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The tides of Venus

Time to set sail to Titan?

After the success of the audacious Entry Descent and Landing (EDL) in delivering the Curiosity rover to Mars, the space engineers of this world are no doubt looking for the next challenge. How about something further away than Mars? And how about landing on terrain that we’ve not explored before – say a liquid? Maybe we could sail about? Seems unlikely, but there’s a place that has all these challenges, the lakes of Saturn’s moon Titan.

Titan has long been one of the most interesting planetary targets in our solar system, though a moon of Saturn it is actually larger (at least by volume) than the planet Mercury. It puzzled us more after it was discovered that it has quite a dense hazy atmosphere. Titan’s atmosphere is pretty similar to ours on Earth; it’s dominated by nitrogen gas and generates a surface pressure of about 1 atmosphere. If you were on the outside of our solar system looking in (like we are currently are for the Alpha Centauri system) it would look a pretty intrigued possibility for life.

The Cassini mission, currently touring about the Saturnian system, revealed the icy moon Titan to be a complex and unique place. Shrouded in its hazy atmosphere, we could only guess at what lay beneath this before Cassini could dispatch its Huygens lander and use the on-board radar to reveal the surface below. It was worth the wait, with Huygens making a squelchy landing into an alien terrain dominated by hydrocarbons and water. Measurements by Cassini spacecraft itself have revealed a ‘methane cycle’ like the water cycle we have on Earth. It really is hydrological, but not as we know it!

A false-color mosaic shows synthetic-aperture radar imagery of Titan’s north polar region, featuing Ligeia Mare the intended desintation for the TiME mission. NASA / Jet Propulsion Lab / USGS

Aside from discoveries of volcanoes, weather and complex organic molecules, one of the most exciting developments in the Cassini mission was the observations of lakes across the Titan surface. Dotted all over the surface and in many shape and sizes, some are big enough to have been name seas – or Maria. Being so far from the sun the average surface temperature of Titan is a chilly -194°C. So rather than water these lakes and seas are thought to be made up of mixtures of methane and ethane, making them a crucial part of the moon’s methane cycle.

But exploring the chemistry, depth and (probably most excitingly) possibility for biology on these hydrocarbon lakes will be impossible before we land an interplanetary boat on these seas. Added to this would be the potential for this probe to paddle about, sampling the atmosphere and mapping the shores, without all the issues that the Mars rovers have had getting their wheels stuck.

An artist’s impression of the Titan Mare Explorer (TiME) probe. Jet Propulsion Laboratory/Corby Waste

How soon will a ‘nautical’ mission take off? There’s nothing planned as yet. Sadly, NASA already have passed once on an opportunity to send a boat to Titan. Named the Titan Mare Explorer (TiME) it was proposed as part of the latest round of Discovery missions, and lost out to theInSight mission which will head to explore the Martian interior in 2016. More recently a Spanish engineering firm revealed concept plans for another mission Titian Lake In-situ Sample Propelled Explorer (TALISE). More ambitions than TiME, this design does incorporate a way of propelling it across the seas , either with wheels or an screw.

Even if a mission to send a boat to Titan gets approved tomorrow, there would still be a seven years or so travel to this frozen world. So until then, I suppose you’ll have to content yourselves with this written view from ‘The Shores of Titan’.

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