Mr. Universe

By MICHAEL D. LEMONICK

David Spergel watched with particular interest one balmy afternoon this past June when a Delta rocket roared into space from Cape Canaveral, carrying an 1,800-lb. satellite on a mission to probe the outer edges of the universe. Not only did the 40-year-old Princeton astrophysicist expect to spend the next few months deciphering the data that the Microwave Anisotropy Probe beams back from space but he was also part of the team that dreamed up the mission and designed the satellite that would carry it out.

Theoretical astrophysicists don't usually get involved in the nitty-gritty of spacecraft design, but Spergel is not your typical theorist. Even in a field in which the most brilliant minds are inevitably compared with Albert Einstein, Spergel stands out. Beginning as an undergraduate at Princeton in the early 1980s, he has navigated from one knotty problem to another--not as a dilettante academic dabbling at the edges but as a key player making important contributions at every turn.

He started out studying the Milky Way and, along with Leo Blitz of the University of Maryland, discovered that our home galaxy is not just a simple spiral of stars and gas but rather a complex construction with warped edges and a bar of stars across the middle. Then he began thinking about dark matter, the invisible stuff that makes up most of the mass of the universe, and realized that Earth should feel a "wind" of particles as it orbits the galaxy--an idea that dark-matter hunters are now testing.

He next took on the mystery of cosmic structure, why galaxies clump together in huge clusters rather than spread uniformly throughout space. He and a colleague suggested that the reason was knots of warped space-time called "topological defects." The idea was brilliant, but observations proved it quite wrong. Many scientists would have fought to save their pet theory. Spergel cheerfully declared it dead and moved on.

It was that display of intellectual honesty, Spergel suspects, that earned him an invitation to work on the microwave satellite. And once having tasted the pleasures of actual rocket science, he could hardly resist an invitation to help design a second spacecraft. The goal of this new mission is to find Earthlike planets orbiting other stars, and it requires solving optical problems that astronomers have never before confronted.

As usual, Spergel knew very little when he began. So, he says, "I got a book and taught myself optics." The result: a revolutionary idea for a telescope that could spot a dim planet in the glare of a bright star, potentially saving NASA billions of dollars and advancing the search for undiscovered planets as much as a decade. "I love exploring the frontiers of science," says Spergel. "I try to choose projects where the answers will be exciting not only for my colleagues but also for everybody else."