|ROSAT (image originally from dlr.de)|
ROSAT is a (mainly) German X-ray telescope which was launched into space on June 1st 1990. It was shut down in February 1999 and has been orbiting the Earth ever since (things already in orbit tends to do that).
But now the altitude of the satellite has become low enough that a re-entry into the atmosphere is imminent.
As of this writing the altitude of the satellite is only 167.2 km (an hour ago it was 170.3 km).
And just like the previous satellite to fall down the exact time of re-entry is not know; there are simply too many unknowns to account for. But predictions can be made.
And according to the Bad Astronomer the expected re-entry is:
...right now as I write this the nominal time of re-entry is sometime on October 23 between 06:00 and 13:00 UT...(Or 8:00 - 15:00 CEST).
I'm not yet sure where it will "fall" but fear not as the odds of debris hitting anyone is as low as 1:2000.