life on Europa
A possible scenario for life on Europa. Image credit: Richard Greenberg.
Hypothetical advanced underwater life
such as might exist in Europa's ocean.
Image: © Adolf Schaller.
Together with Mars, Enceladus, and Titan, Europa is considered one of the most biologically interesting worlds in the solar system. There are several reasons for this, among them: 1) the likely presence of a sub-surface ocean of liquid water (perhaps as much as 150 kilometers deep) which could provide a medium and solvent for life (see Europa, ocean on); 2) intense radiation from Jupiter's magnetosphere striking ice on Europa's surface and releasing oxygen, which if it finds its way into ocean could provide a fuel for life; and 3) the possible presence of undersea volcanic vents, which could furnish energy and nutrients for organisms.
On Earth, in recent years, a profusion of previously unsuspected life-forms has been found at great ocean depths, thriving, in the absence of both light and oxygen, on chemical nutrients welling up through through hydrothermal vents from the interior of the planet. Indeed, many scientists now speculate that terrestrial life may actually have originated under such conditions (see life, origin). Europan life, too, may have arisen in this way.
Advanced life on Europa?
If microscopic organisms developed on Europa, is there the possibility that some of them have evolved into large, multicellular forms? Much depends on how freely oxygen, generated at the surface by the interaction between surface ice and intense incident radiation (from Jupiter's powerful magnetosphere), has been able to make its way down into the ocean. If the Europan sub-surface ocean is rich in ocean it would have the potential to support a rich diversity of complex life, including creatures as large or larger than the great whales on Earth.
When will we know more about potential biology on Europa?
Following the Galileo Extended Mission, which supplied valuable new data on Europa, other spacecraft to this intriguing moon were considered (see Europa, future probes). As JPL's Robert Pappalardo has pointed out, "Icy moons may be the most common habitats for life in the Universe, so studying Europa will help tell us not just whether life exists elsewhere in our Solar System, but how common life may be throughout the Universe." See also ocean and possible life on Callisto.