Pluto's existence at the edge of the known solar system led to questions of its composition: there was early recognition that methane was a significant component of Pluto, but was it mainly composed of ice and gas like its nearest neighbour Neptune? The spacecraft is now headed toward an even more distant world in our solar system's so-called Kuiper Belt, or Twilight Zone. There's no surface rock on Pluto that could produce sand. The ice particles first have to become airborne, which likely happens through sublimation of nitrogen ice that takes methane particles with it in the process. According to Eric Parteli, such dunes formation on the Earth requires sand and stronger winds. Within these highly detailed images, researchers noticed what looked to be an extensive system of unusual dunes stretching 75 miles along the boundary of Pluto's massive Al-Idrisi Montes mountain range and Sputnik Planitia - a nitrogen-ice plain that forms the left lobe of the planet's famous "heart".
Scientists have found evidence of the existence on Pluto dunes of frozen methane.
The likely source of the dune grains is methane ice blown from nearby mountains, although nitrogen ice can not be ruled out, as a source.
One of the most interesting aspects of the research is the implications it has for the study of other planetary surfaces.
The project was led by Matt Telfer, a physical geographer from the University of Plymouth.
These are then transported by Pluto's moderate winds (which can reach between 30 and 40 kmh), with the border of the ice plain and mountain range providing the ideal location for such regular surface formations to appear.
"They just really looked like dunes", she said. It would just kind of feel a lot like you're on another sand dune on the Earth'. "The considerably lower gravity of Pluto, and the extremely low atmospheric pressure, means the winds needed to maintain sediment transport can be 50 times lower".
The scientists estimate that these dunes formed sometime in the last 500,000 years, due to their undisturbed form and the historically convective glacial ice beneath it.
On Pluto, solar radiation also causes temperature gradients in the granular ice layer, which contributes to the ability of dunes to form.
To be able to form, dunes need an atmosphere dense enough to make wind transport possible, a supply of dry particles, and a mechanism that lifts particles off the ground. The driving force of this process may be the heating of the atmosphere by the Sun, which raises the temperature above minus 230 degrees Celsius, that is the freezing point of nitrogen.
Scientists were surprised to find dunes given Pluto's thin, weak atmosphere.