1. Archive

Naturally occurring plutonium is minimal

Question: People protesting the plutonium-powered Cassini space probe use the phrase "No plutonium in space." Is there really no naturally occurring plutonium in space?

Answer: Only an extremely small amount of plutonium occurs naturally. NASA spokesman Donald Savage in Washington said the plutonium used in Cassini is produced artificially in special nuclear reactors by bombarding uranium 238 with neutrons. Uranium is believed to have originated from stellar explosions, he said, so there's a remote possibility that, at some point in the distant past, plutonium might have existed somewhere in space.

Traces of plutonium, especially plutonium 239, occur naturally on Earth in some uranium ores, Savage added. None of the early plutonium that was produced during Earth's formation still exists, by the way, because of the short half-life of uranium 238.

Natural gas vehicles

Question: I saw a taxi with a sign saying it was powered by natural gas. Is there a way to convert an existing car or buy a new one, powered this way?

Answer: Your best bet is to buy a vehicle made to run on natural gas. Such vehicles operate better than gasoline-powered versions that have been converted.

Have a question about the news? Colin Bessonette will try to get an answer. Call (404) 222-2002, or write him at the Atlanta Journal-Constitution, P.O. Box 4689, Atlanta, GA 30302, or e-mail him at q&