Power Unit Put in Shuttle; Telescope Batteries Charged

KENNEDY SPACE CENTER, Fla. —  NASA on Sunday installed a new power unit in the space shuttle Discovery and began recharging the batteries of the Hubble Space Telescope.

Discovery is scheduled to lift off with the $1.5-billion telescope on April 25.

“Right now everything seems to be in the bag for a week from Wednesday,” said George Diller, a spokesman for the National Aeronautics and Space Administration.

Technicians on Saturday took out a faulty auxiliary power unit that forced a scrub of Discovery’s launching last Tuesday. A new unit was then installed, the first time the procedure has been performed at the launching pad.

Discovery’s payload bay doors were opened on Saturday and Hubble’s six nickel-hydrogen batteries were removed for a 130-hour recharging that began Sunday.

NASA decided to take the batteries to the laboratory because they can be recharged at a cooler temperature than at the launch pad, and thus retain more power.

The shuttle’s three auxiliary power units pressurize the hydraulic system used to move wing and rudder surfaces and in the ship’s braking and steering system.

Technicians closed Discovery’s payload bay doors Sunday after the batteries were removed.

The chamber will remain sealed to reduce the risk of getting dust on the telescope’s mirror until the batteries are reinstalled Saturday.

Once in orbit, the telescope named for American astronomer Edwin P. Hubble will enable astronomers to study stars and galaxies so distant that their light has been traveling toward Earth for 14 billion years.