It’s been awhile since we heard much about Lockheed Martin’s GPS III satellite family beyond mention of an early prototype. The next-gen positioning system just took a big step forward with word that the company has successfully powered up the first production craft of the bunch, Space Vehicle One.
Flicking the switch clears it for testing and keeps the GPS III program’s 2014 launch window within view. More importantly, the activation takes us one step closer to improved GPS accuracy for civilians and soldiers alike.
Source: Lockheed Martin
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 1958.
"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.
These belts 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
The 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 resolution.
The identical Radiation Belt Storm Probes will
follow similar orbits that will take them through both the inner and
outer radiation belts. The highly elliptical orbits range from a minimum
altitude of approximately 373 miles (600 kilometers) to a maximum
altitude of approximately 23,000 miles (37,000 kilometers).
CREDIT: JHU/APL, NASA
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.
"The 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.
"More 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."
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 said.
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?"
