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The Search for Life and Biosignatures on Mars: A Mars System Science Approach (Atmosphere, Hydrosphere, Cryosphere,
James W Head1, Robin D Wordsworth2, James L Fastook3
1Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island, USA.
Astrobiology
|August 4, 2026
Summary
The search for Martian biosignatures suggests life may exist in subsurface groundwater systems. Evidence points to a deep, warm Martian biosphere, with potential biosignatures preserved globally.
Area of Science:
- Planetary Science
- Astrobiology
- Geology
Background:
- The search for biosignatures is a primary goal of Mars exploration.
- Understanding Mars' hydrological history is key to identifying potential habitats for life.
- Previous studies suggest transient surface water, but the long-term habitability remains debated.
Purpose of the Study:
- To investigate the characteristics of Mars' hydrological system and its potential to support life.
- To assess the likelihood of long-duration water reservoirs and their habitability.
- To determine the most promising environments for preserving biosignatures.
Main Methods:
- Adopting a Mars System Science approach, integrating data from atmosphere, hydrosphere, cryosphere, lithosphere, and geologic history.
- Focusing on the "follow the water" strategy, examining hydrological cycle components and their interconnectedness.
- Analyzing evidence for vertically vs. horizontally stratified hydrological systems and their temporal evolution.
Main Results:
- Northern lowlands marine environments were likely low volume, transient, and short-lived.
- The Martian hydrological cycle appears abbreviated, horizontally stratified, and globally separated by a cryosphere.
- Sub-cryospheric, warm groundwater systems have existed for over 4 billion years, potentially supporting chemotrophic life.
Conclusions:
- A subsurface "deep biosphere" is a plausible environment for Martian life.
- Catastrophic groundwater release and impact excavation could have dispersed and preserved biosignatures globally.
- Returned sedimentary samples offer a robust method for testing for past Martian life.
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