For the first time, human beings have landed a spacecraft on a comet. The European Space Agency's Rosetta spacecraft arrived at comet 67P/Churyumov-Gerasimenko on 12 November after a journey of ten years and half a billion kilometres.
Already, the scientific discoveries are beginning. But there was an even bigger discovery to be made: scientists can be funny.
Jean-Jacques Dordain, ESA's director general, opened Wednesday's press conference by saying, "We have landed at the right place. It's also the right comet — don't worry."
Rosetta was originally supposed to land on a different comet. Its destination was changed when a sudden delay caused the spacecraft to miss its launch window in 2004.
Everything went smoothly during the flight to 67P, including the separation of a lander called Philae from the mother ship Rosetta. Philae landed, but its signal kept disappearing and coming back — indicating it was still moving, perhaps bouncing up and down like a baby goat, as a French Space Agency official put it. The harpoons that were supposed to hold the lander to the surface hadn't fired. This prompted Philae Lander Manager Stephan Ulamec to say, "Maybe today we didn't just land once; we even landed twice."
The main achievement lies in the precision necessary to land such a spacecraft — automatically — at such a distance. The comet is currently between the orbits of Mars and Jupiter; it's moving at about 66,000 kilometres an hour. Only four kilometres across at its widest point, the object has only 1/10,000th of the Earth's gravity.
What they said
The news was full of vivid analogies. The Guardian and NBC News compared the shape of the comet to that of a rubber duck, while New Scientist compared it to a piece of ginger root. Philae, said NBC, was the size of a washing machine.
Dr Matthew Genge of Imperial College, London, said: "This is the most difficult landing in space history. [It's] like landing a balloon in a city centre on a windy day with your eyes closed."
Dr David Clements, also of Imperial College, London, described the Philae lander as "a truly mould-breaking endeavour".
Describing its descent, The Guardian's correspondent, Stuart Clark, wrote: "Philae will be travelling at a walking pace relative to the comet at touchdown. So the impact it will feel will be the equivalent of a person walking straight into a wall."
When Philae landed, Phil Plait, author of the Bad Astronomy blog, wrote: "I am sitting in my office on Earth, heart in throat & tears in my eyes. This is an amazing, astonishing, and inspiring moment."
The most amusing comments were found on Twitter, under the hashtag #cometlanding.
During Philae's seven-hour descent, @SarcasticRover wrote: "'Are we there yet?' — Basically everyone."
@craigengler wrote: "From the comet's perspective, we just attacked it with a robot armed with a harpoon. This may not end well for humanity."
@EmilyRinde wrote: "The internet canceled out @KimKardashian's magazine cover with the #cometlanding. Faith in humanity restored."
Referring to the ESA scientists' jubilation, @ProResting wrote: "There are similar scenes at EasyJet HQ every time one of their planes lands in the right place & at the right time, too."
The Philae lander (or someone writing on its behalf) also sent out its own tweets in the first person. @Philae2014 wrote: "Touchdown! My new address: 67P!"
MUPUS, a group of German scientists who'd designed Philae's sensors (@Philae_MUPUS) wrote: "We see post-touchdown data! Can't tweet more: need hands for high five and champagne."