(Businessweek, current issue)

When Astronauts Glow, Time to Go

A man in a white spacesuit adjusts his headpiece, prompting a laser to scan his retina for molecular sensors just a few billionths of a meter thick. A red light warns that radiation is accumulating in his white blood cells. Maybe it's time for a sojourn on earth.

This isn't Tom Cruise in a summer blockbuster. Within 10 years, NASA astronauts could be using such headgear to monitor their exposure to deadly radiation in space. So says University of Michigan immunologist James R. Baker Jr., whose team has just received a three-year, $2 million grant from NASA to pursue his invention in collaboration with NanoBio Corp. of Ann Arbor, Mich. Baker's blood sensor consists of polymers called dendrimers, tiny balls just 5 nanometers wide that were designed and synthesized by the team. To these balls, scientists attach fluorescent tags that glow when they are in the presence of proteins from dying cells. Inhaled in a cloud by an astronaut, millions of these molecules would be quickly absorbed by the white blood cells--and would glow when radiation began to kill off the cells.