Chuck Bednar for redOrbit.com – @BednarChuck
Comet 67P/Churyumov–Gerasimenko, better known as the comet being studied by the ESA’s Rosetta spacecraft, is filled with surface pits similar to the sinkholes found on Earth, a team of researchers reported in a paper published Wednesday in the journal Nature.
According to BBC News, Jean-Baptiste Vincent of the Max Planck Institute for Solar System Research in Göttingen, Germany and his colleagues explained in the new study that they believe material located beneath the comet’s surface vaporizes in some areas, causing holes that can no longer support the crust above them.
Vincent said that the collapse of that crust produces cylindrical holes that can be more than 100 meters deep. The largest one, he told the BBC, is roughly 200 meters wide and 200 meters deep, and their discovery “gives us the possibility to look inside the comet for the first time.”
The comet’s pits are believed to form similar to sinkholes on Earth, which occur when rain and other sources of water slowly begin to erode surfaces made out of limestone and similar types of rock. Over time, this results in underground holes that eventually break away the crust above them, allowing them to break through to the surface.
Discovery could reveal the age of the 67P’s surface
Thus far, 18 of these sinkhole-type pits have been located on Comet 67P, all of them located on the northern hemisphere of the four-kilometer wide object. As 67P travels closer towards the sun, it’s believed that buried volatiles will be driven off, opening up more of these hollows, according to BBC News reports.
While these holes may already exist to some degree on the comet, the loss of these volatiles will likely make the situation worse. The dusty ceilings above these voids will be unable to support their own weight, despite the fact that 67P has low-gravity, and will ultimately collapse inwards. This will expose the cavern walls to direct sunlight, causing ice there to melt.
Eventually, they believe these sinkholes will open out into shallow basis, which are also likely to merge. This will allow scientists to better understand how old different types of terrains on the comet are, as regions that are home to several of these pits are also certainly older than those with uncollapsed surfaces.
In their paper, Vincent’s team wrote that the comet’s pits were “probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls… The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural, or compositional properties of the first few hundred meters below the current nucleus surface.”
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