Nasa Messenger mission comes to an end - by crashing into Mercury in flames

A Nasa spacecraft's four-year mission to Mercury has come to a end with the probe smashing into the planet as planned after it ran out of fuel.

The Messenger probe, launched in 2004, has sent back numerous incredible pictures of the tiny, cratered planet closest to the sun - where daytime temperatures often reach 427C.

The 500kg probe crashed into Mercury at 8,750mph, leaving a 50ft wide-crater of its own.

John Grunsfeld, associate administrator for the science mission directorate at Nasa headquarters in Washington, said: "While spacecraft operations will end, we are celebrating Messenger as more than a successful mission. It's the beginning of a longer journey to analyse the data that reveals all the scientific mysteries of Mercury."

One key finding that has already emerged suggests that Mercury harbours abundant frozen water in its permanently shadowed polar craters.

Data received in 2012 indicated enough ice in the planet's polar regions to create a layer two miles thick if spread over an area the size of Washington DC.

Dark deposits on the ice are believed to be composed of organic compounds.

The discovery supports the theory that both water and the building blocks of life were delivered from the outer solar system to the inner planets, including the Earth.

Planetary geoscientist Professor David Rothery, from The Open University, said: "Messenger has been an amazing mission. The only previous Mercury mission, Mariner 10, flew past the planet three times in 1974-5, giving us only an incomplete view.

"Messenger revealed the whole globe in detail, especially its northern hemisphere to which its deliberately eccentric orbit took it closest before soaring upwards to escape the furnace-like conditions near the 400C surface.