Falling German Satellite Poses 1-in-2,000 Risk of Striking Someone This Month

A big German satellite near the end of life is expected to plunge back to Earth this month, just weeks after a NASA satellite fell from orbit, and where this latest piece of space junk will hit is a mystery.

The 2.4-ton spacecraft, Germany’s Roentgen Satellite (ROSAT), is expected to fall Oct.  22 or 23.

The satellite will break up into fragments, some of which will disintegrate due to intense re-entry heat. But studies predict that about 1.6 tons of satellite leftovers could reach the Earth’s surface. That’s nearly half ROSAT’s entire mass.

There is a 1-in-2,000 chance that debris from the satellite could hit someone on Earth, though the likelihood of an injury is extremely remote, German space officials say. For German citizens, the risk of being struck is much lower, about 1 in 700,000.

All areas under the orbit of ROSAT, which extends to 53 degrees northern and southern latitude, could be in the strike zone of the satellite’s re-entry.

The bulk of the debris is likely to hit near the ground/ocean track of the satellite. However, isolated fragments could descend to Earth in a 50-mile (80-kilometer) swath along that track. [Photos: Germany’s ROSAT Satellite Falling to Earth]

The satellite will be the second large spacecraft to make a pre-announced fall from space in as many months. On Sept. 24, NASA’s 20-year-old Upper Atmosphere Research Satellite (UARS) crashed into the Pacific Ocean in a widely publicized death plunge.

The ROSAT project was a collaborative venture among Germany, the United States, and the United Kingdom. It was developed, built and launched on behalf of and under the leadership of the Deutsches Zentrum für Luft- und Raumfahrt (DLR), Germany’s space agency.

The ROSAT satellite undergoing tests in the space simulation chamber at Dornier.
CREDIT: Dornier (now Astrium Friedrichshafen).

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The uncontrollable ROSAT

ROSAT was placed into Earth orbit on June 1, 1990. The highly successful astronomy mission ended after nearly nine years, with commands sent on Feb. 12, 1999, to shut the spacecraft down.

The spacecraft does not have its own propulsion system, so it could not  be maneuvered into a controlled re-entry at the end of its mission.

Moreover, the satellite is zipping through space in deaf and silent mode. That is, ROSAT is no longer able to communicate with DLR’s control center in Oberpfaffenhofen, nor is it possible to establish contact with the spacecraft.

Still, the DLR says the probability of ROSAT coming down over an inhabited area is extremely low.

to read more, go to:    http://www.space.com/13261-german-satellite-falling-earth-rosat-risk.html