Today you'll need your tin-foil hat reinforced

A defunct, seven-ton research satellite that was decommissioned back in 2005 is due to crash back down to Earth today.

NASA says there's 'small' risk that the Upper Atmosphere Research Satellite (UARS), may fall somewhere inopportune - like on your head as you nip down the shop for a packet of fags. Thankfully, much of the satellite's six-ton mass will burn off on re-entry but the remaining 544kg (1,200lbs) could fall just about anywhere and is likely to be spread out over an area some 500 miles long.

Nasa reckons the junk will land in the sea, but that's only because most of the planet's surface is salty water. The biggest single lump is still likely to weigh about 300lbs - which will make a significant dent in your tin-foil hat - or anything underneath it.

To make matters worse, Nasa isn't too sure when the burning lump of twisted metal will fall to Earth. It could be this afternoon, or it could be some 14 hours either side of that.

As it's not landed yet, you might want to stay indoors!