In July, the space shuttle Discovery is slated to deliver two tons of hardware and supplies to the partially built International Space Station. This mission is paid for. As for the 16 more needed to finish assembly, as mandated by President George W. Bush two years ago in his Vision for Space Exploration policy, NASA is short by as much as $5 billion.

We’ve never known
more about the universe than we do right
now—and that’s precisely the problem.
Every significant astronomical discovery of
the past 50 years—afterglow from the
big bang, evidence of dark matter,
planets circling distant stars, just to name a few—has helped to create an ever-larger and more perplexing set of cosmic questions: Is there life on those faraway planets? How
did the first stars form after the big bang?