Funnels eased comet – BBC

Strange pits and craters – a new discovery scientists on the comet Churyumov – Gerasimenko, which is three-quarters of emptiness. As these wells are formed, prompted observations with “Rosetta”.

Set of unusual holes and craters – the new amazing discovery made by scientists using images taken of the European mission “Rosetta” comet Churyumov with – Gerasimenko. Scientific probe arrived at the comet in August last year and in November landed on its surface a landing probe “Fila”. Since then, scientists have managed to please the public not only stunning images of comet reliefs, but also serious scientific discoveries.

So, it was shown that comet water isotopic composition of different from the Earth , and on its surface were described unusual cracks and fractures, as well as strange bumps , called goose bumps. Moreover, scientists have proved that the comet do not have a magnetic field , and even found a ready is about to break the stone into the abyss.

The current article, which appeared in the journal Nature , devoted to unusual pits on the surface of a comet, which scientists noticed immediately upon arrival at the comet probe.

A detailed study of the photos revealed that these pits are real craters, which are formed by the sublimation of ice under the surface of the comet.

is called sublimation transition from solid to gaseous state without going through the liquid phase. Scientists for the first time managed to look at the comet not just as a ball of ice and dust, as well as a complex object that has its own cycles associated with circulation around the sun. They first describe what happens to a comet c over time. “These strange round hole is as deep as wide. “Rosetta” can look right into them, “- said co-author Dennis Boudvits from the University of Maryland.

According to him, the diameter of these holes may be from tens to hundreds of meters.

«We believe that in fact it is a funnel,” – he added. These funnels emerge in the world when erosion removes large amounts of material under the surface, creating a cavity. At some point in the vaults of the cavern collapsing, and remains a funnel.

After analyzing the pictures from the camera OSIRIS, scientists have identified two main types of craters: deep with steep walls and small, similar to the previously found on other comets.

Deep cylindrical funnel diameter of 200 and a depth of about 180 meters on the comet counted 18 pieces. Radiomeasurements comet showed that the average density of the core is about 470 kg / cubic meter, which is two times less than the density of ice. In this gas analyzer and the dust it showed that the silicates and organic rather than ice, represent up to 80% by weight of the comet.

In turn, this means that 75-85% of the comet’s nucleus is empty!

It turned out that jets of gas and dust pulled from the walls of deep craters, and small pits does not. Initially, scientists believed that deep craters formed during the individual emissions of the substance. One of these emissions was observed April 14, 2014 as it approaches the comet probe. Monitor emissions helped determine how much material is ejected in one such event – it turned out that emissions alone can not explain the origin of the craters.

«Then there was a huge mass of ejected material – about 100 tons, but it is small compared with the size of the comet and can explain the origin of the well diameter of only a couple of meters, – says Boudvits. – Holes that we see a lot more. It seems that the emissions are not controlled processes, and one of its consequences. ”

Based on observations, scientists have proposed a model of education of these craters. Heat causes the comet sublimates subsurface ice, consisting primarily of water ice, carbon monoxide and carbon dioxide, forming pores. The pores grow as long as the vaults not descend under its own weight, forming a circular crater. Collapse exposes “fresh” ice, which makes it quickly sublimate, therefore, seem more deep craters are younger. “In a way, these deep craters remind me of craters found on comet 9P / Tempel mission Deep Impact, – says Michael A’Hirn, co-author of the study. – The process is completely different, but they both allow you to further explore the comet. ”