Posted January 16, 2015

Ripples, cliffs and cracks: Rosetta is getting to know its comet

Landscapes in the Solar System don't get much weirder than the ones on comet Churyumov-Gerasimenko and you can read - and see - all about it online. The journal Science has sped up its reviewing process and published a big pile of scientific papers just five months after the Rosetta probe started orbiting around the comet.

Probably most impressive to laypeople and professionals alike are the highly detailed photographs that simply show what the comet's nucleus looks like from close by. By now everybody knows about the strange ducklike shape but there's a lot more going on. Here's a quick video that sums up some of the findings. For more details, read on

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Comets are best known for their spectacular tails. These arise from gas and dust, emitted by the nucleus as it's heated up by the Sun. Comet Churyumov-Gerasimenko has pits in its surface that seem to be the source of this. Some are active, some are filled with dust and look like they're dead (like a dead volcano on Earth). Others don't emit anything now but could start working soon. Since Rosetta will be around for some more time, we might witness the turning on of these gas-emitting pits.

Comets don't have any atmosphere but on this one there are structures that look like ripples in the sand - like the ones that are caused by the wind on Earth. A possible explanation says that gases emitted sideways could blow dust around to form these ripples. Of course such gases are very thin but gravity on a small body like a comet is so weak that dust could be displaced anyway.

Other interesting views include cliffs that probably have been eroded, with boulders fallen off, depressions that look like they have filled up with fluid, and a great big crack in the duck's neck. Many of these observation lead to new questions (how did those features arise?) that will keep scientists occupied for some time to come. 

A nice slide show is to be found hereWired has its own summary of the scientific papers with another slideshow here and links to the papers themselves, mostly paid access, are here. They concern things like the structure of the nucleus and the chemical composition of the nucelus itself and the gases that are blown off.

Meanwhile, the world is eagerly waiting for the comet lander Philae to come back to life as the Sun charges its batteries back up. Since its landing didn't go according to plan Philae hasn't contributed as much to science as it could have but it might make up for that later. Meanwhile, here's the video once more of the landing as it should have gone - a video created by ATG-Europe.

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About Herbert Blankesteijn

Herbert Blankesteijn is a technology journalist from the Netherlands who has written for many prominent Dutch newspapers. He presented and directed television and radio programmes and has 10 books to his name. Herbert is interested in nascent fields such as 3D printing, drones, robotics and the private space business.