The Spirit Rover has stumbled across something interesting today – a rock that is “uniquely martian” that appears to be mostly made of hematite. Opportunity found a lot of this mineral as well – continuing to solidify the case for rivers and oceans of water that seems-now-certainly existed on Mars eons ago. The reason I find this particularly interesting is when I first started paying attention to astronomy, I remember that the whole discussion about astrobiology and extraterrestrial intelligence was focused on liquid water (which requires – basically needs to live between – both a solid surface and a gaseous atmosphere, excluding it from >99.99% of the space in the universe) as a basis for life and therefore intelligence. It was looked at as extra-cool magic life juice (which it is) that was very rare – yet it is one of the very few molecules that you’ll find completely permeating Gaia’s biomass. So, I guess, I’m curious why intelligent life is so rare, seemingly literally confined to one little fleck of rock in the universe. Plus, we’re seeing water everywhere.
Over just the last 5-10 years, the common view on this has shifted dramatically (along with the view about the conditions needed for life to exist). Every extraterrestrial thing we’ve come into contact with over the past few years (Mars, that weird halite meteorite that crashed into a Texas yard a few years ago, Europa (and soon, Titan)) shows hints of liquid water that may age to the earliest days of the solar system.
However, sentient extraterrestrials do not seem to exist. So, perhaps the rarity is in the leap from liquid water to liquid life? If liquid water isn’t rare, perhaps the next step is exceedingly uncommon – like the leap from hot water to extremophile bacteria?