An Astronomy First: Telescopes Double-Team Hawaiian Night SkyMarch 19, 2001 / Posted by: Shige Abe
Text based on a NASA Press Release
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.
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