David Shukman
Science editor, BBC News

Landing on the small, strange world of a comet ranks as one of the greatest achievements in space exploration. Neil Armstrong and Buzz Aldrin would obviously take pride of place.

People might debate the relative prowess of robotic rovers driving on Mars or the Voyager spacecraft edging out of the solar system. But touching down on a primordial lump of rock and ice that dates from the earliest days of the Solar System - and which is hurtling through space at 34,000 mph - is a genuine triumph by any standards.

tweets:, external Last night I held in my hands original works of Galileo & Newton. Today we landed on a comet beyond Mars. Incredible.

Image source, Chris Hadfield

Scientists at mission control are now processing the first images from the surface of the comet.

But they are also getting intermittent drop-out in the communication between the lander Philae and the "mothership" Rosetta, still in orbit.

Paolo Ferri, head of operations at Esa, told BBC News: "We need to stabilise this situation over the next three hours."

We've heard a lot of comments describing what we might learn from the comet, but this is the first time we've heard it described as soup. (Note - we do not expect it to be edible.)

The Ptolemy instrument's lead investigator, Prof Ian Wright from Open University, says:

"The comet is very, very old. Analysing the material in a comet is like looking back in history; it's like a time capsule.

"I like to think of it as frozen primordial soup, and this is the stuff that rained down on the early Earth. The idea that comets may have brought the building blocks of life to Earth is one of the reasons why we want to study them."

Emily also reports that Mark McCaughrean, Esa's senior science adviser, has confirmed the lander's screws - if not its harpoons - have dug into the comet's surface.

Emily tweets from Darmstadt, external:

"Not knowing about the stability is clearly worrisome, but by any reasonable measure Philae is successful, and we can expect good data.

"It's going to take Philae mission controllers some time to understand how stable they are, but in the meantime everything is working great. Yay!"

Arturo Opaso: "Wow, very impressive and exciting! We are all proud, these are the events that make us feel as one. Awaiting for images here in Chile."

We're all waiting, Arturo! Impatience born of enthusiasm...

Rebecca Morelle
Science Correspondent, BBC News

Rebecca tweets from Darmstadt, external:

"Have been hearing how close the #CometLanding was to being pulled last night - they've only told us now it landed! #Rosetta"

Gloria Jefferson: So very well done to all involved at the European Space Agency. Proud to be a member of humanity on such a day.

tweets:, external "Hollywood is good, but Rosetta is better" - great quote from our CEO Dr David Parker #CometLanding

Our colleagues at #BBCtrending write:

The sound coming from comet 67P/Churyumov-Gerasimenko has caught the imagination of hundreds of thousands on social media.

The scientists are just as surprised as social media users.

"This is exciting because it is completely new to us. We did not expect this and we are still working to understand the physics of what is happening," Karl-Heinz Glaßmeier, head of Space Physics and Space Sensorics at the Technische Universität Braunschweig, Germany, explained on the ESA Rosetta blog, external.

tweets, external: Deciding whether to re-fire the harpoons is tricky - without the hold-down thruster, presumably @Philae2014, external could recoil? #CometLanding

The Esa Operations team confirms, external that the harpoons designed to attach Philae to the comet did not fire.

But they say the lander is in great shape, and the team is "looking at refire options".

tweets:, external Philae sank about 4cm... but the harpoons didn't fire and the thruster problem was real and so it also didn't fire? Yow, the drama continues! #CometLanding

tweets, external: It looks like @Philae2014, external made a fairly gentle touch down on #67P based on amount of landing gear damping #CometLanding

Watch the celebrations in a new addition to the "key video" tab above.

"We're down on the surface", said Esa's Prof Mark McCaughrean.

tweets, external: "No rest for the wicked..."

They appear to be referring to presenter and University of Oxford astronomer Prof Chris Lintott, external.

David Shukman
Science editor, BBC News

tweets, external: I've never seen a leading planetary scientist leap for joy before - Prof Monica Grady at #CometLanding - coming up on News at Six

Further checks are now needed to ascertain the state of the lander, but the fact that it is resting on the surface of the speeding comet is already a huge success.

It marks the highlight of the decade-long Rosetta mission to study comets and learn more about the origins of these celestial bodies.

The head of the European Space Agency underlined Europe's pride:

"We are the first to have done that, and that will stay forever,'' said Esa director-general Jean-Jacques Dordain.

Image source, Esa

Dan Jakubowski: This is mankind's greatest feat in Space Exploration since landing on the Moon in 1969. Congratulations to all from Cleveland, Ohio USA.