Вадим Дудченко
Администратор портала

University of Exeter’s Dr. Adrien Morison and colleagues have shown how vast ice forms have been shaped in Sputnik Planitia, a nitrogen-ice-filled basin on the dwarf planet Pluto.

Sputnik Planum basin: this scene, which is about 250 miles (400 km) across, uses data from New Horizons’ Ralph/MVIC instrument. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute.

“Ice sublimation is a common geomorphic process at the surface of solid planets: for instance, sublimation of carbonic ice draws a variety of spectacular depressions on the Martian south polar cap,” the researchers said.

“On Earth, penitentes observed in high-altitude deserts are attributed to snow sublimation.”

“In the outer Solar System, some of Pluto’s terrains rank among the most emblematic landforms created by sublimation.”

“In summer 2015, the flyby by NASA’s New Horizons spacecraft revealed that Tombaugh Regio, sitting slightly north of Pluto’s equator, is the richest province in this regard.”

“Owing to the specific nature of Pluto’s tenuous atmosphere, nitrogen (N2) is considered to be the key ingredient.”

“The 1,000-km- (621-mile) wide Sputnik Planitia, the western part of Tombaugh Regio, is shown by climatic models to provide the dominant source of nitrogen ice involved in climate cycles.”

“The surface of the ice exhibits remarkable polygonal features — formed by thermal convection in the nitrogen ice, constantly organizing and renewing the surface of the ice. However, there remained questions behind just how this process could occur.”

Temperature anomalies under the icy surface of Sputnik Planitia on Pluto as predicted by computer model presented by Morison et al. Image credit: A. Morison / S. Labrosse / G. Choblet.

In their new study, Dr. Morison and co-authors used sophisticated modeling techniques to show that Sputnik Planitia’s ice forms are formed by the sublimation of ice, a phenomenon where the solid ice is able to turn into gas without going through a liquid state.

According to the team, sublimation of the nitrogen ice powers convection in the ice layer of Sputnik Planitia by cooling down its surface.

“We conducted a series of numerical simulations that showed the cooling from sublimation is able to power convection in a way that is consistent with numerous data coming from New Horizons — including the size of polygons, amplitude of topography and surface velocities,” the scientists said.

“It is also consistent with the timescale at which climate models predict sublimation of Sputnik Planitia, beginning around 1-2 million years ago.”

“It showed that the dynamics of this nitrogen ice layer echo those found on Earth’s oceans, being driven by the climate.”

“Such climate-powered dynamics of a solid layer could also occur at the surface of other planetary bodies, such as Triton (one of Neptune’s moons), or Eris and Makemake (from Kuiper’s Belt).”

The study was published in the journal Nature.

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A. Morison et al. 2021. Sublimation-driven convection in Sputnik Planitia on Pluto. Nature 600, 419-423; doi: 10.1038/s41586-021-04095-w

 



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