As the European Space Agency's (ESA) Rosetta spacecraft continues its mission by accompanying comet 67P/Churyumov-Gerasimenko (67P, for short) on its journey into the inner solar system, sensing instruments have been studying it prior to an attempted a landing by Rosetta's Philae probe. As a result, the spacecraft has collected enough information to render a map of the various areas on the surface of the comet showing that it is composed of several different regions created by a range of forces acting upon the object.
Images of the comet's surface were captured by OSIRIS, the scientific imaging system aboard the Rosetta spacecraft, and scientists analyzing them have divided the comet into several distinct regions, each characterized by different classes of features. So detailed are these images that many have been captured at a resolution of one pixel being equal to a 30 inch square (194 sq cm) on the comet surface, even though the comet is still shadowing 67P at a distance of 39 miles (62 km).
"Never before have we seen a cometary surface in such detail," said OSIRIS Principal Investigator Dr. Holger Sierks from the Max Planck Institute for Solar System Science. "It is a historic moment – we have an unprecedented resolution to map a comet."
Areas containing cliffs, trenches, impact craters, rocks, boulders and parallel grooves have been identified and mapped. Some of these appear to be caused by aspects of the activity occurring in and around the nucleus of the comet, such as where particles from below the surface are carried up by escaping gas and vapor and strewn around the surface in the surrounding area.
"This first map is, of course, only the beginning of our work," said Dr. Sierks. "At this point, nobody truly understands how the surface variations we are currently witnessing came to be."
The newly-generated comet maps and images captured by the instruments on Rosetta will now provide a range of detail on which to finalize possible landing sites for the Philae probe to be launched by Rosetta to 67P. As such, the Rosetta team will meet in Toulouse, France, on September 13 and 14 to allocate primary and backup landing sites (from a list of sites previously selected) with much greater confidence.
Over the coming months, as the Rosetta spacecraft and comet 67P move further into the solar system and approach the sun, the OSIRIS team and other instruments on the payload will continue to observe the comet's surface for any changes. It is not expected that the features will vary in any large or dramatic manner in this time, but any changes seen will help in understanding the way in which the object may alter as it traverses the solar system.