Space probe nears journey's end

This month's major event isn't really observed in the sky but rather on TV, in the papers and on the Internet. For the first time in 23 years since the Voyager probes the space probe Cassini is arriving at Saturn and is guaranteed to give us extraordinary photos and research opportunities.

Cassini, so named after the 17th century Italian observer Giovanni Cassini who discovered four of Saturn's moons and the famed division in the rings that bears his name, has been en route since its launch almost seven years ago.

Aside from making news for carrying plutonium with it to generate electricity, it's been on an incredible journey with two Venus flybys, one Earth and one Jupiter flyby that were used as gravity assists in order to conserve fuel. Now it has finally arrived and will go into an orbit around Saturn.

The size of a minivan, Cassini is the largest planetary probe ever launched. It's anticipated to send half a million photos of Saturn, its rings and its 31 moons back to Earth during the next four years. About 260 scientists from 17 countries are participating in the evaluation of the data that it sends back, as well.

Saturn's moon Titan is large and cold enough at minus 290 degrees F that it is the only moon in the solar system that retains an atmosphere. That atmosphere consists primarily of nitrogen and methane. Beneath its thick cloud cover, lakes and perhaps oceans of methane may exist and it might constantly rain this liquefied gas.

This scenario on Titan may provide the best conditions in our solar system for something very precious: life. Any such discovery would probably be microorganisms that are completely different from what we're used to, having adapted to those frigid temperatures.

To hopefully supply answers, Cassini will deploy another probe Huygens, so named after the 17th century Dutch physicist Christian Huygens who identified Saturn's rings as rings in December.

Huygens will plunge through Titan's atmosphere and, perhaps, will float in its methane ocean, sending data from the moon's surface. As I mentioned, this will be armchair astronomy for us.

But at the end of August, the early risers among us will be able to see Saturn again low in the Eastern sky during predawn hours. At that time, it will be easy to find because Venus appears right next to it. And as far as Venus is concerned, it may be the only planet visible throughout July. It can be seen low but bright in the northeast around 3 a.m. when even on the Kenai it's "dark" enough to make out a bright planet.

Venus has by now recuperated from last month's historic transit in front of the sun, the first in 122 years. The next will be in eight years and won't happen again until 2117.

The Venus Transit was visible from Europe, Asia, Africa and the east coast of North America because they had daylight. But Alaska has a lot of daylight, so I went to Barrow and had success. I hooked up with six other enthusiasts, we set up our gear and peeked on and off through the constant haze surrounding Barrow during the six-hour transit.

Our photos can be seen on my Web site, chinook.kpc.alaska.edu/~ifafv/lecture/lecsky.htm, where I also have some links to Cassini- and Saturn-related Web sites.

Andy Veh is the physics and astronomy instructor at Kenai Peninsula College. He can be reached at aveh@uaa.alaska. edu.