The mountains discovered on Pluto during the flight of the New Horizons spacecraft to the dwarf planet in 2015 are covered with a blanket of methane ice, creating bright deposits strikingly like the snow-capped mountain ranges found on Earth.
A new study conducted by an international team of scientists, including researchers from NASACalifornia’s Ames Silicon Valley Research Center analyzes data from New Horizons Plutoatmosphere and surface, using numerical simulations of Pluto’s climate to reveal that these ice caps were created by a very different process from that of Earth.
“It is particularly remarkable to see that two very similar landscapes of Earth and Pluto can be created through two very different processes,” said Tangui Bertrand, a postdoctoral fellow at Ames and lead author of an article detailing these results. Nature Communications. “Although theoretically objects like NeptuneThe moon Triton may have a similar process, nowhere else in our solar system are there icebergs like this except the Earth. “
Atmospheric temperatures on our planet decrease with altitude, mainly due to the cooling caused by the expansion of the air when moving upwards. The cool atmosphere in turn cools the surface temperatures. As a moist wind approaches the mountain on Earth, its water vapor cools and condenses, forming clouds and then the snow seen on the mountain tops. But on Pluto, the opposite happens. The atmosphere of the dwarf planet is actually warming with increasing altitude, as the more concentrated methane absorbed by the sun’s radiation. However, the atmosphere is too thin to affect surface temperatures, which remain constant. And unlike the rising winds on Earth, Pluto is dominated by winds that travel on mountain slopes.
To understand how the same landscape can be created with different materials and under different conditions, researchers developed a 3D model of Pluto’s climate at the Laboratoire de Météorologie in Paris, France, simulating the atmosphere and surface over time. They found that Pluto’s atmosphere had more gaseous methane at warmer, higher altitudes, allowing the gas to saturate, condense, and then freeze directly on mountain peaks without forming clouds. At lower altitudes there is no methane freezing because there is less of this gaseous methane, making it impossible for condensation to occur.
This process not only creates the methane ice caps in Pluto’s mountains, but also similar characteristics of the crater’s rims. The mysterious spiky terrain that can be found in the region of Tartarus Dorsa around Pluto’s equator is also explained by this cycle.
“Pluto is indeed one of the best natural laboratories we need to study in connection with physical and dynamic processes, when compounds that regularly pass between solid and gaseous interact with a planetary surface,” Bertrand said. “The flight of New Horizons has revealed amazing glacial landscapes from which we continue to learn.”
Reference: “Pluto’s equatorial mountains are covered by methane frosts as a result of a unique atmospheric process” by Tanguy Bertrand, François Forget, Bernard Schmitt, Oliver L. White and William M. Grundy, October 13, 2020, Nature Communications.
DOI: 10.1038 / s41467-020-18845-3