FORT DAVIS, TEXAS — Astronomers often refer to their telescopes as "light buckets." The bigger the bucket, the deeper astronomers can peer into the heavens.
Last week, engineers at the University of Texas' McDonald Observatory here hoisted the final piece of machinery - a six-ton tracking mechanism - onto what will be the world's second-largest light bucket. The new Hobby-Eberly Telescope, with a mirror measuring 9.2 meters (30.2 feet) in diameter, may signal a fundamental change in the way telescopes are built and the way astronomers conduct their research.
Built for $13.5 million, about 15 percent of the cost of a comparable-sized telescope, the HET is an example of scientists getting a bigger bang for the buck in an era of shrinking budgets for astronomy. The HET is also part of a new trend in making research results available to scientists via the Internet.
From the beginning, the design team knew that HET would have to be built on the cheap. Instead of a huge, expensive mirror, the telescope uses a complex honeycomb of 91 hexagonal mirrors. UT astronomers also decided to put the mirror in a fixed position, rather than building the complex machinery needed to tilt it. A smaller tracker will follow stars across the night sky.
'Limit your desires'
"If you want to build a world-class facility on a university-type budget, you have to limit your desires," explains Frank Bash, director of McDonald Observatory, the facility that will run the HET.
Such frugality will probably continue to keep other projects from reaching astronomical costs, he adds. "The trends in society and the cost of telescopes are working against astronomers who are building bigger and bigger telescopes, because the cost of building the telescopes goes up so rapidly and society hasn't shown an increased willingess to fund basic research." As such, he says, "telescopes will have to be more specialized."
Bruce Margon, a University of Washington astronomer and chairman of the Association of Universities for Research in Astronomy, calls the HET design a "fiendishly clever idea. By having a restricted number of instruments and a restricted piece of the sky, and by building a very large amount of collecting area, they've succeeded in making an instrument that is equivalent to a huge instrument for a much lower price."
Unlike other optical telescopes, the HET will not be able to take pictures of faraway objects. Instead, it will only do spectroscopy, the study of the light waves emitted or absorbed by celestial objects. Astronomers use spectroscopy to determine the temperature, speed, and chemical composition of stars.
To design and pay for the new telescope, UT astronomers teamed up with scientists from Pennsylvania State University in State College, Stanford University in Palo Alto, Calif., and two German schools - Ludwig-Maximilians University in Munich and Georg-August University in Goettingen. The five schools will share access to the facility depending on the amount of money each school contributed. Additional time on the scope will be given to non-consortium astronomers depending on the merit of their research proposals.
The HET will also be used in an unconventional manner that could be called "virtual astronomy." Scientists will not have to travel to the observatory, located 460 miles southwest of Dallas, in order to use it. Instead, they will send in requests indicating which objects or coordinates in the sky they want to examine. A computer will collate the requests and determine which areas of the sky the telescope will look at and when. This type of automated access, called "queue scheduling," will maximize the HET's actual observing time. When the observations are completed, astronomers will receive the results of their query via the Internet.
The HET is one of several huge telescopes coming on-line this decade. A quintet of eight-meter-wide telescopes is under way in Chile. Two eight-meter-wide telescopes, the Subaru and Gemini North, are being built on the island of Hawaii atop Mauna Kea. That location already has pair of identical new telescopes, Keck I and Keck II, each of which contains a mirror 9.8 meters across. The two telescopes were built at a total cost of $170 million.
For an idea of the collecting power of this new class of telescopes, consider that Isaac Newton revolutionized astronomy in 1672 when he showed English scientists the reflector telescope he built with a two-inch-wide mirror. The new class of mirrors like those used on Keck and the HET have more than 37,000 times more light-gathering capacity than the one Newton built. The telescopes are powerful enough to peer into distant galaxies and to search for planets orbiting around stars.
Steve Maran, a spokesman for the American Astronomical Society, says the high cost of the Keck telescopes compared with the HET may inspire the construction of more telescopes with a fixed mirror. "Presumably, this is the future of larger and larger telescopes, because you get a lot of collecting area for your buck," he said.
Spawn of HET
Although the HET won't see "first light" - the first time the telescope will be used for stargazing - for a few more weeks, the project's designers are talking with astronomers in South Africa about building an identical facility there. And nine months ago, UT astronomers presented a scientific paper on a project that will use the HET design for a telescope 25 meters in diameter that will cost an estimated $200 million.
Dr. Margon says telescopes are going from the "propeller age to the jet age." The combination of computer-aided design and the introduction of more powerful light-detection devices is allowing astronomers to build telescopes that were considered science fiction a few decades ago.