Martin. Brown’s office announced Aug. 15 that he signed SB718 by Sens. Richard Roth, D-Riverside, and Sen. Stephen Knight, R-Palmdale. It expands an aerospace tax credit...
 
 
Air Force photograph by SSgt. Sean Martin

Bomber crews showcase take-off talents

https://www.youtube.com/watch?v=F_8qr7ojpWg&feature=player_embedded Air Force photograph by SSgt. Sean Martin A B-52H Stratofortress starts its engines during a Minimum Interval Takeoff on Barksdale Air Force Base, La., Au...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>