Saturn’s Titan Is Changing

The giant smog-shrouded moon of Saturn, Titan, is changing – both in situ and in the minds of planetary scientists.  Several news stories show not only dynamic processes in play, but revolutions in what scientists think about the moon and its history.  Readers will need to determine which ideas are solidly based on observational evidence.

1. Punching bag:  Where did Titan get its thick nitrogen atmosphere, unique to the bodies of the outer solar system?  Yasuhito Sekine, a planetary scientist at the University of Tokyo, believes the nitrogen came special delivery, in the form of comets, during a theoretical period called the Late Heavy Bombardment.
       Space.com and New Scientist parroted Sekine’s ideas without stopping to ask why the comets left their gas at Titan and not the other moons.  Space.com did ask, however, where the impact craters went.  Perhaps they were covered up somehow.  The article quoted one other planetary scientist who called Sekine’s idea “an interesting hypothesis.”
2. Falling sky:  A Cassini press release from Jet Propulsion Laboratory says that Titan’s atmospheric haze is dropping as the sun moves northward, changing Titan’s seasons from equinox to solstice.  In just a few months, the news feature said, the upper haze layer dipped from 310 miles to 240 miles.  Chicken Little was not interviewed for reaction, although the caption said he was “notified”.
3. Unobservable ocean:  Space.com says that “all signs point to hidden ocean” under Titan’s surface.  “Certain details of Titan’s orbit and rotation aren’t compatible with the behavior of a celestial body that is completely solid all the way through,” the short article stated.  “But these details make a lot of sense if the huge moon is assumed to have a subsurface ocean, likely of liquid water, researchers said.”
       If true, the ocean (estimated 100 miles or more beneath the icy crust) is composed mainly of water – not of hydrocarbons necessary to replenish Titan’s atmospheric methane.  The article did not address the problem of keeping volatile, short-lived methane around for billions of years.
       The article threw in the L-word, saying that Titan “is considered one of the leading candidates to host life beyond Earth.”  Rose-Marie Balland [Royal University of Belgium], whose team is proposing the ocean model, was not shy about leaping beyond scientific knowledge: “Astrobiologists do not not really know yet what are the necessary conditions for life to emerge,” she said, “but it seems that the presence of water is a requirement.”
4. Familiar shores:  Space.com posted a video animation, based on actual radar data, of a flyover of Titan’s large southern lake, Ontario Lacus (warning: loud Kinect ad precedes and follows the video).  Steve Wall explains the bays, beaches and bathtub rings of the lake, thought to be filled with liquid ethane and methane, surrounded by water ice mountains.
5. Separated at birth:  Live Science floated the idea that Titan has look-alikes.  “Some Alien Planets May Be Like Saturn’s Moon Titan,” Charles Q. Choi speculated after hearing astrobiologist Chris McKay speculate about planets around red dwarfs, and even “rogue planets” careening through space in the dark without a star to warm them.  Maybe they should understand a Titan they can see before speculating about unseen brethren.

Last month the BBC News recounted the success of the Huygens Probe, the first spacecraft to land on Titan.  Now, it’s about TiME to return to Titan to explore its lakes: the Titan Mare Explorer (TiME) is one of several proposed missions after Cassini to return to Titan’s maria and investigate them at sea level.
    PhysOrg and New Scientist reported on the proposal from Johns Hopkins to land a floating craft in one of the lakes.  As it drifts with the breeze, it could “measure the lake’s depth with sonar and taste the brew of chemicals it contains” looking for signs of life.  A decision about which proposed planetary missions gets funding should be made in 2012.
    Live Science posted a video tour of Cassini highlights at Saturn, its rings and moons – but did not discuss Titan (warning: loud Kinect ad again).

Titan is surely one of the most intriguing bodies in the solar system.  It’s even more intriguing because of the intrigue among scientists it generates, who need a league to avoid fatigue from trying to keep this young moon going for billions of years (04/09/2011, 02/19/2011, 10/07/2010).