Shuttle Launch Advanced a Day

KENNEDY SPACE CENTER, Fla. — Engineers successfully test fired a new hydraulic power unit aboard the shuttle Discovery on Wednesday, prompting NASA to move up the delayed launch of the Hubble Space Telescope from next Wednesday to Tuesday.

“Everyone believes we’re now ready to fly and all of us are looking forward to the data the Hubble Space Telescope will produce as it begins its exploration of the universe,” shuttle program chief Robert Crippen said in a statement.

Under the new plan, the launch is to be at 8:31 a.m. EDT Tuesday, 14 days after the ship was grounded by a malfunction in its power steering system.

Discovery and its $1.5-billion payload, the most expensive satellite ever built, were grounded April 10 just four minutes before liftoff when one of the shuttle’s three auxiliary power units malfunctioned. The APUs provide hydraulic power to the shuttle’s engines and wing flaps for steering during the climb to space.

A replacement APU was installed in Discovery’s cramped engine room over the weekend.

With Discovery declared shipshape for launch, engineers pressed on with a 5 1/2-day procedure to recharge the Hubble Space Telescope’s batteries for a second launch attempt. The batteries, removed from the telescope Sunday, will be back at full power Friday.

Completing the APU replacement ahead of schedule was a major achievement for NASA.