[Astrobiology (Journal)] The most important quest in Mars exploration is the search for biosignatures. We adopt a Mars System Science approach, calling on information from the atmosphere, hydrosphere, cryosphere, lithosphere, and geologic history for an integrated organizational framework of inquiry.
We “follow the water” by focusing on the characteristics of the hydrological system/cycle, their individual component water reservoirs, and their relationships and interconnectedness through time.
We examine the ancillary hydrological cycle environments/processes (fluvial, lacustrine, glacial, cryospheric, groundwater) required for a robust, vertically integrated hydrological cycle to support long-duration northern lowlands oceans, arguably the largest proposed water reservoirs in Mars’ history.
We find that northern lowlands marine environments are likely to be low volume, transient, and short lived, prior to freezing and sublimation. Temporally associated hydrological system components (e.g., valley networks, lakes) are generally poorly integrated and characterized by intermittent, short-duration wet periods. T
his highly abbreviated hydrological cycle is likely to be not vertically integrated but instead horizontally stratified and thus potentially characterized by a global cryosphere separating the surface from a deeper, subsurface geothermally warmed groundwater system. Evidence for a horizontally stratified hydrological system can be traced back in time to the Late Noachian.
The observed high erosion rates and the presence of phyllosilicates in the Early/Middle Noachian may have been predominantly due to the effects of the three most recent large impact basins, Hellas, Isidis, and Argyre, and their accompanying transient global deluges of hot, torrential rainfall. Sub-cryospheric, long-duration (over 4 billion years), warm subsurface groundwater systems and related chemical reactions provide an environment favorable to troglodytic chemotrophic biota in a globally connected martian “deep biosphere.”
If life developed on Mars, catastrophic release and dispersal of subsurface groundwater and impact excavation mean that biosignatures are likely to have been introduced and preserved globally. Samples of sedimentary environments returned to Earth may therefore offer a robust test of whether Mars ever possessed life.
- The Search for Life and Biosignatures on Mars: A Mars System Science Approach (Atmosphere, Hydrosphere, Cryosphere, Lithosphere, Geologic History), Astrobiology (Journal) via PubMed
- The Search for Life and Biosignatures on Mars: A Mars System Science Approach (Atmosphere, Hydrosphere, Cryosphere, Lithosphere, Geologic History), Astrobiology (Journal) via PubMed
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