The prospects of finding even bacterial life as we know it are pretty slim for Titan ( see Hubble Space Telescope image above). Titan is an exciting place for planetary astronomers because it is the only moon in our solar system with an atmosphere, and the thickness of this atmosphere is sufficiently high that surface conditions might be suitable for forming complex molecules; perhaps similar to the pre-biotic molecules that existed here on earth 4 billion years ago. But it is so cold that few astrobiologists hold out much hope that bacterial life forms will be found there.
As for Europa, the interiors of some of the moons of Jupiter have, perhaps, liquid water since the satellites are ice-rich, and they are under tidal gravitational stress by Jupiter; Io being a particularly dramatic instance of what these stresses can do to a planet. But whether this means organic molecules might be present, we have no way of knowing for certain. There is now substantial evidence for liquid water below the icy crust of Europa, which means that with energy, water and dissolved minerals, this could be one of the most exciting hunting grounds for extraterrestrial life we will have available to us for centuries to come.
Copyright 1997 Dr. Sten Odenwald
Return to Ask the Astronomer.