Posted: Thu, Jul 26, 2001, 3:28 PM ET (1928 GMT)
A report published Thursday suggests that an ocean of liquid water could exist within Callisto, the outermost of Jupiter's four large moons. According to the research published in Thursday's issue of the journal Nature, heat generated by radioactive decay in Callisto's core would escape through the moon's crust of ice and rock far more slowly than once thought. This trapped heat could warm portions of the interior of the moon enough to create a layer of liquid water, similar to the ocean of liquid water thought to exist within Europa, another of Jupiter's large moons. Scientists suggested in the late 1990s that Callisto might have such an ocean based on magnetic field data collected by the Galileo spacecraft, but since the moon is not subject to the same tidal heating forces that warm Europa, researchers were unsure whether there was any way to keep the interior of Callisto warm enough for liquid water. While Europa's liquid water interior has interested scientists because of the possibility it could harbor life, scientists say it is far less likely conditions within Callisto could support even the simplest forms of life.

Related Links:

•  Nature Science Update article
•  SPACE.com article