Titan is Saturn’s largest moon. If you go outside some evening now, you’ll be able to see Saturn, looking like a very bright yellow star. If you have a small telescope, you should have little trouble seeing its rings and its largest moon, which now, thanks to the space probe Cassini and its lander, Huygens, is just a little less mysterious than it used to be.
The sky and surface of Titan seems to be mostly colored in various shades of orange, at least based on the early photographs returned by Huygens, the lander that the space probe Cassini (still orbiting Saturn and still sending back data) dropped on Titan. By the clocks here in California, early on the morning of January 14, 2005 that Volkswagen sized spaceship blasted through the dense atmosphere of Titan, slowed to subsonic speed, dumped its heat shield, popped a parachute, and floated gently down onto mud.
But it was not ordinary mud made of dirt and water. Instead, it was mud made of a mixture of dirt and liquid methane and ethane: something like liquid natural gas. The temperatures outside were far from Earth normal, as well. The thermometer onboard registered a chilly 280 degrees below zero. That’s colder than the coldest recorded temperature in Antarctica at Vostok on July 21, 1983. By comparison, Antarctica was only a balmy 129 degrees below zero.
Near Huygens landing spot, a lake of methane gently sloshed in the chilly breeze. Apparently there are rivers of the stuff, too, washing down from nearby mountains.
And it’s not that Titan has no water. In fact, it has quite a lot. But it is all frozen solid, hard as granite. The “stones” visible in some of the early photographs are thus not made of rock at all. They’re just dusty ice cubes.
An airplane would have no trouble flying on Titan. Its air is about fifty percent thicker than the atmosphere on Earth at sea level, but it is all smog. So whereas a jet here carries fuel and then sucks oxygen in through its scoops to make the fuel burn, an airplane on Titan would have to carry oxygen and then suck in the fuel from the atmosphere!
The Huygens space probe that landed only had enough battery power to survive for about half an hour. But in that brief time, it relayed back close to 400 photographs, along with many other sensor readings of the surface. Meanwhile, its mother ship, the Cassini space probe, continued its orbit around Saturn, where it continues to take pictures of Saturn and its satellites, now more than eight years later.
The Huygens lander was named after Christaan Huygens, the Dutch astronomer who first discovered Titan. Built by the European Space Agency, it hitched a ride on Cassini for the last seven years. It was a billion mile trip. Huygens and Cassini are now so far away from Earth that it takes its radio transmissions over an hour to get here, even traveling at the speed of light. The speed of light is about 186,000 miles per second. At that speed, it would take you less time than an eyelid flutter to go from Los Angeles to New York and back. Therefore, everything that Huygens did—the entry into the atmosphere, its landing, its sending of signals back to Earth—was fully automated. Its battery had in fact already gone dead by the time Earth received its first signals.
The mother ship Cassini, was named after the Italian-French astronomer Giovanni Cassini, who is also known as Jean Dominique Cassini. He watched the planet so much that he noticed a space inside Saturn’s rings. He discovered there were actually two main rings. This gap between them is still called the “Cassini Division.”
The Cassini spaceship is huge. In fact, it is one of the largest interplanetary spacecraft ever built, and the third heaviest unmanned spacecraft ever launched into space. It is about the same size as a thirty passenger school bus and weighs close to 6 tons. It’s way bigger than the Curiosity rover currently tooling about Mars.
Cassini has twelve high-tech instruments capable of twenty-seven different science investigations. To operate them, the spacecraft has an elaborate electronic system that consists of more than seven and a half miles of cabling, some 20,000 wire connections and 1,630 interconnect circuits. It was built by the wizards at the Jet Propulsion Laboratories in Pasadena, which is a part of NASA.
For constant updated information and some truly spectacular pictures, check out the official Cassini-Huygens home page at saturn.jpl.nasa.gov, operated by NASA. And don’t put www in front of that address; it won’t work if you do.