Nitrogen-rich world near Saturn unveiled
Delta channels beneath an orange haze support a theory that this moon may be Earth's nearest kin in solar system.
When the Huygens spacecraft dipped its golden nose beneath the clouds of a distant moon Friday, it at last drew back the curtain on perhaps the most mysterious and exotic object in the solar system.
For more than 20 years, scientists have peered at pictures of Titan and untethered their imaginations. Here was an object unlike any other known to astronomy: A planet-size satellite with a thick atmosphere rich in the chemicals that once made up Earth's primordial ooze. Yet the very object of intrigue - the orange smog that cloaks the moon - made it impossible to see what was going on at the surface.
Now, Huygens's snapshots have begun to sketch fantasy into reality. In the half-light of a veiled world 886 million miles from the sun and 290 degrees F. below zero, Huygens has left little doubt that Titan was once - and could still be - covered in rivers and lakes of liquid or organic goo.
The pictures are so graphic they bewilder scientists, who see compelling evidence of shorelines and drainage channels where fluids once flowed, reshaping the landscape as water molds terrain on Earth.
Titan is too cold for any known form of life. But in a solar system where most of the solid objects fell dormant long ago - their complexions now changed only by the odd asteroid impact - Titan offers an intoxicating view of a world that might still be alive with processes at once Earth-like and incomprehensible.
"It would have been hard to expect too much more - except perhaps splashing into a lake," says Bruce Betts, a scientist at the Planetary Society in Pasadena, Calif. "But that was made up for by the fact that no one expected these landforms to be so fascinating."
In fact, no one was sure if the mission was going to work. No program had ever attempted to land on a planet or moon beyond Mars, and it was up to European Space Agency (ESA), a relative novice, to do it. While NASA's Cassini probe carried Huygens to the Saturn system, ESA had to manage the 2-1/2 hour descent to the surface - an anxious time for an organization that recently lost a Mars lander. They succeeded with few glitches. Huygens continued sending data for more than an hour after landing. "It's one of the harder missions one could conceive," says Dr. Betts. "It really shows that they're a major player."
By Friday evening, their efforts had begun to reveal the biggest piece of unexplored territory in the solar system. On a world where the atmosphere is thicker than the Earth's but has gravity similar to that on the Earth's moon, Huygens parachuted into Titan's deep orange pall.