NASA’s Cassini spacecraft has now officially entered the last phase of its mission – the “Grand Finale,” with the last-ever close flyby of Titan and the first of 22 final orbits which will take the spacecraft closer to Saturn than ever before, passing between the inner rings and the planet itself. Cassini has today just completed the first of these passes (with results pending for a few hours as of this writing), which will culminate on Sept. 15 with the spacecraft plunging into Saturn’s atmosphere to meet its fiery end. It will be a sad but incredible ending to an incredible mission.
Twelve years ago today, one of the most incredible space missions ever was accomplished: the first landing of a probe on an alien moon. And this wasn’t just any moon, but Titan, largest moon of Saturn and one of the most fascinating worlds in the Solar System. Although much colder than Earth, Titan mimics some of the processes found here such as its hydrological cycle, but with liquid methane/ethane instead of water. Titan had been observed extensively by telescopes and from Saturnian orbit, but this was the first time the surface could be seen up close.
For the first time, the Cassini spacecraft has documented extensive rainstorms in the equatorial regions of Titan. The rains were already known to fill the many lakes near the moon’s north and south poles, but now also appear to occur at lower latitudes, in seasonal cycles reminiscent of those on Earth, except of course, that Titan’s rains are liquid methane instead of water. But the hydrological processes are remarkably similar.
There are also many riverbeds on the surface, and the Huygens probe had previously landed in or near one of them back in 2005 and found the surface soil still damp.
More images and animated video clips here.