Levitation key to long-debated mystery of how recent and present-day martian landscapes form
October 27, 2017

Europlanet 2020 RI / Open University Press Release 
**EMBARGOED until Friday 27 October 2017, 10:00 BST (09:00 UTC) **
Levitation key to long-debated mystery of how recent and present-day martian landscapes form

Scientists from The Open University (OU) have discovered a process that could explain the long-debated mystery of how recent and present-day surface features on Mars are formed in the absence of significant amounts of water.

Experiments carried out in the OU Mars Simulation Chamber – specialised equipment that is able to simulate the atmospheric conditions on Mars – reveal that Mars’s thin atmosphere (about 7 mbar – compared to 1,000 mbar on Earth), combined with periods of relatively warm surface temperatures, causes water flowing on the surface to boil violently. This process can then move large amounts of sand and other sediment, which effectively ‘levitate’ on the boiling water. This means that relatively small amounts of liquid water moving across Mars’s surface could form the large dune flows, gullies and other features that characterise the Red Planet.

Jan Raack, Marie Skłodowska-Curie Research Fellow at The Open University and lead author of the research, said: “Whilst planetary scientists already know that the surface of Mars has features such as dune flows, gullies and recurring slope lineae that occur as a result of sediment transportation down a slope, the debate continues about what is forming these recent and present-day active features. Our research has discovered that the levitation effect caused by boiling water under low pressure enables the rapid transport of sand and sediment across the surface. This is a new geological phenomenon that doesn’t happen on Earth, and could be vital to understanding similar processes on other planetary surfaces.”

Raack conducted these experiments in the Hypervelocity Impact (HVI) Laboratory based at the OU. He added: “The sources of this liquid water will require more observational studies; however, the research shows that the effects of relatively small amounts of water on Mars in forming features on the surface may have been widely underestimated. 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 insights to help us better understand these processes on our closest planetary neighbour.”

The research, which has been published on Friday 27 October 2017 in the academic journal Nature Communications, is funded by the Europlanet 2020 Research Infrastructure through the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 654208, and co-authored by academics* from the STFC Rutherford Appleton Laboratory, Universität Bern, and Université de Nantes. The initial research concept was developed by Susan J. Conway of Université de Nantes.

Further information
*The research, ‘Water induced sediment levitation enhances downslope transport on Mars’, was developed in collaboration with the following academics:
Jan Raack (lead author), Manish R. Patel, Matthew R. Balme – School of Physical Sciences, Faculty of STEM, The Open University, Milton Keynes
Clémence Herny – Physikalisches Institut, Universität Bern, Switzerland
Sabrina Carpy, Susan J. Conway – Laboratoire de Planétologie et Géodynamique, Université de Nantes, France.

After the embargo expires, the paper will be available at: https://www.nature.com/articles/s41467-017-01213-z

On Mars, locally warm surface temperatures (~293 K) occur, leading to the possibility of (transient) liquid water on the surface. However, water exposed to the martian atmosphere will boil, and the sediment transport capacity of such unstable water is not well understood. Here, we present laboratory studies of a newly recognized transport mechanism: “levitation” of saturated sediment bodies on a cushion of vapour released by boiling. Sediment transport where this mechanism is active is about nine times greater than without this effect, reducing the amount of water required to transport comparable sediment volumes by nearly an order of magnitude. Our calculations show that the effect of levitation could persist up to ~48 times longer under reduced martian gravity. Sediment levitation must therefore be considered when evaluating the formation of recent and present-day martian mass wasting features, as much less water may be required to form such features than previously thought.

Media contacts
Darry Khajehpour,
Media Relations Officer
Open University
+44 (0)1908 652520

Anita Heward
Press Officer
Europlanet 2020 RI
+44 (0) 7756 034243

Notes for Editors

About The Open University
The Open University (OU) is the largest academic institution in the UK and a world leader in flexible distance learning. Since it began in 1969, the OU has taught more than 1.8 million students and has almost 170,000 current students, including more than 15,000 overseas.

Space Science is one of The Open University’s Key Strategic Research Areas. OU research into space contributes to major global challenges through scientific exploitation of imaging and detection technologies and to building the Space sector of the UK economy. For further information please visit: www.open.ac.uk/research/main/our-research/space

The OU has a 42 year partnership with the BBC and has moved from late-night lectures in the 1970s to co-producing around 35 prime-time series a year such as The Hunt, Exodus: Our Journey to Europe, Full Steam Ahead and The Big C and Me on TV, and Inside Science, The Bottom Line and Thinking Allowed on Radio 4. Our OU viewing and listening events attracted 250m people in the UK last year which prompted more than 780k visits to the OU’s free learning website, OpenLearn: www.open.edu/openlearn/

Regarded as the UK’s major e-learning institution, the OU is a world leader in developing technology to increase access to education on a global scale. Its vast ‘open content portfolio’ includes free study units, as well as games, videos and academic articles and has reached audiences of up to 9.8 million across a variety of online formats including OpenLearn, YouTube and iTunes U.

The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302). The Open University is authorised and regulated by the Financial Conduct Authority in relation to its secondary activity of credit broking.

About Europlanet
Since 2005, Europlanet has provided Europe’s planetary science community with a platform to exchange ideas and personnel, share research tools, data and facilities, define key science goals for the future, and engage stakeholders, policy makers and European citizens with planetary science.

The Europlanet 2020 Research Infrastructure (RI) has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208 to provide access to state-of-the-art research facilities across the European Research Area and a mechanism to coordinate Europe’s planetary science community. The project builds on a €2 million Framework 6 Coordination Action and €6 million Framework 7 Research Infrastructure funded by the European Commission. The Europlanet collegial organisation, linked by a Memorandum of Understanding (MoU), has a membership of over 85 research institutes and companies.

Europlanet project website: http://www.europlanet-2020-ri.eu
Europlanet outreach website: http://www.europlanet-eu.org
Follow on Twitter via @europlanetmedia