This weekend my mind is occasionally sneaking away from the necessities of everyday life to take a virtual vacation in the world of Titan. This is the nearest to sci-fi that the world’s space community has ever ventured. It’s real, things are happening there now, and I love it.
I’m also intrigued by Amazon drones, morphogenesis, free diving, planning a trip to Morocco, and a great many other things. But there’s nothing like Titan.
Titan is the largest moon of the ringed planet Saturn and bigger than the planet Mercury. The NASA-led international Cassini satellite soared to within 1400 kilometers (870 miles) of its surface on Saturday (Nov. 30, 2013), and I’m waiting to know what shape it is in – literally. The moon’s outer layer, a shell that reminds me of hard rubber sprinkled liberally with rock, possibly spouting with the occasional water fountain, changes shape as Saturn’s gravity pulls on it. A moon made of solid rock might be bent out of shape to the extent of a moderate 3 meters, but the tides of Titan are ten times that much.
And there may be some kind of life, or the beginnings of life, on Titan. A dozen years ago, Jonathan Lunine, a Cassini scientist then at the University of Arizona (he’s now at Cornell), told me “there are only three objects — Mars, Europa, Titan — that may have undergone significant organic chemical evolution. Titan may host the kinds of organic chemical reactions that preceded and initiated life on Earth 4 billion years ago. To see methane in action, forming clouds and rain, makes Titan a very attractive astrobiology target.”
About the same time astronomers at the Paris-Meudon Observatory announced that they had found bright reflecting areas in Titan’s midsection that they thought might be caused by methane ice, formed atop a mountainous plateau. Then scientists at Northern Arizona University discovered that sparse clouds appear in Titan’s atmosphere each day. The planet was alive geologically if not biologically.
It’s remarkable to me that these opinions emerged four years before the Cassini satellite and its detachable European probe, Huygens, approached Saturn. Reason: Titan was so smog-bound that it was very difficult to figure out what lay beneath those murky clouds. Enter synthetic aperture radar (SAR). This wonderful instrument sent radar beams slicing through the cloud to the surface and back to detectors in the spacecraft, making it possible to build up high definition images (see image above).
When my book Solar System came out in 2002, it contained just one image of fascinating Titan – a custard-colored navel orange that was somewhat darker at the top than at the bottom. Disappointing. But today we have many SAR images of the moon’s terrain, and some fascinating surface images from the Huygens probe. Geoscientists envisage a most unusual planet, made up largely of ice and water but covered by that partly solid, partly liquid surface and with a relatively small, solid yet watery core.
Titan has many lakes, not the kind anyone would want to sail on, for they are composed of liquid hydrocarbons like ethane and methane. The lake pictured above, Ligeia Mare, is big enough to rank with America’s Great Lakes. This weekend the Cassini team is understandably keen to know whether, on this close encounter, their faraway craft will be able to “see” waves on Titan’s lakes with its SAR eyes. It’s a mystery that the lakes, after being scoured many times by Cassini instruments, appear to be completely calm and inert despite evidence of wind elsewhere on the moon. Finding and measuring waves would be a great boon to exploration, for this information would show whether the stuff in the lakes is viscous and if so, how viscous. In turn this would give important clues to the chemical makeup of the lakes and the nature of the wind that would be required to generate the waves.
Two or three dozen fictional books and films were produced about Titan before we really knew anything anything about it; it is supposedly a prime site for future colonization (not on my vacation list); and several new spacecraft, including a Montgolfier balloon, have been suggested though not yet added to the NASA list of future missions. From my point of view, Cassini is doing an absolutely brilliant job for its NASA masters, still out there and reporting its new, genuinely marvelous discoveries.