Titan May Have Water Ocean Under the Surface

RedEaredSlider writes "NASA's Cassini probe, in orbit around Saturn, may have discovered evidence for a liquid water ocean under the surface of Titan, Saturn's largest moon. The data comes from radar observations of the surface that measure Titan's rotation and tell how it is oriented relative to the plane of its orbit — its axial tilt. According to a paper to be published in an upcoming issue of Astronomy and Astrophysics (preprint PDF at arXiv.org), the new data showed that many of the planet's surface features were in the wrong place, sometimes off by as much as 30 kilometers (19 miles). Titan always presents the same face toward Saturn, just like the Moon does to Earth. But in those situations, one expects that the moon will be in the 'Cassini state,' which means that the axial tilt will have a certain value. In Titan's case, the axial tilt was measured at 0.3 degrees. That seemed too high if one assumed Titan was a solid body."

Comments

Re:Like Europa?

[Maritz]

The existence of liquid water on Europa is already pretty much a done deal due to the surface features that have been photographed. Richard Greenberg's "Unmasking Europa" is a particularly interesting read on the subject in my opinion as he outlines a strong case that the ice is much thinner than some planetary scientists believe. There are regions on the surface known as 'chaos' that appear to be formed by melt through from beneath the surface. Interestingly the celestial mechanics pointed to very high tidal forces on the Galilean moons just before the first Voyager probe arrived there and almost immediately found the incredibly actively volcanic Io.

If there is water beneath Titan's surface I would imagine that it represents a much more difficult target for a drill/melt through probe than Europa, because of the thick atmosphere and the unknown rigidity of the surface, as well as the dangers of landing in liquid. Having said that, it's great to have more potential habitats in the solar system. Enceladus's ice plumes indicate possible pockets of water below the icy crust there too.

The Europa-Jupiter System mission is scheduled for 2020 and should give a much richer pool of data on Europa, the Galileo probe sadly malfunctioned and was only able to provide a tiny fraction of the data that was intended, so there are relatively few high resolution photos available of Europa. The entire Europa catalogue can fit on one CD. The EJSM mission should also be able to settle the issue of just how thick the ice on Europa is. In his book Greenberg argues that the entire surface is recycled on the order of every few hundred thousand years at most, meaning that material from the surface could be cycled down to the ocean below, which would boost the chances of some kind of life existing considerably.

One thing we can be pretty sure of is that if life is detected on Europa, we have to conclude that life is very likely indeed to be commonplace in the Universe.