When I was a boy, maybe 10, I hauled an old four-inch refracting telescope that my great aunt kept on the veranda of her summer house out onto the lawn and began pointing it at various stars. Stars look pretty much the same through a telescope as they do to the naked eye, only brighter. But planets look very different. And suddenly, there it was, Saturn, floating majestically upon the inky seas of the universe, its rings fortuitously at full tilt, as they are only about every 15 years. I began shouting, “It’s Saturn! It’s Saturn!” and dancing with excitement. My aunt, greatly amused, thought I was becoming hysterical, as I suppose I was.
For the last 13 years, I and millions of others have been dancing through the Saturnian system itself, thanks to a remarkable space probe called Cassini.
The Cassini space mission ended this morning when, on orders from NASA, it plunged into Saturn’s dense atmosphere and burned up. It was sending data up until the very end and almost certainly broke up within seconds of its last transmission at 7:55:46 AM (EDT).
What a journey it has been. It was launched on October 15, 1997, flew by Venus twice and earth and Jupiter once each to gain momentum (the planets, therefore, slowing down infinitesimally and moving ever so slightly further from the sun to conserve the angular momentum). It reached Saturn, 950 million miles from the sun, on July 1, 2004, the first space probe to orbit the giant ringed planet.
For the next 13 years, Cassini explored the planet, its rings, and its fascinating astronomical zoo of satellites (Saturn has 62 moons at last count, Cassini having discovered seven of them.) The most interesting of these satellites is Titan, larger than the planet Mercury, and second in size among the solar system’s moons only to Jupiter’s Ganymede. It is the only moon in the solar system to have a dense atmosphere (like Earth’s, mostly nitrogen).
On January 14, 2005, a module, named for Christiaan Huygens who had been the first (in the 17th Century) to decipher Saturn’s rings and who discovered Titan, landed on that world and took 350 pictures before succumbing to the deep cold on the moon’s surface.
They revealed a world both wildly exotic and strangely familiar. Titan is the only body in the solar system besides earth to have liquids on its surface—rivers, lakes, and seas of liquid methane.
There are far too many things that were explored in this remarkable, nearly flawless mission, to go into here. NASA has a list of some of the major ones. But it will be years before the mountains of data sent home by Cassini will be fully analyzed.
