This newest photo release from the European Space Agency’s Rosetta spacecraft has got to be the biggest anticlimax from an otherwise thrilling mission so far. However, the science behind the photo completely eclipses Comet 67P/Churyumov-Gerasimenko’s monochrome surface.
“As it turns out, 67P/C-G looks dark grey, in reality almost as black as coal,” said Holger Sierks, from the Max Planck Institute for Solar System Research (MPS) and principal investigator for Rosetta’s OSIRIS instrument, in a Rosetta blog update today (Dec. 12).
Taken through OSIRIS’s three color filters of red, green and blue, this photographic version of the familiar comet is our first ‘true color’ view of the dusty surface since Rosetta arrived in orbit in August. Although there are some very slight color variations, the comet would look just like this to the human eye — predominantly dark grey.
OSIRIS stands for Optical, Spectroscopic, and Infrared Remote Imaging System, and the instrument has been painstakingly capturing every small detail on the comet’s surface.
When observed from afar, long before Rosetta arrived at 67P, astronomers had an idea that the cometary surface would have, on average, a greyish color. But on closer inspection, Rosetta mission scientists are surprised by how grey the body is, even on the finest of scales. This signifies that the comet’s nucleus has very little compositional variations on its surface.
One would normally expect to see a slightly blue hue over regions dominated with ice, for example. Although other instruments on Rosetta suggest there is an abundance of ice throughout the comet, its presence certainly isn’t seen by OSIRIS. Instead, 67P is homogeneously covered in a fine dust that gives it a very uniform appearance.
Read more at Discovery News
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