(2012) Rod Pyle, Prometheus Books, trdpbk, £??.??, 348pp, ISBN 978-1-616-14589-7
When my New Worlds for Old went to press in December 1978, there had been only six wholly successful missions to Mars. It was possible to cover them in detail in one substantial chapter, and it didn't date for a long time. Twenty years later, due to the hiatus in US and Russian missions from 1976 to 1989, and then the failures of Phobos 1 and 2, Mars Observer and Mars 96, Patrick Moore was able to follow the same mission-by-mission approach in Patrick Moore on Mars (Cassell, 1998) with only two more missions to add, Mars Pathfinder/Sojourner and Mars Global Surveyor, the latter barely started.
With MGS now ended, but having had Mars Odyssey, Mars Express, Spirit, Opportunity, Mars Reconnaissance Orbiter, Rosetta/Philae, Phoenix and several failures meantime, the historical account is much more complicated especially because most of those spacecraft are still there and still operating, constantly adding new information in their various ways. Probably to write such a book now, one would have to write a general description of the planet, noting each mission's contributions where appropriate.
There are other ways to tackle the subject. Oliver Morton's Mapping Mars (Fourth Estate, 2002), followed the evolution of Martian cartography, and the stories of the individuals responsible. Destination Mars traces the missions in chronological order, but picks up a method previously used by Henry S.F. Cooper Jr. in The Search for Life on Mars (1981). That book was compiled out of pieces originally researched and written for New Yorker, with different sections of the book profiling different researchers. Rod Pyle's short chapters on the achievements of each spacecraft are interspersed with interviews of prominent researchers taking part in the respective missions. The earlier ones are from the archives of California Institute of Technology for historical reasons Caltech's Jet Propulsion Laboratory is not part of NASA, though it has been responsible for all US planetary exploration except for the Pioneer missions to Jupiter, Saturn and Venus. From Mars Pathfinder onwards, all the interviews are by Pyle himself. As Robert Manning of JPL says in the Foreword, 'What I know now and what I have come to know for a long time is that space exploration is a deeply human endeavour'.
The only problem with that approach is that all those accounts of how people look, dress, and became involved in Mars exploration, can add up to an impression that the book consists of little but character portraits. The book left me with that impression, until I went back through it making notes of the new technical and factual information I had highlighted in the first read. Although the accounts of the missions are less detailed than those in New Worlds for Old and Patrick Moore on Mars, there is plenty to learn here.
In particular the slant put on the findings of the Phoenix mission, analysing soil and ice near the north polar cap, is much more positive for the search for life than most media coverage suggested. When the Phoenix lander found perchlorates in the Martian soil, the general response seemed to be that they made the existence of life still less likely. But according to Peter Smith of the University of Arizona, 'it turns out that chlorine in perchlorate form is very stable, very soluble in water, and lowers the freezing point of water, so if you concentrate perchlorate, you get a very low freezing point in brines, and life could survive in those brines. Second, there are microbes on Earth that live on perchlorate. They use it as an energy source.'
What is truly jaw-dropping, however, are the revelations in Pyle's August 2011 interview with Dr. Chris McKay of NASA Ames Research Centre. The cited source is a Discovery News release which is still available online: evidently the findings were published in the Journal of Geophysical Research, December 2010, but I must admit I did not see any fanfare about them at the time. To understand their significance, you have to appreciate the 35 years of controversy over the Gas Chromatograph Mass Spectrometer results from the Viking landers in 1976. Despite the possible but ambiguous indications of biological activity in the other experiments, the GCMS detector failed to find organic compounds in the soil; hence the famous quote from Dr. Gerald Soffen, 'All the signs suggest that life exists on Mars, but we can't find any bodies.' The only positive result came from a soil sample taken from under a rock, the only time that was done, and it found acetone, which might have been a contaminant from the cleaning process back on Earth though if so, it was very bad luck that it was in the chamber used to test that particular sample. Subsequent tests indicated that Viking's GCMS would have been insufficiently sensitive to detect organic compounds on the surface in Antarctica's Dry Valleys, although microorganisms are prolific below the ground and inside the rocks. At times the discussion has become heated enough for claims that there's a conspiracy to promote the Viking results as wholly negative.
Immediately after the Phoenix discovery, McKay reran the Viking experiments using perchlorate-enriched soil from the Atacama desert, and produced perfectly matching results. In the presence of perchlorate, organic compounds in the desert soil broke down when heated to produce the compounds detected by Viking. And if that wasn't enough, the same results were found with soil from the Dry Valleys. Inferring the presence of organic compounds in the Viking samples doesn't prove that there is or was life on Mars, but it demolishes the generalisation that the Vikings proved there was no life. The Discovery release begins with a statement from McKay that there was no justification for testing with perchlorates until they were detected on Mars, and ends with one from a colleague saying the 20-year gap in Mars exploration might never have happened if these results had been available at the time.
This is a handsomely produced book, in highly readable format, and the colour photographs make it a useful addition to the Mars shelf. For instance, one shows the graphic creation of an incoming image from Mariner 4, described but not reproduced in Morton's Mapping Mars. But if it's the first book to include the bombshell in the paragraph above, it will be a collector's item for that reason alone.
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