Usually we think of life as occupying the narrow range of environmental conditions in which we ourselves conduct our everyday lives. The concept of bacteria and other organisms in boiling water, in frozen sea ice, at great depths in rocks of the earth, and in the deep ocean is stimulating.
Life could exist on others planets as well. Some meteorites from Mars contain organic matter preserved inside that suggests life could have existed on our sister planet. Think of the implications for even more distant planets, stretching out to Jupiter.
The Galileo space probe has detected two moons of Jupiter-Europa and Triton-that have subtle blue coloration that suggests water. Scientists have compared Galileo data with satellite pictures of Antarctica on Earth, and concluded that the frigid surface of Europa could be covered with great fissured sheets of water ice. Liquid water is thought to exist beneath the ice because of internal heat. Europa has a long history of impacts from comets rich in hydrocarbon gases, so hydrocarbons are likely to be present there.
Europa could have the makings of gas hydrates somewhere beneath the ice at the right temperatures and pressures. Imagine being beneath the ice and watching colored hydrate snow crystals forming in the ocean. Watch them float upward to accumulate as drifts beneath the ice sheets.
Given liquid water and hydrocarbons as hydrates, some of the molecular precursors for life as we generally understand it appear to be present on Europa. Hopefully, our grandchildren will test the hypothesis of life in the hydrate niche on Europa itself!
A colorized image of Europa taken by the Galileo spacecraft. (Courtesy of the Jet Propulsion Laboratory).
