Subscribe free to our newsletters via your
. 24/7 Space News .

Subscribe free to our newsletters via your

Study finds surprising variability in shape of Van Allen Belts
by Staff Writers
Los Alamos NM (SPX) Feb 25, 2016

Learn about the Van Allen Belts and how new findings from NASA's Van Allen Probes could impact how we protect technology in space. Image courtesy Los Alamos National Laboratory. Watch a video on the research here.

The shape of the two electron swarms 600 miles to more than 25,000 miles from the Earth's surface, known as the Van Allen Belts, could be quite different than has been believed for decades, according to a new study of data from NASA's Van Allen Probes that was released Friday in the Journal of Geophysical Research.

"The shape of the belts is actually quite different depending on what type of electron you're looking at," said Geoff Reeves of Los Alamos National Laboratory's Intelligence and Space Research Division and lead author on the study. "Electrons at different energy levels are distributed differently in these regions."

Understanding the shape and size of the belts, which shrink and swell in response to magnetic storms coming from the sun, is crucial for protecting our technology in space. The harsh radiation isn't good for satellite's health, so scientists want to know just which orbits could be jeopardized in different situations. Los Alamos has been studying space weather and its effects on national security satellites since the 1960s, when the U.S. launched the Vela satellites to support nuclear treaty verification.

Since scientists first began forming a picture of these rings of energetic particles in the 1950s, understanding of their shape has largely remained unchanged - a small, inner belt, a largely empty space known as the slot region, and then the outer belt, which is dominated by electrons and is larger and more dynamic than the others.

But this new analysis reveals that the shape varies from a single, continuous belt with no slot region, to a larger inner belt with a smaller outer belt, to no inner belt at all. Many of the differences are accounted for by considering electrons at different energy levels separately.

"It's like listening to different parts of a song," said Reeves. "The bass line sounds different from the vocals, and the vocals are different from the drums, and so on."

The authors of the study, from Los Alamos National Laboratory and the New Mexico Consortium, found that the inner belt - the smaller belt in the classic picture of the belts - is much larger than the outer belt when observing electrons with low energies, while the outer belt is larger when observing electrons at higher energies. At the very highest energies, the inner belt structure is missing completely. So, depending on what one focuses on, the radiation belts can appear to have very different structures simultaneously.

These structures are further altered by geomagnetic storms. When high-speed solar wind streams or coronal mass ejections - fast-moving magnetic material from the sun - collide with Earth's magnetic field, they send it oscillating, creating a geomagnetic storm. Geomagnetic storms can increase or decrease the number of energetic electrons in the radiation belts for days to months, though the belts return to their normal configuration after a time.

These storm-driven electron increases and decreases are currently unpredictable, without a clear pattern showing what type or strength of storm will yield what outcomes. There's a saying in the space physics community: if you've seen one geomagnetic storm, you've seen one geomagnetic storm. But, it turns out, those observations have largely been based on electrons at only a few energy levels.

"When we look across a broad range of energies, we start to see some consistencies in storm dynamics," said Reeves. "The electron response at different energy levels differs in the details, but there is some common behavior. For example, we found that electrons fade from the slot regions quickly after a geomagnetic storm, but the location of the slot region depends on the energy of the electrons."

Often, the outer electron belt expands inwards toward the inner belt during geomagnetic storms, completely filling in the slot region with lower-energy electrons and forming one huge radiation belt. At lower energies, the slot forms farther from Earth, producing an inner belt that is bigger than the outer belt. At higher energies, the slot forms closer to Earth, reversing the comparative sizes.

The twin Van Allen Probes satellites expand the range of energetic electron data we can capture. In addition to studying the extremely high-energy electrons - carrying millions of electron volts - that had been studied before, the Van Allen Probes can capture information on lower-energy electrons that contain only a few thousand electron volts. Additionally, the spacecraft measure radiation belt electrons at a greater number of distinct energies than was previously possible.

"Previous instruments would only measure five or ten energy levels at a time," said Reeves. "But the Van Allen Probes measure hundreds."

Measuring the flux of electrons at these lower energies has proved difficult in the past because of the presence of protons in the radiation belt regions closest to Earth. These protons shoot through particle detectors, creating a noisy background from which the true electron measurements needed to be picked out. But the higher-resolution Van Allen Probes data found that these lower-energy electrons circulate much closer to Earth than previously thought.

"Despite the proton noise, the Van Allen Probes can unambiguously identify the energies of the electrons they're measuring," said Reeves.

Precise observations like this, from hundreds of energy levels, rather than just a few, will allow scientists to create a more precise and rigorous model of what, exactly, is going on in the radiation belts, both during geomagnetic storms and during periods of relative calm.

"You can always tweak a few parameters of your theory to get it to match observations at two or three energy levels," said Reeves. "But having observations at hundreds of energies constrain the theories you can match to observations."

+ Watch a video here

Los Alamos co-authors of the paper are Reiner Friedel, Brian Larsen, Ruth Skoug, and Herbert Funsten. The co-author from the New Mexico Consortium is Mick Denton. The higher energy electron data came from the Magnetic Electron Ion Spectrometer (MagEIS) built by The Aerospace Corp. The lower energy electron data come from the Helium Oxygen Proton Electron (HOPE) spectrometer, which was designed and built at Los Alamos. The Johns Hopkins Applied Physics Laboratory in Laurel, Md., built and operates the Van Allen Probes for NASA's Science Mission Directorate. The mission is the second mission in NASA's Living With a Star program, managed by NASA's Goddard Space Flight Center in Greenbelt, Md. DOI: 10.1002/2015JA021569


Related Links
Los Alamos National Laboratory
Space Technology News - Applications and Research

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Previous Report
Study shows dried plums provide protection from bone loss due to radiation
College Station TX (SPX) Feb 23, 2016
Dr. Nancy Turner, a Texas A and M AgriLife Research scientist in College Station, was one of a team of researchers who recently studied different interventions to protect from radiation-induced bone loss. The study showed consuming dried plums can protect from ionizing radiation that increases oxidative damage in skeletal tissues and results in an imbalance in bone remodeling. Reduced bone ... read more

NASA releases strange 'music' heard by 1969 astronauts

NASA chooses ASU to design and operate special satellite

Chinese scientists invent leak detection system for moon exploration

Aldrin recounts successes and challenges of historic space journey

Jarosite in the Noctis Labyrinthus Region of Mars

Trace Gas Orbiter and Schiaparelli are joined

Footprints of a martian flood

Russia plans return to Mars, Moon despite money woes

NASA Space Program Now Requires Russian Language

Alpha Centauri: Our First Target for Interstellar Probes

Tourists could soon benefit from direct flights to Baikonur Space Center

Orion Simulations Help Engineers Evaluate Mission Operations for Crew

China's moon lander Chang'e-3 enters 28th lunar day

Staying Alive on Tiangong 2

China Conducts Final Tests on Most Powerful Homegrown Rocket

Last Launch for Long March 2F/G

Orbital ATK Completes OA-4 Cargo Delivery Mission to ISS for NASA

Scott Kelly returns to earth, but science for NASA's journey to Mars continues

Send your computer code into space with astronaut Tim Peake

Black Mold Found in Cargo Prepared for ISS, Resupply Mission Delayed

SpaceX warns of failure in Wednesday's rocket landing

Launcher and satellite preparations continue for Ariane 5's mission with EUTELSAT 65 West A

SpaceX postpones rocket launch until Thursday

Russian rocket engines ban could leave US space program in limbo

Imaging technique may help discover Earth-like planets

Longest-Lasting Stellar Eclipse Discovered

Astronomers take images of an exoplanet changing over time

First detection of super-earth atmosphere

Real or virtual - can we tell the difference

Study shows dried plums provide protection from bone loss due to radiation

Russian Space Intelligence Center to Receive New Radars

Eternal 5D data storage could record the history of humankind

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.