Pluto's marvelous methane dunes surprise scientists
June 1, 2018
Scientists have discovered a large swathe of desert-like dunes on Pluto composed of frozen grains of methane, a research published in the journal Science on Thursday showed.
The parallel rows of dunes, spread over roughly the size of Tokyo, were spotted on images taken by NASA's New Horizons spacecraft during its 2015 flyby.
They are located at the boundary between Pluto's heart-shaped nitrogen glacier called Sputnik Planitia and the Al Idrisi Montes mountain range made of frozen water, scientists said.
The discovery came as a surprise as scientists doubted that Pluto's extremely thin atmosphere could muster the wind to create the features common in deserts on Earth.
"Pluto, even though it's so far away from Earth and so very cold, has a riot of processes we never expected to see," Brigham Young University planetary scientist Jani Radebaugh said. "It is far more interesting than any of us dreamed, and tells us that these very distant bodies are well worth visiting."
Similar yet different
Scientists likened Pluto's dunes to those in California's Death Valley and China's Taklamakan desert, but with a very different composition.
"It's a little bit lower density than sand we're used to holding on the Earth," Radebaugh said. "So it would feel lighter in your hand, but it would still be granular and would kind of flow off your hand, and your feet would kind of crunch them as you're walking along."
Pluto, which is smaller than Earth's moon, orbits roughly 3.6 billion miles (5.8 billion kilometers) away from the sun, almost 40 times farther than Earth's orbit. Its surface is marked by plains, mountains, craters and valleys.
Methane, carbon monoxide, carbon dioxide and nitrogen exist on the dwarf planet in solid state because of Pluto's absolute zero temperatures.
Pluto's gentle winds
Scientists suggest nitrogen ice coating the surface of Sputnik Planitia transformed into gas that lifted methane particles into the air, which were then deposited by Pluto's gentle winds.
The team has yet to determine the height of the dunes, but say they are at least tens of meters tall.
Dunes have been found elsewhere in solar system — on Mars, Venus, Saturn's moon, Titan, and even a comet. But Pluto's are the only ones known to be composed of methane.
"Given we have dunes on the scorching surface of Venus under a dense atmosphere, and out in the distant reaches of the solar system at minus 230 degrees Celsius (minus 382 Fahrenheit) under a thin atmosphere, yes, dunes do have a habit of cropping up in a lot of surprising places," University of Plymouth planetary scientist Matt Telfer said.
ap/rt (Reuters, AP)