It has even changed the way we understand the cosmos. “Before Hubble, people conjectured that galaxies evolved with time,” says C. Robert O’Dell, professor of astrophysics at Vanderbilt University in Nashville and, as project scientist at the Marshall Space Flight Center from 1972 to 1983, a major figure in the early development of the telescope. “Hubble has allowed one to actually see those changes.” Quasars, for instance, turn out to be a kind of smoking gun. Unimaginably powerful sources of radio emissions, brighter than entire galaxies, quasars were initially viewed as mysterious objects found billions of light-years from us but unknown in our own galactic neighborhood. Were they just oddities, loners in the cosmos? Hubble images showed, on the contrary, that quasars always occur at the cores of distant galaxies and derive their energy from material being sucked into black holes that lie even deeper within the galactic centers. Which is to say that galaxies billions of years ago were different from what they are now.

“The name of the game is nail things down,” says O’Dell. “And that’s what Hubble has really done.”

Hubble also confirmed that planets, like quasars, form as the result of normal, not fluky, processes. Stars condense from huge clouds of swirling interstellar gas. Hubble has shown that not all the swirling material is drawn into the star. Some of it winds up orbiting the newborn star. “That disk of material that’s left behind is the material from which planets can form,” O’Dell says. “Before Hubble, we had spectroscopic and photometric evidence. But when you actually see these disks going around these nascent stars, then it all becomes believable. In the case of our sun, if you look at the distribution of planets across the sky, you see they’re all in the same plane. That’s because they came from the same disk of material left behind as this cloud that was forming the sun was collapsing.”

In 1929, when Edwin P. Hubble announced his discovery of the expansion of the universe, its rate—known as the Hubble constant—could only be estimated. The telescope named for him has provided more accurate measurements of the constant, resulting in a more reliable estimate of the age of the universe-between 13 billion and 14 billion years.

Triumph tends to look inevitable in retrospect. It isn’t, of course, and the Hubble’s development from pipe dream to reality was an especially long and bumpy ride. The father of the space telescope, astrophysicist Lyman Spitzer, first proposed the idea in 1946, championed it in the halls of Congress in the 1970s, and lived to conduct research with it before his death in 1997. The advantages of a space-based observatory were clear from the start: The atmospheric turbulence that blurs terrestrial telescopes would be surmounted, and parts of the spectrum that are absorbed by the atmosphere would become visible. Beginning in the 1960s, the encouraging results of feasibility studies gave the idea momentum, although there were also a few prominent naysayers who expressed doubt that a space telescope could ever be stabilized well enough to produce decent results.

The 1970s played out like a tag-team match between Congress, NASA, and the astronomical community. Funds were granted, funds were cut off; astronomers lobbied, Congress reconsidered; NASA scaled down, President Carter approved. Then came the turf wars—both within NASA and between NASA and the Space Telescope Science Institute that astronomers had insisted be set up to manage the science.

Meanwhile, in 1976, a young Ph.D. named Edward J. Weiler landed his first job, as a researcher for Lyman Spitzer, who was chairman of the astronomy department at Princeton. As a child, Weiler had scrambled out of bed before dawn to watch Alan Shepard and John Glenn blast off. Equipped with a cardboard telescope that his father, a steelworker, bought him, Weiler decided, at age 13, that he “wanted to go to Northwestern, be an astronomer, and work for NASA.” He was already showing signs of decisiveness.

Spitzer put Weiler to work on Copernicus, an early NASA satellite observatory for which he was principal scientist. Before long, Weiler was director of operations for the observatory at NASA’s Goddard Space Flight Center. In 1978 Nancy Roman, the first chief scientist for what was then called the Space Telescope and NASA’s first chief of astronomy, offered Weiler a job. The 29-year-old found himself at a crossroads.

“I was working for Lyman, who was a great scientist, a great thinker, a visionary,” Weiler recalls. “I was publishing three to five papers a year. That’s pretty good. But I had to ask myself: ‘Am I ever going to be at the level of Lyman Spitzer?’ Probably not. So when I was offered the job at NASA, which was a lifelong dream anyway, I thought, ‘Maybe I’ll have more impact on the field by, instead of doing the research, enabling the research to be done by other people.’”

In 1979 Roman wanted to retire and recommended that Weiler succeed her. “He was enthusiastic, levelheaded, and a steady worker,” she says. “I felt quite comfortable leaving the program in his hands.”

Weiler quickly discovered that being chief scientist was “a refereeing job,” and there were plenty of disputes to referee. Growing up in Chicago, he had held his own as a Cubs fan in a White Sox neighborhood, so he didn’t shy from conflict. Weiler has a round, boyish face, but there’s pugnacity in his jaw, penetration in his blue eyes, and no nonsense in his plain-spoken Midwestern manner. Remarks Giovanni Fazio, an astronomer at the Harvard-Smithsonian Center for Astrophysics, “There’s no wishy-washy about that guy.”

He needed every bit of that fierce determination. “If you wanted to figure out how to really screw up the management of something, you’d duplicate the Hubble program,” Weiler says. “We had no prime contractor. Perkin-Elmer [which made the optical telescope assembly] and Lockheed [which made the spacecraft] were co-primes. Goddard was responsible for the scientific instruments and operations. Marshall [Space Flight Center] was responsible for development. It was hard to figure out who was in charge on any given day. There were a lot of tensions.”

Weiler’s make-or-break moment came shortly after the launch, in April 1990. The discovery that the 2.4-meter primary mirror suffered from a spherical aberration—the result of a 1.3-millimeter measuring error during testing—“shattered the dreams of many people,” John Bahcall says. Very simply, the pictures were blurry. Weiler became NASA’s main spokesperson at the pressure-packed daily press conferences. “The message I kept giving was, ‘Yeah, we screwed up, but we’ve got a way to fix it, and we’re going to do it by December of 1993,’” Weiler says. “Of course, nobody believed us because Hubble didn’t have a good record of being on cost or on schedule for anything. But the hell of it is, we did it.

“It was an incredible team effort. For once, it didn’t matter whether you wore a Johnson Space Center badge or a Hubble badge or a headquarters badge. It was one team.”

On late-night TV, the Hubble was being compared to Mister Magoo, even though it managed to produce valuable science before shuttle astronauts installed the corrective optics and backup camera. “Ed insisted above all else that we be straightforward and honest about what we knew, and he saw us through those terrible times when people were making fun of us,” says Bahcall. “Ed helped us keep our sanity and keep focused on what had to be done.”

Since the restoration in 1993 and the plug-in of more advanced new instruments and cameras on three later shuttle missions, Hubble has exceeded all expectations. In 1996 it produced the deepest image of the cosmos ever recorded. The Hubble Deep Field image, as it was called, penetrated as many as 13 billion years into the past—the light it recorded had been traveling that long—to assemble a picture of the universe when it was only about 1 billion years old.

“We pushed Hubble to limits we never even dreamed possible,” Weiler says. Hubble’s limit was supposed to be 2010, when NASA planned to bring the telescope back to Earth. However, this summer a committee of experts recommended that Hubble compete with other projects for an instrument upgrade that could keep it up and running for a few more years.

For Weiler, Hubble’s body of work “raises not just a scientific question but a fundamental human question. Are we alone in the vast universe?” Don’t bet on it. In the last 500 years, he notes, “we arrogant humans” have found that Earth isn’t the center of the universe—nor is the sun, nor is our galaxy. Now our solar system has been revealed to be just one of many.

“What’s the last crumb on the plate of human arrogance?” Weiler asks. “Obviously, that we’re the only life in the universe. I think in the 21st century we are going to prove otherwise.”