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 January 30, 2015

News: Taliban claims responsibility for attack on Americans at military base near airport - The Taliban claimed responsibility Jan. 30 for a shooting incident at a military base attached to Kabul’s international airport yesterday that killed three American civilian contractors and an Afghan national, saying the attacker had infiltrated the ranks of the security forces. Commission...
 
 

News Briefs January 30, 2015

Military judge weighs restrictions on Gitmo female guards A military judge is deciding whether to continue restricting the use of female guards at Guantanamo. Navy Capt. J. Kirk Waits heard closing arguments Jan. 29 at the base in Cuba during a pretrial hearing for Abd al-Hadi al-Iraqi. Waits didn’t say when he will rule. Hadi...
 
 
Air Force photograph by 1st Lt. Jake Bailey

Cope South experts exchange knowledge, techniques

Air Force photograph by 1st Lt. Jake Bailey TSgt. Sam Bishop, center left, and SSgt. Jeffrey Stephens discuss propeller maintenance with Bangladesh air force maintainers, from the 101st Special Flying Unit, during exercise Cope...
 

 

Air Force names 2-star to lead F-35 Integration Office

With the initial operating capability date of the F-35 Lightning II quickly approaching, the Air Force appointed Maj. Gen. Jeffrey Harrigian as the director of a larger Air Force F-35 Integration Office, Feb. 1. In addition to gaining new leadership, the F-35 Integration Office will also grow from a staff of four to 12 and...
 
 
boeing-ana2

Boeing announces ANA’s commitment to more jetliners

Airline continues fleet modernization with Boeing airplanes Boeing and All Nippon Airways announced Jan. 30 the airline’s intent to purchase three 787-10 Dreamliners to add additional flexibility to the airline’s 787 fleet....
 
 
Air Force photograph by Scott M. Ash

Air Force risks becoming too small to succeed under sequestration

Air Force photograph by Scott M. Ash Air Force Chief of Staff Gen. Mark A. Welsh III testifies before the Senate Armed Services Committee Jan. 28, 2015, in Washington, D.C., as Commandant of the Marine Corps Gen. Joesph F. Dunf...
 




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>