International Technology : To World’s Astronomers, Northern Chile Is Heaven : Giant new telescopes will make it the best place on Earth to view the universe. Europeans are leading the effort.


Hundreds of astronomers come to northern Chile each year seeking to unravel the riddles of the universe. Arlin Crotts, from Columbia University, was here hoping to add to humankind’s sketchy knowledge of how stars are born in turbulent clouds of galactic gas.

As a visiting astronomer at Cerro Tololo Inter-American Observatory, Crotts was using a telescope with a light-gathering mirror four meters (13.1 feet) in diameter, now the largest in the Southern Hemisphere and one of the biggest in the world. He said he was focusing on the Large Magellanic Cloud, a gaseous galaxy being ripped asunder by tidal forces that arise from the gravitational pull of the nearby Milky Way.

“So in the process of being torn apart, this gas is running into itself, being compressed, being shocked by collisions,” he explained. “And when you compress gas, you form stars--although that process is a little mysterious.”

Crotts, 34, puts little expression in his beard-fringed face, but when he talks about cosmic mysteries, his words twinkle with enthusiasm--as they do when he talks about northern Chile. This area, with three international observatories and two dozen telescopes, is a mecca for astronomers.

“When you combine all these telescopes, it’s got to have more square meters than anywhere else,” Crotts said.


From lofty peaks like Cerro Tololo, the telescopes look through crystalline desert skies that are cloudless 300 nights a year or more. To take advantage of these excellent conditions, more and better telescopes are being planned. When the next generation of super-telescopes is in place, experts say, northern Chile will have the most favorable combination of equipment and conditions on Earth for optical astronomy.

For example, European countries are preparing to build a new Chilean observatory that will boast a battery of four giant telescopes, each with a mirror measuring 8.2 meters (26.9 feet) in diameter. They will be linked electronically, yielding far greater power than any other system in the world.

“I think northern Chile is going to be the premier site in world astronomy,” said Stephen Heathcote. “When these telescopes are built, it very definitely will be.”

Heathcote, a staff astronomer at Cerro Tololo, said northern Chile’s only rival in astronomical equipment and visual conditions is Mauna Kea, which at 13,796 feet is Hawaii’s highest peak. (By comparison, the Cerro Tololo observatory is 7,220 feet above sea level.)

Four big new telescopes, including two with multiple-mirror assemblies equivalent to 10-meter circular mirrors, are to be installed at Mauna Kea by the end of the century. But no instruments there will be as powerful as Europe’s planned battery in Chile. And Heathcote said that Mauna Kea, which gets “clouded out” much more frequently than northern Chile, is running out of space for more new telescopes.

There is no shortage of good sites in northern Chile. Its three existing international observatories are on different mountains less than a two-hour drive from La Serena, a pleasant provincial capital and beach resort 250 miles north of Santiago, the national capital.

* Cerro Tololo observatory was built in 1963 by the U.S. government’s National Science Foundation and is operated by an association of American universities. In addition to its prestigious 4-meter telescope, Tololo has five others with smaller mirrors.

* Las Campanas, an observatory run by the Carnegie Institute, is the smallest of the three observatories. It has three telescopes, including a highly rated 2.5-meter (8.2-foot) instrument that has the widest field of view of any large telescope in the world.

* La Silla, the European Southern Observatory, is operated by governments of Western Europe. It has 14 telescopes, including the 3.5-meter (11.6-foot) New Technology Telescope, or NTT, the most advanced of its kind.

With the 4-year-old NTT, the Europeans have taken a technological leap ahead of the American observatories here. Its “thin meniscus” mirror (the term describes a shape that is concave on one side and convex on the other) is mounted on dozens of computerized levers, or “actuators,” that automatically make minute adjustments in the reflecting surface to correct distortions caused by gravity as the Earth and the telescope turn. The system, called “active optics,” gives the NTT’s images a sharpness that other telescopes rarely achieve.

Active optics was made possible by high-powered computers, which are needed to quickly calculate and correct mirror distortions.

Like the NTT, the four new 8.2-meter telescopes planned by European astronomers will have thin meniscus mirrors and active optics. Europe is building the new observatory on a barren peak named Paranal near the city of Antofagasta.

The Paranal complex, called the Very Large Telescope or VLT, is expected to be completed by the end of this decade or the beginning of the next. Hardware alone will cost an estimated $250 million.

When all four telescopes are in place, they will be linked via an advanced technology that combines light from separate mirrors. This will give the VLT the light-gathering power of a theoretical telescope with a 16-meter (52.5-foot) mirror.

“This will be by far the world’s largest telescope,” said Bo Reipurth, a La Silla staff astronomer from Denmark.

“Each time one has made bigger telescopes, one has seen new things one didn’t know about before,” he said. “The hope for the VLT is that we will be able to look so far out in the universe--and that means we will be able to look so far back in time--that eventually we will be able to learn about the beginnings of the universe.”

Reipurth, 44, said Europe has been pulling ahead of the United States in astronomy for more than a decade because of reduced American financing for that and other areas of science. “We’ll have to see if Bill Clinton will put more emphasis on basic research than in the last 12 years, 15 years, in the United States,” he said.

The Americans who operate Cerro Tololo are hoping at least to stay in the same league with the Europeans by putting an 8-meter (26.2-foot) active optics telescope, dubbed Gemini Southern, on a nearby mountain called Cerro Pachon. The planned telescope would be built in conjunction with an identical one, Gemini Northern, to be installed on Mauna Kea.

Columbia University and the University of North Carolina are planning a 4-meter active optics telescope at Pachon, while the Carnegie Institute and the University of Arizona plan another new telescope with a 6.5-meter (21.3-foot) mirror at Las Campanas.

The $176-million Gemini construction budget is to be financed by the National Science Foundation (50%), Britain (25%), Canada (15%), Chile (5%), Argentina (2.5%) and Brazil (2.5%).

If the 8-meter Gemini Southern is not built, American astronomy will be left behind in the race to explore the southern skies with state-of-the-art telescopes. And that means settling for an inferior view of some of the most important parts of the near universe. The two Magellanic clouds, which are the closest galaxies to the Milky Way, can be seen only from the Southern Hemisphere.

Even with Gemini Southern, American observatories will not be able to match the capability of the Europeans’ VLT, acknowledged Robert Williams, director of the Cerro Tololo observatory. The Europeans already have gained advantages over the United States with their 3.5-meter NTT at La Silla, said Williams, 52, a lanky Californian.

“They’ve had some nice observations,” he said. ‘I’m pleased for science. I’m glad someone is doing it. I wish we were doing it.”

That is not to say that “nice observations” are lacking at the U.S.-financed observatories of northern Chile. Las Campanas was first to find the spectacular 1987 Super Nova, or exploding star, in the Large Magellanic Cloud. And Tololo’s 4-meter mirror has excelled in the discovery of “faint blue galaxies” at the far edges of the known universe.

Time on northern Chile’s telescopes is precious. To come to Tololo for two or three nights at a telescope, astronomers must apply nine months in advance. A committee of American university astronomers reviews their project proposals, ranks their scientific merit and schedules telescope time. More than half of the proposals are rejected, Williams said.

If an astronomer’s allotted time is spoiled by clouds, that’s just hard luck. Arturo Gomez, a Chilean member of the Tololo support staff, said a graduate student whose scheduled observations are clouded out may be unable to finish work for a doctoral degree.

“We have seen people cry here,” Gomez said. “Their careers depend on those nights.”