Nature's Tiniest Space Junk

Solar sails and sun shields for orbiting telescopes are also vulnerable to space dust. "The bigger you are the more likely you are to get popped by something," noted Cooke. Solar sails have lots of surface area so they make big targets.

In the inner solar system, where the meteoroid population is greatest, sails will lose one or two percent of their total area to meteoroid strikes every ten years. "It's important to build sails out of materials that don't propagate rips," says Cooke. "Otherwise meteoroids could pose a big problem for such spacecraft."

Keeping track of space dust, which is spread throughout the inner solar system, is a big job. The radar in Huntsville can only detect meteoroids that crash into Earth's atmosphere above the southeastern United States.

Suggs noted that a world-wide network of forward-scatter radars would provide a global picture of the near-Earth meteoroid swarm. As our planet plows through the dusty background, scientists could use such a network to sample the meteoroid population all around Earth's orbit.

The Marshall facility, which Suggs says is "working beautifully," costs less than 500 US Dollars (plus a PC to control the receiver and analyse the echoes in real time). But going global might not be easy. "Our challenge now is to figure out a calibration scheme that will work everywhere, regardless of how many transmitters are nearby and how they're distributed. We're breaking new ground and we still have lots of work to do."

Note: Radar isn't the only way to detect meteoroids (although it is the best way to record small ones). In places with dark skies, observers can usually spot 2 or 3 bright sporadic meteors each hour. You can also see the solar system's swarm of meteoroids glowing in the night sky by means of reflected sunlight. Sky watchers call such glows the Zodiacal Light and the "Gegenschein." - Tony Phillips