Reblogged from http://www.ascensionwithearth.com/2013/03/nasa-discovers-new-radiation-belt.html#more
By Charles Q. Choi | SPACE.com
A ring of radiation previously unknown to science fleetingly surrounded Earth
last year before being virtually annihilated by a powerful interplanetary shock
wave, scientists say.NASA’s twin Van Allen space probes, which are
studying the Earth’s radiation belts, made the cosmic find. The surprising
discovery — a new, albeit temporary, radiation belt around Earth — reveals how
much remains unknown about outer space, even those regions closest to the
planet, researchers added.
After humanity began exploring space, the
first major find made there were the Van Allen radiation belts, zones of
magnetically trapped, highly energetic charged particles first discovered in
"They were something we thought we mostly understood by now, the
first discovery of the Space Age," said lead study author Daniel Baker, a space
scientist at the University of Colorado.
were believed to consist of two rings: an inner zone made up of both high-energy
electrons and very energetic positive ions that remains stable in intensity over
the course of years to decades; and an outer zone comprised mostly of
high-energy electrons whose intensity swings over the course of hours to days
depending primarily on the influence from the solar wind, the flood of radiation
streaming from the sun.
The discovery of a temporary new radiation belt
now has scientists reviewing the Van Allen radiation belt models to understand
how it occurred.
Radiation rings around Earth
giant amounts of radiation the Van Allen belts generate can pose serious risks
for satellites. To learn more about them, NASA launched twin spacecraft, the Van
Allen probes, in the summer of 2012.
The satellites were armed with a
host of sensors to thoroughly analyze the plasma, energetic particles, magnetic
fields and plasma waves in these belts with unprecedented sensitivity and
Unexpectedly, the probes revealed a new radiation belt
surrounding Earth, a third one made of super-high-energy electrons embedded in
the outer Van Allen belt about 11,900 to 13,900 miles (19,100 to 22,300
kilometers) above the planet’s surface. This stable ring of space radiation
apparently formed on Sept. 2 and lasted for more than four weeks.
feature was so surprising, I initially foolishly thought the instruments on the
probes weren’t working properly, but I soon realized the lab had built such
wonderful instruments that there wasn’t anything wrong with them, so what we saw
must be true," Baker said.
This newfound radiation belt then abruptly and
almost completely disappeared on Oct. 1. It was apparently disrupted by an
interplanetary shock wave caused by a spike in solar wind speeds.
than five decades after the original discovery of these radiation belts, you can
still find new unexpected things there," Baker said. "It’s a delight to be able
to find new things in an old domain. We now need to re-evaluate them thoroughly
both theoretically and observationally."
On Aug. 31, 2012, a giant prominence on the sun erupted,
sending out particles and a shock wave that traveled near Earth. This event may
have been one of the causes of a third radiation belt that appeared around Earth
a few days later, a phenomenon that was observed for the very first time by the
newly-launched Van Allen Probes. This image of the prominence before it erupted
was captured by NASA’s Solar Dynamics Observatory.
A radiation mystery
It remains uncertain how this temporary
radiation belt arose. Van Allen mission scientists suspect it was likely created
by the solar wind tearing away the outer Van Allen belt.
"It looks like
its existence may have been bookended by solar disturbances," Baker
Future study of the Van Allen belts can reveal if such temporary
rings of radiation are common or rare.
"Do these occur frequently, or did
we get lucky and see a very rare circumstance that happens only once in a
while?" Baker said. "And what other unusual revelations might come now that we
are really looking at these radiation belts with new, modern tools?"
scientists detailed their findings online Feb. 28 in the journal