Sand 'levitating' on boiling water shapes Martian landscapes

Small amounts of boiling water causes sand on Mars to 'levitate' and move around, according to a study that could solve the mystery of how features such as large dune flows and gullies are formed on the red planet.
Experiments carried out in a simulation chamber which is able to recreate the atmospheric conditions on Mars showed that Mars' thin atmosphere combined with periods of relatively warm surface temperatures causes water flowing on the surface to violently boil.
This process can then move large amounts of sand and other sediment, which effectively 'levitates' on the boiling water.
This means that, in comparison to the Earth, relatively small amounts of liquid water moving across Mars' surface could form the large dune flows, gullies and other features, which characterise the red planet.

"Whilst planetary scientists already know that the surface of Mars has 'mass-wasting' features - such as dune flows, gullies, and recurring slope lineae - which occur as a result of sediment transportation down a slope, the debate about what is forming them continues," said Jan Raack, research fellow at The Open University in the UK.
"Our research has discovered that this levitation effect caused by boiling water under low pressure enables the rapid transport of sand and sediment across the surface," said Raack.
"This is a new geological phenomenon, which doesn't happen on Earth, and could be vital to understanding similar processes on other planetary surfaces," he said.

"We need to carry out more research into how water levitates on Mars, and missions such as the ESA ExoMars 2020 Rover will provide vital insight to help us better understand our closest neighbour," he added.