Greetings from Week 3 of planetary atmospheres! Last week, we discussed exotic cloud types on so-called Hot Jupiter exoplanets, the challenges for liquid water on Mars, and how to estimate winds from satellite imagery. This week, it’s all about liquid hydrocarbons on Titan.Titan is the largest moon of Saturn and, like Earth, its atmosphere is dominated by nitrogen. Also like Earth, it has a hydrological cycle involving rain, clouds, rivers, and lakes–though in the case of Titan, we get methane rain rather than water rain. The topography of Titan, as gathered by the Huygens probe, is characterized by extensive dried-out channel networks that provide evidence for past flood events. And hydrocarbon lakes have been observed at high latitudes!
A mission to land a “boat” on one of the methane lakes of Titan is currently under review by NASA.
(As a HUGE aside, I recently read a story in which the characters–who live in a green, lush forest–believed that oceans no longer exist. I find this very frustrating. If it rains that means there’s a hydrological cycle, and the water has to come from somewhere. If it rains a lot, then there needs to be a large source of water, like an ocean. I get that in post-apocalyptic societies, much knowledge is lost. But this still feels like idiot plotting to me.)
The target for the first extraterrestrial sea exploration is Ligeia Mare, which is larger than Lake Superior. The backup target is Kraken Mare (awesome name, no?). The Titan Mare Explorer (TiME) is proposed to launch in 2012 and splashdown on Titan in 2023 for a 7-year cruise. The scientific objectives are the following:
- Determine the chemistry of a Titan sea
- Determine the depth of a Titan sea
- Constrain marine processes on Titan
- Determine how the local meteorology over the sea varies on diurnal timescales
- Characterize the atmosphere above the sea
I think I might have a crush on Titan. Or maybe it’s the inherent romance of a sea voyage under a Saturn-filled sky. The mash-up of the familiar with the alien gives me shivers. Out of all the planetary atmospheres I’ve studied so far, Titan has the most obvious similarities to Earth from a weather perspective. Though, you know, METHANE. Ligeia Mare might look like a gigantic oil slick.
In podcast-listening news, two stories jumped out at me recently, both on Escape Pod. “Asteroid Monte” by Craig DeLancey was a thoroughly enjoyable space-adventure/buddy-cop story with aliens. Also, the narration by Rajan Khanna really shone. And “‘Run,’ Bakri Says” by Ferrett Steinmetz, with its brilliantly ratcheted tension, in which a girl becomes a terrorist while stuck in a time loop to save her idiot brother. I enjoyed the parallels drawn to video games, and I haven’t been able to stop thinking about this story. Go check them out.