Back then I totally bought the idea of reusable spacecraft — after all, the space age had begun with rocket planes like the X-15 that went up and glided back down. But the shuttle’s design had been compromised by politics and economics — a more expensive and safer version would have put the crew far above, as on the towering Moon rockets, rather than surrounded by booster rockets and a giant fuel tank in the clunky arrangement that prevailed — and NASA’s managers were drinking their own Kool-Aid.

On the morning of Jan. 28, 1986, I was crossing the parking lot at the Jet Propulsion Laboratory in Pasadena, Calif., on my way in for the last day of Voyager 2’s encounter with Uranus, when a reporter from USA Today came running out and into a phone booth. I asked him about the impending launching of Challenger, with the schoolteacher Christa McAuliffe aboard. “It blew up,” he blurted.

I went inside to find my colleagues in the press room staring hollow-eyed at television screens. Half of the screens showed Uranus, looking like a big eye surrounded by its tenuous rings; the other half showed the Y-shaped cloud that was all that was left of Challenger and its crew of seven.

Buck Rogers dreams died that day. They died a second death on Feb. 1, 2003, when the Columbia broke apart on re-entry, killing another seven people, after foam insulation had punched a hole in the wing.

I didn’t catch up with the space shuttle again until 1993, when I watched the astronauts train like underwater ballet dancers in a pool in Huntsville, Ala., to carry out repairs on the Hubble Space Telescope, which had been famously and humiliatingly launched with a misshapen mirror. Late one day, an engineer suggested that Story Musgrave, the lead astronaut on that crew, change his routine and turn around at one point to adjust his torque wrench. Dr. Musgrave dressed him down, saying such last-minute changes put the mission in danger.

The Hubble missions, five in all, were the shuttle’s finest hours. In the end, of course, the Hubble did need the shuttle, and its astronauts. It all came to a wonderful high-tech, low-tech climax two years ago, when Michael J. Massimino, channeling his Uncle Frank fixing a car on Long Island, yanked a handrail off the side of the telescope to get at a broken spectrograph underneath it.

That spectrograph could someday give us a clue to finding another Earth.

Hubble is alone now with the stars, its vision as peerless as designed. But America still has no vision at all for its space program, no plan for where to go next or how.