Sunday, April 12, 2015

Rosetta: comet wind mystery may be solved.

Scientists from the Rosetta mission may have solved the puzzle features on Comet 67P that look like they were produced by the wind.

Dust appears to be getting blown along the surface, a surprising finding on an 'airless' body like a comet. But the features could instead be created when cometary particles surrounding the nucleus fall back down again, disturbing the surface and leaving a mark. Dr Stefano Mottola outlined details to a major science meeting in Texas, USA. Some 17 different regions have been identified on the comet where materials appear ti be getting moved. These '' wind tails '' are seen around boulders, where the rock acts as a natural obstacle to some process - forming a streak of material "downwind" with it. All tails are aligned in the same direction: north to south. "it's amazing" said Dr Mottola, who is chief scientist on Rosetta's Rolis instrument.

Although, the team has come up with a formation mechanism. A process called splash saltation, invokes a stream of falling particles that cause surface dust grains to be ejected from their original positions. Another thing Dr Mottola told the audience at the 46th Lunar and Planetary Science Conference (LPSC) is: " We are postulating that particles that are falling, smash down... and they trigger the saltation of other particles, without the necessity of having some kind of wind".

He was addressing a special session on the Rosetta mission.




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