Light and Magic
On a clear night--with this telescope--you can see forever.
- By Eric Adams
- Air & Space magazine, July 2000
In the world of big, powerful telescopes, there is one accomplishment that none have been able to claim. It has no scientific value, really, but it would thrill both astronomers and the general public and ensure a lifetime of bragging rights to the first to do it.
Sitting in his office at the European Southern Observatory's Very Large Telescope in northern Chile, overlooking an expanse of brown hills and valleys leading to the Pacific Ocean five miles away, VLT director Roberto Gilmozzi smiles as he edges toward the revelation. "When this telescope is complete, it will have the angular resolution equivalent to that of a telescope with a mirror 132 meters [433 feet] in diameter," Gilmozzi begins. "That means that we will, if we wanted to, be able to resolve and photograph Apollo debris left on the moon."
Now, there are many, many other celestial targets that the ESO is much more interested in-distant galaxies, dim nebulas, extrasolar planets-but that would be a sensational stunt. Many thought it impossible, given how minuscule even the largest Apollo remnant-something about the size of a delivery van-would be from a quarter of a million miles away. But with the giant leap that the ESO is about to take in Chile, this and a lot of other accomplishments are indeed going to be possible. Gilmozzi is coy, though, about whether the moon shots will actually make it into the observing schedule. "It would certainly make for some good PR, wouldn't it?" he asks.
It would. It would also prove Gilmozzi's point: that the VLT is an exceptionally powerful instrument. Built atop a truncated mountain in the Atacama Desert, the VLT is actually four identical 8.2-meter-diameter reflecting telescopes-two of which are now operational-that can be used independently or be linked, through a process called interferometry, to create what is essentially a single ultra-large-aperture telescope. Technologies called active and adaptive optics, plus a prime geographic location-one of the driest places on earth-will enable the VLT to operate with virtually no atmospheric distortion, and its remote location will also give it the darkest skies possible. All of this will make the VLT capable of seeing farther and in greater detail than anything before it. It will capture images at least 50 times sharper than those obtained by the Hubble Space Telescope. It will answer many questions, and raise many new ones-and it will probably place Europe at astronomy's fore.
"The VLT is already the best-working telescope in the world," says British cosmologist Simon White, director of the Max-Planck Institute for Astrophysics in Munich. White visited the VLT last year to capture details of the rotation of spiral galaxies. "This is the first time in a century that the foremost optical astronomy instrument has been a non-U.S. facility. When complete, the VLT interferometer will open an entirely new range of phenomena for study-if it works to spec."
The VLT's potential isn't lost on the Americans. Says Robert Gehrz, president of the American Astronomical Society and a University of Minnesota physics and astronomy professor: "If they can get that thing to work as an interferometer, that's going to be a breakthrough that will make it the most powerful facility in the world. There's no question about that-and I'll probably be applying for time on it."
The VLT was conceived in 1977; in the years since, the ESO, a consortium made up of Germany, Italy, Denmark, France, Belgium, Sweden, Switzerland, and the Netherlands, has spent $500 million on it. All of its major advances have been tested at the New Technology Telescope in La Silla, Chile. But the VLT is one of the most complicated observatories ever built, and its success won't really be verified until 2006, when its four telescopes focus on the same speck of light and it begins coming up with answers to questions about galactic evolution, the insides of quasars and black holes, and, Gilmozzi promises, the precise nature of the planets orbiting stars other than our sun.
The VLT may as well be on another planet itself. Getting to Cerro Paranal, the mountain on which the VLT was built, is a multi-leg, often multi-day affair. Visitors fly first to Santiago and then 800 miles north to Antofagasta, an isolated, sprawling port city of 250,000 that exists primarily to support the dozens of mines in the region. Here, families flock to the rocky beaches-better for sunbathing than swimming-that span Antofagasta's western shore.