Saturn's moon Titan may have an underground ocean on which its crust slides like a giant, floating icecap, pushed and pulled by climate-driven winds.
The discovery, to be announced in tomorrow's issue of the journal Science, was made when scientists tried to match corresponding features on radar maps created during two-and-a-half years of flybys by the Cassini spacecraft.
Each of the flybys had mapped a swath of the moon's surface; on 19 occasions, the craft crossed over the same areas twice.
But on the revisits, easily recognizable geologic features weren't at the expected coordinates, with some of them out of place by about 20 miles (30 kilometers).
Obviously, hills and valleys weren't swapping places, said Bryan Stiles, a radar engineer at NASA's Jet Propulsion Laboratory in Pasadena, California.
Rather, the maps didn't align because Titan's surface wasn't rotating at quite the expected rate.
That was a surprise, because scientists had thought that Saturn's enormous gravity would keep the same side of Titan pointed directly at the planet, just as one side of Earth's moon always faces us.
One possible explanation was that Titan's rotation had been altered by a large, recent asteroid impact. But such impacts occur infrequently, Stiles said.
A more likely prospect, he said, is that Titan's crust is moving on top of something more slippery than rock or ice.
"There has to be some effect causing the spin to be different from what we had thought. And the most obvious cause that we can come up with is this deep ocean."
It is beginning to sound like a lot of the icy moons have subterranean oceans. I have to speculate here that this may be a universal characteristic of icy bodies greater than a certain mass. Much like the iron core aspects of our own terrestrial style worlds.
On the other hand, this seems like an excellent SF setting. Imagine a world where Europa-esque life arose under the all encompassing ice cap. Then intelligent life arises and realized there's a whole lot more above the great cold world. The first expedition beyond is undertaken and...they pop up in the middle of a methane rather than water based ecology. Much whackiness ensues.
Journey to the Center of...Titan?!
ReplyDelete"The first expedition beyond is undertaken and...they pop up in the middle of a methane rather than water based ecology. Much whackiness ensues."
ReplyDeleteHopefully they sent probes first to find out what conditions above the ice were like.
This idea reminds me of C. S. Lewis' The Silver Chair, which depicted a race of little humanoids living in giant caves deep underground. They were horrified at the thought of going aboveground because it was wide open with no roof, just the sky stretching out forever.