The Keck Interferometer
At the summit of Mauna Kea, Hawaii, NASA astronomers have linked the two 10-meter (33-foot) telescopes at the W. M. Keck Observatory. The linked telescopes, which together are called the Keck Interferometer, make up the world's most powerful optical telescope system. Image credit: NASA/JPL-Caltech
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NASA researchers are preparing to use the giant twin telescopes of the W.M. Keck Observatory together as a single, high-powered instrument in coming years to search for planets and planetary systems around nearby stars.

The recently completed Keck II Telescope, the second of the 10-meter (33-foot) diameter telescopes atop Hawaii's Mauna Kea, is to be formally dedicated in ceremonies at the observatory on Wednesday, May 8.

Using the Keck telescopes in interferometric studies, wherein the two telescopes will make concurrent observations of the same object in space, will provide a dramatic increase in light-gathering and resolution over a single telescope. These studies will lay much of the groundwork for NASA's Origins Program, one goal of which is to seek planets around nearby stars.

"We're excited about the capability to combine the world's two largest telescopes into one very large 'light bucket,"' said Dr. Wesley Huntress, NASA's Associate Administrator for Space Science. "It will enable us to test this technique on the ground and learn how to operate such systems before we build a large interferometer in space to search for Earth-like planets."

The W.M. Keck Foundation has provided more than $150 million toward funding the telescopes. The observatory was constructed and is managed by the California Association for Research in Astronomy (CARA), a partnership of the California Institute of Technology and the University of California.

"We now know that there are Jupiter-like planets around some other stars," said Dr. Edward C. Stone, chairman of the board of CARA, vice president of Caltech and director of NASA's Jet Propulsion Laboratory in Pasadena, CA. "One of the objectives of the Keck telescopes is to detect even more planets around nearby stars. We'll be looking primarily for Jupiters because Jupiters are so much easier to detect than much smaller Earth-like planets. But if there's a Jupiter-like planet around a given star, that would be a prime place to look with more sensitive space-based instruments for Earth-like planets."

"NASA's involvement in the telescopes will broaden the science base by bringing in the national community of astronomers," said Keck Project Manager Gerald M. Smith. With the research and development investment in the Keck facility, "we should be able to accomplish some science that would not have otherwise been done," Smith added.

The Keck II Telescope, like its sibling Keck I, uses a mirror composed of 36 hexagonal pieces of glass, individually polished and assembled, to form a huge, perfectly parabolic reflecting surface. This segmented mirror is much thinner, and therefore lighter in weight, than a solid mirror could be, which is the key to building such a large instrument.

In addition to doubling the amount of observing time available at the Keck Observatory, Keck II will allow a wider array of observing instruments to be used. Scientists have designed and built three specialized spectrographs -- instruments for recording an object's spectrum -- for use on Keck II that will make possible an observational program with great flexibility and range.

Keck II will also have an adaptive optics facility, a method of compensating for the slight distortions caused by atmospheric turbulence. People see distorted starlight as twinkling, but for a telescope making a long exposure, the star looks slightly blurry. The adaptive optics system will be able to detect these tiny distortions and make one hundred tiny adjustments per second to the mirror to compensate for them and maintain the sharpest possible image.

NASA has committed to provide $7 million a year for a total of $44 million for construction and $2 million a year for operating costs as part of a cooperative effort to develop and use infrared and optical interferometry wherein the two telescopes will make concurrent observations of the same object. NASA's Jet Propulsion Laboratory, Pasadena, CA, manages the agency's participation in the W.M. Keck Observatory is provided through the agency's Office of Space Science, Washington, D.C.

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