Catching a Comet

2/5/06 – 2/11/06

By C. Zaitz

Stardust. What a pretty name for a spaceship. Especially one that’s spent most of its life in deep dark outer space looking for little pebbles and debris left behind from the formation of the solar system. If you hadn’t caught it on your favorite media outlet, the news is that we’ve successfully brought little pieces of a comet back to earth! I know what you’re thinking. “What’s the big deal? Pieces of comets tumble to earth all the time. We call them meteors or shooting stars!” It’s true; meteors are actually often pieces of a comet that have been left in a trail in space as the comet melts or sublimates (goes from solid to gas). The earth plows through these dusty paths in its orbit around the sun, and the little particles come slamming through the air, heat up and create bright streaks in our night sky.

Sometimes a large chunk of comet debris will actually make it through the atmosphere unharmed and land on earth. It’s rare but sometimes folks will find these fragments of comet or asteroid and give them to museums, keep them or sell them for large amounts of cash to collectors. But these little bits of space rock aren’t very helpful to scientists. In their journey around the sun and their tumble to earth, the particles have been changed and contaminated. Once the meteor comes anywhere near earth’s atmosphere, all the creepy crawlies that live up there can embed themselves in the rock and fool us into thinking that there are critters in outer space. The only way to get a pristine sample of comet material is to go out into the near vacuum of space and collect the dust there. That was the mission of Stardust. It’s a desk-sized 770 pound spacecraft on a five year mission, and as of last month the mission ended successfully as its parachutes deployed to literally deposit Stardust gently on planet earth.

Stardust held the pristine particles of comet dust, as well as cosmic dust (yes, that darned stuff is everywhere, apparently) in a substance called Aerogel. Aerogel is a space-age highly porous substance (it’s about 97 % air!) that can capture little dust particles without changing their shape or contaminating them. I was able to see a little chunk of Aerogel at a workshop once. It looked like nothing I’d ever seen before. We weren’t allowed to handle it because the moisture from our hands would disintegrate it, yet you could put a propane torch to it and it wouldn’t even blink. Right now scientists are digging into the Aerogel to harvest the dust and particles, and once they retrieve enough they can begin to study, for the very first time, the elements that were present at the very birth of our solar system.

Some people conjecture that comets may be the couriers of water to planet earth. Some people think maybe carbon and sugars on comets may have implanted the building blocks of life on earth. Some people never give comets much thought. But in the coming months we will be studying our comet bits and trying to piece together those early days of solar system formation.

Meanwhile, our lovely solar system orbits Sol as usual. Mars still beams down at us from the early evening southern sky, and Saturn follows close on his heels. Jupiter won’t be seen until morning hours, but shines brightly to wake the sun earlier and earlier each morning! The moon grows fatter every evening and will be full on the 13th.


Until next week, my friends, enjoy the view!