Comets

Photo of the surface of the area of the comet 67P/Churyumov-Gerasimenko known as Agilkia taken by the Philae lander from a 9 m height (Photo ESA/Rosetta/Philae/ROLIS/DLR)

A special issue of the journal “Science” describes an early analysis of data collected by the lander Philae in its descent to the surface of the comet 67P/Churyumov-Gerasimenko. Its mission was short and ESA engineers can’t get a stable contact after those of recent weeks but the data collected were very helpful. Another very interesting study just appeared about the interaction of the comet with the solar wind.

One of the pits in the area called Seth on the surface of the comet 67P/Churyumov-Gerasimenko (Image ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

An article published in the journal “Nature” describes a research on a series of 18 pits on the comet 67P/Churyumov-Gerasimenko. They are nearly circular and some of them are a source of activity, emitting jets of gas and dust. They were discovered a long time ago but an analysis of the images collected by ESA’s space probe Rosetta’s OSIRIS camera allowed to establish that probably they were formed following a collapse of the surface.

Six of the icy areas on the surface of the comet 67P/Churyumov-Gerasimenko found by the Rosetta space probe (Image ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

The OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) camera on ESA’s space probe Rosetta allowed to identify 120 icy areas on the surface of the comet 67P/Churyumov-Gerasimenko. A study of the presence of ice has just been published in the journal “Astronomy & Astrophysics”. That presence was well known but Rosetta’s observations allowed to understand the phases of transformation into gas, how much of it forms the comet’s coma and tail and what falls back to the surface.

The area of the comet 67P/Churyumov-Gerasimenko where Philae landed (Ellipse: ESA/Rosetta/Philae/CONSERT; Image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

During the weekend the lander Philae resumed communications from the surface of the comet 67P/Churyumov-Gerasimenko. It’s been almost exactly seven months since Philae ran out of battery power and, because its position didn’t allow it to recharge them using its solar panels, had gone into hibernation. Now ESA is preparing new plans to try to make the most of the period in which the comet will be close enough to the Sun to provide the energy needed for Philae to work.

Picture of the comet 67P/Churyumov-Gerasimenko taken by the Rosetta space probe on May 20, 2015 that shows gas jets coming from its nucleus (Photo ESA/Rosetta/NavCam)

The journal “Astronomy and Astrophysics” will publish an article that illustrates a discovery about the atmosphere of the comet 67P/Churyumov-Gerasimenko generated by the sublimation of the ice it contains. Water, but also carbon dioxide, are turned into steam but thanks to the instrument Alice of the space probe Rosetta it was possible to discover that these molecules get broken and that this happens in two stages.