The Cassini spacecraft which left earth 7 years ago is finally about to arrive at it’s destination: Saturn. See the Cassini-Huygens homepage for up to date info on mission status. A short synopsis follows:The site gives the official history of the mission: “Launched from Kennedy Space Center on Oct. 15, 1997, the Cassini-Huygens spacecraft will reach the Saturnian region in July 2004. The mission is composed of two elements: The Cassini orbiter that will orbit Saturn and its moons for four years, and the Huygens probe that will dive into the murky atmosphere of Titan and land on its surface. The sophisticated instruments onboard these spacecraft will provide scientists with vital data to help understand this mysterious, vast region.”

In 1997 there was much concern expressed in the media concerning the nuclear fuel used to power the craft. The fear was that if there was a mishap during launch, radioactive particles might “rain” down on our heads. The technology is not an onboard nuclear reactor, but instead uses the heat given off during radioactive decay to produce electricity. The same technology was used in the Voyager series spacecraft in the 70’s.

Because the Cassini spacecraft is so large and heavy, it had to take a roundabout way to Saturn, and could not fly directly there. Using a technique called gravity assist, Cassini used carefully planned flybys of planets to gain momentum and swing itself toward Saturn. This is why it took so long to get there, but there was no other viable method to propel such a heavy craft so far. The physics behind this technique make a game of billiards seem terribly simple by comparison.

In December, the Huygens probe will decend to the large Saturnian moon, Titan. Titan is the only moon in our solar system with it’s own atmosphere, so that should be an interesting investigation.

The first human probe to reach Saturn was Pioneer 11 in 1979. Followed by the infamous Voyager I in 1980 and Voyager II in 1981.