German Rosat spacecraft makes uncontrolled re-entry

The Roentgen Satellite (Rosat) re-entered the Earth's atmosphere between 01:45 and 02:15 GMT, BBC News reports.

Just as for Nasa's UARS satellite, which plunged into the atmosphere in September, there was high uncertainty about the final moments of Rosat.

But if the timings are correct, any wreckage would probably have dived into the Indian Ocean - although no eyewitness reports have yet come in.

If anything did manage to make landfall, the likely areas to be affected would have been Myanmar and China.

What made the redundant German craft's return interesting was that much more debris was expected to survive all the way to the Earth's surface.

Experts had calculated that perhaps as much as 1.6 tonnes of wreckage - more than half the spacecraft's launch mass - could have ridden out the destructive forces of re-entry and hit the planet.

In the case of UARS, the probable mass of surviving material was put at only half a tonne (out of a launch mass of more than six tonnes).

The difference is due to some more robust components on the German space agency (DLR) satellite.

Rosat was an X-ray telescope mission and had a mirror system made of a reinforced carbon composite material. This mirror complex and its support structure were expected to form the largest single fragment in what could have been a shower of some 30 pieces of debris to make it through to the surface.

But again, as was the case with UARS, any Rosat wreckage was strongly tipped to hit the ocean, given that so much of the Earth's surface is covered by water.

For full version see http://www.bbc.co.uk/news/science-environment-15402157