We have heard a lot about Europa. Locked in Jupiter’s orbit it is one of the smoothest celestial bodies in our solar system. We believe that enveloping an iron core, similar to Earth’s, is a massive ice crust comprised of more than double the water found here at home. Its greatest spectacle is very common knowledge today; that according to the best evidence it seems there may be a vast liquid ocean, perhaps 100km deep, under a shell 30km across. On the list of things I hope to see in my life, footage sent back from the oceans beneath is in competition for top spot.
Amazingly there is almost an even more extraordinary satellite in our solar system – Titan. Reading the details we know about Titan seem to place it closer to the realms of science-fiction than reality, but how often does that seem to be the case. Views of that most awe-striking planet, Saturn, are obscured from Titan’s surface by a dense, orange organonitrogen haze. Overall its atmosphere is mostly nitrogen, but as a strange parallel to our familiar Earth its atmosphere is adorned with clouds of methane and ethane gas. Hidden under its orange haze, Titan is only revealing its mysteries very slowly. It may be that these clouds are part of a cycle similar to that of water on Earth; including seasons, rain, and resulting rivers and seas. Certainly we know that there are dunes shaped by wind, and pictures of these can be seen on the Wikipedia page I include below. Confirming the presence of Titan’s stable bodies of liquid has been a major focus as they mark the first observed aside from our own. Radar analysis of one of Titan’s polar regions in 2006, by the Cassini spacecraft, revealed many vast lakes, seas and tributary systems. Intriguingly the lakes analysed only varied in height by 3mm at their surface, suggesting either that the winds in this region were low, or that the pools are filled with a very viscous fluid. Similar to Europa, under this strange world above, again it is thought that liquid oceans are hidden within. The vague impression we have of Titan – a cold and mysterious world tantalisingly rich with organic molecules, along with liquid bodies, and perhaps a hidden ocean yet to be confirmed – has meant that it has been studied feverishly since Voyager 1 gave us our first real glimpse in 1979. There are plans to land a probe in one of its polar lakes (images of which can also be seen on the page below), but only when the project can win the never ending funding battle at NASA. It just lost out to a mission that plans to send a probe to Jupiter in 2022 to investigate Europa, and two of Jupiter’s other moons, in more detail. Either way, we wait with patient anticipation.