Rejuvenating observatory: green light given for space telescope repairs.

After 3 years of uncertainty following the Columbia disaster, NASA this week gave the go-ahead for a shuttle mission to carry astronauts to refurbish the 16-year-old Hubble Space Telescope and to install new detectors that would vastly improve its capabilities.

"This is fantastic news," says Matt Mountain, director of the Space Telescope Science Institute in Baltimore. "We're getting a completely new telescope."

The shuttle flight, scheduled for mid-2008, would endow Hubble with the most sensitive ultraviolet spectrograph ever flown. The device is designed to trace the distribution of galaxies and intergalactic gas. The crew would also install an infrared camera to record galaxies even more distant than the ones Hubble can now image.

The crew would also revitalize the system for pointing the telescope, replace all six gyroscopes, and attempt to repair an imaging spectrograph that stopped working in 2004. NASA estimates that the $900 million mission would add 5 years to Hubble's life, extending it until 2013.

NASA Administrator Michael Griffin approved the flight, the fifth such mission to repair Hubble. Because of safety concerns about the shuttle, a second, rescue shuttle will be on the launch pad during the 2008 mission.