Unmasking Europa ~ Richard Greenberg

Fascinating non-fiction book about Europa, one of the moons of Jupiter, and about the scientific process of understanding and publicising the findings of the Voyager and Galileo probes to the Jovian system. Although this book is now eight years old (having been published in 2008), in the absence of new close-up observations of Europa since the Galileo mission was completed, it still remains quite relevant and interesting.

Greenberg outlines in great detail the evidence for a sub-surface ocean on Europa, which by now is overwhelming. I found the discussion of the pattern of cracks in the icy surface, and their relationship to the tidal stresses from Jupiter and the other large moons, particularly interesting.

The main disagreement which Greenberg and his team had with the rest of the Galileo researchers was about how thick the icy crust must be. He believes that it is at most a few kilometres thick, and that the ocean regularly communicates with the surface, opening up cracks and melting patches of ice, making them an ideal spot to investigate for signs of life (the book predates the discovery of plumes being ejected from Europa).

But Greenberg shows how the political process (yes, there is politics in scientific research!) instead pushed aside his group’s conclusions and enforced a different view of a deep ocean which only remotely interacts with the surface. The published NASA consensus was that the icy crust must be tens of kilometres thick and that the ocean does not interact directly with the surface.

Time and further expeditions will reveal the truth, of course. But Greenberg’s evidence is very persuasive. It’s a fascinating study in itself of how scientific research sometimes proceeds.