Space camera glitch.NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. has announced some bad news about the 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. . The spacecraft has been orbiting Earth and collecting information about space since 1990. Now, Hubble's sharpest camera has died, and there's no way to bring it back to its full power. Until it broke down, the 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. ) was the most popular instrument on board, accounting for two-thirds of the observations made by the orbiting telescope. It also captured the deepest picture ever taken of the universe, which reveals disks of gas and dust turning into planets around other stars. The ACS was installed in March 2002. [ILLUSTRATION OMITTED] Trouble struck on Jan. 27, when Hubble suddenly went into "safe mode." This means that it shut off detectors that it didn't need, including several in the ACS. An investigation showed a glitch A temporary or random hardware malfunction. It is possible that a bug in a program may cause the hardware to appear as if it had a glitch in it and vice versa. At times it can be extremely difficult to determine whether a problem lies within the hardware or the software. See glitch attack. in the electrical system that powered the camera. As a result, two sensors on the ACS that detect visible light failed. Since last June, those detectors had been running off backup power An additional power source that can be used in the event of power failure. See UPS and backup.  A Half Minute of Backup This roomful of lead acid batteries stands ready to drain itself entirely in less than a minute. after another problem with the spacecraft's main power supply. "The seemingly permanent loss of the ACS is a blow to the astronomical community," says astronomer Lynne Hillenbrand of the California Institute of Technology California Institute of Technology, at Pasadena, Calif.; originally for men, became coeducational in 1970; founded 1891 as Throop Polytechnic Institute; called Throop College of Technology, 1913–20. in Pasadena. Near the end of February, engineers plan to switch the Hubble camera back to the original power system. They hope the changeover will revive a detector that collects ultraviolet light Ultraviolet light A portion of the light spectrum not visible to the eye. Two bands of the UV spectrum, UVA and UVB, are used to treat psoriasis and other skin diseases. . [ILLUSTRATION OMITTED] Sometime in early February, three more instruments should come back online--including a less sensitive camera that uses visible light, a camera that detects near-infrared light, and fine-guidance sensors, which track the motions of stars. By collecting light in longer exposures, the Hubble's wide-field camera might be able to fill in for the ACS in some cases. And NASA points out that it has plenty of projects to keep Hubble's remaining instruments busy. Astronauts will return to the spacecraft in September 2008 to service and repair the telescope. They'll install a new infrared camera and a sensitive ultraviolet spectrograph, which measures wavelengths of light. They will also try to fix a spectrograph that has stopped working. Repairs to the ACS itself would be too risky and take too much effort to be worthwhile. As originally planned, Hubble was scheduled to operate until 2010. This date is approaching rapidly, Hillenbrand says. More hardware failures like this one are increasingly likely in the coming years.--E. Sohn |
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