Telescope tuned up: back to work for orbiting observatory. (This Week).
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 (ACS). 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). This instrument works only at supercold temperatures, and it stopped functioning in 1999, after a coolant leak.
The astronauts attached a new refrigerator, which "appears to be alive," says Edward Cheng of NASA's Goddard Space Flight Center 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 plans for Hubble to continue collecting data until 2010.