Habitability of Mars: How Welcoming Are the Surface and Subsurface to Life on the Red Planet?

Abstract

Mars is a planet of great interest in the search for signatures of past or present life beyond Earth. The years of research, and more advanced instrumentation, have yielded a lot of evidence which may be considered by the scientific community as proof of past or present habitability of Mars. Recent discoveries including seasonal methane releases and a subglacial lake are exciting, yet challenging findings. Concurrently, laboratory and environmental studies on the limits of microbial life in extreme environments on Earth broaden our knowledge of the possibility of Mars habitability. In this review, we aim to: (1) Discuss the characteristics of the Martian surface and subsurface that may be conducive to habitability either in the past or at present; (2) discuss laboratory-based studies on Earth that provide us with discoveries on the limits of life; and (3) summarize the current state of knowledge in terms of direction for future research.

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“…Others have been tested in the BIOMEC experiment on the exterior of the ISS for their ability to survive in Mars simulation conditions complete with ionizing radiation. I will quote just the summary for each category from (Sielaff et al, 2019):…”

Radar Observations of Liquid Water in the South Polar Region of Mars: Indications from Astrobiology Perspectives

“…The planet Mars, which is in the habitable zone of the solar system and is one of the closest planets to Earth, stands in contrast to Venus; therefore, it has attracted much attention and exploration as the most likely planet for future human colonization [3][4][5]. Its nature has sparked interest in the possibility of life's existence on Mars [6][7][8]. Human exploration of Mars through spacecraft missions started in the 1960s, with the hope of discovering extraterrestrial life on the planet [6,[9][10][11].…”