Astronauts Give Hubble New Focus They Install Guidance Sensor During Second Spacewalk Of Trip

Working in the blackness of space, astronauts gave the Hubble Telescope a sharper aim Friday night to go with its new, stronger eyes.

Spacewalkers Joe Tanner and Gregory Harbaugh had only the light of their helmets while installing a new guidance sensor, about the size of a baby grand piano.

“I think it’s in there. Yes sir!” Harbaugh said.

The astronauts, making the second spacewalk of the Hubble renovation, replaced a worn guidance sensor, one of three that lock the telescope onto its targets, often billions of light years away.

The device provides incredible pointing stability, comparable to holding a laser beam focused on a dime 200 miles away, about the distance between Washington and New York.

Tanner removed the old guidance sensor and installed the new one while riding on space shuttle Discovery’s crane. “Ever so gently,” urged Harbaugh, floating nearby.

The astronauts noted that the telescope’s insulation had long, spiderlike cracks. The damage wasn’t there three years ago during the first repair mission.

Other Hubble parts to be installed by Harbaugh and Tanner in the open cargo bay: an electronic package for the sensor and a new data recorder.

During the first spacewalk the night before, Mark Lee and Steven Smith plugged two new science instruments into Hubble to expand its vision of the cosmos.

Lee and Smith turned in a by-the-book performance 370 miles above the Earth during the first of four spacewalks to modernize the $2 billion Hubble, which was launched in 1990.

The new instruments - a spectrograph with two-dimensional detectors and a near-infrared camera - should be 30 to 40 times more efficient and powerful than the old ones, and allow astronomers to peer back into the universe practically to the beginning of time.

During their 6-1/2-hour spacewalk, Lee and Smith used top-of-the-line power tools as well as old-fashioned muscle power to replace two 1970s-era spectrographs with modern gear.

“From an astronomical point of view, it is almost impossible to imagine the Hubble Space Telescope being any better than it’s been for the last three years, but you guys have made it so,” said Mission Control’s Jeffrey Hoffman.

The two new components passed initial electrical tests.

Lee and Smith will go back out tonight to install more Hubble parts.