A new study based on data collected from New Horizons has shown there is a possibility of dunes of methane on Pluto.
Dune have been found on Earth, Mars, Venus, Titan and Comet 67P, but the dunes on Pluto are not of sand but likely made up of tiny grains of solid methane. The findings are based on detailed images obtained by New Horizons. When analyzing the data, Matt Telfer and colleagues spotted a collection of 357 pale ridges, as well as six darker wind streaks, located on one of Pluto’s largest features, a vast plain called Sputnik Planitia.
“What makes this discovery surprising,” writes Alexander Hayes in a related Perspective, “is that the sediment can be mobilized despite Pluto’s tenuous atmosphere, whose surface pressure (1 Pa) is 100,000 times lower than Earth’s.”
Along the western area of the plain, the ridges run parallel with a mountain range, but farther east, they shift their orientation and become more spread out, a pattern also seen in the wind streaks. Several clues revealed that these landforms were created by wind; namely, the locations of the ridges and their distribution patterns demonstrate this.
Modeling by the authors shows that wind can create these dunes once the grains are airborne; however, a process called sublimation is required first, to lift the grains from the planet’s surface. In this process, the Sun heats surface ice enough that gas is released into the atmosphere, lofting particles into the air as a result.
The likely source of the dune grains is methane ice blown from nearby mountains, say the authors, although nitrogen ice cannot be ruled out, as a source.
“If an extremely tenuous atmosphere like that of Pluto can support the generation of bedforms from wind-driven sediment,” poses Hayes in his Perspective, “what kind of aeolian activity might we see on places like Io or Triton?”