The Titan

Ever since man began to understand the cosmos, the desire to find other habitable celestial bodies in the universe has only grown. We have ventured our own solar system looking for habitable bodies as well as peeked into the distant corners of our galaxy through our tremendously powerful telescopes looking for signs of life. Though we don’t have a strong proof or confirmation of existence of life outside our planet, all of us, deep down, believe that aliens do exist. I mean, come on, we can’t seriously think that we are all alone in the universe, can we? Our neighboring planet, the Mars, has been and is being studied for signs of life. Another such celestial body in our solar system which has been probed and analyzed is the Titan, the largest moon of the second largest planet of our solar system.

Fig: The Huygens Probe

                                                              Fig: The Cassini Spacecraft

Of the 62 known moons (all of which have confirmed complex orbits, only 52 named till now and the rest 9 are under study), the Titan is the largest. It is also the second largest moon in the solar system, after Ganymede of the Jupiter. Its size is comparable to that of the red planet Mars. The feature that interests us the most is its dense atmosphere, comprising primarily of roughly 95% nitrogen and 5% methane. Its atmosphere extends up to 600 km above the surface, which led to the belief that it is the largest moon in the solar system until the Voyager confirmed that Ganymede was actually larger. Our understanding of the Titan was so limited until the arrival of the Cassini-Huygens spacecraft on it. This mission, commonly referred to as the Cassini mission, was launched by NASA in association with the European Space Agency on October 15th, 1997. It arrived at Saturn on 30th June, 2004. The Huygens probe, equipped to study Titan (built by the European Space Agency), was dropped on to the surface of Titan on January 14th, 2005. The descent lasted for 2.25 hours. And this became the first, and so far the only landing in the outer solar system. The probe lasted for another 72 minutes on the surface and revealed magnificent images of the surface of the giant moon which showed striking similarity to that of the earth. "At Saturn's largest moon, Titan, Cassini and Huygens showed us one of the most Earth-like worlds we've ever encountered, with weather, climate and geology that provide new ways to understand our home planet,"- says the NASA’s official website on the Cassini Mission.

Diameter	5150 km (almost as large as Mars)
Surface temperature	179˚C
Surface pressure	1.6 bar
Orbital period	16 Earth days

Table: Some statistical facts about the Titan

Fig: Layers of the Titan

Titan is the only other celestial body in the solar system to have stable liquid bodies on its surface- lakes of liquid methane. Though the primary cell membrane compounds of earthly life can’t exist in such an environment, the possibility of other molecules constituting the membranes of the life forms (if present) also exists. Scientists have identified acrylonitrile as one such compound in its atmosphere. As it also rains in the Titan, there exists a high possibility of it getting mixed with the lakes of methane on the surface, thereby giving rise to life, which of course it not confirmed yet.

Fig: Surface of the Titan as mapped by the Huygens Probe (Courtesy: NASA)

The weather on the planet was strikingly similar to that on earth. The Cassini was lucky enough to see glimpses of the transition from fall to winter at Titan’s south pole. The surface is covered with dunes, resembling those of sand dunes on earth, except they are thought to be made of ice coated with hydrocarbons falling from the sky. The remarkably astonishing similarity in surface of the Titan and the earth has really fascinated the scientists. Possibility of existence of life can’t be avoided and its habitability may increase in the far future. Scientists predict that if the Sun increases its temperature and becomes a red star, the temperature of the Titan can be high enough to hold stable oceans on the surface. The fact that underground water deposits have also thought to have been existing on the satellite push the habitability prospect further. And may be one day, man may colonize another celestial body.

Written by:
Divyajyoti Biswal