Fascinating Alien and Earth-Like World of Titan. Methane Lakes, Subsurface Oceans, Seasons...

    Methane Lakes Found on Titan by Cassini Spacecraft: NASA/ESA/ASI


History of Discovery of Titan
Galileo discovered 4 new moons of Jupiter with improved telescope in 17th century. Inspired by Galileo, a Dutch astronomer Christiaan Huygens discovered Titan on March 25th,1655. Its not visible to the naked eye. Titan is the largest moon of Saturn out of 82 discovered moons. Titan is also the second largest moon in our solar system after Gaynemade (One of Jupiter's moon). Titan is slighly bigger than the planet Mercury. Nearly 300 years later, a Dutch-American astrnomer found something exceptional while observing Titan. He found that Titan actually has atmosphere and that is made of methane. Further observations from earth using Hubble Space Telescope and other ground based telescopes revealed that Titan’s atmosphere was dense and hazy. What lies beneath the clouds was unkown. It increased curiosity of astronomers. Astrobiologists are fascninated by earth-like features on Titan.

Then on Sept.1,1979, a NASA spacecraft few through the saturn sytem and found a blue haze around the planet. The atmsophere was dense. Then in 1980 and 1981, Voyager 1 and 2 spacecraft (which are now beyond our solar sytem into interstellar space) passed through saturn system but cameras on voyager couldn't penetrate hazy dense atmosphere to peak into the surface. But voyager images did reveal a featureless orange world made of primarily nitrogen along with methane clouds, Propane and other organic molecules something like earth's atmosphere. What lies beneath was still unknown. Voyager's images also showed that north and southern hemispheres have different brightness hinting that the Titan might have seasons like earth.

After 7 year long journey, Cassini-Huygens probe finally entered saturn's orbit on July1st, 2004. It is the heaviest spacecraft weighing almost 3000kgs that has ever to orbit Saturn and Huygens probe would land on the moon Titan, making it the first ever spacecraft to land in outer solar sysytem. On 24th Oct, 2004 Cassini made it's first close fly-by around Titan where spacecraft sent back images to earth. Spacecraft was 1200 km from Titan during fly-by. 

The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and its rings in this true color snapshot from NASA's Cassini spacecraft.

On Christmas night 25th Dec,2004, Huygens probe detached from the cassini spacecraft and started its 20 day cruise towards Titan to land on the surface. On 14th Jan, 2005 Huygens descended for 2 hours and 27 minutes through dense atmosphere and landed on Titan mud surface. It has taken hundreds of images during the descent revealing the wonderful world of Titan. River channels, shoreline like features and even pebble like stones on the surface and moutain like features. Huygens lasted for 72 minutes before the battery died out. But it has revealed Titan like never before with gigabytes of crucial scientific data. Huygens is the only spacecraft which landed in outer solar system. During the descent, onboard instruments recorded wind sounds. Listen to the audio of descent of Huygens lander while landing on in the following link and Landing Animation.

Watch NASA animation of Huygens descent and landing below.
Watch Huygens Descent Animation NASA

Listen to the audio of the winds recorded during descent of Huygens Lander.

Artistic Illustration of Huygens Landing on Titan: NASA

Aerial View Huygens lander while descent at an altitude of 10 km above Titan.
ESA/NASA/JPL/University of Arizona























Rocky Surface with pebbles captured by Huygens Lander.



Cassini also made many fly-bys of Titan during its 13 year mission from 2004-2017. It has revealed that surface has many lakes of methane and hydrocarbon oceans, sand-dunes, methane rivers running to seas etc.  More intriguingly, Casini saw methane rain fall in north pole during Titan's summer. Titan's atmosphere extends about 370 miles high (about 600 kilometers), which makes it a lot higher than Earth's atmosphere. The mission also provided evidence that Titan is hiding an internal, liquid ocean beneath its surface, likely composed of water and ammonia. Titan is alive and many earth like features. It takes 16 earth days to revolve Saturn once. Titan is the only world in our solar system to have liquid oceans on surface beyond earth. Cassini measured the the depth of largest methane lake which is 525 ft. Titan’s subsurface water could be a place to harbor life as we know it, while its surface lakes and seas of liquid hydrocarbons could conceivably harbor life that uses different chemistry than we’re used to—that is, life as we don’t yet know it. Titan could also be a lifeless world.

   Methane rain fall on north pole during Titan's Summer captured by Cassini NASA/ESA
Cassni has made 127 flybys around Titan to study Titan and also to alter it's orbit around Saturn. Finally, after 127th flyby, when Cassini finally running out of fuel, the spacecraft plunged into Saturn and crashed itself ending its 20 year long mission since launch. Cassini-Huygens discovered that Titan has clouds, rain, lakes and rivers of liquid hydrocarbons, as well as a subsurface ocean of salty water. And of all the places in the solar system, Titan is the only place besides Earth known to have liquids in the form of rivers, lakes and seas on its surface. It was a great space mission which expanded the understanding our existence in this universe. 


Sreekanth Panjala
Science Popularizer | Writer