Come with me to an alien world called Titan and its mysterious ice dunes in a place called Shangi-La, first seen by…human eyes on Jan. 14, 2005.
Saturn’s planet-sized moon was analyzed in detail by NASA’s Cassini spacecraft, making more than 120 passes of Titan before the mission’s end with a suicide dive into the planet in September 2017. There is an incredible system of lakes that remind planetary scientists of Minnesota, the land of 1,000 lakes.
With one strange twist…the lakes and rivers are fluid methane and ethane, gases on Earth but liquids at minus -250 F. degrees below zero! The world of Titan is wet and wild, hidden in its own organic, orange smog of nitrogen that has tantalized astronomers for 100 years.
Orbiting 400,000 miles outside the phenomenal rings of Saturn, Titan was discovered by Dutch astronomer Christian Huygens in 1655 with four-inch reflector telescope he made. Today, any backyard telescope will show the giant moon as a tiny star.
Whipping around Saturn in just over 15 days, it was soon determined that Titan was 3,200 miles wide and just a few hundred miles smaller than the biggest moon in the Solar System, Jupiter’s frozen world Ganymede. Both moons are larger than planet Mercury and former planet Pluto.
Since the 1920s when technology allowed telescopes to analyze atmospheres of the planets and moons in our Solar System, Titan has been a big mystery and the target of all interplanetary dreams. It is the only moon with a substantial atmosphere and only one like the Earth with stable liquids on the surface.
So intrigued have been astronomers to see beneath the clouds of Titan that in 1980 the Voyager 1 spacecraft was diverted by Saturn’s gravity to the moon, though that made it impossible for a flyby of Uranus and Neptune, like it’s twin Voyager 2 did in the mid-1980s.
Nothing was revealed of the surface because of the global shroud, a big disappointment and a mistake to fly there in hindsight despite the surprise discovery mostly hydrogen, like Earth, in its atmosphere. More images and data of Uranus and Neptune to compliment those of Voyager 2 would have had more scientific value.
NASA’s $2 billion Cassini changed all that. Before orbiting Saturn in 2004, the probe ejected toward Titan a small lander called Huygens. As it floated under a parachute, Huygens imaged lakes and rivers in a shocking revelation of liquid methane and ethane on the surface. The tire-sized robot set down on the edge of a lake, its heat melting the frozen methane as it nestled.
Huygens took a series of photos showing a landscape of round, eroded rocks and analyzed the atmosphere. After 90 minutes, its batteries died and it remains on the surface of Titan.
As the science platform Cassini orbited Saturn once every 100 days or so, it made close passes by some of the planet’s 60 plus moons, including Titan. In 13 years, it made 127 close encounters with the large moon, and its special infrared radar that penetrated the dense clouds.
So, a very detailed map of the surface of Titan has been created by the Cassini team. That globe looks very much like Earth, except the incredible freezing temperatures of down to minus -290 F. degrees below zero.
Locked in rotation with one side always facing Saturn, the ringed world would be huge in the Titan sky covering two outstretched human hand-spans!
Titan has become a real world with features named after exotic places, like the bright terrain of Xanadu and the pure methane sea Mare Ligeia. And a vast area of wind-blown dunes in a mysterious region called Shangra-La, where the Huygens probe landed on the shores of a small methane lake. There are few impact craters visible on Titan, evidence that the surface is actively being changed by the weather dynamics.
Titan’s methane liquid lakes and rivers with deltas are mostly in the northern hemisphere, creating a global climate with seasonal weather patterns that are barely understood. There are even “cryovolcanoes” of active liquid eruptions bringing water and ammonia from the interior to the surface.
Buckling of tectonic plates has created mountain ranges like on Earth, though they are just a mile high or so. Titan’s surface is very diverse and complex, maybe rivaling Earth in its complexities.
The clouds of nitrogen are 150 miles thick, and are tinted orange from sunlight interacting with the ammonia and methane, creating a dozen organic, carbon-based compounds that mimic models of Earth’s primitive atmosphere.
And that is tantalizing for possible life. What could exist in rivers of flowing methane? Is there something growing in the rains of ethane over rocky mountain ranges?
For sure NASA dreamers have Titan missions in their future plans, hopefully to land and analyze the landscape. And possibly stumble across a living organism or two in that frozen alien landscape.
All the images of Titan, Saturn, its rings and other moons are available for viewing at the official Cassini website—Cassini Imaging Central Library for Operations, www.ciclops.org. The imagery is breathtaking and worth the time to surf around what astronomers know about amazing Saturn.