Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

Yup, it looks like a nice day for a sail.  It’s cloudy, of course, but you certainly won’t let that stop you.  You don your sailing suit and head down for the beach.  Off we go on our grand adventure!  I wonder what the fishing will be like today?  Two or three hours later, you’re fish-free, and the battery on your sailing suit is getting low.  So you head back to the habitat after a marvelous day on the lake. 

Hmmm, that’s odd.  I certainly don’t have any batteries in MY sailing suit.  But this little tale isn’t about you, or me and it takes place in the distant future.  Because our heroine isn’t sailing on Earth; she’s sailing on the only other place in the solar system that we know of that has liquid lakes.  And those batteries in the sailing suit are extremely important because the temperature outside isn’t a balmy 70 or 80 degrees; it’s minus 270 degrees F. and she’s sailing on Saturn’s Moon, Titan.

Radar images of methane lakes on Titan near the Moon’s north pole  NASA/JPL

At –270 degrees, the land surface the habitant is built on is mostly water ice because at –270, water ice isn’t ice as we know it here on Earth.  It’s a rock made from orderly crystals.  And the volcano on the distant horizon of her habitat isn’t erupting lava or molten rocks, it’s erupting molten water.  And at –270 degrees, the lake certainly isn’t made of water.  It’s made of liquid methane.

You know all about methane, many of you used it at your last fiesta because methane is also known as natural gas.  It’s what comes in those big blue tanks.  But at normal Earth temperatures and pressures, methane is always a gas.  It takes extreme cold to make methane a liquid.

Methane is also the simplest building block for life.  We are all carbon-based.  The reason that carbon is so important to life is that it’s one of the few molecules that can form long chains with itself.  We’re built of long chains of carbon molecules strung together, with other stuff stuck on.  Methane is the simplest carbon molecule.  The chemical formula for methane is CH4, which means one atom of carbon with four atoms of hydrogen stuck on all the sticking points.

Methane is extremely reactive with oxygen, as people who’ve been unlucky enough to be involved in a rapid oxidation of methane have discovered.  It’s also the last thing most of them discover since the rapid oxidation of methane produces a natural gas explosion.  If you regulate that oxidation you eventually produce barbequed spareribs or chocolate chip cookies. There would be no rapid oxidation of methane on Titan because there’s no free oxygen.  Free oxygen is produced by our kind of life and although there’s lots of liquid water in other places besides Earth, there is absolutely no free oxygen which says that our kind of life doesn’t exist anywhere else in the solar system in any kind of great abundance (although the lack of free oxygen doesn’t rule out the possibility of bacterial-sized life on Mars).

A ‘coastline’ on Titan taken by the Huygens probe as it descended to the surface of Saturn’s largest Moon  NASA/JPL

But what of life as we do NOT know it?  Chemical complexity is probably an absolute necessity for any kind of reproducing life, which is why carbon’s self-attachment and chain-forming habits are important.  Most of the long-chain carbon molecules on Earth were assembled at some point by something living.  There are long-chain molecules on Titan too.  Did they spontaneously form or were they also assembled? 

The Cassini spacecraft continues to circle Saturn.  It’s sent back marvelous pictures and the data collected by the Huygens probe that landed on Titan is still being analyzed.  These latest discoveries about the lakes that circle Titan’s north pole were made by the Cassini spacecraft’s smog penetrating radar.  (And yes, with all that hydrocarbon on Titan, the 98% nitrogen atmosphere [Earth’s atmosphere is 78% nitrogen] is contaminated with good old garden-variety smog.) 

	Dark regions in radar images generally mean smoother terrain, while bright regions mean a rougher surface.  Some of the new radar images sent back by Cassini show channels leading in or out of a variety of dark patches.  The curves in the channels strongly imply they were carved by liquid.
Flow channels on Titan  NASA/JPL

Some of the dark patches and connecting channels are very flat and completely black -- they reflect back essentially no radar signal, which means they must be extremely smooth.  Virtually the only thing on Earth that exhibits that degree of flatness and smoothness is the placid surface of an unruffled lake.  In some cases rims can be seen around the dark patches, suggesting the deposits that might be formed by evaporating liquid.

So, will humans ever sail on the lakes and seas of Titan?  Only time will tell but if we aren’t too stupid in our dealings with each other it could happen.  And are there fish in those lakes?  Stay tuned.  The answer could be right around the corner!