Entries in UARS (2)


German ROSAT Satellite Expected to Hit Earth Sunday

NASA(WASHINGTON) -- A German satellite is expected to fall back to Earth Sunday, marking the second time a satellite has hit Earth in the past month, an occurence that typically happens only once per year.

Last month UARS re-entered the atmosphere, and now ROSAT is barreling back toward Earth, too. ROSAT, which was designed to map X-rays in the sky, was launched on a Delta 2 rocket from Florida in 1990.

While functioning in space, ROSAT found roughly 110,000 stars, supernovas and cosmic rays emitting X-rays.

The German Space Agency is putting the chances at one in 2,000 that someone will be struck by a piece of ROSAT. That works out to odds of about one in 14 trillion that any one of the 7 billion or so people on Earth will be whacked by a piece of the satellite.

The threat of someone being hit by a piece of UARS was one in 3,200. The remnants ended up falling in the remote Pacific Ocean.

ROSAT will likely end up in the sea as well, since 75 percent of Earth is covered by water.

Still, it's too soon to tell where it will crash. It's something that the U.S. space agency and the German space agency, who are monitoring ROSAT's re-entry, won't be able to tell until hours before re-entry.

Solar activity is the prime force that will determine how quickly the satellite falls back to earth.

NASA orbital debris scientist Mark Matney told ABC News there is a lot of junk up in space waiting to come down on us.

"The U.S. space Surveillance Network has catalogued 16 thousand things in Earth orbit, many of them are quite small pieces of debris, but about 7,000 of those are large objects, spacecraft and large rocket bodies, we have made quite a mess up there," Matney said.

Germany's ROSAT X-ray astronomy satellite is smaller than UARS but is a bigger threat because most of the satellite is made of heat resistant components, including its 880-pound primary mirror, which will be the single largest fragment to survive re-entry.

It's estimated that up to 3,750 pounds of the decaying satellite could survive re-entry.

ROSAT was turned off in 1999 and its altitude has gradually dropped from 350 miles above the Earth to 149 miles today. The threat area is 53 degrees north to 53 degrees south.

Copyright 2011 ABC News Radio


NASA UARS Satellite Crashes Into Earth: Location Unknown

PRNewsFoto/NASA(WASHINGTON) -- The abandoned 6-ton Upper Atmosphere Research Satellite (UARS) entered the earth's atmosphere early this morning but where it crashed remains unknown, according to NASA.

In an update posted on NASA's website, the "decommissioned Upper Atmosphere Research Satellite fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. EDT Sept. 24."

Officials said it entered the atmosphere somewhere over the Pacific Ocean but the "precise re-entry time and location are not yet known with certainty."

On Friday, officials predicted the satellite would be passing over Canada, Africa and Australia, and vast areas of the Pacific, Atlantic and Indian oceans.

However, NASA said earlier that the risk to public safety is very remote. So far there have been no reports of injuries.

NASA said some 26 chunks of the old satellite—which is roughly the size of a bus—are likely to survive the descent, and fall at hundreds of miles per hour over an area of some 500 square miles. The agency said it knows of no case in which people have been hurt by space junk.

"We believe that the risk is sufficiently low that no one needs to change their behaviors," NASA's Mark Matney said.

Bill Ailor, principal engineer at the Aerospace Corp., studies incoming space junk for the Air Force. He said pieces of other satellites have come crashing down into villages, farms and random datelines around the planet.

"I actually think a lot of this kind stuff comes down and nobody knows what it is and just thinks it's junk and ignores it," Ailor told ABC News.

Ailor and his colleagues study satellite components in a lab to figure out what will burn up and what will become a potential threat—just like the pieces of the UARS satellite.

But according to Nicholas Johnson, NASA's chief orbital debris scientist, any one person's chances of getting hit by debris are tiny—something like 1 in 21 trillion. The chances that of the 7 billion people on Earth, one of them, somewhere, could be hit are more like 1 in 3,200.

Despite those odds, Ailor said that a hazard is a hazard.

"Five hundred pounds of stainless steel represents a hazard—if you're standing under it," Ailor joked.

Launched in 1991, the UAS satellite is the largest NASA satellite to fall back to Earth uncontrolled since Skylab in 1979.

Skylab was much larger—about the size of a house—and debris fell in the Australian Outback and the Pacific.

Copyright 2011 ABC News Radio

ABC News Radio