Permanent Human Settlement of the Earth, Space and Ocean Frontiers

Sunday, February 25, 2007

Titan's Methane Lakes

The massive “moon” Titan that orbits Saturn is a wonder of worlds. It is larger than the planet Mercury and it has an atmosphere ten times deeper than the earth’s but with an atmospheric pressure of 1.7 ATM – about the same as under 21 feet of sea water. (This is due to Titan's less significant gravity and icy core.)

I have lived for more than a month at this exact pressure, and although this fact may seem somewhat meaningless (and it is), it is still fun to think that I have lived as Titan’s surface pressure!

But there are some things about Titan that are quite earthly! It has a few similarities to earth, such as its atmosphere composition. It is composed primarily of molecular nitrogen (as is Earth's) with no more than 6% argon and a few percent methane. There are also trace amounts of at least a dozen other organic compounds: ethane, hydrogen cyanide, carbon dioxide and water. The organics are formed as methane, which dominates in Titan's upper atmosphere. No oxygen assures the planet does not catch fire!

But it is that methane that makes things interesting on Titan. On the earth, it is a nusance, "greenhouse gas", as some believe. But on Titan, it drives the interesing atmopheric chemistry. With a surface temperature of minus 290 degrees Farenheit, it forms methanse and ethane as percipitants – or clouds and even rain! These clouds are probably composed of methane, ethane or other simple organics and this fascinating organic soup rains down on the planet-moon, creating river channels and complex esutaries. It is assumed that the Casinni probe Huygens may have landed on a methane “mud-flat” ajoining a methane esutary.

Shown at the top is a photo of a Casinni radar image that depicts methane lakes on Titan – deep bodies of liquid methane lapping at shores of ice rocks that can never melt. Shown at the left is a true-color picture of one of those "shores" taken by the Hyygens probe on touchdown complete with ice rocks.

OBTW – the next Casinni flyby of Titan is in just 12 days.

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