Bored with exploring Mars, Lee Billings urges scientists to seek life on Jupiter’s moon Europa, which likely holds “double or even triple the amount of water in Earth’s oceans”:
After the revelations of Galileo, a minor cottage industry arose among planetary scientists estimating the volume of Europa’s ocean and the thickness of overlying ice, all in hopes of pinning down what sort of life might exist in that dark watery world – and how accessible it might be to future probes. After more than a decade of debate, the general consensus is that Europa’s abyss is more than 100 kilometers deep. … Whether the ice is thick or thin, the key question facing astrobiologists is really whether sufficient free energy exists within Europa’s sunless depths to support a biosphere – for life, if it is anything, is hungry. If scant useful energy is available beneath Europa’s ice, as many researchers suspect, the ocean could at best be a sparsely populated habitat for alien microbes. But if energy is plentiful, Europa could boast rich ecosystems of complex multicellular organisms – perhaps even something as magnificent and fearsome as Earth’s predatory deep-sea giant squid.
He adds:
Many scientists suspect such sea floor oases were where our planet’s life first emerged from inanimate matter. If the overlying ice crust is thin and mobile enough, useful energy could also trickle down from above, via heat and ejecta from the occasional cometary impact, or from the upwelling mineral salts that oxidize at the surface before slowly filtering down through fractures in the ice. It increasingly seems that, unlike Mars, which, just maybe, might have been able to support a robust biosphere deep in its geological past, Europa probably offers a rich haven for extraterrestrial life right now.
(Photo: Europa, a moon of Jupiter, appears as a thick crescent in this enhanced-color image from NASA’s Galileo spacecraft. By NASA/JPL/University of Arizona)
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