A 'heart' of nitrogen ice, responsible for Pluto's winds

New research led by Tanguy Bertrand, an astrophysicist and planetary scientist at NASA's Ames Research Center in California (USA), has shed light on how the famous heart-shaped plane of frozen nitrogen on the dwarf planet Pluto controls the winds in its thin atmosphere, leading to large discolourations on its shiny surface.

Experts used information gathered by NASA's New Horizons spacecraft during which the spacecraft captured an impressive array of images and data about the distant alien world.

Back in 2015, the structure looked like a large cartoon heart from a distance. Upon closer inspection, the large basin revealed itself to be a geological wonder. That basin is known as Sputnik Planitia. The basin forms the "left lobe" of the heart, while the right side is home to nitrogen glaciers and highlands.

Now, new research shows that Pluto's famous heart-shaped structure, called Tombaugh Regio (named after the astronomer Clyde Tombaugh, who discovered Pluto in 1930), governs its atmospheric circulation. When the "frozen heart" beats, it controls the Plutonian wind.

Pluto's atmosphere is about 100,000 times thinner than the Earth's

Discovering how Pluto's atmosphere behaves provides scientists with yet another place to compare the information with our own planet, identifying similar and distinctive features between Earth and a dwarf planet billions of kilometres away.

The research, which is based on advanced computer modelling, has provided more information about how this unusual landscape interacts with its surroundings. They took data on Pluto's topography and ice distribution gathered by New Horizons and performed computer simulations of possible climate cycles to discover how the circulating gas might affect its surface characteristics.

So, nitrogen gas which is also found in the air on Earth, comprises most of Pluto's thin atmosphere, along with carbon monoxide and methane. Frozen nitrogen also covers part of Pluto's heart-shaped surface. During the day, a thin layer of this nitrogen ice is heated and becomes steam. At night, the vapour descends, settles, and forms ice. Each heat/cold sequence is like a heartbeat; with each periodic evaporation and relocation of material, the resulting atmospheric disturbance pumps nitrogen winds across the surface of the planet (west winds occur approximately 40 kilometres above the surface).

"This highlights the fact that Pluto's atmosphere and winds, even if the density of the atmosphere is very low, can affect the surface," said Bertrand, who leads the Journal of Geophysical Research.

Scientists believe that if the winds were to move in a different direction, Pluto may be unrecognizable: "Sputnik Planitia may be as important to Pluto's climate as the ocean is to the Earth's climate," Bertrand said.

Reference: T. Bertrand, F. Forget, O. White, B. Schmitt, S.A. Stern, H.A. Weaver, L.A. Young, K. Ennico, C.B. Olkin Pluto's beating heart regulates the atmospheric circulation: results from high resolution and multi-year numerical climate simulations. Journal of Geophysical Research: Planets, 2020; DOI: 10.1029/2019JE006120