The European Space Agency (Esa) is getting ready to put a probe on Mars.

Its Schiaparelli robot will attempt the risky descent to the surface in the coming hours, after a 500 million km journey from Earth.

The touchdown is regarded as a dress rehearsal for a much more important venture in four years' time when Esa will bid to place a very expensive rover on the planet.

This six-wheeled vehicle will drill beneath the surface to search for life.

Getting the smaller Schiaparelli robot down ought to be the simpler affair. But as the scientific record shows, Mars is not the most welcoming of places, even for the most sophisticated of hardware.

About half of the missions despatched to Earth's near neighbour have failed. Many of these were lost on the way, missed their target, or crashed on arrival.

For Europe, the Schiaparelli spacecraft is a chance to wipe away the disappointment of the Beagle-2 lander, which in 2003 got down successfully but then almost immediately suffered a terminal malfunction.

Schiaparelli will hope to fare better. It will use a combination of a heatshield, a parachute and a cluster of rockets to slow down its initial atmospheric entry speed of 21,000km/h to a hovering zero just above the surface.
The 600kg robot's final two metres will see it dump down on to its belly.

The Esa probe will emit UHF tones during the descent that an Indian radio telescope will try to capture and relay to controllers here in Darmstadt, Germany.

Touchdown occured at 14:58 GMT (15:58 BST; 16:58 CEST). If the Indian facility can still hear Schiaparelli at the top of the hour, it will mean the Italian-built module must have reached the Martian terrain intact.
"Everybody's smiling, everybody's optimistic but you can sense the tension as well," said Mark McCaughrean, Esa's senior science advisor.

"I think as the hours tick by now towards that moment - to those six minutes as we plummet through the atmosphere - there's going to be a lot more nerves. But we're going to do this because it teaches us hard lessons about how to operate in space."