Telescope tuned up: back to work for orbiting observatory. (This Week).
A rejuvenated Hubble Space Telescope Hubble Space Telescope (HST), the first large optical orbiting observatory. Built from 1978 to 1990 at a cost of $1.5 billion, the HST (named for astronomer E. P. Hubble) was expected to provide the clearest view yet obtained of the universe. floated away from the space shuttle Columbia on Saturday, March 9, after astronauts spent a week renovating the observatory.
Columbia's crew began the mission March 1. Despite a problem with the shuttle's cooling system early on, the trip progressed as planned, and Columbia's robotic arm damped onto Hubble last Sunday.
Over the next 5 days, four astronauts performed 36 grueling hours of space walks to replace worn components and add new devices (SN: 3/2/02, p. 132).
The most crucial task was to replace Hubble's power-control unit, which had lost some of its capacity. The unit hadn't been designed to be removable, says Holland Ford of the John Hopkins University in Baltimore. The procedure required shutting Hubble's power off for the first time in its 12-year history. However, the telescope started up again with no apparent adverse affects.
The astronauts also installed the new Advanced Camera for Surveys The Advanced Camera for Surveys (ACS) is a third generation axial instrument aboard the Hubble Space Telescope (HST). The initial design and scientific capabilities of ACS were defined by a team based at Johns Hopkins University. (ACS (Asynchronous Communications Server) See network access server. ). The size of a telephone booth, the ACS should allow Hubble to see further than ever before. The 7-hour procedure went "flawlessly," says Ford, who leads the ACS team. Early tests suggest that the camera works.
The final space walk, on March 8, focused on an existing Hubble component: the Near Infrared Camera and Multi Object Spectrometer (NICMOS NICMOS: see infrared astronomy. ). This instrument works only at supercold temperatures, and it stopped functioning in 1999, after a coolant coolant (kōō´lnt),
The astronauts attached a new refrigerator, which "appears to be alive," says Edward Cheng of NASA's Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately 6.5 miles northeast of Washington, D.C. in Greenbelt, Md. But since this cooler is unlike any used before, it's hard to guarantee success in reviving NICMOS, he adds.
Scientists should know by mid-April if NICMOS is back in action, and at about that time, they hope to produce the first useful images from the ACS.
Hubble's uniquely serviceable nature "gets you a lot of bang for your buck," says Cheng. NASA NASA: see National Aeronautics and Space Administration.
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Independent U.S. plans for Hubble to continue collecting data until 2010.