Well, it's time to bring out the hemlock, boys," sighed Jean Oliver in June 1990. The deputy of NASA's cope, Oliver just received devastating news: the $1.5 billion scope, launched the previous April to peer deeper into space and time than anything ever built, was severely nearsighted. No amount of tweaking or rewriting of software would fix it. But on the other end of the line, Hubble senior scientist David Leckrone wasn't about to give up. "Better make it Scotch," he told Oliver. "We still need you guys."

With the space shuttle Endeavor scheduled to rocket off the launch pad at the Kennedy Space Center this week, thousands of Hubble engineers, astronomers, contractors and astronauts will find out whether they should have opted for hemlock after all. In a high-stakes mission that "has become a litmus test of everything NASA does," as space-policy guru John Logsdon of George Washington University puts it, seven astronauts will try to repair Hubble's myopia during a record-breaking five spacewalks. Their success or failure will determine more than whether the telescope fulfills its promise of discovering the origin and fate of the universe. After NASA lost the $1 billion Mars Observer and the $67 million NOAA-13 weather satellite this year, this may be the agency's last shot at proving it belongs on the final frontier. Says NASA's Edward Weiler, "This project is going into the history books: as a national disgrace or as a great American comeback."

The only reason NASA has a shot at salvation is that the telescope's 2.4-meter main mirror has, NASA associate administrator Lennard Fisk says, "a perfect defect." The mirror's flaw is so precise--contractor Perkin-Elmer ground it too flat at the edges by.000039 inch, so light doesn't focus--that physicists easily figured out the needed optical fix. Even better, Hubble is the first satellite built with handholds, rings, restraining bars and footholds to accommodate spacewalking grease monkeys. Most of the bolts are identical, too, so astronauts need to use only one wrench. In fact, this week's mission had been planned even before Hubble was launched. NASA just didn't know that a routine 20,000-mile checkup was going to become a make-or-break flight. But the team thinks it can pull it off. Says James Crocker, an optics expert at the Space Telescope Science Institute (STSI), "People have invested too much of their lives to let this be a failure."



The investment can be measured in midnight optics sessions, shower-room epiphanies, launch-pad troubleshooting and endless second-guessing. Throughout the summer of 1990 a "strategy panel" brainstormed fixes for Hubble's myopia: knowing which contact lens would correct the perfect defect was obvious, but getting the lens into place was anything but. "Some really crazy ideas came out," says Peter Stockman, STSI's deputy director: one, sending an astronaut down the barrel of the scope to place corrective mirrors, could have shredded her life-support system.

Then, as serendipity would have it, Crocker took a shower in a hotel near Munich. He became intrigued by the shower head, which slid vertically on a track and tilted 90 degrees. What if, he wondered, NASA built an instrument that slid into one of Hubble's instrument bays, then deployed corrective mirrors? "It just flashed," Crocker says. "The Germans make great cars. And great plumbing fixtures." They dubbed the fix "Corrective Optics Space Telescope Axial Replacement": COSTAR. It would slide into a module occupied by a highspeed photometer, like a new drawer in a file cabinet, intercepting the light beams from the errant mirror and focusing them. In January 1991, the agency launched a crash program to build COSTAR. "But how do you go from a Tinkertoy model to a deployable instrument in two years?" Weiler thought. Not easily: of four companies tapped by NASA, only the upstart Tinsley Co. of Richmond, Calif, came through with optically perfect mirrors. Meanwhile, Ball Aerospace in Boulder, Colo., called Murk Bottema out of retirement. A Dutch-born engineer graced with an uncanny feel for optics, Bottema belonged to the old school: in weeks his back-of-the-envelope scribbles showed how to arrange COSTAR's 10 coin-size silver mirrors on a telescoping boom so they would snap into the path of Hubble's fuzzy light beams. (Bottema died last year; COSTAR carries a plaque honoring him.)

Now it's up to the astronauts. Completing all the scheduled repairs would constitute a minor miracle. Half of Hubble's gyroscopes have failed; several measuring devices flicker on and off like Christmas lights; solar panels are wimping out and will also be replaced (diagram). And lots can go wrong. Rocketing into space on four G's is not exactly a prescription for keeping COSTAR's precisely aligned mirrors in place. A klutzy astronaut could doom it, too: COSTAR must be positioned with a precision of .005 inch. And with 600 wires jammed into a space the size of a fist, COSTAR could simply frizz out.

To improve the odds, the astronauts have choreographed and rehearsed every minute of their chores. They spent 400 hours under-water in a tank to simulate the weightlessness of orbit. They hung in cherry pickers beside a full-scale model of the telescope at the Smithsonian Air & Space Museum to practice their moves and handholds. They flew on the "vomit comet" flight simulator and used virtual-reality helmets (a training first) to simulate repair tasks. In weeks of 14-hour days, they also glided across an "air-bearing floor"--a sort of giant air-hockey table--to feel how the phone-booth-shaped COSTAR will move in frictionless, weightless space. Engineers threw hundreds of glitches at the astronauts: the designated gremlins broke a bolt off the telescope, bent pins inside an electrical conductor and told the crew that one spacewalker was sick, all to see how they handled emergencies. Not all the challenges were scripted. Spacewalker Story Musgrave got frostbite on his fingers while testing tools in a 300-degrees-below-zero room. (NASA redesigned the gloves.) And during a shuttle flight last August an astronaut testing a screwdriver found himself, not his screw, spinning.

Seven days into the flight, astronauts Kathryn Thornton and Tom Akers will step into the void, float to the telescope (snared four days before by the robot arm) and slip the $23 million contact lenses into Hubble. It's no ordinary house call for the outerspace optometrists. For months NASA has been protesting the unfairness of tying the future of the agency to one mission. Fair or not, the countdown has begun.