Rosetta tracks debris around comet

This blog post is based on the papers “Orbital elements of material surrounding comet 67P/Churyumov-Gerasimenko,” by B. Davidsson et al, and “Search for satellites near comet 67P/Churyumov-Gerasimenko using Rosetta/OSIRIS images,” by I. Bertini et al, which are both accepted for publication in Astronomy and Astrophysics. Ever since its approach to and arrival at Comet 67P/Churyumov–Gerasimenko, Rosetta has been investigating the nucleus and its environment with a variety of instruments and techniques. One key area is the study of dust grains and other objects in the vicinity of the comet. Earlier this year, an analysis of measurements from GIADA – Rosetta’s Grain Impact Analyzer and Dust Accumulator – and images from the OSIRIS camera revealed hundreds of individual grains, either bound to the comet's gravity or flowing away from it. These included small grains as well as much larger chunks, with sizes ranging from a few centimetres to two metres. Lumps up to four metres in size were also identified by NASA's EPOXI mission in the environment of Comet 103P/Hartley 2 after its flyby of this comet in 2010. A new study based on OSIRIS images has now built on these previous detections of cometary chunks, using dedicated observations to perform a dynamical study and determine, for the first time, the orbits of four pieces of debris, the largest of them half a metre in size, in orbit around 67P/C-G. “Previous studies were based on a handful of images of a given field, and this was sufficient to detect chunks of material and say that they are moving. However, to determine their trajectories and demonstrate whether they are truly bound to the comet, we need dozens of images taken over an extended period of time,” explains Björn Davidsson, an OSIRIS scientist at Uppsala University, Sweden, and lead author of the paper […]

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