No Easy Pieces: Sloan Telescope Builders Battled Moths, Balky Software and Broken Mirrors

A new book about the Sloan Digital Sky Survey documents the myriad unexpected challenges in undertaking a large and ambitious astronomy project















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This was scary: mirrors are under high internal stress, and cracks propagate. All work stopped, nobody touched anything. French and Gillespie called Jim Gunn and then Fermilab's Bill Boroski, the project manager who had just replaced Jim Crocker. That was early afternoon, and within a few hours everybody was discussing options on phonecons. French thought it might be a project killer and worried about people's jobs: fixing the mirror could cost half a million dollars and take a year or two, and French had just moved with his wife from Seattle to Apache Point, and newly hired observers had been buying houses nearby.

Jim and Boroski both flew out the next morning; glass experts from Arizona's Mirror Lab came to inspect. The mirror had cracked in a meandering circle around its center, the crack stopping an inch or so before closing on itself. "Oh, man," French thought, "it could shatter the whole mirror, it could fall into a million pieces. You just don't know what's going to happen, mirrors are very unpredictable." Jim, French, and another new UW engineer, Larry Carey, covered the cracked center with foam and tape, then gingerly took the mirror off the telescope and moved it into the support building. The Mirror Lab experts drilled tiny holes at the ends of the crack, a temporary fix that stopped the crack from continuing.

Jim flew to the Mirror Lab and everyone discussed what to do. They examined the mirroring surface and found it had not distorted. The glass was under too much stress to just squirt cement into the crack. But because the primary mirror has a hole in its center through which light passes on its way back from the secondary, the center of the secondary doesn't receive much light. So French drove the mirror to the Mirror Lab, the Mirror Lab cut out the crack, leaving a hole in the center, and capped the hole. French's worries had been pessimistic: the fix cost only around $50,000, and the mirror came back to Apache Point in three months, the following January, the beginning of the new millennium.

Meanwhile, Jim rechecked the design he'd done on the computer for the mirror's controls and found he'd made some typos that caused one little rod to be a little too long, so every time the mirror moved, it hit the rod and eventually broke. "There was no problem with the secondary until I broke it," Jim said. "Most decidedly it was my mistake." Gillespie thought it was Jim's dark moment: "Nobody yelled at anybody about it, though," he said.

Michael Strauss thought the project had just about used up most of its nine lives. The Sloanies all knew they were running on borrowed money, and they thought, as Jill Knapp said, that their sponsors' reaction would be that the broken mirror was "the last damn straw—these people can't do anything right and now they've gone and broken their mirror. Forget it." That the sponsors worked out a way to stay in the game, Jill thought, was partly because of Strauss's and Fan's quasars. "This beautiful science—it was like lifting up the corner of the tent and getting a look at what was inside, and the world could see it. And that got us through, I think." A month later, on January 26, 2000, the fixed secondary was reinstalled on the telescope, and it worked just fine. The observers went back to battling moths and white sands, rebooting software, and looking for sucker holes in the cloud cover.

Excerpted from A Grand and Bold Thing: An Extraordinary New Map of the Universe Ushering In a New Era of Discovery by Ann Finkbeiner. Copyright © 2010 by Ann Finkbeiner. Excerpted with permission by Free Press, a Division of Simon & Schuster, Inc.



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  1. 1. WilliamStoertz 08:04 AM 8/21/10

    Classical! A very good story to encourage young budding scientists to keep at it, learning to overcome all these various problems, from living situation and technical glitches to adjustments needed in the fundamental theories themselves. Good testimony!

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No Easy Pieces: Sloan Telescope Builders Battled Moths, Balky Software and Broken Mirrors

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