U.S. space agency officials are discussing whether to abort the flight of the shuttle Columbia because of a problem with its cooling system. Columbia took off from Florida only Friday on a mission to overhaul the Hubble space telescope and extend its vision deeper into the cosmos.

Columbia and its crew of seven are closing in on the Hubble with a suite of equipment to rejuvenate it, including a camera to boost its visual sensitivity by 10 times.

But mission officials say one of two radiator systems that remove heat from the shuttle is underperforming. Freon coolant circulation is slightly reduced, apparently because of a blockage in the coolant line.

U.S. space agency flight rules require two cooling systems to work well for a shuttle mission to continue.

Shuttle program manager Ron Dittemore says flight engineers are analyzing the problem and will decide later Saturday whether to cancel the rest of the mission.

But he is optimistic it will proceed as planned. "Our initial looks at the system show it to be stable, even with the degradation," he said. "Based on what I heard today, I think we'll have the right analysis and the right reviews to allow us to continue to press on with the mission.

If the radiator issue does not abort the flight, Columbia's robot arm will remove the Hubble telescope from orbit on Sunday and place it in the shuttle's cargo bay. Two alternating pairs of astronauts will conduct five consecutive spacewalks beginning Monday to install the new, more powerful camera and other equipment to revive some aging systems.

The camera uses new technologies not available when the observatory was deployed from a shuttle 12 years ago. Astronomers hope it will allow them to see the universe's first stars and galaxies as their faint light arrives from the distant past, a time when the cosmos was only several hundred thousand years old. They also hope for the first direct observation of planets around other stars in our galaxy.

Other hardware to be installed aboard the Hubble includes new solar wings and a control box to distribute its power, a new gyroscope to point the observatory, and a small cooling system to restore an infrared camera that has been dormant since 1998.