LIVERMORE, Calif. - The best Earth-based images ever taken ofNeptune and Titan, Saturn's largest moon, will be revealed today atthe annual meeting of the American Astronomical Society inAtlanta.
The images of the distant celestial bodies were captured ininfrared light using the W.M. Keck II telescope in Hawaii, theworld's largest. They are among the first Keck images taken withadaptive optics technology, which uses rapid mirror adjustments toremove Earth's atmospheric turbulence from the telescope's images,producing unprecedented clarity.
Taken in the past months, the images surpass what would bepossible using even the Hubble Space Telescope. They reveal giantNeptunian storms driven by prevailing winds of 600 miles per hour.The Titan images reveal features that could be frozen landmassesseparated by chill hydrocarbon seas and lakes.
The images are the work of a team of researchers led by Dr. ClaireMax of the U.S. Department of Energy's Lawrence Livermore NationalLaboratory, and include scientists from the University of Californiaat Berkeley, UCLA, and Keck Observatory. The work was supported bythe Energy Department, the National Aeronautics and SpaceAdministration and the National Science Foundation's Center forAdaptive Optics. The Keck I and II telescopes are operated by theCalifornia Association for Research in Astronomy.
Neptune and Titan were chosen as early subjects for Keck's newadaptive optics system because they are bright but mysterious objectsof which little is known, but which offer enticing spatialdetail.
On Neptune, a giant gas ball of a planet 2,800,000,000 miles fromEarth, Keck's infrared detectors penetrated into the deep layers ofthe planet's roiling atmosphere, where giant storms are born of theheat generated by the planet's still-contracting core. Storm featuresare pulled completely across the face of the planet as Neptune whirlsthrough its 16-hour day. At the north pole, a mysterious haze crownsthe planet.
Keck's adaptive optics images of Neptune are helping scientistsstudy the planet's storms and their evolution, a first step towardunderstanding Neptune's weather and climate.
"Neptune is one of the most dynamic of the giant planets," saidDr. Bruce Macintosh of the Livermore Lab. "It's always changing.Being able to study it from the ground on a continuous basis, ratherthan waiting for a spacecraft to fly by, is a huge advantage."
The images of Titan will tell astronomers about the complexsurface composition of the Saturnian moon, a frigid world some 800million miles from the sun. Titan has a nitrogen-rich atmospheresimilar to that of the early Earth. Sunlight shining on thisatmosphere produces a deep orange haze that obscures Titan's surfacefrom view at visible wavelengths.
Livermore scientists Macintosh and Dr. Seran Gibbard have beenstudying Titan for several years at Keck using earlier imageprocessing techniques and computer models. But Keck's new adaptiveoptics images, taken in infrared light, have much greatersensitivity. They pick out features "that may be cold hydrocarbonseas and lakes," said Gibbard. Other features might be highlands, andone dark area appears to be a large impact crater or great basin.
In 2004 the Cassini spacecraft, built by NASA and the EuropeanSpace Agency, is scheduled to land the Huygens probe on Titan. Keck'snew images will help researchers determine beforehand whether theprobe will plunge into the first extra-terrestrial sea or land on asolid surface.
"Combining the power of Keck with adaptive optics is taking us tonew worlds," said Livermore's Max. "That's an extremely excitingprospect as we enter the next millennium."
Adaptive optics works by using a continuously deformable mirrorand a lightwave sensor to correct light beaming into a telescope. Thesensor determines how much Earth's atmosphere is disturbing the lightreaching the telescope, and relays this information to the deformablemirror, which corrects the image every few milliseconds. LawrenceLivermore researchers worked with Keck scientists on installation ofthe Keck adaptive optics technology.
In coming months, a new spectrograph will be added to the Keckadaptive optics system. This will help answer questions about thechemical composition and physical state of the features newly seen onNeptune and Titan.
Founded in 1952, Lawrence Livermore National Laboratory is anational security laboratory, with a mission to ensure nationalsecurity and apply science and technology to the important issues ofour time. Lawrence Livermore National Laboratory is managed by theUniversity of California for the U.S. Department of Energy.
For information on the W.M. Keck Observatory, MaunaKea, Hawaii, contact: Andrew Perala at (808) 885-7887 oraperala [at] keck.hawaii.edu.
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