Inside Titan..

The plunge continues. Cassini is accelerating toward the inner Saturn system, which seems to lack the witches brew of organic molecules that darken (and in the case of Titan, may drench) the outer moons. It seems to be mostly water ice hereon in, though VIMS, UVIS and the main cameras of ISS will need to confirm this.

Live coverage of Saturn Orbital Insertion begins on NASA TV tomorrow at 8:30 pm CST - first pictures arrive at daybreak. This 96-minute braking maneuver may be the longest "live" chemical rocket burn in the history of space exploration - although Jupiter is far more massive, Galileo was able to use Io as a gravitational parachute to dump much of its excesse velocity, and only had to use its main engine for 49 minutes. Cassini will have something Galileo lacked - a spare rocket engine. The tale of Galileo's problematic engine can be found here.

Galileo's Unified Propulsion Module (built by EADS (then MBB) on behalf of the West German space agency) had a critical problem with the thrusters. In 1987, after Galileo was shipped back to JPL after the Challenger loss, a German comsat called TVSat 1 developed a stuck solar panel. To free the panel, the operators tried to shake it loose through prolonged firing of the thrusters. To their shock and horror, the thrusters blew up. Galileo had the same thrusters.
JPL's concern was that a prolonged burn (like the 49 minutes of JOI) would have lead to a bad day.

The fix was to limit all firings to short, minute-long pulses - including JOI - so Galileo burped its way into Jupiter space...