About Saturn & Its Moons
Titan - Surface
Cassini's radar and camera systems have peeled back the obscuring haze of Titan's atmosphere, finally revealing to us what was the largest piece of unexplored terrain in the solar system. The Huygens probe descent and landing on Titan in 2005 provided actual views from the surface of this distant world.
Cassini has shown that Titan has few impact craters, meaning that its surface must be relatively young and some combination of processes erases evidence of impacts. This is the case for Earth as well; craters on our planet are eroded by the relentless forces of flowing liquid (water, in Earth' case) and wind. These forces are present on Titan as well. Tectonic forces - the movement of the ground due to pressures from beneath –-also appear to be at work on Saturn's largest moon.
Methane is generally a gas on Earth, but at Titan’s frigid temperatures (-290 degrees Fahrenheit or -179 degrees Celsius) it is able to exist as a liquid. Methane clouds rain onto the surface, and this rain forms drainage channels that slice the water ice bedrock of Titan' uplands. Liquid methane also pools in standing ponds and giant lakes in the polar regions.
The Huygens probe, which Cassini carried with it to Saturn, landed in an area that appeared to be a floodplain, complete with rounded cobblestones of rock-hard water ice. The ground around the landing site was soaked in liquid methane. Scientists think Huygens might have come to rest in an area where rains wash nearby hills clean of dark hydrocarbon particles that drift down from the skies.
Titan' upland areas are not as high as those on Earth. The tallest mountains are probably only a few hundred meters above the surrounding terrain. Huygens spotted drainage patterns leading down from upland areas near its landing site that were obviously carved by flowing liquid.
Hydrocarbon particles created in the upper atmosphere seem to collect in low-lying areas where winds shape them into great fields of dark dunes. The dunes are not unlike those seen in the desert of Namibia in Africa.
Titan is a rich and complex world which still holds many mysteries, despite all we'e recently learned via Cassini and Huygens. Researchers are continuing to monitor the surface as the seasons change to see if new lakes form or old ones evaporate, and are searching for additional evidence that cryovolcanoes –- that is, volcanoes that spew slush for lava –- are active on the surface, replenishing the methane in the giant moon' smoggy atmosphere.