White powder from outer space?

Over the course of the 100 days followingthe Columbia accident, NASA and the EPA responded to 12,000 calls from residents in Texas and Louisiana about space shuttle debris sightings.

Representatives fromNASA and the EPA personally investigated every call. The EPA was responsible for checking the debris for hazards, rendering it safe, and then transporting it to one of the four collection centers along the debris pathin Texas. The NASA representative madean initial determination whether or not...