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Posts Tagged ‘plasma’

Researchers Find That Earth’s “Plasmaspheric Hiss” Protects Against A Harmful Radiation Belt

February 18, 2015 Leave a comment

Courtesy of the reasearchers/Haystack Observatory

Courtesy of the reasearchers/Haystack Observatory

High above Earth’s atmosphere, electrons whiz past at close to the speed of light. Such ultrarelativistic electrons, which make up the outer band of the Van Allen radiation belt, can streak around the planet in a mere five minutes, bombarding anything in their path. Exposure to such high-energy radiation can wreak havoc on satellite electronics, and pose serious health risks to astronauts.

Now researchers at MIT, the University of Colorado, and elsewhere have found there’s a hard limit to how close ultrarelativistic electrons can get to the Earth. The team found that no matter where these electrons are circling around the planet’s equator, they can get no further than about 11,000 kilometers from the Earth’s surface — despite their intense energy.

What’s keeping this high-energy radiation at bay seems to be neither the Earth’s magnetic field nor long-range radio waves, but rather a phenomenon termed “plasmaspheric hiss” — very low-frequency electromagnetic waves in the Earth’s upper atmosphere that, when played through a speaker, resemble static, or white noise.

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Stanford Scientist Closes In On A Mystery That Impedes Space Exploration


New research by Stanford aeronautics and astronautics Assistant Professor Sigrid Close suggests she’s on track to solve a mystery that has long bedeviled space exploration: Why do satellites fail?

In the popular imagination, satellites are imperiled by impacts from “space junk” – particles of man-made debris the size of a pea (or greater) that litter the Earth’s upper atmosphere – or by large meteoroids like the one that recently exploded spectacularly over Chelyabinsk, Russia.

Although such impacts are a serious concern, most satellites that have died in space haven’t been knocked out by them. Something else has killed them.

The likely culprit, it turns out, is material so tiny its nickname is “space dust.”

These natural micro-meteoroids are not directly causing satellites harm. When they hit an object in space, however, they are traveling so fast that they turn into a quasi-neutral gas of ions and electrons known as plasma. That plasma, Close theorizes, has the potential to create a radio signal that can damage, and even completely shut down, the satellites they hit.

Full Story: http://news.stanford.edu/pr/2013/pr-space-dust-threat-022613.html

X-ray Laser Takes Aim At Cosmic Mystery

December 12, 2012 Leave a comment

Scientists have used powerful X-rays from the Linac Coherent Light Source (LCLS) at the U.S. Department of Energy’s (DOE) SLAC National Accelerator Laboratory to study and measure, in atomic detail, a key process at work in extreme plasmas like those found in stars, the rims of black holes and other massive cosmic phenomena.

The results explain why observations from orbiting X-ray telescopes do not match theoretical predictions, and pave the way for future X-ray astrophysics research using free-electron lasers such as LCLS. With its brilliant, ultrafast X-ray laser pulses, LCLS allows scientists to create and measure atomic processes in extreme plasmas in a fully controlled way for the first time.

“Measurements conducted at the LCLS will be important for interpreting X-ray emissions from a plethora of sources, including black holes, X-ray binaries, stellar coronae and supernova remnants, to name a few,” said Gregory V. Brown, a physicist at Lawrence Livermore National Laboratory who participated in the research.

Full Story: http://www6.slac.stanford.edu/news/2012-12-12-cosmic-lcls.aspx
Also: https://www.llnl.gov/news/newsreleases/2012/Dec/NR-12-12-01.html

Thin Current Sheets In Space: Where The Action Is


Much of the exciting action is space is confined to thin boundaries. The Universe is filled with plasma, a charged gas consisting of ions and electrons. Thin sheets with currents separate large plasma regions in space. Scientists at the Swedish Institute of Space Physics (IRF) have now finally measured the fundamental properties of one of the waves mixing and accelerating plasmas within these sheets.

Around Earth, the processes accelerating electrons which hit the atmosphere and cause beautiful auroras are often initiated in thin current sheets. Similar processes, auroras and thin current sheets are found around other planets such as Jupiter and Saturn. Plasma regions close to the hot solar surface are separated by thin current sheets, and similar boundaries should also be common around distant stars. In man-made plasmas, thin boundaries are found in the tokamak plasma employed in nuclear fusion research and space observations may help us understand fusion plasmas.

Full Story: http://www.irf.se/Topical/Press/?dbfile=Thin%20current%20sheets%20in%20space:%20where%20the%20action%20is%20&dbsec=P4

Elusive Matter Found To Be Abundant Far Above Earth

January 25, 2012 Leave a comment

Cold plasma has been well-hidden. Space physicists have long lacked clues to how much of this electrically charged gas exists tens of thousands of miles above Earth and how the stuff may impact our planet’s interaction with the sun. Now, a new method developed by Swedish researchers makes cold plasma measurable and reveals significantly more cold, charged ions in Earth’s upper altitudes than previously imagined.

At these lofty elevations, storms of high-energy charged particles — space weather — roil the atmosphere, creating auroras, buffeting satellites, and sometimes wreaking havoc with electronic devices and electric grids on Earth. The new evidence of abundant cold (i.e. low-energy) ions may change our understanding of this tumultuous space weather and lead to more accurate forecasting of it, scientists say. The finding might also shed light on what’s happening around other planets and moons — for instance, helping explain why the once robust atmosphere of Mars is so wispy today.

“The more you look for low-energy ions, the more you find,” said Mats André, a professor of space physics at the Swedish Institute of Space Physics in Uppsala, Sweden, and leader of the research team. “We didn’t know how much was out there. It’s more than even I thought.”

Full Story: http://www.agu.org/news/press/pr_archives/2012/2012-02.shtml