Kraken Mare: The Largest Lake of Titan

Posted: 20 June 2014

 

An artist's impression of Kraken Mare on Titan.
An artist’s impression of Kraken Mare on Titan.

“Below the thunders of the upper deep, Far, far beneath in the abysmal sea, His ancient, dreamless, uninvaded sleep, The Kraken sleepeth”  – Tennyson.

Below the piercing orange sky, the massive alien sea gleams. Kraken Mare – named after the fabled monster of Norse legend – is the first stable body of surface liquid discovered off-Earth, and one of the most distinctive awe-inspiring me geographical features of Saturn’s largest moon: Titan.

Having concentrated on science fiction for my previous Posts, here is an irresistible opportunity to cover this distant geological phenomenon. Kraken Mare, Ligeia Mare, (named after one of the Sirens of Greek mythology), and Punga Mare, (named after the Maori ancestor of sharks and lizards) all cluster around Titan’s North Pole.

Aeons ago, a Stars and Planets book (then) reliably informed me that TEN moons orbited Saturn; now, with the amazing advances in astro-exploration and observation, the total, as of this month – stands at a staggering SIXTY TWO! As one of the most amazing wonders of the universe, two other subjects were dropped in order to accommodate this as the main topic of my latest Post.

 

A diagram showing the layout of lakes at Titan's North Pole.
A diagram showing the layout of lakes at Titan’s North Pole.

“…An exotic chemistry that could illuminate the origins of life. Titan could hardly be a more alluring destination. Surely we should be launching a boat to explore its distant shores?” – New Scientist 24 May 2014.

This intriguing episode of interstellar exploration began in March 1997, when the Huygens probe – named after Christiaan Huygens, the 17th century Dutch astronomer who discovered Saturn’s largest moon – was launched on a seven-year voyage to Titan. When Cassini reached Titan in 2004, hopes of finding reflected sunlight from the surfaces of suspected hydrocarbon lakes faded fast. Actually, at the south polar region, a dark expansive feature, which came to be known as Ontario Lacus, was the first lake of Titan to be recognised as such.

The Huygens probe landed near Titan’s equator on 14 January 2005. Although it detected no areas of liquid, a report said it “strongly indicated the presence of liquids in the recent past.” Following analysis of the moon’s surface by a penetrometer, it can be described as a “sand made of ice grains.”

On 22 July 2006, passing over the northern hemisphere, Cassini discovered a collection of large smooth areas covering the surface near the North Pole. The definitive evidence for methane-filled lakes on Titan was announced in January 2007. On 8 July 2009, the Visual & Infrared Mapping Spectrometer (VIMS) picked up a dramatic specular reflection of what has been identified as Kraken Mare’s southern shoreline. 

In a photo taken in July 2009, sunlight glints off the surface of Kraken Mare
In a photo taken in July 2009, sunlight glints off the surface of Kraken Mare

“Don’t make your surfing vacation reservations for Titan just yet” – Dr Jason Barnes.

Another awesome geographical feature of saturn’s larget moon is known as the “Throat of Kraken”; it forms a narrow strait, similar in scale to the Strait of Gibraltar. With gravity much lower compared to our Earth, and the liquid less dense, the tidal current could cause whirlpools. This is apt, considering the feared Kraken’s reputation for creating whirlpools and devouring whole ships. Yet radar results reveal that Ligeia Mare is “smooth as silk” suggesting that the real Seas of Tranquility are to be found in this sector of the solar system.   

There are plans for a submersible craft to explore the geology, and the chemistry of these lakes; it would be designed to search for organic molecules and measure the isotopic mix of its chemical composition to compile data on how Titan formed and evolved.

In a more poignant twist to this astronomical tale, scientists announced on 13 February 2008, that these polar lakes contains hundreds of times more natural gas and other liquid hydrocarbons than all the oil and natural gas reserves on Earth put together. In addition, they could hold 300 times the volume of Earth’s known oil reserves. This instantly brings to mind a wild SF scenario of mega-companies racing to extract their share of the riches of Titan!

On a final note, we have to wonder how long – or how soonboundless time, money and resources will be swiftly made available to make this science fiction become science fact!

 

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