Thick vs. Thin

A 1999 article in Science first got me excited about the new science of “astrobiology,” although it probably had the opposite effect on most readers. The article—by a young post-doc at Caltech, Eric Gaidos, and a couple of his senior colleagues, Ken Nealson and Joe Kirschvink—seemed to put a damper on the rising speculation about life on Europa. Gaidos et al. considered the implications of the canonical interpretation: that the ice crust on Europa was so thick that any ocean must be isolated from the surface. Having accepted the prevailing thick-ice dogma, they then concluded that, because the ocean was separated from chemical oxidants at the surface, there must be severe limitations on life on Europa. If life existed at all, it would be minimal in its isolated and sealed liquid ocean.

Even with speculation about chemistry and energy from possible undersea volcanism, life would be limited. Giant squid with “eyes the size of dinner plates” (as proposed tongue-in-cheek by Chyba of the SETI Institute) were ruled out as were the weird advanced forms of Europan aquatic life appearing as fanciful illustrations in popular science magazines. All these speculatice forms of life were snuffed under the official thick layer of solid ice.