HALIFAX, NOVA SCOTIA — Over Christmas, a little under 900 million miles away, the European Space Agency's Huygens probe detached from NASA's Cassini mother craft and began the last stage of a seven year expedition - an expedition which will end with a (hopefully gentle) impact on the surface of Titan, Saturn's largest moon.
This rendezvous will occur on January 14, and there are hopes that after sampling the moon's atmosphere on the way down, the probe might survive the landing well enough to send a few more hours of data before the batteries die out. As is typical of these enterprises, almost every agency taking part (and some that aren't) has its own Web site, and a slightly different perspective, on the mission - so there's no shortage of information available to those interested in Earth's most recent foray into interplanetary tag.
Welcome to Saturn on the web.
For surfers who haven't been following the Cassini mission to date, and may want to catch up on events since the spacecraft reached Saturn in late June, NASA's Jet Propulsion Laboratory has created the Ring-Side View of Saturn - a slightly less than three minute Flash slideshow featuring recent images taken by the Cassini spacecraft. The presentation (also available in HTML) includes natural and enhanced-color images of the gas giant and a few of its more significant moons - and a promise of "more to come" in the future.
Once the animated portion is complete, visitors can also follow tabs at the top of the page - linking to an interactive and text-enhanced Gallery of the planet, its rings, moons and a few Jupiter-like storms, a Science section, addressing such questions as Saturn's apparently decelerated rotation since the Voyager probes in the early 1980s, and links to NASA's two home pages for the mission.
Of the two, the main JPL page for the Cassini/Huygens mission offers regularly updated information, additional images and multi-media, and a countdown clock to Huygens' encounter with its destiny. While looking confusingly like its JPL associate, NASA's primary Cassini-Huygens site offers a slightly different choice of information in an essentially identical layout, but also boasts a Flash presentation of its own.
More user-directed and adding some short video interview clips to the mix, "Journey to a Ringed World," covers much of the same territory as "Ring-Side View," but it does also hold a few extra details about Saturn's other moons as well as a brief explanation of NASA's interest in Titan.
Central to the Exploratorium: Cassini Mission to Saturn & Titan Web site is a helpful interactive aid for visualizing the 'geography' immediately around the sixth planet. A scrolling schematic of Saturn's rings and moons designates more than two dozen features - each linking to basic data, background information and images. (Though, ironically, the link to information about the ring's Cassini Division seems non operational.) An essay about just what qualifies as a "moon" (is five miles across big enough to make the cut?), and links to past and upcoming RealVideo webcasts round out the distinctive offerings of the Exploratorium site.
And finally, if you'd to like to learn more about some of the Cassini images from the people who process them, the Ciclops (Cassini Imaging Central Laboratory for Operations) home page has a brief introduction to the mission's "Imaging Science Subsystem," news updates and the "Cassini Imaging Diary," favorite images and periodic essays by the imaging team leader, and an exclusive, behind-the scenes look at what the team does in its spare time. (Even more images of Saturn, from Cassini and other missions, can be found in the archives of NASA's Astronomy Picture of the Day.)
Saturn is clearly visible in the night sky at this time of year, and the rings can be seen with even low-power telescopes - but for detail, we have to depend on eyes that are much closer than the surface of this planet. Thanks to the Web, anyone with an Internet connection can see images that, during the time of the Voyager flybys, would have only been available to scientists and news organizations - and if nothing else, this increased access adds a whole new dimension to the concept of virtual tourism.