Hubble is fitted with a new "eye"

Camera designed to clear telescope's blurred vision

Endeavour's spacewalking astronauts attacked the Hubble Space Telescope's infamous optical problems early this morning, equipping the $1.5 billion spacecraft with a large new camera designed to remove the blur from its photographic observations.

Astronauts Story Musgrave and Jeff Hoffman successfully installed the $100 million Wide Field Planetary Camera II aboard the observatory during a near seven-hour spacewalk that concluded about 4 a.m.

With three of the mission's planned spacewalks now completed, the list of accomplishments by Endeavour's Hubble repair crew is beginning to swell.

NASA can now declare the $700 million mission at least a "minimal" success under the criteria it established before the venture began -- the installation of the 620-pound wedge-shaped camera and the new gyroscopes inserted two days ago.

"Today, we took a giant leap," said NASA Hubble program scientist Ed Weiler, noting the camera is responsible for collecting half of the telescope's science harvest.

Tonight, spacewalkers Tom Akers and Kathy Thornton plan to install a second large corrective optics box in the aft end of the telescope. The $50 million Corrective Optics Space Telescope Axial Replacement, or COSTAR, should complete the task of erasing the distortion created by the observatory's flawed 94-inch-wide primary mirror.

Astronauts deployed the boxcar-sized space telescope in April 1990. Within weeks, astronomers discovered a focusing problem that was quickly traced to the flawed reflector.

The telescope is designed so that all of the light gathered by the big mirror is channeled to the observatory's four cameras and spectrographs.

"I hope we have a lot of eager astronomers ready to use this beautiful thing," Hoffman said as he and Musgrave carefully shoved the wide field camera into the observatory.

"I'm looking forward to seeing the pictures," said Hoffman, a one-time high energy astrophysicist.

The Hubble's mirror flaw has prevented astronomers from achieving several of of the observatory's most ambitious and intriguing science goals.

Among them are an accurate estimate of the age of the universe, spotting planets around neighboring stars, proving the existence of black holes and describing the faint, distant objects that comprised the earliest features of the cosmos.

The stakes of achieving those objectives, said the telescope's most fervent supporters, reach far beyond the arcane realm of scientific lecture and publication.

The discoveries could reveal whether the cosmos will expand forever or eventually collapse in a cataclysmic reversal of the Big Bang, the powerful explosion that many experts believe was the genesis of the universe.

The strategy to repair the optical flaw evolved quickly after the telescope's 1990 launch. But it could not be executed until Endeavour's astronauts rendezvoused with the 13-ton observatory Saturday and maneuvered it into the cargo bay with the shuttle's 50-foot long robot arm.

The strategy involved the installation of the wide-field camera and the COSTAR. Among the maze of optics in the new camera are four small precisely ground mirrors that intercept the un-focused light of the telescope's flawed reflector and refocus it.

Similarly, the COSTAR is equipped with 10-coin-sized mirrors that should properly refocus the light from the reflector for the observatory's faint object camera and a pair of spectrographs. The spectrographs enable astronomers to analyze the light from celestial objects, revealing chemical composition and other physical properties.

Musgrave and Hoffman also fastened two new magnetometers to the telescope, devices that serve as compasses for the observatory's pointing system.

However, they encountered a difficulty during the procedure which required them to fasten the new electronic compasses atop the old ones, which have experienced intermittent failures. The metal casings around one of the old ones crumbled.

During one of the remaining spacewalks, the astronauts will be asked to cover them to keep the loose material from contaminating the telescope's restored optics.

With a final, fifth spacewalk late Wednesday, astronauts hope to accomplish all seven major repair objectives that NASA spelled out as achieving full mission success as well as four other less critical tasks.

The final planned spacewalks will add an electronic drive motor for the solar arrays to ensure they will track the sun as the observatory orbits the Earth, new computer memory for the telescope and a backup power cable for one of the science instruments.

The astronauts plan to redeploy the telescope early Friday. The 11-day repair mission is scheduled to end with a landing Monday at the Kennedy Space Center in Florida.