Rosetta, Philae, and comet 67P

History is made as the Philae lander touches down on the surface of comet 67P after a ten year journey on the Rosetta probe.

Something amazing happened today.

510 million kilometres away at just after 0835 GMT, a one-metre cube of science started steadily falling away from the probe that’s carried it for the past ten years. After dropping for seven hours, the cube bumped onto a ball of ice flying through our solar system at 65,000kph with a closing speed just over walking pace. It fired some harpoons into the surface to keep itself stable, and sent a signal back to Earth that it was ready to begin work.

The probe is the European Space Agency’s Rosetta, the cube is the Philae lander, and the comet is 67P/Churyumov–Gerasimenko.

Half an hour later, at 1603, that signal from Philae reached us.

The effort required to set all this up is staggering. Since its launch in 2004 Rosetta had to slingshot around Mars once and Earth three times to build up enough speed to catch the comet. The Philae lander has no engine, so Rosetta had to release at exactly the right time, angle and speed to ensure the trajectory it followed coincided with the landing site. Get it slightly wrong, and much of the €1,400m mission cost would sail past the target and be lost to space. Or smash into it with such force that it shattered. Or bounce back before it could tether itself down. Or fall over after landing on a surface angled more than 30 degrees. The ESA does not insure its space vehicles.

Why do we care about comets?

Much as that clump of ice at the back of your freezer preserves scraps from ancient meals, comets trap material from the birth of our solar system. The sun, planets and asteroids of our system were formed as dust from a nebula span and clumped together, but over billions of years that initial material has changed and reacted into different stuff. The dust that’s frozen within 67P will be unchanged, giving us information about exactly what we’re all made from. Previous studies have shown that comets are rich in compounds of carbon, hydrogen, oxygen and nitrogen; all the stuff that makes up the amino acids essential for life. Philae will dig into the surface of 67P to examine more precisely than ever before what amino acids exist within the ice. There’s a theory that life may have been seeded on Earth by comets—matching the acids would be a key piece of evidence. We can also check the water molecules that make up the ice itself to see how closely the composition matches that of our own oceans. A good match would suggest a fraction of our surface water comes from melted comets (which in turn means a tiny bit of every cup of tea you drink originally flew through space).

The ESA is great at Twitter

I know very little about any of this, so if you want to know more start with the ESA’s page and dig outwards from there. I will say that the ESA has managed social media brilliantly. There’s the official feed on their page, plus the usual Twitter account (@esa) with sensible stuff. But there are also a pair of accounts speaking on behalf of the probe (@ESA_Rosetta) and lander (@Philae2014). They’re brilliant—go and read them both right now. Someone who included their MBE after their Twitter name (rarely a good sign…) called these puerile, which manages to be both accurate and completely miss the point.

If we can have films about anthropomorphised robotic trash compactors, we can definitely have stories of this pair of deep-space explorers pushing the very edges of experimental science. “Appeals to children” is not a bad thing, especially when your funding is entirely reliant on the next generation being fascinated by exploration.

After all, there’s no logical justification for spending so much money to put a box on a comet.

But if we just exist, without ever wondering how we came into being and how the universe around us was made, are we really worthy of the consciousness that makes us special?


PS: One exception to ESA doing social media well. British scientist Matt Taylor, one of the lead ESA chaps, chose to appear to camera wearing a shirt covered in semi-naked women. If there’s deep-seated sexism within your key staff, maybe try and at least hide it on the day the world is looking at you?

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Re sexism – you may have missed the bit when one of the (off camera) scientists offered to swap tops with Monika Jones, after she admired it. Her response “stop flirting, I still have a job to do…”

Clearly his excitement over the landing got the better of him.

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