MISS on Mars – Biosignatures in Sandy Deposits on Earth and Beyond

Noffke, Nora¹, Dina Bower¹, Robert M. Hazen², Nathalie Cabrol³ (1) Old Dominion University, Norfolk, VA (2) Carnegie Institution of Washington, Washington, DC (3) NASA Ames - SETI Institute, Moffett Field, CA

Significant astrobiological studies on the detection of extraterrestrial life have been conducted in chemical deposits such as evaporites, or carbonates. Both modern and fossil sediments host biosignatures that indicate presence of existing or past life.

In contrast, this contribution focuses on physical deposits such as aquatic sand or sandstone. Those sediments are affected not by chemical processes such as mineral precipitation or early cementation, but predominantly by hydraulic (= physical) parameters.

From the early Archean to today, sandy tidal environments on Earth are colonized by benthic microbiota that form microbial mats. The response of the microbial mats to the hydraulic reworking of the substrates gives rise to specific traces, sedimentary structures that record the microbial activities. E.g., the microbial mats withstand erosion by biostabilization, or they react to deposition of sediment by baffling and trapping. Those specific sedimentary structures were termed “Microbially induced sedimentary structures – MISS”, and display a great variety of morphologies, geometries, and sizes.

Because of its past habitability potential and demonstrated history of aqueous environments, Mars is a promising candidate for the search of MISS. This search would require a payload designed to complete a multi-step investigation, including the detection in orbit of suitable candidate sites. Favorable sites for MISS include shallow water environments, which make them relevant to the current NASA "follow the water" strategy. A landing mission could be sent in a follow-up stage to search, identify, and confirm the presence of MISS (if any). Such investigation could include a rover using a shallow drill or hammering device; microscopic capabilities, compositional, chemical, and mineralogical capabilities, and tests on biogeneicity of potential biosignatures.