Origin of Life on Mars: Suitability and Opportunities.

Andrew Steele,Horton E. Newsom,Patrick J. Gasda,Benton C. Clark,Scott J. VanBommel,Nina L. Lanza,Vera M. Kolb,Jesús Martínez-Frías,Christopher H. House

doi:10.3390/life11060539

Abstract

Although the habitability of early Mars is now well established, its suitability for conditions favorable to an independent origin of life (OoL) has been less certain. With continued exploration, evidence has mounted for a widespread diversity of physical and chemical conditions on Mars that mimic those variously hypothesized as settings in which life first arose on Earth. Mars has also provided water, energy sources, CHNOPS elements, critical catalytic transition metal elements, as well as B, Mg, Ca, Na and K, all of which are elements associated with life as we know it. With its highly favorable sulfur abundance and land/ocean ratio, early wet Mars remains a prime candidate for its own OoL, in many respects superior to Earth. The relatively well-preserved ancient surface of planet Mars helps inform the range of possible analogous conditions during the now-obliterated history of early Earth. Continued exploration of Mars also contributes to the understanding of the opportunities for settings enabling an OoL on exoplanets. Favoring geochemical sediment samples for eventual return to Earth will enhance assessments of the likelihood of a Martian OoL.

Highlights

The history of the proposition whether there is life on Mars has been a roller-coaster of disjoint conclusions
Mars has many specific differences from Earth (10× smaller mass, 200× less atmosphere, 6× to 20× less H2 O per unit surface area, 50× less volcanism, and no plate tectonics or spreading centers), it has many, perhaps all, of the ingredients needed for various scenarios proposed for the origin of life
Because we have a minimum date for the origin of life (OoL) on Earth [264,293], we can compare the array of suitable settings on Mars and Earth in those earliest times to gauge whether it is reasonable to expect that life could or should have arisen on Mars

Summary

Introduction

The history of the proposition whether there is life on Mars has been a roller-coaster of disjoint conclusions. More modern studies cast doubt, and the initial space exploration of Mars with snapshot images during fast flybys left the impression that the red planet was far more Moon-like than Earth-like (Mariner 4, 6, 7). The residual water ice cap was observed in the south polar region and water vapor detected in the sparse atmosphere [1], the crater-littered surfaces and lack of evidence of a substantial hydrosphere cast further doubt as to whether. 9 orbiter imaged numerous geological features, such as braided and networked channels, which attested to stages of fluid erosion, including flowing water and runoff [2], notwithstanding the confirmation that the contemporary climate of Mars is too cold and too dry for the significant persistence of liquid water. The Viking missions verified the cold, dry surface and discovered a global soil that was lacking in organics or any firm indications of metabolic activities [3].

Methods

Results

Discussion

Conclusion