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.


 
 

 

Headlines April 1, 2015

News: Iranian aircraft buzzed U.S. Navy helo in Persian Gulf - An Iranian aircraft buzzed a Navy helicopter operating in the Persian Gulf earlier this month, a U.S. military official said March 31. Active duty suicides up in 2014 - Suicides among active duty members of the military increased in 2014, though reservists and members of the...
 
 

News Briefs April 1, 2015

Germany, France, Italy plan to develop military drones Germany and France plan to work together with Italy to develop military surveillance drones that could also carry weapons. French President Francois Hollande said after meeting German Chancellor Angela Merkel March 31 that it is important for Europe to be independent in both manufacturing drones and in...
 
 
Northrop Grumman photograph

AirRobot, Northrop Grumman Remotec sign distribution agreement for unmanned aerial systems

Northrop Grumman photograph An AirRobot unmanned aerial system flies at Fort Benning, Ga.. Northrop Grumman Remotec is the sole reseller of the systems to law enforcement and first responders under a distribution agreement sign...
 

 

Raytheon awarded $528 million AMRAAM contract

Raytheon has been awarded a $528,797,459 fixed-price incentive, firm target contract modification for Advanced Medium Range Air-to-Air Missiles. Raytheon will provide AMRAAM Lot 29 missiles and other AMRAAM system items. This contract involves foreign military sales. Work will be performed in Tucson and is expected to be complete by January 2018. This award was booked...
 
 

Raytheon, DRS team for Army’s third Generation IFLIR B-Kit

Building on their combined platform integration experience, Raytheon and DRS Technologies have entered into a teaming agreement for the U.S. Army’s 3rd Generation Improved Forward Looking Infrared program B-Kit “Raytheon and DRS have teamed to provide an IFLIR solution that provides our military supremacy in reconnaissance, surveillance and target acquisition,” said Dr. Taylor...
 
 

U.S. Air Force awards Raytheon $91.5 million for MALD-J

Raytheon Company received a $91.5 million U.S. Air Force contract modification award for the Miniature Air Launched Decoy Jammer missile. The contract modification is for Lot 8. Work will be performed in Tucson and is expected to be complete by June 2017. This award was booked in the first quarter 2015. MALDÆ is a state-of-the-art,...
 




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>