An underground ocean on Titan? The apparent detection of low frequency radio waves makes liquid water beneath the surface of the huge Saturnian moon a possibility, according to research led by Fernando Simoes (Centre d’Etudes Terrestres et Planetaires, Saint Maur, France). Simoes and team have been studying what New Scientist is describing as an ‘enigmatic radio signal’ that the European Space Agency’s Huygens probe detected as it descended to Titan’s surface in 2005.
The signal seems not dissimilar to what lightning produces on Earth, where low frequency signals bounce between the ground and the upper atmosphere, in the process attenuating some frequencies while enhancing others. But Titan’s surface seems to be a poor reflector, meaning there may be a better one below. Thus the talk of an ocean, although it’s just one candidate. “We do not need a subsurface ocean but require a subsurface reflector,” Simoes told New Scientist. “If a subsurface ocean exists, the solid-liquid interface would be a good reflector.”
Still in question is the possibility of extraneous vibrations within the radio instrument itself, although the team’s testing has so far failed to reveal any evidence of this. If a body of water is there, it’s probably deep, perhaps fifty kilometers down. A vast ocean rich in ammonia is an exciting prospect indeed, but waiting for future Cassini flybys is necessary for confirmation. If an ocean can be found by analyzing Titan’s behavior under the gravitational pull of Saturn, we’ll have yet more reason for astrobiologists to ponder the outer icy moons as abodes of life.