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Entries in ROSAT (2)

Saturday
Oct222011

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

Thursday
Oct202011

Another Satellite Headed for Earth

An artist's impression of the ROSAT satellite in space. It is expected to re-enter the atmosphere this weekend. (German Aerospace Center)(HOUSTON) -- A German satellite called ROSAT, launched in 1990 to map X-rays in the sky, is now in a decaying orbit, and Germany's space agency said Thursday it was likely to be caught by the outer layers of the atmosphere sometime Saturday or Sunday.

Like NASA's UARS satellite last month, ROSAT is large enough, and sturdy enough, that pieces of it are likely to survive re-entry. The German Aerospace Center said the odds that somebody, somewhere, could get hit are one in 2,000 -- though your personal chances of being that unlucky someone are more like one in several trillion.

"The main thing we worried about was people getting the wrong message and people panicking," said Mark Matney of NASA's orbital debris office in Houston, which tracked UARS and is now watching ROSAT.

Where and when will the satellite come down? It’s hard to be precise. Like UARS, it passes 53 degrees north and south of the equator on each orbit, which means it gets as far north as Edmonton, Canada, and as far south as Punta Arenas, Chile.

"It will not be possible to make any kind of reliable forecast about where the satellite will actually come down until about one or two hours before the fact," said Heiner Klinkrad of the European Space Agency. "In the final phase, ROSAT will be 'caught' by the atmosphere at which point...it will go into 'free fall.'"

After that, some pieces of debris could fall in a narrow oval about 300 miles long. But NASA reminds people that 70 percent of Earth is water, and much of the rest is desert, mountain, tundra or open farmers' fields. Despite the much-debated population explosion, we humans only live on a low percentage of the planet's surface.

Copyright 2011 ABC News Radio







ABC News Radio