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article imageTitan's Secret: A Subsurface Ocean

By Tea Lulic     Jun 13, 2007 in Science
A new study says that a mysterious signal of low frequency radio waves on icy Saturn's moon Titan could possibly point to an existence of an underground ocean of liquid water. What can we conclude about this? Take a guess - aliens, fossils, space animals?
Forget about Mars! Let's turn to something different or something we would have never thought of. Let's turn to Saturn's moon Titan. If you have ever read anything about Titan, you would know that its surface is largely composed of water ice which is kept rock hard because of its surface temperature which ranges to about -178 Celsius. However, according to theoretical models of the moon's interior the ammonia rich water which can be found deep beneath the surface could possibly stay liquid - perhaps even forming an ocean.
The research done by Fernando Simoes of the Centre d'Etudes Terrestres et Planetaires in Saint Maur, France might be the first actual, observational evidence of ocean's existence. It is based on an enigmatic radio signal detected by the European Space Agency's Huygens probe (it actually descended on the moon's surface).
The radio signal that was detected was a low frequency one: around 36 Hertz. The Huygens radio team noticed it just a couple of hours later and since then, they have worked to try and pin-point the meaning of it or what it might represent.
Echo Effect
If we think of anything that is similar to this on Earth, we would be able to see that lightning works in the same manner. It produces a similar low frequency radio waves which then bounce back and forth between the ground and the upper parts of our atmosphere. This results in precisely defined frequencies (which are similar to that found on Titan).
Now, if we take a look at Titan's surface, we would see that it is basically formed out of ice. Since ice is not a really good reflector of radio waves, something must be underneath this surface which reflects the signals. The team says that an ocean underneath the surface would do a great job at reflecting these radio waves.
"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."
Instrumental Effects
Even though researchers know for certain that something exists underneath the surface, they do not know how far it lies. They are also very puzzled by some aspects of the signal. The most puzzling thing is that the signal is 10 times more stronger than that found on Earth (if we think of lightning).
Because of this, the team suspected that other parts of the probe were interfering, but laboratory experiments with copies of the instruments have ruled this out.
They also tested whether parts of the radio instrument vibrate at 36 Hertz to actually produce this signal. So far this does not appear to be the case. However, the team will investigate this at lower temperatures - the ones actually found on Titan.
"At the present stage we are convinced [that whatever] it is, at least it is not an obvious artefact," Simoes says.
Buried Deep
Ralph Lorenz (Cassini science team member who did not participate in the experiment) says that there is a big possibility of the existence of an ocean beneath the surface.
"A subsurface water ocean is certainly expected on Titan, probably with 10% or more of ammonia acting as antifreeze," he told New Scientist. "It would likely be 50 kilometres beneath an ice crust."
He also states that there is a highly likelihood that a subsurface ocean is creating radio echoes. However, Jonathan Lunine from University of Arizona, believes that it is almost impossible that radio waves could penetrate 50 or more kilometers needed to reflect the signal from a subsurface ocean.
Squeezed and Stretched
The evidence of this ocean could come about later on from Cassini spacecraft. Scientists will use uneven gravitational pull to analyze this further.
"Expect nothing until 2009 in terms of a conclusion," he told New Scientist. "But the conclusion they do get could be definitive."
If an ocean does indeed exist, the life is most likely possible. In 2000 a scientists by the name of Andrew Fortes published a study that said that life would be possible on Titan if a subsurface ocean existed. Recently, scientists were open about discussing other planets in our solar system. They stated that planets which are now seen as the least likely to hold life, will be the ones which will most likely bloom with life.
The research seems plausible (so far). In my opinion, it is even more plausible than research done on Mars (and the recent speculation about the existence of puddles - I mentioned antigravity in that article and how the pictures that were analyzed were taken at the steepest slope on Mars). Again, we should be skeptical about this, but it is a promising research and I hope that soon we will get some answers. For now, we can only use our imagination as to what will happen and what could be found on Titan if an ocean is present.
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