Comet 67p/Churyumov-Gerasimenko proved to be one of the darkest objects in the Solar system
Scientists working with the VIRTIS instrument, mounted on Board the European probe “Rosetta”, has published the results of the analysis of the data collected by the device from August to December 2014.
Compare the albedo of different bodies in the Solar system. Enceladus (moon of Saturn) is 100%, the Earth Is 31%, the Moon is 12% and the comet 67P – 6%. Image: NASA/JPL/Space Science Institute (Enceladus); ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/ UPM/DASP/IDA and Gordan Ugarkovich (Earth); Robert Vanderbei, Princeton University (Moon); ESA/Rosetta/NAVCAM (67P/C-G).
One of the first studies was the measurement of the albedo of a celestial wanderer. Albedo – the reflectivity of the surface, in other words, albedo indicates how much sunlight is reflected from the kernel. The results were surprising – the albedo of the comet is only 6%, about half the albedo of our natural satellite!
This value tells us that the surface of the comet contains many minerals (e.g. iron sulfide) and compounds based on carbon. Also, a low albedo indicates that the surface of the nucleus very little or no water ice. But this does not mean that the comet is deprived of its water reserves.
“Of course,this does not mean that the comet is not rich in water, just no water ice in its surface layer, depth of which exceeds slightly more than one millimeter. The reason for this lies in the recent history of the evolution of the comet, since repeated passage in the vicinity of the Sun caused the sublimation of surface ice,” explains Fabrizio Capaccioni (Fabrizio Capaccioni), the team leader, working with the VIRTIS instrument.
There is another interesting result that emerged from researchers during the data analysis tool. On the whole surface of the comet were detected macromolecular organic compounds. Some of them are similar to carboxylic acids.
“The formation of such compounds requires the presence of volatile molecules, such as methanol, methane or carbon monoxide, which can freeze at very low temperatures. Thus, these compounds must be formed at large distances from the Sun, in the early stages of the formation of the Solar system. This suggests that we are faced with a comet, which hides in its structure traces of primordial chemical compounds that have formed with our Solar system, or perhaps even in an earlier era,” said Fabrizio Capaccioni.