NASA's Cassini spacecraft buzzed Titan last year, coming close enough to taste the Saturnian moon's atmosphere. The data acquired has implications for our understanding of life throughout the galaxy, as well as Earth's own past.
Meanwhile, just this month astronomers used the NSF-supported Gemini Observatory to capture the first images of clouds over Titan's tropics. The images clarify a long-standing mystery linking Titan's weather and surface features, viewed by some scientists as an analog to Earth when our planet was young.
The effort also served as the latest demonstration of adaptive optics, which use deformable mirrors to enable NSF's suite of ground-based telescopes to capture images that in some cases exceed the resolution of images captured by space-based counterparts.
On Titan, clouds of light hydrocarbons, not water, occasionally emerge in the frigid, dense atmosphere, mainly clustering near the poles, where they feed scattered methane lakes below. Closer to the moon's equator, clouds are rare, and the surface is more similar to an arid, wind-swept terrain on Earth. Observations by space probes suggest evidence for liquid-carved terrain in the tropics, but the cause has been a mystery.
Emily Schaller from the University of Hawaii and her colleagues used NASA's Infrared Telescope Facility, situated on Hawaii's Mauna Kea, to monitor Titan on 138 nights over a period of two years, and on April 13, 2008, the team saw a tell-tale brightening. The researchers then turned to the NSF-supported Gemini North telescope, an 8-meter telescope also located on Mauna Kea, to capture the extremely high-resolution infrared snapshots of Titan's cloud cover, including the first storms ever observed in the moon's tropics.
The team suggests that the storms may yield precipitation capable of feeding the apparently liquid-carved channels on the planet's surface, and also influenced weather patterns throughout the moon's atmosphere for several weeks.
The second largest moon in the solar system, Titan has long been of interest for hopeful exobiologists. As the only other body we know of with surface bodies of liquid, complete with nitrogen, methane and complete seasonal weather weather patterns (similar to Earth's). It even has beaches, though you'll need a little more than a swimsuit to visit. Vast bodies of chemicals constantly stirred by wind and wave, heated over a gentle sunlight heat with the occasional dash of articles from Saturn's magnetosphere for spice - a perfect recipe for life. Just like a certain planet you might be familiar with (look down if you forget).
Of course there a few minor differences from our own blue-green globe. There's no oxygen for one thing, but if you think that's a problem then you're guilty of "aerobic respiration prejudice" (don't worry, most multicellular organisms are). It's also really quite amazingly cold - so cold that it has awesomely-named "cryovolcanoes", where boiled (or even just melted) water is enough to set off seismic-level explosions. Again, that's a barrier that's been overcome by homegrown Earth bacteria, so there's no reason it couldn't be managed elsewhere.
Cassini's onboard instruments have detected hydrocarbons containing up to seven carbon atoms. How important is that for life? Here's a hint: molecules with carbon in them are called organic, and those without are inorganic. Carbon is kind of a big deal, and the more (and more complicated) carbon compounds present the further towards the great cosmic chemical cocktail that is "life" you are. Some scientists believe that the Titanian interior, with its greater temperature, could already host microbial life - but it'll be a while before we can check that (unless we get real lucky, and some alien cells get real unlucky, with a cryovolcano eruption). One thing's for sure - the craft is only on the sixth of forty-five planned flybys so we can expect to hear a lot more about this real soon.
PS: Yes, it is ironic that we're expecting Titanic lifeforms to be single celled.
Posted by Luke McKinney. Photo Credit: James Estrin/New York Times.