Water on Mars and Life (Advances in Astrobiology and Biogeophysics)
Growing evidence, based on observations from orbiters, landers and telescopes, indicates that Mars may still have numerous hidden water reservoirs. Moreover, from the point of view of habitability, Mars is a prime target for astrobiologists in search of extant or extinct microbial life because we know that life exists in earth’s permafrost regions, such as parts of Siberia and the Antarctic, which are the closest terrestrial analogues to Mars. Water on Mars and Life surveys recent advances made in research into water on Mars together with its astrobiological implications. This volume addresses not only scientists working in the field but also nonspecialists and students in search of a high-level but accessible introduction to this exciting field of research.
A collection of papers on a fascinating topic, January 1, 2007
In the past month, more and more of us have begun to believe that liquid water has indeed flowed on the Martian surface at least once or twice in the past decade.
Well, what does all this mean about the past and present reservoirs of water on Mars? Could it be that Mars once supported life? Could it do so now?
While the findings from the past couple of years are too recent to be included in this book, I think this volume does put many of these questions into proper perspective.
We start with the history of water on Mars. That includes what we think we’re learning from meteorites (we’d probably know much more if we had some sample return data). It also covers questions of atmospheric evolution (which certainly pertain to the question of whether subsurface water-ice-reservoirs exist at present there), analogies between conditions from which early life probably arose on Earth and conditions on ancient Mars, and hydrated minerals on Mars.
Next is a section on water reservoirs on Mars at present. This includes a discussion of the global distribution of subsurface water as measured by Mars Odyssey, an article on polar caps, a paper on ground ice in the Martian regolith, and a paper by the editor about the water cycle in the atmosphere and shallow subsurface. The conclusion here is that the seemingly tiny amount of atmospheric water (only a trillion kilograms) is still enough to account for observed Martian gullies.
The final section is about aqueous environments and the implications for life. It starts by asking about the potential for evidence of life on Mars that might be preserved in sediments and mineral precipitations associated with polar lakes, streams and springs. The next question to be addressed is whether ancient (and recent) lakes on Mars could have been possible habitats for life (or be the last oases of life there at present). After that comes a paper on impact craters, water, and microbial life. Impacts can cause water to be trapped in not only in craters but in fractures of shocked rocks.
If life did exist on Mars (or still exists there), is it in salty water? Quite possibly it is, and we can read about it in the penultimate paper on microbial life in brines, evaporites, and saline sediments. While the Viking mission experiments failed to detect any life on Mars, those missions did not, of course, examine any regions where there was liquid water.
The final paper is about the lessons for Mars exploration that we can derive from the microbiology of deep-sea hydrothermal vents. As evidence gets stronger that life on Earth may have arisen in or near such vents, the question of whether such vents also existed on Mars becomes more interesting.
I recommend this book.