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 October 20, 2014

News: Navy grounds ‘Top Guns’ - The F/A-18s needs spare parts and in too many cases they’re being taken from brand new jets. This is a risk to national security and pilots’ lives.   Business: Boeing seeks revised schedule for U.S. aerial tanker - Boeing is revising its master schedule for developing the new U.S. Air Force...
 
 

News Briefs October 20, 2014

New military medical team to help with Ebola in U.S. Defense Secretary Chuck Hagel has ordered the military to prepare and train a 30-member medical support team that could provide short-term help to civilian health professionals if there are more Ebola cases in the United States. His spokesman, Rear Adm. John Kirby, says the team...
 
 

Dragon ‘fires up’ for flight

The Air Force and NATO are undergoing a cooperative development effort to upgrade the avionics and cockpit displays of AWACS aircraft belonging to the 552nd Air Control Wing at Tinker Air Force Base, Okla., and the NATO E-3 Sentrys from Geilenkirchen, Germany. The Diminishing Manufacturing Sources Replacement of Avionics for Global Operations and Navigation, otherwise...
 

 
Boeing photographs

Boeing-built X-37B successfully completes third flight

Unmanned spacecraft concludes record-setting 674-day mission   Boeing photograph A third mission of the Boeing-built X-37B Orbital Test Vehicle was completed on Oct. 17, 2014, when it landed and was recovered at Vandenberg...
 
 

Boeing concludes commercial crew space act agreement for CST-100/Atlas V

Boeing has successfully completed the final milestone of its Commercial Crew Integrated Capability Space Act Agreement with NASA. The work and testing completed under the agreement resulted in significant maturation of Boeing’s crew transportation system, including the CST-100 spacecraft and Atlas V rocket. NASA in July approved the Critical Design Review Board milestone for Boeing’...
 
 

AF to release small business research solicitations

The Air Force Small Business Innovation Research and Small Business Technology Transfer program office is set to release its fiscal year 2015 list of topics Oct. 22, on the SBIR/STTR website.  Small businesses and research institutions with expertise to address the topics’ technology challenges are encouraged to submit proposals. During 2014, the Defense Department SBIR...
 




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>