JPL: Two telescopes are better than one.

From: Brian D Williams (
Date: Thu Mar 15 2001 - 09:16:36 MST

PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011

Contact: Jane Platt (818) 354-0880


     Proving that two telescopes are better than one, NASA
astronomers have gathered the first starlight obtained by linking
two Hawaiian 10-meter (33-foot) telescopes.

     This successful test at the W.M. Keck Observatory on Mauna
Kea makes the linked telescopes, which together are called the
Keck Interferometer, the world's most powerful optical telescope
system. The project will eventually search for planets around
nearby stars and help NASA design future space-based missions
that can search for habitable, Earth-like planets.

     "Successfully combining the light from the two largest
telescopes on Earth is a fabulous technical advancement for
science," said Dr. Anne Kinney, director of NASA's Astronomical
Search for Origins program, which includes the Keck
Interferometer project. "Using them in this way gives us the
equivalent of an 85-meter (279-foot) telescope. This will open
the possibility of obtaining images with much greater clarity
then ever before possible."

     "This is a major step in the creation of a whole new class
of astronomical telescopes that will have an enormous impact on
future knowledge," said Dr. Paul Swanson, the Keck Interferometer
project manager at NASA's Jet Propulsion Laboratory, Pasadena,
Calif. "Historically, breakthrough technologies like the Hale 5-
meter (200-inch) and the Hubble Space telescopes have made
discoveries way beyond the purpose for which they were originally

     Monday night, March 12, starlight from HD61294, a faint star
in the constellation Lynx, was captured by both Keck telescopes
and transported across a sophisticated optical system across the
85 meters (275 feet) separating the two telescopes. In an
underground tunnel that links the telescopes, the collected light
waves were combined and processed with a beam combiner and
camera. In order to properly phase the two telescopes, adaptive
optics on both telescopes removed the distortion caused by the
Earth's atmosphere. In addition, the optical system in the tunnel
adjusted the light path to within a millionth of an inch.

     Testing of the Keck Interferometer will continue for the
next several months. Limited science operations, including the
search for planets, are expected to begin this fall. Scientists
around the world will soon be invited to propose studies they
would like to conduct using the Keck Interferometer. Their
proposals will undergo a formal review and selection process.

     Since 1995, astronomers have discovered almost 50 planets
orbiting other stars. With current technology, they can find very
large, Jupiter-like planets, 300 times as massive as Earth, that
are located close to their parent stars. Such planets are not
likely to harbor life. The Keck Interferometer will be able to
detect planets farther from their parent stars, which means their
reflected light would be dimmer and harder to detect.

     The unique pairing process will help pave the way for future
interferometers in space, such as the Terrestrial Planet Finder,
which will look for Earth-like planets. "This first light from
the Keck Interferometer marks a dramatic step forward and will
help us accomplish the ultimate goal of the Origins Program -- to
search for signs of life beyond by examining the light from
'Earths' orbiting nearby stars," said Dr. Charles Beichman, the
Origins chief scientist at JPL.

     An interferometer uses multiple telescopes to gather light
waves, then combines the waves in such a way that they interact,
or "interfere" with each other. A similar phenomenon can be
observed by throwing a rock into a lake and watching the
resulting ripples, or waves. If a second rock is thrown into the
water, the new set of waves either bumps up against the first set
and changes its pattern, or it joins together with the first set,
making larger, more powerful waves. In astronomy, the idea is to
combine the light waves from the multiple telescopes to simulate
a much larger telescope. This enables scientists to capture
images of much smaller objects or to determine their size or
position with much greater accuracy.

     The development of the Keck Interferometer is managed by JPL
for NASA's Office of Space Science, Washington, D.C. JPL is a
division of the California Institute of Technology in Pasadena.
The W.M. Keck Observatory is funded by Caltech, the University of
California and NASA, and is managed by the California Association
for Research in Astronomy, Kamuela, Hawaii.

     Additional information and images are available at and .

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3/14/01 JP

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