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Habitat Suitability Indices for Potential Surficial Brine Environments on Mars

Presentation #213.05 in the session “Mars the Gathering!”.

Published onOct 03, 2021
Habitat Suitability Indices for Potential Surficial Brine Environments on Mars

In ecology, habitat suitability index (HSI) models are quantitative ways of representing the potential for an environment to support a species or model organism. These indices apply known environment-species relationships, such as temperature tolerances, to predict organism survival, reproduction, and development, as well as the environment’s potential for species recruitment. HSIs also allow for a consistent way of comparing different habitats and to examine their ability to support life over time.

Recently, Méndez et al. (2021) suggested applying such ecological models to astronomy and planetary science in order to resolve the habitability of extraterrestrial environments. Thus, here we develop, validate, and apply two HSIs to Mars, which given the level of environmental data available from both orbiters, landers, and global circulation models, provides an excellent opportunity for HSI application. Additionally, recent work has shown the possibility of (meta)stable brines on present-day Mars, which could provide the liquid water environment required for life (Rivera-Valentín et al., 2020). Our HSIs are primarily based on temperature and humidity (i.e., water activity), as these two environmental parameters are known to be significant stressors for life (e.g., Merino et al., 2019) while at the same time being important for liquid stability (Chevrier et al., 2020).

The developed HSIs were validated against often used Mars analogs on Earth, the Atacama desert and the Antarctic dry valleys. Model inputs were data from weather research stations, assimilated observational and model data, and measurements of microorganism activity at both sites. For Mars, model inputs were derived from the MarsWRF (Weather Research Forecasting) model, as well as environmental measurements from the Phoenix lander and Mars Science Laboratory Curiosity rover. The HSI metric outputs were then studied to identify where and when, specifically during the day and season, Mars is, relatively speaking, the most habitable. Such results can help inform the exploration of the Martian surface, in particular with regards to planetary protection protocols. Additionally, they can be extended to earlier periods of high or low obliquity to trace the evolution of Martian habitability over time.


Chevrier, V. F. et al. (2020) PSJ, doi: 10.3847/PSJ/abbc14.

Merino, N. et al. (2019) Frontiers in Microbiology, doi: 10.3389/fmicb.2019.00780.

Méndez, A. et al. (2021) Astrobiology, doi:10.1089/ast.2020.2342.

Rivera-Valentín, E. G. et al. (2020) Nature Astronomy, doi: 10.1038/s41550-020-1080-9.

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