ROSAT, another satellite turned space junk, expected to fall to Earth this weekend

on October 21, 2011 at 12:04 PM, updated October 21, 2011 at 9:05 PM
ROSAT satelliteView full sizeAn artist's impression of the ROSAT satellite in space. The German-designed and managed satellite, dead since 1999, is expected to come crashing to Earth this weekend. (German Aerospace Center photo)

STATEN ISLAND, N.Y. -- It hasn't been a month since the defunct Upper Atmosphere Research Satellite (UARS) fell from the sky somewhere over Indonesia. Now another piece of space junk is about to crash to Earth, probably this weekend.

The Roentgen Satellite, a German-designed and managed space-based telescope launched by NASA in 1990, created X-ray images of the entire sky. It quit working in 1999 and has been drifting toward its rendezvous with doom ever since.

ROSAT, as the minivan-size satellite is called, is expected to make its fiery and wholly uncontrolled descent sometime Saturday or Sunday. Just where it will come down cannot be predicted.


Track the ROSAT orbit in real time


Weighing in at 2.7 tons, ROSAT is considerably smaller than the 6.5-ton UARS, which hit the Pacific shortly after midnight, Eastern Daylight Time, on September 24. Though smaller, ROSAT is said to be built of more heat-resistant materials, so there's a reasonably good chance large pieces of the satellite may survive the plunge through the Earth's atmosphere, which can generate temperatures of more then 3,000 degrees.

Accurately predicting the fate of a doomed satellite is notoriously difficult because the forces that affect how fast the orbit decays are very complex. Toward the end, the predictions about ROSAT will still have an accuracy window of about 10 hours.


ROSAT facts


Like UARS, the ROSAT satellite follows a roughly polar orbit, which means it spends much of its time over the world's great oceans, but it inevitably passes over virtually every land mass. So the chances of it dropping in on Staten island, or any other populated area, while statistically remote, cannot be ruled out.