Proving that two telescopes are better than one, NASA
astronomers have gathered the first starlight obtained by
linking two Hawaiian 10-meter 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, Earthlike
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 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 (JPL), Pasadena, CA. “Historically, breakthrough
technologies like the Hale 200-inch and the Hubble Space
telescopes have made discoveries way beyond the purpose for
which they were originally built.”
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 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’d 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, which
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 Earthlike 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, DC. JPL is a
division of the California Institute of Technology (Caltech).
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,
HI.
Additional information and images are available on the
Internet at:
http://www.jpl.nasa.gov/pictures/keck
