An ocean on… Titan?!
March 20th, 2008 at 9:00 pm (Geology, Spacecraft)
I came across an article today describing the latest extraterrestrial ocean hypothesis — that one exists beneath the crust on Titan. That’s right, a subsurface ocean, in this case probably composed of water and ammonia. This is in contrast to the so-last-year news about methane lakes on Titan, which are widely accepted. Usually Enceladus or Europa get all of the press with regards to potential oceans, so this is pretty unexpected. From the article:
“Using data from the radar’s early observations, the scientists and radar engineers established the locations of 50 unique landmarks on Titan’s surface. They then searched for these same lakes, canyons and mountains in the reams of data returned by Cassini in its later flybys of Titan. They found prominent surface features had shifted from their expected positions by up to 19 miles. A systematic displacement of surface features would be difficult to explain unless the moon’s icy crust was decoupled from its core by an internal ocean, making it easier for the crust to move.”
I’m curious about these observations. I’m sure that the scientists involved have already applied an appropriately sized dose of skepticism to this subsurface ocean theory, but my gut reaction would be that an error in measurement is far more likely than a decoupled crust and core separated by a liquid ocean (where are you, Mr. Occam?). (In fact, if the displacements really are “systematic” then a measurement bias/error is an even more likely candidate explanation.) I’ll have to look for the upcoming article in Science!
jim said,
March 20, 2008 at 10:12 pm
I just read that on the BBC, which seems to suggest there were other reasons for this theory, like the seasonal change in spin.
wkiri said,
March 21, 2008 at 8:29 am
Thanks for the additional link!
I think they’re referring to the same observations — finding the landmarks in the “wrong” places implies an altered spin rate. Pretty weird stuff!
Heuristics Inc. said,
March 21, 2008 at 8:47 am
Heh, look at where the researcher works.
That article doesn’t have enough info to really decide whether it’s the right approach.
Do you think measurement error would be implied by a consistent offset? “Up to 19 miles” implies that it’s not consistent. But wouldn’t you expect the whole crust to shift in a piece also? Strange. Unless the covering is disconnected in pieces. Better find the real article :)
-bill
wkiri said,
March 21, 2008 at 8:55 am
Exactly, Bill. I almost wish they wouldn’t post these teaser previews before the article with the actual science content is available!
Note that the researchers are from both APL and JPL :)
Rex said,
March 21, 2008 at 6:47 pm
I caught the same BBC article, though I–hilariously enough–didn’t read it slowly enough to catch that they said “Titan”. The Cassini radar images look really nice (700m resolution is way more than enough to detect a 25km movement), so I can believe that they’re not basing their information on three or four spurious pixels here and there, but I’m still really curious to see how compellingly interesting the movements are. If there really are giant subsurface oceans, I’d expect tidal forces to cause all sorts of interesting ruptures and geysers on the surface unless the surface was very, very pliable.