I began reviewing each episode of Cosmos, but was sidetracked by a multitude of other things. Much delayed, I finally found the time to watch episode six, “Travelers’ Tales.”
Strange that I waited so long for this one, because this is the episode I remember most from my youth as the reason to make science my way of life. “The world is my country,” Sagan quotes Christiaan Huygens in this episode, “Science my religion.”
In particular, the final sequence, a journey through the rings of Saturn and to the surface of the cloudy moon Titan, struck me as the sorts of wonder promised by science. When Cosmos was first shown, we were in the midst of the greatest voyages of discovery in history, those of the Viking, Mariner, and finally the Voyager spacecraft. What would we find in these faraway worlds? Wonder . . .
Sagan mentioned that he couldn’t wait for the Cassini probe to reach Saturn and send a lander to Titan. Sagan, of course, didn’t survive long enough to see this mission succeed, but succeed it did. Now we can know so much more about Titan than Sagan was ever able to know himself. Now we can know just what’s down there.
Let’s take a real visit, aboard the Huygens spacecraft, launched by Cassini to the surface of Titan.
I am the Huygens spacecraft, named for a human from 17th century Earth, the first human to view through a telescope my own final destination, the Saturnian moon called Titan. On Christmas Day, 2004, I left the only home I had ever known, the Cassini spacecraft, and began my short journey toward the cloud-covered world larger than Mercury, with an atmosphere thicker than Earth’s.
On January 14, in the year 2005, I enter this atmosphere, taste its composition, measure its thickness, and begin my descent. As I fall, I deploy a parachute that captures the thick nitrogen and methane sky and slows my rapid descent. I open my eyes and look around.
What wonders I see! Below me are rivers that flow, not with water, but with liquid methane. Far to the north, beyond the reach of my own cameras, Cassini will spot entire lakes of liquid hydrocarbon. This place is a pyrotechnician’s dream. Were there free oxygen here and a single random spark, the entire frozen world would go up in flames.
For two and a half hours I drift toward the landscape below. I land, finally, near a plateau called Xanadu, after the mythical pleasure dome sanctuary imagined by the human poet so long ago. Around me are rocks, made not of silicate, but of water ice, frozen so solid as to behave like solid stone. Chips of these stones, a sand of water ice, surround me everywhere. On Earth, sand grains are washed and worn by the action of liquid water. On this world, the “sand” is water, and is worn by liquid methane, which rains from the sky and rolls across the surface. Titan is the first world besides Earth where we have seen standing bodies of any liquid. Truly an amazing sight.
More wonders abound. Here there are ice volcanoes, driven by the tidal forces of giant Saturn. The volcanoes spew out not molten lava, but liquid methane and ammonia, and may be the source of the atmosphere blanketing the planet. The pressure of the atmosphere here at the surface is about what one would feel at the bottom of a swimming pool on Earth – were you to visit me here, you would literally swim through a sea of nitrogen and methane.
In this bizarre, very cold, but very active landscape, could anything be alive? Though I have taught you much you never knew before, there are many questions I cannot answer. My time is short here. My batteries grow weak, and I become weary. After barely an hour in this world of amazement, I am silent. You must come here again. When you come, find me, won’t you? Find this place, the place where, for the first time, living beings from Earth landed a probe on the moon of another world. I . . . will wait.