Will the wonders in this distant corner of our solar system ever cease? In recent months, our travels have taken us to realms around Saturn never before visited by spacefaring vehicles, showing us vistas never before seen by human eyes.
Those same trajectories over the high latitudes on Saturn and across its rings also carried us over the north polar region of Titan. What we have found is an explorer's dream: vast areas, equivalent in size to terrestrial seas, very likely holding the liquid methane and ethane that, over time, has rained down from Titan's dark and hazy skies onto the icy landscape below.
A combination of the images gathered by our cameras as we flew over Titan's northern terrains, along with the synthetic imagery constructed from Cassini's radar signals, has sketched out for us, with both broad and delicate strokes, the nature and geography of this remote place. Skimming over the pole, we find a region carved and pitted with dark depressions of various sizes. In the lower resolution natural color and infrared images, their outlines look smooth. In the higher resolution radar imagery, they are jagged and irregular, like the coastline of Maine. Most of these appear to Cassini's radar as the uniformly darkest regions yet observed: a strong, though not incontrovertible, indication that liquid hydrocarbons fill these basins.
The majority of the basins are small to medium in size; two are enormous. And considering the small size of Titan compared to the Earth, the largest of these are in fact equivalent in relative surface area to the mid-size seas on our planet.
What's more, these new discoveries at Titan's northern extremes now lend support to our suggestion of nearly two years ago, that the lake-like features with similar geologic form dotting the moon's south polar terrain -- one equivalent in relative size to the Earth's Black Sea -- may also be liquid-filled.
In all, it appears we have found surrounding both poles of Titan extensive wetlands, stippled with basins of wide-ranging sizes awash with wet hydrocarbons. It seems that the surface liquids on Titan -- at least in the current season -- have preferentially collected at the poles. Why this should be the case remains a mystery.
And so our exploits roaming the high reaches above and below Saturn and its companions have not only treated us to a whole new way of looking at the planet and its rings, but have shown us a remarkable and hitherto secreted place on Titan, seemingly more fantastic than real, of darkened scene, unimaginable cold, with methane clouds aloft and shorelines lapped by the aggregate alien rains of a myriad Titan years.
Will the wonders in this distant corner of our solar system ever cease? Not likely.
Carolyn Porco Cassini Imaging Team Leader CICLOPS Boulder, CO