NASA IS TRYING TO TRACK DOWN several hundred aging travelers who flew to the moon and back 40 years ago and now live quietly across the United States.

The agency announced last week that it is still searching for several hundred "moon trees" grown from seeds carried aboard the Apollo 14 command module that orbited the moon in 1971. Part science experiment, part public relations campaign, the idea was to see whether space flight affected their ability to sprout.

If you know of a moon tree, you can e-mail Dave Williams (dave.williams@nasa.gov), a curator at NASA's National Space Science Data Center in Greenbelt, MD.