Why Titan is so interesting for space exploration

The climate, which includes wind and methane rain, has created surface features similar to those found on Earth

by Lorenzo Ciotti
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Why Titan is so interesting for space exploration
© Wikimedia Commons

Titan is the largest natural satellite of the planet Saturn. Discovered by Dutch astronomer Christiaan Huygens on March 25, 1655, Titan was the first moon observed around Saturn at the time and the fifth in the entire solar system. It is also the only satellite in the solar system with a dense atmosphere.

Titan's atmosphere is 95% nitrogen. There are also minor components such as methane and ethane, which thicken to form clouds. The average surface temperature is very close to the triple point of methane where the liquid, solid and gaseous forms of this hydrocarbon can coexist.

The climate, which includes wind and methane rain, has created surface features similar to those found on Earth, such as dunes, rivers, lakes and seas, and, like Earth, has seasons. With its liquids and its thick atmosphere, Titan is considered similar to the primordial Earth, but with a much lower temperature, where the methane cycle replaces the hydrological cycle present on our planet.

Titan is composed mostly of water ice and rocky material. Its thick atmosphere prevented observation of the surface until the arrival of the Cassini-Huygens space mission in 2004, which made it possible to reach the surface with a landing vehicle.

Titan
Titan© Wikimedia Commons
 

Why Titan is so interesting for space exploration

Cassini-Huygens exploration led to the discovery of lakes of liquid hydrocarbons in the satellite's polar regions. Geologically the surface is young, considering that there are some mountains and possible cryovolcanoes, but it is generally flat and smooth with few impact craters observed.

Titan may have been much more geologically active in the past. Models of Titan's internal evolution suggest that the crust was only 10 kilometers thick until about 500 million years ago, allowing large amounts of low-viscosity water magma to escape from cryovolcanoes and obliterate any surface features that formed before that time.

Subsequently, when the crust reached 50 km thickness, it prevented the constant resurfacing of magma, and any active cryovolcano after that point would have erupted much denser and more viscous aqueous magma with greater quantities of ammonia and methanol.

This would suggest that Titan's methane is no longer constantly being added to its atmosphere and could be completely depleted within a few tens of millions of years.