Star pilots

Pointing telescopes is their business, finding stars their mission

Twilight has barely stretched an indigo veil over the southern Arizona sky when astronomer Kenneth Hinkle swivels his chair to face a bearded figure at the control panel of the closest machine humanity has to a star ship.

"Let's try Alpha Tauri," he says.

"Alpha Tauri it is," comes the reply.

With the tap of a keyboard and click of a mouse, Hal Halbedel triggers a delicate ballet between a massive telescope and its protective 100-ton dome.

As the dome's opening and the telescope's mirror align, the shimmering star - the bull's eye in the constellation Taurus - appears on a TV monitor, and Mr. Halbedel begins to tweak the telescope's focus.

"Ooh, you're good," Dr. Hinkle says with a grin.

"Hey, I do this for a living," Halbedel replies, smiling.

Indeed, if you have a star, nebula, or galaxy you need to visit, Halbedel is one of a small group of people worldwide who will get you there. Known by various titles, most of them polite, these modern-day Han Solos are linchpins of astronomy. Many headline-grabbing discoveries would never be made without mountaintop star pilots, who must act as technicians, weather forecasters, and (unlike Han Solo) diplomats, as well as operate telescopes.

"You can't overstate what these people do. They are absolutely critical," says Ben Oppenheimer, an astronomer at the University of California at Berkeley. "They don't get much credit, but they can make or break a research project."

For theorists who spend their time trying to explain how the cosmos works, a computer, white board, markers, and a stack of results from others' observing runs are their stock in trade. For observational astronomers, however, the currency is telescope time.

Competition for time "on the sky" is fierce. For example, the National Optical Astronomy Observatory (NOAO) in Tucson, which runs telescopes in Chile and Hawaii as well as at the Kitt Peak National Observatory, gets requests for an average of three to four times more nights on its glass than are available.

Even when reviewers approve a project, an astronomer is likely to get only two or three nights on the largest telescopes. That's it for at least six months - often for the year. To an astronomer with tenure at a major university and who may have several projects under way at once, telescope time truncated or lost to weather, technical problems, or a poor operator is annoying. For a graduate student struggling to earn a PhD, a postdoc hoping for a full-time job at a college or university, or an assistant professor looking for tenure, delays or marginally productive observing runs could mean the difference between studying the cosmos or selling insurance.

The star pilots are there to help ensure the visiting researchers remain astronomers by helping them gather as much information as possible during their observing period. At Kitt Peak, a mountaintop Mecca for astronomy some 55 miles west of Tucson, Halbedel is the eminence grise among seven telescope operators. They work six or seven nights in a row, then get several consecutive days off. They can face observing schedules that list dozens of targets a night, or they can keep the telescope locked on a faint object for hours while the instruments tease as many photons as possible from the night sky.

Star pilots come with mechanical or technical skills, a deep appreciation for the night sky, and a sufficiently even temperament to remain calm in the face of broken pumps or grumpy astronomers who apply less-than-polite monikers to observing assistants who close the dome because rain, snow, or excessively high winds threaten the telescope.

"All you can do is tell them that you understand their situation," Halbedel says. The alternative to shutting down for one night is risking damage that may take weeks to repair, he adds, ruining the opportunities for several astronomers. The time may belong to the astronomer, but the operator rules the telescope.

Tonight, Halbedel and Hinkle - who oversees the spectrograph at the business end of the 4-meter Mayall telescope - are working with Craig Kulesa, a graduate student at the University of Arizona who is studying conditions in stellar nurseries such as the Flame Nebula, part of a structure known formally as NGC2024.

"Where do you want to go?" Halbedel asks.

"Zeta Ori," Mr. Kulesa replies, referring to the easternmost star in Orion's belt, NCG2024 lurks nearby.

Once the telescope arrives at the target, the guide system kicks in, and the spectrograph begins its work, Halbedel reflects on the changing role observing assistants have undergone over the 29 years he's worked on the mountain.

"There were no computers, so there were always things to adjust. You really had to learn how to massage the machinery," he says. Even today, microphones in the dome keep operators in the control room attuned to every thump, grind, and whir the telescope makes.

The observing assistant's role "is constantly being redefined," adds Robert Thicksen, supervisor of the Mt. Palomar Observatory near Escondido, Calif.

At one time, he says, night assistants, observing assistants, observing associates, or remote observers - as they are variously known - were little more than chauffeurs for big telescopes. At the observatory's famed 200-inch Hale telescope, the NAs would monitor the scope from a control panel inside the often frigid dome. The astronomer "rode the telescope" in a cage at the telescope's prime focus, high above the main mirror.

While the NA controlled the dome and the telescope's most-sweeping motions, fetched the midnight sandwiches, and stood ready to act as mechanic or medic in an emergency, the astronomer took photographs, using glass plates for film. The researcher also would keep the telescope on target by looking at a guide star through an eye piece and using a hand paddle to control fine changes in the telescope's position.

If a night assistant proved exceptionally competent, the astronomer might eventually allow that person to take the images and review the data.

Now, telescopes have grown more sophisticated, with subsystems monitoring or governing everything from mirror temperature and shape to dome temperature. An increasing number of telescopes use adaptive optics - a laser-based system for getting the sharpest possible image by canceling the distorting effects of the Earth's atmosphere. A variation is being installed at a 3.5 meter telescope on the mountain that will constantly, subtly shift the orientation of the telescope's smaller "secondary" mirror to reduce the atmosphere's "twinkle" effect. Halbedel notes that while the Mayall telescope is modest by today's standard, it still takes four computers talking with each other to run it.

And while some astronomers may be repeat customers, as they were in the old days, their visits are too rare to allow them to become proficient at operating the larger telescopes themselves.

If life on the mountaintop can be technically and diplomatically demanding, it also places constraints on an operator's social life - constraints familiar to anyone who has to work the swing shift regularly. You work nights, while your friends work days.

Kitt Peak's remoteness and a work schedule out of sync with much of the rest of humanity's have contributed to a high turnover-rate among observers recently, NOAO officials acknowledge. Yet some observing assistants have found ways to avoid the social penalties.

Bill Gillespie, who has worked as an observing assistant for three months, acknowledges that he came to the mountain with years of experience at isolated jobs. Following high school, he joined the Navy and served aboard the USS Corpus Christi, a nuclear attack submarine. He also worked as an electrician and welder in Alaskan oil fields where shifts were defined as three months on and three off.

"I like the schedule here," he allows. "You get blocks of time off to work on projects like building small telescopes or learning how to set up computer networks. Or you can just go skiing."

The job also can provide some operators with scientific rewards. On Mt. Hopkins, about 50 miles southeast of Kitt Peak, Perry Berlind has been taking observations for astronomers at the Whipple Observatory for nine years. Unlike his counterparts on Kitt Peak, he often works without an astronomer at his side. Instead, he gets a list of targets, gathers the data himself, then e-mails the results to the project's lead investigator. He says he's been credited with discovering five supernovae, stellar explosions whose violent bursts of energy are valued as "standard candles" for more accurately gauging the expansion rate of the universe.

(c) Copyright 2001. The Christian Science Monitor