The Rosetta mission will do something never before attempted: land on a comet. The spacecraft is now on its way to intercept comet 67P/Churyumov-Gerasimenko in January 2014 and land a probe on it for what promises to be an amazing view. But what we know of comets so far comes from a few flyby missions. So, with surface composition and conditions largely a mystery, so how did engineers prepare to land on something that could be either solid ice or rock, or a powdery snow or regolith – or something in between?



They had to design the Philae lander so it could land equally well on any surface. In the tiny gravitational field of a comet, landing on hard icy surface might cause Philae to bounce off again. Alternatively, hitting a soft snowy one could result in it sinking. To cope with either possibility, Philae will touch as softly as possible. In fact, engineers have likened it more to docking in space.

Philae will fire harpoons to secure itself to the comet; additionally, the landing gear is equipped with large pads to spread its weight across a broad area (kind of like snowshoes.)

While landing on a comet will certainly be nail-biting, having a front row seat for when the comet gets closer to the Sun is the most highly anticipated part of the mission.

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“In some ways, a flyby is just a tantalizing glimpse of a comet at one stage in its evolution,” says Claudia Alexander, project scientist for the U.S. Rosetta Project at JPL. “Rosetta is different. It will orbit 67P for 17 months. We’ll see this comet evolve right before our eyes as we accompany it toward the Sun and back out again.”

We’ll be able to watch as it becomes “something poetic and beautiful, trailing a vast tail,” said Alexander. For once, we’ll be able to watch the surface of a comet transform in front of our eyes instead of relying on artist concept drawings! Additionally, the Rosetta spacecraft up above will be busy mapping the comet’s surface and magnetic field, monitoring the comet’s erupting jets and geysers, measuring outflow rates, and much more. Together, the orbiter and lander will build up the first 3-D picture of the layers and pockets under the surface of a comet.

Comets are considered a gold mine for astronomers who want to know what conditions were like back in the early days of our Solar System. And the data and images from this mission promises to be some of the most stunning we’ve yet seen.

Find out more about the Rosetta mission in the accompanying video, or see the ESA Rosetta website.

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