After eight years of study, NASA has approved the construction of an unmanned satellite that will scan the entire sky in infrared light to reveal nearby cool stars, planetary "construction zones" and the brightest galaxies in the universe. An estimated $300-million mission, the Wide-field Infrared Survey Explorer, or "WISE," is scheduled to launch into an Earth orbit in late 2009. It will spend seven months collecting data a few times a day. Edward L. Wright, a University of California, Los Angeles professor of physics and astronomy, is WISE's principal investigator. NASA's Jet Propulsion Laboratory in Pasadena will manage the mission, with JPL's William Irace as project manager. Artist's concept of the Wide-field Infrared Survey Explorer. (Image: NASA/JPL) Like a powerful set of night-vision goggles, WISE will survey the cosmos with infrared (IR) detectors hundreds of times more sensitive than those used in previous survey missions. "This mission has incredible power for discovery," Wright said. "I expect that what we find will be amazing. There is still so much we don't know." Wright said that 99 percent of the sky has not been observed yet with this kind of sensitivity, and that the survey should be able to find and observe at least 100 million galaxies and hundreds of nearby cool stars that are currently unknown. "Approximately two-thirds of nearby stars are too cool to be detected with visible light," Wright said. "WISE will see most of them." He added that proto-planetary discs around stars presumably condensing into a planetary system show up in the IR. "Several have been detected, and we will be able to see many more in the Milky Way galaxy," Wright said. "In addition, we will be able to study star-forming regions in nearby galaxies and star formation in distant galaxies." Such extensive sky coverage means that the mission will find and catalog all sorts of celestial eccentrics, including perhaps elusive brown dwarfs close to the Earth. Brown dwarfs, the missing link between gas giant planets like Jupiter and small, low-mass stars, are failed stars about the size of Jupiter, with a much larger mass. They can be detected best in IR, but even within the IR are very difficult to detect. "Brown dwarfs are lurking all around us," said Peter Eisenhardt, project scientist for WISE and JPL. "We believe there are more brown dwarfs than stars in the universe, but we haven't found them because they are faint." Wright, Eisenhardt and other scientists recently identified brown dwarfs using NASA's IR Spitzer Space Telescope. Wise will vastly expand the search, uncovering those brown dwarfs closest to Earth that might make ideal targets for future planet-hunting missions. Recent Spitzer findings support the notion that planets might orbit brown dwarfs. Galaxies in the distant, or early, universe were much brighter and dustier than our Milky Way galaxy. Their dusty coats light up in IR wavelengths. "It's hard to find the most energetic galaxies if you don't know where to look," Eisenhardt said. "We're going to look everywhere." The spacecraft's detectors will be approximately 500 times more sensitive than those of a previous IR survey mission, called the Infrared Astronomical Satellite, a joint European-NASA venture that operated in 1983. WISE will also provide a complete inventory of dusty planet-forming discs around nearby stars, and find colliding galaxies that emit more light, specifically IR light, than any other galaxies in the universe. WISE is expected to produce more than 1 million images, from which hundreds of millions of space objects will be cataloged. WISE may be able to confirm the existence of dark energy, which scientists believe comprises more than 70 percent of the universe, and which Albert Einstein postulated in 1917. Einstein later believed that to be a serious blunder, but it looks like he was correct, Wright said. The cryogenic instrument will be built by the Space Dynamics Laboratory in Logan, Utah, and the spacecraft will be built by Ball Aerospace and Technologies Corporation in Boulder, Colo. Science operations and data processing will take place at the JPL/Caltech Infrared Processing and Analysis Center. For more information, visit: http://wise.ssl.berkeley.edu