Space

March 24, 2014

NASA spacecraft reveal new Zebra Stripesí structure in Earths inner radiation belt

Scientists have discovered a new, persistent structure in Earths inner radiation belt using data from the twin NASA Van Allen Probes spacecraft.

Most surprisingly, this structure is produced by the slow rotation of Earth, previously considered incapable of affecting the motion of radiation belt particles, which have velocities approaching the speed of light.

Data from the Van Allen Probes Ion Composition Experiment (RBSPICE) on board each of the twin spacecraft orbiting Earth revealed that the highly energized population of electrons of the inner radiation belt is organized into very structured patterns that resemble slanted zebra stripes. Scientists had previously believed that increased solar wind activity was the primary force behind any structures in our planets radiation belts. These zebra stripes were shown to be visible even during low solar wind activity, which prompted a search for a new physical mechanism of their generation. That quest led to the surprising discovery that the stripes are caused by rotation of Earth. The findings are reported in the Mar. 20 issue of the journal Nature.

It is because of the unprecedented high energy and temporal resolution of our energetic particle experiment, RBSPICE, that we now understand that the inner belt electrons are, in fact, always organized in zebra patterns, said Aleksandr Ukhorskiy of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., co-investigator on RBSPICE and lead author of the paper.

Furthermore, our modeling clearly identifies Earths rotation as the mechanism creating these patterns. It is truly humbling, as a theoretician, to see how quickly new data can change our understanding of physical properties.

Because of the tilt in Earths magnetic field axis, the planets rotation generates an oscillating, weak electric field that permeates through the entire inner radiation belt. To understand how that field affects the electrons, Ukhorskiy suggested an analogy: If the inner belt electron populations are viewed as a viscous fluid, these global oscillations slowly stretch and fold that fluid, much like taffy is stretched and folded in a candy store machine, he said. This stretching and folding process results in the striped pattern observed across the entire inner electron belt, extending from above Earths atmosphere (about 500 miles, or 800 kilometers, above the planets surface) up to roughly 8,000 miles (13,000 kilometers).

The radiation belts are dynamic doughnut-shaped regions around our planet, extending high above the atmosphere, made up of high-energy particles (electrons and ions) that are trapped by Earths magnetic field. Radiation levels across the belts are affected by solar activity (such as solar storms) and can ebb and flow. During active conditions, radiation levels can dramatically increase, which can create hazardous space weather conditions that harm orbiting spacecraft and endanger humans in space. It is the goal of the Van Allen Probes mission to understand how and why radiation levels in the belts change with time.

This is another fundamental understanding made possible thanks to the highly detailed data being returned from these remarkable spacecraft, said Louis Lanzerotti, distinguished research professor of physics at the Center for Solar-Terrestrial Research at the New Jersey Institute of Technology, principal investigator for RBSPICE, and a co-author on the paper. It is amazing how Earths space environment, including the radiation belts, continue to surprise us even after we have studied them for over 50 years. Our understanding of the complex structures of the belts, and the processes behind the belts behaviors, continues to grow, all of which contribute to the eventual goal of providing accurate space weather modeling.

This finding tells us something new and important about how the universe operates, said Barry Mauk of APL, Van Allen Probes project scientist and an author of the paper. The new results reveal a new large-scale physical mechanism that can be important for planetary radiation belts throughout the solar system. An instrument similar to RBSPICE is now on its way to Jupiter on NASAs Juno mission, and we will be looking for the existence of zebra stripe-like patterns in Jupiters radiation belts.

NASA launched the twin Van Allen probes in the summer of 2012. APL built and operates the 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 28, 2015

Business: Rafale, Mistral on agenda for Le Drian in Malaysia, India – French Defense Minister Jean-Yves Le Drian is due to visit Malaysia Aug. 30, with talks expected to cover the Rafale fighter jet and Mistral helicopter carrier, website La Tribune reported. U.S. Army to choose new landing craft next year – In line with the Pentagon’s...
 
 

News Briefs August 28, 2015

Boeing plans to lay off some Southern California workers Boeing has announced that it plans to lay off employees at its Southern California-based satellite division. The Los Angeles Times reports that the aerospace giant said Aug. 25 that it will lay off as many as several hundred employees at the El Segundo factory. Boeing says...
 
 

Special tactics Airmen killed in hostile incident

Two special tactics airmen, who were deployed in support of Operation Freedom’s Sentinel, were killed near Camp Antonik, Afghanistan, Aug. 26. Capt. Matthew D. Roland, 27, and SSgt. Forrest B. Sibley, 31, were at a vehicle checkpoint when two individuals wearing Afghan National Defense and Security Forces uniforms opened fire on them. NATO service members...
 

 

Hurricane Hunters to fly Tropical Storm Erika

The Air Force Reserve Hurricane Hunters are operating out of Homestead Air Reserve Base, Fla., flying their state-of-the-art WC-130J Super Hercules into Tropical Storm Erika in support of the National Hurricane Center in Miami. The 53rd Weather Reconnaissance Squadron flew four missions into the tropical storm from their deployed location at St. Croix in the...
 
 
LM-MUOS

U.S. Navy, Lockheed Martin ready to launch MUOS-4 Aug. 31

The U.S. Navy and Lockheed Martin are ready to launch the fourth Mobile User Objective System secure communications satellite, MUOS-4, from Cape Canaveral Air Force Station, Fla., Aug. 31 aboard a United Launch Alliance Atlas V...
 
 

Pentagon probing alleged distorting of war intelligence

The Pentagon’s inspector general is investigating an allegation that the military command overseeing the anti-Islamic State campaign distorted or altered intelligence assessments to exaggerate progress against the militant group, a defense official said Aug. 26. The official was not authorized to discuss the probe publicly and so spoke on condition of anonymity. The investigation was...
 




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>