Mars Extant Life:
What’s Next?

The conference “Mars Extant Life:  What’s Next” was convened November 5–8, 2019, in Carlsbad, New Mexico. This three-and-a-half-day conference focused on understanding and discussing strategies for seeking possible extant life on Mars. Inspired by the prior conference, “Biosignature Preservation and Detection in Mars Analog Environments” (May 16–18, 2016, in Lake Tahoe, California), which addressed the search for ancient life, this conference promoted broad community discussion of numerous extant life hypotheses that have evolved in response to discoveries by ongoing Mars orbiter and surface missions.

The venue of Carlsbad was chosen because it offers the opportunity for field observations at two important terrestrial analog environments (caves and salt deposits), and in Mars planning it is imperative to remember that first and foremost, Mars is a field location. The conference had 82 abstract contributions and 71 participants in attendance (from the U.S., Mexico, Germany, and France), including many graduate students and early career scientists. Student travel grants were provided by the Mars Program Office at the NASA Jet Propulsion Laboratory (JPL). Institutional support was provided by the NASA Mars Exploration Program, the Mars Program Office JPL/Caltech, the NASA Astrobiology Institute, the National Cave and Karst Research Institute, the Lunar and Planetary Institute, and the Universities Space Research Association.

The purpose of the conference was to review and discuss constraints on the possibility of extant life on Mars as well as possibilities for advancing this sector of science. A specific goal was to answer two questions of practical relevance to NASA’s Mars Exploration Program:  (1) Where, on Mars, should we advocate looking for evidence of extant life (and how strong are the relevant technical arguments)? (2) What detection methodologies would be most effective?

A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia (“oases”), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order):  caves, deep subsurface, ices, and salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, and instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceeds the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories, in analog field sites, and from theoretical modeling.

A full report of the conference findings will be published in an upcoming issue of Astrobiology. For more information about the conference, including links to the program and abstracts, visit https://www.hou.usra.edu/meetings/lifeonmars2019/.

— Text provided by Brandi Carrier and Dave Beatty