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A Snapshot of Earth's Evolution


We've all heard the expression, "You get what you pay for," but when it comes to space missions that play out hundreds of millions of miles above our heads--which may also sum up most people's understanding of said missions--the American public is often left wondering what it is they've purchased. This is particularly true in the case of unmanned spacecraft that take off without the patriotic fanfare that accompanies human-piloted missions, rocketing upward to gather information that involves words of many syllables and chemical compounds whose symbols you haven't seen since you bid your high-school Periodic Table of the Elements goodbye.

The UA is doing what it can to change that, however, with a series of events related to the Cassini-Huygens mission that are designed to make the most exciting aspects of the mission accessible to adults and kids alike. "In general," says UA Associate Professor of Planetary Sciences and Geosciences David Kring, "any of the NASA spacecraft missions are the nation's spacecraft missions, and for that reason alone, we want to make sure the public has an opportunity to understand exactly what it is we are doing."

Descending to a New World--an outreach event whose apex will be the unveiling of the first images taken by the Huygens probe--will take place from 5 to 9:30 p.m. Saturday, Jan. 15, at the Kuiper Space Sciences building, 1629 E. University Blvd. (next to Flandrau Planetarium).

The Cassini spacecraft launched in October 1997 with the Huygens probe on board; for seven years, scientists--including many at the UA who were heavily involved in the mission--eagerly anticipated its arrival at Saturn. After years of orbit-hopping while it swung from planet to planet on its planned course, Cassini arrived at Saturn and jettisoned the Huygens probe on Dec. 24; "and the probe is currently in free-fall toward the moon Titan," Kring sums up.

Huygens--outfitted with three parachutes and a heat-shield designed to withstand temperatures reaching 3,000 degrees Fahrenheit--is traveling at a speed of 13,000 miles per hour toward the surface of what is perhaps Saturn's most interesting moon--a moon about which "we have guesses," as Kring says. "But from the preliminary information we have from Cassini, which has flown by a few times, some of those guesses are clearly wrong."

But wrong is just as exciting as right for those following the mission, whose ultimate objective is a greater understanding of the origins of our own planet and of the solar system itself.

"Saturn is important because it is one of the giant planets that will hopefully tell us something about the origin of the solar system," says Kring. "It preserves many of the primordial gasses of the solar nebula ... a disc that existed around the sun before the planets formed. We're also interested in Saturn because ... detecting planets in other solar systems is very difficult; but when we do, they are Jupiter-sized and Saturn-type planetary objects."

Our interest in Titan is even more personal: "It is laden with hydrocarbons," says Kring, "and very-early Earth is thought to have been rich in hydrocarbons. What occurred very early in Earth's evolution may still be occurring on Titan; studying Titan may give us a better understanding of Earth."

What might we see on Titan? "Well, we already know that methane is in the atmosphere of Titan," says Kring, "and that may condense into methane droplets and fall as rain. The methane rain could potentially pool, form steams or rivulets; if there are impact craters, those bowls could fill as small lakes, and within those lakes, other chemical reactions could begin. There are likely to be hills, if not mountains, perhaps plateaus as in Northern Arizona, but we're not sure what they may be composed of. They may be rocky, or icy, or a mixture. We're hoping these images will tell us."

When Huygens does reach Titan's surface--after making its way through the moon's thick atmosphere--it will mark the most distant touchdown in the solar system by a human-made object. (If that alone doesn't blow your mind, you and I are very different.)

In addition to a series of new exhibits that cover the overall mission as well as delve into the specifics of the planets, people and scientific instruments involved, the Saturday event will feature lectures; a video of early tests of Huygens' imager conducted over Picacho Peak; the unveiling of the photos themselves; small children involved in baking-soda-fueled volcanic eruptions; slightly older children on the loose with liquid nitrogen ("We'll do some experiments to get them to understand how cold it actually is on Titan," says Kring. "It's minus 280 degrees on the surface; that's a hard temperature to understand"); and a star party on the lawn for those interested in viewing Saturn, the comet Macholtz and more.

"It's true of our country that we are a nation of explorers," says Kring. "We always have been, and we will continue to be; we're constantly pushing back frontiers. In this case, the added excitement comes from the fact that this was built by people right here in Tucson, and we want to share that excitement with our friends and neighbors."

Free parking for the event is available in the Second Street garage; for additional information, call 621-9692.

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