Titan: Another special neighbor

This week’s mapping by Cassini of mountains on Titan brings back into focus another intriguing member of our solar system.

Cassini has found what is believed to be the highest mountain on Titan, a 10,948 peak near the equator.

Titan is bigger than Mercury and smaller than Mars. It is not a hospitable place. The surface temperature is about minus 280 degrees Fahrenheit and the air pressure is approximately 22 pounds per square inch compared with roughly 15 psi on earth. Titan’s gravity is slightly less than that of the Moon.

Yet NASA has described Titan as “ . . . one of the most Earth like worlds we have found to date.” The reasons lie in the unique combination of Titan’s composition, its distance from the Sun and its place in the orbit of Saturn.

That combination gives Titan seasonal changes, a methane cycle similar to Earth’s water cycle, standing lakes (methane), rivers (methane), erosion of its surface by wind, rain and water, and sub surface geological activity.

In many ways, Titan’s environmental system functions like Earth’s but under a different set of natural parameters.

Despite Titan’s discovery in 1655 by Christiaan Huygens, little was known of it until the Cassini-Huygens probe arrived in 2004. A by-product of Titan’s methane cycle is the formation of a thick haze in its upper atmosphere preventing observation of its surface or even meaningful study of the atmosphere itself. The inset pic is a true color image of Titan.

Titan in true color
Titan in true color

Over the last ten years NASA has considered at least two missions to follow Cassini in the exploration of Titan.

In 2007, NASA began planning the Titan Explorer mission, combining it in 2009 with ESA’s planned exploration of Enceladus. The Titan exploration would have been conducted by two landers (not rovers) on Titan’s surface, one on land and the other on a lake. The landers would have relayed data to a balloon in Titan’s atmosphere for transmission back to Earth. That mission was shelved in favor of NASA’s planned mission to Jupiter.

The second mission being considered by NASA is in Phase II study. The mission would involve puting a submarine into Titan’s largest lake, Kraken Mare. The inset pic shows the submarine at work beneath the surface.

Submerged in the Ktaken Mare
Submerged in the Ktaken Mare

Cassini has another Titan-fly by on April 4th, another sometime in July and another in December.

The Cassini mission is scheduled to end 2017.