Projects per year
Abstract
The thermodynamic availability of water (water activity) strictly limits microbial propagation on Earth, particularly in hypersaline environments. A considerable body of evidence indicates the existence of hypersaline surface waters throughout the history of Mars; therefore it is assumed that, as on Earth, water activity is a major limiting factor for martian habitability. However, the differing geological histories of Earth and Mars have driven variations in their respective aqueous geochemistry, with as-yet-unknown implications for habitability. Using a microbial community enrichment approach, we investigated microbial habitability for a suite of simulated martian brines. While the habitability of some martian brines was consistent with predictions made from water activity, others were uninhabitable even when the water activity was biologically permissive. We demonstrate experimentally that high ionic strength, driven to extremes on Mars by the ubiquitous occurrence of multivalent ions, renders these environments uninhabitable despite the presence of biologically available water. These findings show how the respective geological histories of Earth and Mars, which have produced differences in the planets' dominant water chemistries, have resulted in different physicochemical extremes which define the boundary space for microbial habitability.
Original language | English |
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Pages (from-to) | 427-442 |
Journal | Astrobiology |
Volume | 16 |
Issue number | 6 |
Early online date | 23 May 2016 |
DOIs | |
Publication status | Published - 6 Jun 2016 |
Keywords
- Habitability
- Mars
- Salts
- Water activity
- Life in extreme environments
Fingerprint
Dive into the research topics of 'Ionic strength is a barrier to the habitability of Mars'. Together they form a unique fingerprint.Projects
- 1 Finished
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Searching for life on Mars: Searching for life on Mars: analogue and technology-based approaches
Cousins, C. R. (PI)
The Royal Society of Edinburgh
1/05/15 → 30/09/18
Project: Fellowship
Profiles
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Claire Rachel Cousins
- School of Earth & Environmental Sciences - Reader in Earth Sciences
- St Andrews Centre for Exoplanet Science
Person: Academic