Saturn's Moon Enceladus Grabs the Attention of Alien Life Hunters

Reports that there may be large amounts of water in liquid form just under the surface of Enceladus, a moon of Saturn, has brought the satellite to the attention of scientists in the field of astrobiology – the study of life on worlds other than Earth.

 According to a NASA press release, "the presence of liquid water inside Enceladus would have major implications for future astrobiological studies on the possibility of life within icy bodies of the outer solar system." Scientists theorize that the presence of water, plus the presence of organic compounds, may result in the evolution of simple life forms.

Such a theory, of course, has yet to be tested. Unlike their colleagues in other branches of biology, astrobiologists do not yet have bacteria, plants or animals to study. Instead, they are left to theorize about the possibility of life on other planets and moons.

Despite the hostility of most real estate in the Solar System, astrobiologists have raised the issue of life in a number of widely differing environments.

 While Enceladus has shot to near the top of the list of potential life zones, Mars holds the title of long-time astrobiology favorite. Space probes have never conclusively proven that life exists or has existed on Mars, but have not entirely disproven it either. Confusing readings from an experiment on a Viking lander, coupled with possible fossilized bacteria found in a meteorite that may have originated from Mars, have left open the question that some sort of organism might exist on the Red Planet.

Also high on the list of potential homes to extraterrestrial life is Europa, a moon of Jupiter. Like Enceladus, Europa may have a large sea of liquid water just under the surface.

 Even Jupiter and Venus have been suggested as potential oases of life. This is despite the fact that both planets, at first glance, seem extremely inhospitable to any form of biological activity. The late Carl Sagan and others have theorized that floating life forms could exist in the clouds of Jupiter, a theory that inspired the short story A Meeting With Medusa by science fiction author Arthur C. Clarke. In his book Venus Revealed, David Grinspoon, the principal investigator for NASA's Exobiology Research Program, speculates that Venus could also have spawned life when it was more hospitable, and that such life could still exist in a narrow band in the planet's upper atmosphere.

In all likelihood, the life forms that future astrobiologists may study will not be little green men, but simple bacteria-like organisms. Nevertheless, the finding of even the humblest life form will bring with it a host of scientific and philosophical implications. In anticipation of that day, astrobiologists continue their quest for ET: the bacterium.

Enceladus: NASA, http://commons.wikimedia.org/wiki/File:Enceladusstripes_cassini.jpg

Meteorite: NASA, http://commons.wikimedia.org/wiki/File:ALH84001_structures.jpg

Bacteria: US Agricultural Research Service, http://commons.wikimedia.org/wiki/File:E_coli_at_10000x.jpg