If there's life on Mars, it could be under the ice

Publicly released:
International
NASA/JPL-Caltech/University of Arizona
NASA/JPL-Caltech/University of Arizona

Those searching for life on Mars should look within its ice, according to international researchers. The team say life almost certainly can't exist on the surface of the planet due to the radiation from the Sun, however, ice deposits in the mid-latitudes could theoretically provide a shield from that radiation while still allowing enough sunlight through to sustain microbial life. The researchers calculated what that middle ground would be, and say ice with just 0.01-0.1% of dust in it could provide a habitable area about 5-38 centimetres deep and in cleaner ice, even more habitable areas could be possible between 2.15 and 3.1 metres deep. They say this is all theoretical and just because life could exist there, doesn't mean it does, but their calculations provide a description of where the search for life on Mars should focus.

Media release

From: Springer Nature

Astrobiology: Potential microbial habitats in Martian ice *IMAGES*

Dusty ice exposed at the surface of Mars could provide the conditions necessary for the presence of photosynthetic life, according to a modelling study. The findings, published in Communications Earth & Environment, suggest that ice deposits located in the planet’s mid-latitudes should be a key location in any search for life on Mars.

High levels of harmful ultraviolet radiation from the Sun make current life on the surface of Mars almost certainly impossible. However, a sufficiently thick layer of ice can absorb this radiation and could protect cells living below its surface. Any life in these conditions would need to be in a so-called radiative habitable zone — shallow enough to receive enough visible light for photosynthesis, but deep enough to be protected from the ultraviolet radiation.

Aditya Khuller and colleagues calculated whether such a radiative habitable zone could exist in ice with the dust content level and structure of the ice observed on Mars. They found that very dusty ice would block too much sunlight, but that in ice containing 0.01–0.1% dust, a habitable region could potentially exist at depths between 5 and 38 centimetres (depending on the size and purity of the ice crystals). In cleaner ice, a larger habitable zone could exist between 2.15 and 3.10 metres deep. The authors explain that dust particles within the ice could cause occasional localised melting at depths of up to approximately 1.5 metres, providing the liquid water necessary for any photosynthetic life to survive. They suggest that the polar regions on Mars would be too cold for this process, but that subsurface melting could occur in mid-latitude areas (between approximately 30 and 50 degrees latitude).

The authors caution that the potential existence of theoretically habitable zones does not mean that photosynthetic life is, or has ever been, present on Mars. However, it does suggest that the few instances of exposed ice in the Martian mid-latitudes could be key areas for future searches for life to focus on.

Multimedia

An image from NASA’s Mars Reconnaissance Orbiter
An image from NASA’s Mars Reconnaissance Orbiter
An image from NASA’s Mars Reconnaissance Orbiter
An image from NASA’s Mars Reconnaissance Orbiter
Holes formed by cryoconite on Alaska’s Matanuska Glacier in 2012
Holes formed by cryoconite on Alaska’s Matanuska Glacier in 2012

Attachments

Note: Not all attachments are visible to the general public. Research URLs will go live after the embargo ends.

Research Springer Nature, Web page The URL will go live after the embargo ends
Journal/
conference:
Communications Earth & Environment
Research:Paper
Organisation/s: California Institute of Technology, USA
Funder: A part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We would like to thank Joe Aslin, Candice Bedford, KathleenWilliamson, Matt Cooper, Carol Stoker, and one anonymous reviewer for very helpful feedback that greatly improved the paper. We would also like to thank Matt Cooper for providing the Greenland glacier radiation measurements, along with Erin Burkett, Scott Perl, Alejandro Martinez, Rahul Kushwaha, and Arnav Banerji for helpful discussions.
Media Contact/s
Contact details are only visible to registered journalists.