Sinkholes are apparently not a feature found on Earth only. The Rosetta comet has been reported to have some on its surface!
One of the pits on the Rosetta comet. Photo credits: Vincent et al., Nature Publishing Group.
The famous comet identified by the Rosetta spacecraft was seen to have bizarre, round holes on its surface. It was initially thought that the holes accounted for the 100-kilogram volume of dust that was also spotted. This observation has now been interpreted differently by Rosetta researcher Dennis Bodewits, from the University of Maryland.
“When we do the math, it turns out that these holes are too big. If you calculate the amount of material that comes out of such a hole, that would be a much bigger outburst than what we saw,” he said in a statement to IFLScience.
According to Bodewits and his team, the pits are similar to the sinkholes we find on Earth.
Wait. Now, what if the Philae lander also part of the Rosetta mission currently found on the surface of the comet falls into one of the sinkholes? Bodewits has reassured that this is not likely to happen.
“You only find sinkholes in specific places on the comet, and that was an important result by itself because it means that the interior is not homogenous. For whatever reason, some parts of the surface are different that others. Luckily for Philae, there are no sink holes where he is now,” says Bodewits.
The researchers explain that solid water might be trapped under the surface and warms up to eventually be converted into vapour directly, a process that might be happening when the comet approaches the sun. This would result in the formation of a hole under the surface which widens with time such that the latter collapses, creating circular features.
“Comets are extremely cold: they have a lot of ice in their interior. And these comets are also in the vacuum of space, so the water goes directly from ice to vapor: It’s a process called sublimation,” Bodewits explains.
On further inspection, the scientists found that the depths of some of the holes were found to be as large as their widths. Others were shallower though. The deep ones even had gas emanating from their sides.
“The shallower ones are probably an older version of the deeper ones,” says Bodewits. Over time, they’ve been partially filled in with dust and debris.
He also explains that comets are not yet fully understood:-
“We don’t really know what comets are made of. We have a good clue: There’s CO (carbon monoxide) and CO2 (carbon dioxide); there’s water. But in the end, we can only see what comes out of the comet”.
He also reiterated the good news that the Rosetta project would continue till next year.
“To really follow a comet into an extended part of its orbit and see how it changes, is just a treasure trove,” he said.