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 August 1, 2015

News: Marine F-35 jets deemed ready for combat – A small batch of the highly anticipated – and much criticized – F-35B Joint Strike Fighter jets have been approved for combat by the U.S. Marine Corps.   News: Reports: China to sell J-10 fighter to Iran, Syria? – Iran is rumored external link to be buying 150...
 
 

News Briefs August 3, 2015

Russian military helicopter crashes during air show, one dead A Russian military helicopter crashed Aug. 2 during an aerobatic display, killing one of its crewmembers and injuring another, the Defense Ministry said. The Mi-28 helicopter gunship was part of a flight of helicopters performing aerobatics at the Dubrovichi firing range in Ryazan region, about 170...
 
 
Army photograph by John Andrew Hamilton

Improved Multiple Launch Rocket System tested at White Sands Missile Range

Army photograph by John Andrew Hamilton A Multiple Launch Rocket System with an improved armored cab fires a training rocket during a test. The rockets were simple training rockets and not equipped with a warhead, but still gen...
 

 

Missile Defense Agency, Raytheon demonstrate SM-6’s new anti-ballistic missile defense capability

In a first-of-its-kind test, the U.S. Navy fired a Raytheon Standard Missile-6, intercepting and destroying a short-range ballistic missile target at sea. The successful U.S. Missile Defense Agency test proved a modified SM-6 can eliminate threat ballistic missiles in their final seconds of flight. “SM-6 is the only missile in the world that can do...
 
 

Northrop Grumman-developed stealthy data link validated as combat ready with U.S. Marine Corps

the U.S. Marine Corps achieving F-35B initial operating capability, the Multifunction Advanced Data Link waveform developed by Northrop Grumman has been proven a key combat-ready capability of the F-35 Lightning II program. MADL is a high-data-rate, directional communications link that allows fifth-generation aircraft to communicate and coordinate tactics covertly. During testing of the Lockhee...
 
 

Lockheed Martin technology helps pilots, UAS operators share data, stay safe

As Unmanned Aircraft Systems take to the skies, it is essential for safety that UAS operators and pilots are aware of each other. To help provide this shared situational awareness, Lockheed Martin has deployed the first components of a UAS traffic management system that is available to the UAS community now. Lockheed Martin’s online Flight...
 




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=""> <s> <strike> <strong>