Messenger closes in on Mercury crash-landing

Messenger closes in on Mercury crash-landing After more than a decade in space and four years orbiting Mercury, Nasa's Messenger mission is set to reach its explosive conclusion. The spacecraft is expected to crash into the planet's surface at 20:46 BST on Thursday; its last fuel was burnt in a final manoeuvre on 24 April. After reaching Mercury in 2011, Messenger has far exceeded its primary mission plan of one year in orbit. It is only slowly losing altitude but will hit at 8,750mph (14,000km/h). That means the 513kg craft, which is only 3m across, will blast a 16m crater into an area near the planet's north pole, according to scientists' calculations. The high-speed collision, 12 times faster than sound, will obliterate the history-making craft. And it will only happen because Mercury has no thick atmosphere to burn up incoming objects; for this same reason the planet is struck by similarly-sized meteors once every month or two - and they a...