Iapetus! A week and a half ago we found ourselves flying high above its leading hemisphere, peering for the first time into the dark uncharted terrain of Cassini Regio. Craters everywhere. Basins wider than the Saturnian moon, Mimas. And feathery black streaks and bright pole-ward facing crater walls near the region's northern limits ... the tell-tale signs of something that long ago blanketed the leading side of this strange moon. Stranger still, Iapetus' dark hemisphere is bisected by a startling, unique, 1300-km long equatorial ridge that in places reaches the mountainous heights of 20 kilometers, rivaling the tallest peaks in the solar system. Hats off to Arthur C. Clarke. Somehow, he must have known.
Now, we are once again bound for Titan, following 43,000 kilometers behind the Huygens probe. Separated from Cassini 2.5 weeks ago, the probe is at this very moment racing silently towards Titan at a swift 7 kilometers per sec, or 17,000 miles per hour. In just 3 days, it will impact the top of the atmosphere and rapidly decelerate, making a glowing fireball that no one will see and a sonic boom no one will hear ... shock waves spread 'round a world in an alien planetary system far, far away.
It will be another two hours after atmospheric entry before the mother ship reaches Titan. In that time, we will come to know this place. The probe will descend through the thick layered smog of the upper stratosphere and eventually dive below the haze into the dimly lit environment near the surface. It will drift with the wind and spin as it falls. It will record panoramic images of the scene below, sift through the electromagnetic radiation reflecting off the surface, and sense the properties of the Titan atmosphere, in many ways sister to our own. Should it touchdown in a lake of liquid hydrocarbons or land on hard frozen ice, it - and we - will know.
All these precious, hard-earned bits of knowledge, encoded into a stream of ones and zeroes that will ride the telemetry signals back to the orbiter, will find their way to Earth three hours later.
The first images taken from 150 kilometers above the surface will likely look very much like the landing site images we've already seen, but subsequent images will grow rapidly in detail. The landing site itself is diverse, with regions of bright and dark and surface streaks looking similar to other areas on Titan. This is good, for what we learn from this thrilling two hour voyage will guide us in understanding Titan in all its complexity.
We are about to enter a cold and misty wilderness, never before touched by anything human. This will be a tale to tell, of exploration, discovery and intrigue, not unlike those told by Jules Verne a century and a half ago. Only this time, it will be real.
We are capable of extraordinary achievements, and this will surely be one of them.