The Rosetta spacecraft, managed by the European Space Agency (ESA) has recorded images and other data from comet 67P/Churyumov-Gerasimenko, and now, some of that information has been released to the public.
Rosetta readings show astronomers that comets are far more complex than anyone believed, featuring basins, cliffs, and a coating of deep black powder. The atmosphere of the comet is becoming thicker as the frozen body approaches the Sun.
The spacecraft approached the comet in August 2014, taking the most detailed measurements ever made of the frozen body. Instruments on board the craft revealed the comet has a total volume of 5.13 cubic miles, and its mass was found to be around 11 billion tons. This investigation reveals that the comet is likely highly porous inside, featuring clumps of ice and dust, separated by empty spaces.
Mission engineers were able to identify 19 geographically-distinct regions over the surface of the comet, and five different terrains. Some segments of the frozen surface are smooth ice, while others feature a rocky surface. Dust is predominant in some areas over the surface of the comet, large scale depressions mark other regions, and brittle materials with pits and circular formations are predominant elsewhere.
Much of the northern hemisphere of the comet is covered in dust. The icy body heats as it approaches the Sun from the depths of space. This allows some of the ice to sublimate directly into gas, which lifts dust into a thin atmosphere. Much of this material is released at velocities too slow to overcome even the weak gravitational pull of the comet, and it returns to the surface, landing as a dusty coating.
Jets, ejecting gas into the atmosphere that will one day develop into a cometary tail, were found both on the "neck" of the two-lobed comet, as well as from pits around the body.
Ripples in dust, much like those seen in terrestrial sand dunes, were spotted on the comet, deposited by gases emanating the icy body. "Shadows" were seen in dust patterns where boulders blocked deposits of the material over the comet.
"On larger scales, many of the exposed cliff walls are covered in randomly oriented fractures. Their formation is linked to the rapid heating-cooling cycles that are experienced over the course of the comet's 12.4-hour day and over its 6.5-year elliptical orbit around the Sun," European Space Agency officials wrote in a report detailing the findings.
Rosetta launched into space in 2004, and is currently following the comet on its journey around the Sun. The pair will make their closest approach to our stellar neighbor on August 13, 2015, at a distance of 116 million miles, a length roughly 25 percent greater than that between the Earth and Sun.
Astronomers released a remarkable seven articles in the latest issue of the journal Science, discussing findings about the comet discovered utilizing the Rosetta spacecraft.