US astronauts equip Hubble on third spacewalk

UHOUSTON, Texas: Spacewalking astronauts revived a crippled camera and installed a second new scientific instrument aboard the Hubble Space Telescope
on Saturday, extending an ambitious effort by the crew of the shuttle Atlantis to overhaul the 19-year-old observatory into the weekend. The nearly seven-hour spacewalk by John Grunsfeld and Drew Feustel will be followed on Sunday by the fourth in a series of five daily excursions intended to equip the high flying telescope for at least another five years of observations. Since hoisting Hubble into Atlantis's cargo bay last week, the shuttle's seven astronauts have achieved six of the mission's highest priorities. In addition to the Saturday's revival of the Advanced Camera for Survey and installation of the new Cosmic Origin Spectrograph, the list of achievements include the addition of the Wide Field Camera-3, a new science computer, gyroscopes and power storage batteries. Hubble, a cooperative project between NASA and the European Space Agency, is headed for a new scientific summit, a perch from which astronomers can search for the oldest star systems, map the large scale structure of the universe and study planet forming processes around other stars. "We are batting 1000," said Dave Leckrone, NASA's chief Hubble astronomer, told a news briefing. "We have just an extraordinary capability to image the universe, much more powerfully that what we had before by far." Saturday's spacewalk breathed new life into camera for surveys, a seven-year-old instrument that was crippled by a short circuit in January 2007. The breakdown slowed a campaign to unravel the mysteries of dark matter and dark energy, two little understood forces that influence the structure and expansion of the universe. During the repair, Grunsfeld, a 50-year-old astronomer, and Feustel, a 43-year-old geologist, opened the camera to extract and replace four circuit boards and attach a new external power source. Grunsfeld, who is visiting the space telescope for a third time, removed 32 tiny screws using an assortment of hand ratchets and cutters to revive the imager. A custom cover plate kept the tiny fasteners from floating into the telescope, where it could have caused harm. Saturday's outing began with the installation of the new Cosmic Origins Spectrograph, an instrument that analyzes the light from stars, planets and other astronomicalS astronauts equip Hubble on third spacewalk