Associated Press Astronaut John Grunsfeld, left, is seen at one end of stowed solar panels in the cargo bay of the Space Shuttle Columbia while astronaut Richard Linnehan uses the Remote Manipulator System's robotic arm to move around during a spacewalk Monday. Grunsfeld and Linnehan spent seven hours outside installing a new solar wing on the Hubble Space Telescope.

CAPE CANAVERAL, Fla. - Spacewalking astronauts widened the Hubble Space Telescope's eyes to the universe yesterday by installing the most advanced optical camera ever launched for studying the heavens.

James Newman and Michael Massimino made room for the $76 million Advanced Camera for Surveys by pulling out the last of the 12-year-old Hubble's original scientific instruments.

The new camera will allow Hubble to peer deeper into space, all the way back to some of the early phases of the universe more than 12 billion years ago, when galaxies began to form.

"You guys just paved the way for a lot of Ph.D.s in the years to come," said astronaut Richard Linnehan, who monitored the 7 1/2-hour spacewalk from inside space shuttle Columbia.

It was the fourth spacewalk in as many days for Columbia's crew and the longest one yet. One final excursion was planned for Friday; astronauts will attempt to resuscitate an infrared camera that has not worked for three years.

Newman slid the new camera into Hubble on guide rails as Massimino called out the clearances for the 875-pound device, about the size of a phone booth but considerably more fragile. Within minutes, the camera was all the way in and latched down tight.

It passed its initial tests. Flight controllers in Maryland will spend the next month or two fine-tuning the instrument. Astronomers hope to begin using it by early May.

The instrument, which took five years to develop and build, is actually three cameras in one. Altogether, it will provide twice the field of view, twice the clarity and five times the sensitivity of Hubble's current workhorse, the 8-year-old Wide Field and Planetary Camera.