HILO, Hawai'i — The three largest and most powerful optical telescopes on Mauna Kea still haven't resumed normal operations since the Oct. 15 earthquakes jolted the Big Island, knocking hundreds of tons of sophisticated mountaintop astronomical equipment out of their precise alignments.

Dollar estimates of the damage to the telescopes were not available, but the earthquakes were so powerful that they shoved the entire 400-ton Gemini North telescope an eighth of an inch over on its base, said Scott Fisher, public outreach scientist for Gemini.

The damage to the telescopes also cost some of the world's leading astronomers precious, expensive observatory time in a highly competitive field.

Researchers who were scheduled for observation time on the W.M. Keck Observatory during the earthquake recovery period will have to reapply for time on the telescopes later, as will two other astronomers who had been scheduled for time on Gemini.

"One night of observing at Keck observatory can keep a research team busy for several years, depending on the project, so a loss of one night could potentially be a significant setback," said Laura Kinoshita, public information officer for Keck.

When the astronomers reapply, "there's no guarantee they'll get that time back, and there's no guarantee that some other team in Europe might not have been able to get the discovery ahead of them," she said.

'DIGGING INTO THE GUTS'

Jolts from the earthquakes, which measured 6.7 and 6.0, were felt throughout Hawai'i but did the most damage on the Big Island.

On Mauna Kea, the shaking was particularly violent at Gemini's secondary mirror near the top of the telescope, damaging a pistonlike mechanism on the upper mirror. To repair it, engineers are taking apart much of the telescope and waiting for replacement parts from the Mainland manufacturer, Fisher said.

"We have to remove basically the entire top end of the telescope to get to the part that's broken, and it's really a long process," he said. "You are digging into the guts of the telescope, so it's a major surgery."

The shaking did not damage the primary or secondary mirrors themselves, but the secondary mirror can't operate properly until repairs are made. That secondary mirror is used to correct for image distortions caused by turbulence in the Earth's atmosphere, and without it "we just can't work," Fisher said.

The secondary mirror itself complicates the repairs because "you have this million-dollar piece of glass right there that you have to be extremely careful with," he said.

After the earthquake moved the huge telescope on its base, technicians also had to recalibrate the telescope's complex alignment system so it will point at exactly the locations in the cosmos that astronomers want to study. That work has been completed, Fisher said.

Gemini is not expected to resume normal operations until Thursday.

SLOWLY, WORK RESUMES

At the W.M. Keck Observatory, home of the most powerful optical telescopes in the world, astronomers used one of the twin 33-foot telescopes to make limited observations on Oct. 27, Monday and Tuesday, the first research done at the observatory since the earthquakes.

Those observations with Keck I were part of a study of the stellar disk of the Milky Way galaxy, but also were used to test some newly completed repairs, said Kinoshita.

The telescopes, which are 300 tons each and stand 80 feet tall, each rocked on their mounts, damaging their brake pads and seismic restraints. As they rocked in the earthquake, "they twisted and bent hardware," Kinoshita said. "All of our software, all of our pointing and control systems need to be updated because the telescopes moved."

The tests of Keck I showed that the pointing systems are still "off target a little bit," Kinoshita said. Keck II suffered similar damage and still hasn't resumed operations.

"Our instruments are designed to be precise to a level of nanometers, which is a thousand times thinner than a strand of human hair, so just the slightest movement can pretty much misalign a lot of optics," Kinoshita said.

"It's almost like setting the telescope up when we first began science (at Keck) 13 years ago. ... We have to almost go through the same set of exercises we did when we brought it on-sky for the very first time in 1993, and for Keck II in 1996."

The 700-ton concrete domes that surround and protect the sensitive telescopes also moved in the earthquake and knocked the bearing wheels under the domes out of alignment, but that damage has been repaired.

"We are pleased with the success we've achieved so far, but there are still significant issues which need to be resolved before normal, full-scale operations can resume," said Observatory Director Taft Armandroff in a written statement .

Experts at the 27-foot Subaru Telescope operated by the National Astronomical Observatory of Japan are also trying to cope with problems of alignment and pointing caused by the earth shaking.

The observatory has been conducting "engineering observations" since Oct. 24 to test the equipment, but it is unclear when those tests will be completed and normal operations can resume, said Tetsuharu Fuse, astronomer and public information officer for the telescope.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.