Rosetta Probe Touches Down On Speeding Comet

The Rosetta mission has successfully landed a probe on a comet moving at 34,000mph in a historic first for space exploration.

Scientists cheered and punched the air in the European Space Agency (ESA) control room when they received confirmation that the Philae lander was sending signals from the comet - 300 million miles away.

ESA Director-General Jean-Jacques Dordain told a delighted audience: "This is a big step for human civilisation."

Staff at the Lander Control Center in Cologne said information they were receiving suggested the probe had made a "soft, gentle" landing.

But celebrations were tempered by the discovery that Philae's two harpoons "did not shoot" as planned, casting doubt over whether the probe was properly anchored to the comet.

Anchoring is necessary because gravity on the comet is 100,000 times weaker than on Earth so the potential for "bounce-back" is a major challenge.

Mission controllers now think the probe may have bounced after first coming into contact with the comet.

Philae lander manager Dr Stephan Ulamec said: "What we know is we touched down. We had a very clear signal there and we also received data from the lander.

"That's the very good news. Not so good news is that the anchoring harpoons apparently did not fire.

"We're still don't fully understand what has happened.

"Hopefully we are sitting there in safety in a position slightly different to the original landing and we can start a scientific sequence."

There was a nail-biting wait of seven hours between the probe's detachment from the Rosetta orbiter at 9am UK time and touchdown on the duck-shaped comet's surface.

Philae had to negotiate a distance of 22km (14miles) between the orbiter and the comet and land on the 4km (2.4miles) wide lump of ice and dust as it hurtled through space.

There had been concerns after a problem with the lander's active descent system emerged overnight and for a while put the final approach in jeopardy.

A thruster intended to counteract rebound at touchdown could not be activated - meaning latching onto the comet was completely dependent on the dishwasher-sized probe's harpoon and ice screw system.

But confirmation of the successful landing came at 4.03pm UK time and ESA operations tweeted: "RECEIPT OF SIGNAL FROM SURFACE European Space Agency receiving signals from @Philae2014 on surface of comet #67P/CG #cometlanding."

In the final phase of the mission scientists said they were surprised to find the rock - called 67P/Churyumov-Gerasimenko - was "emitting a song".

The Rosetta Plasma Consortium (RPC) said it believed the comet was releasing particles into space which were becoming electrically charged and causing fluctuations in its magnetic field.

The £1bn mission is designed to analyse the composition and density of a comet to better understand the origins of our solar system.

The Rosetta mission blasted off from French Guiana in March 2004 and has travelled more than four billion miles to reach its target.

Scientists used gravity to act as a catapult, plotting co-ordinates which took the orbiter around the Earth three times and Mars once.

They even placed the spacecraft into deep space hibernation to conserve energy - it woke up after 31 months when it passed close to the Sun and was charged by solar rays.

Chief scientist Matt Taylor said the analysis of the data from the surface, together with Earth-based observations, could provide our most detailed ever snapshot of a comet.

It is believed that comets which formed over four billion years ago could hold the key to how Earth was 'seeded' with water and organic matter, providing the building blocks for life.

Mr Taylor told Sky News: "This particular class of comet, Jupiter class comets, showed a similar flavour of water to what we see on Earth so possibly comets could have delivered the Earth's oceans, so water - and ultimately us, because we are made of water."