Mars has long been believed to have been cold, dead and dry for aeons, but there is now striking new proof that not only was Mars a relatively warm and wet place in geologically recent times, but that even today there are vast reserves of water frozen beneath the planet's surface. As well as casting fascinating new insights into Mars' past, this discovery is also forcing a complete rethink about the mechanisms of global planetary change and the possibility that there is microbial life on Mars.
David Harland considers the issue of life on Mars in parallel with the origin of life on Earth. At the time the Viking instruments were designed, it was thought that all terrestrial life ultimately derived its energy from sunlight, and that the earliest form of life was the cyanobacteria with chlorophyll for photosynthesis. It was assumed the same would be the case on Mars and that microbial life would be on or near the surface that the Vikings had sampled.
In parallel with these NASA projects, the European Space Agency developed the Mars Express remote-sensing orbiter, which has detected traces of methane that may have been released by microbes. If microbial life is found on Mars, will it be based on DNA? Will this indicate that life developed independently? Or that it has characteristics in common with the most ancient forms of terrestrial life? If life is found on two planets in the same planetary system, this would favour the panspermia hypothesis. And if martian life is radically different, then in light of the discovery of planetary systems around other stars, this would, as remarked by Philip Morrison of MIT, "transform life from the status of a miracle to that of a statistic". These are all questions that the exploration of Mars for life are aimed to answer.
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From the reviews:
"David Harland's book is well times, as he succinctly sums up the history of Mars exploration, linking together the early telescopic observational stuff with the modern, represented by the wildly successful Sprit and Opportunity rovers.There's also a highly informative section on the chemical basis of life, in which we learn about the extremophiles that live next to hot thermal vents on the Earth's sea bed. Approximately 230 well-labelled and informative pictures and dozens of diagrams alone make the book good value, and one feels again some of the excitement when reading over the last 60 pages about the landings and explorations of the US Spirit and opportunity. His fine interpretations of how it all hangs together to paint a picture of an ancient Martian history in which large standing bodies of water almost certainly exited on the planet makes a book that anyone interested in Mars should have." Steve Tidey (Astronomy Now)
"This is a typical David Harland book - lots to praise . . Narrowly focussed, it covers man's progress in understanding the nature of the red planet, Mars, and whether it has, or once had, liquid water and perhaps life. It is written in an easy style and flows nicely in spite of the comprehensive detail. . The book is well illustrated with monochrome drawings and sketches, especially of spacecraft." (Roger Feasey, AAS Journal, September, 2006)
"The book is organized as an historical review of observations and theories about Mars from telescopic observation, followed by a chronological description of Mars exploration from space probes. The historical section is full of fascinating information, with many stories . that give a detailed background as to the state of knowledge of Mars up to the start of the space race and how it was obtained. . there is a wealth of detail and many interesting anecdotes." (The Observatory, Vol. 126 (1195), December, 2006)
"The prolific MrHarland has come up with a real winner in this slim but highly readable volume. . The book is profusely illustrated with maps and photos from the various missions, and there is even a very nice selection of colour plates, particularly of the spectacular views from the rovers. This really is a very fine book, and anyone interested in Mars exploration would get much out of it." (Liftoff, Issue 233, May/June, 2006)
