We Are Not Alone – Why We Have Already Found Extraterrestrial Life Authors: Dirk Schulze-Makuch and David Darling Publisher: One World Publications ISBN: 978-1-85168-719-0 Price: £12.99 (Pb), 187pp
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I was rather incredulous of the subtitle of this book: Why We Have Already Found Extraterrestrial Life. Really? This was news to me. I had to read more!

Fortunately, the contents are little more restrained than the title, although the authors – one a Professor of Astrobiology at Washington State University, the other a well-known popular science writer – really do think there is enough evidence to say that there is microbial life on Mars. Their evidence is primarily in the form of the controversial results from the Viking landers in the 1970s, particularly from the Labelled Release and Pryolitic Release experiments. They argue that the other Viking experiments that came up negative were ill-equipped for the task; indeed a version of one of the experiments, the Gas Chromatograph Mass Spectrometer, also failed to find evidence for microbial life in Antarctica’s Dry Valleys, despite subsequent experiments since proving that life does exist there.

Half the book is about Mars, the other half covers other locales in the Solar System - life in Venus' clouds, on Europa and Titan, and various exoplanets. But it all left me more confused. In the article about Viking in the February 2010 issue of Astronomy Now, Jack Farmer of Arizona State University claimed that "Few scientists interpret the results of the Labelled Release experiment as indicating life." So which is it? We Are Not Alone does feel a little biased. Most eye-opening is their claim that deposits seen in gullies on Mars were formed by liquid water running there today, yet the consensus of scientific opinion seems to be that the Mars Reconnaissance Orbiter has conclusively shown that the deposits in the gullies are from dry avalanches, not water. With statements like this, it does call into question some of the conclusions of the book, which is a shame as it spoils an otherwise good read. As for whether there is life on Mars, I think the question is still open for debate.

Keith Cooper