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 July 23, 2014

News: Israel’s Iron Dome defense in line for tripled U.S. spending - Israel’s iron Dome missile defense system may end up getting triple the U.S. funding that the Defense Department sought for it in March. Ukraine asked U.S. for systems to counter Russian missiles - A month before the United States says a Russian missile likely brought...
 
 

News Briefs July 23, 2014

U.S. military deaths in Afghanistan at 2,194 As of July 22, 2014, at least 2,194 members of the U.S. military had died in Afghanistan as a result of the U.S.-led invasion of Afghanistan in late 2001, according to an Associated Press count. The AP count is three less than the Defense Department’s tally. At least...
 
 
Raytheon photograph

Raytheon completes key Air, Missile Defense Radar reviews

Raytheon photograph Partially-populated, full-sized Air and Missile Defense Radar array. Raytheon has completed two critical program reviews for the new Air and Missile Defense Radar, the U.S. Navy’s next generation integ...
 

 
Insitu photograph

Insitu demonstrates long endurance capabilities of Integrator unmanned aircraft

Insitu photograph Insitu’s Integrator unmanned aircraft recovers via SkyHook; the aircraft recently completed a 24-hour endurance flight. Insitu announced July 22 the successful 24-hour flight of its Integrator unmanned a...
 
 

NASA partners punctuate summer with spacecraft development advances

Spacecraft and rocket development is on pace this summer for NASA’s aerospace industry partners for the agency’s Commercial Crew Program as they progress through systems testing, review boards and quarterly sessions under their† Space Act Agreements with the agency. NASA engineers and specialists continue their review of the progress as the agency and partners move...
 
 

U.S. Navy selects Northrop Grumman for ship self-defense system

The U.S. Navy has awarded Northrop Grumman a $12 million task order for a full range of engineering services to continue modernizing the Ship Self-Defense System Mark 2. The contract has a potential value of $61 million over five years, if all options are exercised. SSDS MK2 is a combat system designed for anti-air defense...
 




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>