Imaged just before the NASA probe made close approach on July 14, this new view of Pluto’s icy Sputnik Planum region reveals hundreds of pits, a few hundred meters wide by a few tens of meters deep, swarming across the surface. Composed of ices such as nitrogen, planetary scientists are making an early guess that these features are caused by sublimation, but the alignment and location of the pits are a mystery.
Sublimation occurs when an ice turns directly into a vapor without turning into a liquid — like “dry ice” on Earth (carbon dioxide ice), the ice will change phase into a gas without passing through the liquid phase. As there is little atmospheric pressure on Pluto, sublimation is a dominant process; as the abundant surface ices are heated, they vent gases into the tenuous atmosphere, forming a surprisingly complex interplay between the surface and atmosphere.
Indeed, the surprising lack of impact craters on Sputnik Planum shows the surface is constantly being refreshed by new ice likely being layered from the atmosphere and these pits are physical evidence of this bizarrely active ice layer.
“Pluto is weird, in a good way,” said New Horizons project scientist Hal Weaver, of Johns Hopkins Applied Physics Laboratory in Laurel, Md. “The pits, and the way they’re aligned, provide clues about the ice flow and the exchange of volatiles between the surface and atmosphere, and the science team is working hard to understand what physical processes are at play here.”
It’s hard not to imagine what this landscape would look like if we could stand on the surface of Sputnik Planum. We already know that this region is pretty much flat, but the inclusion of these pits would make it look like an ocean of dramatic sinkholes in the ice stretching to the horizon.
Read more at Discovery News
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