Cape Canaveral, Fla. ? Despite its extra safety precautions, NASA needs real mission time to recapture its peak flying form after the shuttle fleet’s long grounding, former agency personnel said before this week’s launch date.

In interviews with The Associated Press, retired managers and astronauts expressed concerns about an aging fleet, the loss of experienced engineers, and 2 1/2 years without the pressures of a real flight. Much of the preparation has been done on simulators, where mistakes do not kill.

“Up to now, there has been absolutely no pressure,” said Bob Sieck, who was shuttle launch director for 52 flights.

For their part, the mission’s managers say NASA is in excellent shape to fly.

“The crew has been training nearly constantly,” countdown manager Pete Nickolenko said Monday as the clocks ticked down toward Wednesday’s launch of Discovery. “I think it’s safe to say their skills are quite sharp, and they are ready.”

The National Aeronautics and Space Administration hopes to mount a convincing comeback as it prepares for launch here at Kennedy Space Center. It will be the first shuttle flight since Columbia broke up in February 2003, killing all seven aboard.

In interviews, former agency personnel – including some who advised NASA on how to resume missions – agreed that the shuttle can probably fly safely. But they said it would take time for NASA to regain its flying groove.

The space shuttle Discovery sits on launch pad 39B at the Kennedy Space Center at Cape Canaveral, Fla. Wednesday's launch will be the first since the Columbia disaster in 2003.

Down time detrimental

The shuttle is the most advanced vehicle ever built, but it needs regular workouts like a car to keep it in good running shape, the experts said. With a long rest, some of the shuttle’s 2.5 million parts can become dry, dirty or stiff.

“There’s an old saying that to keep vehicles flying, you have to keep them in the air,” said Jim Wetherbee, an astronaut who served on an independent technical unit formed by NASA after Columbia’s loss. Wetherbee became an astronaut in the months before the 1986 Challenger disaster and flew six shuttle missions afterward.

Also, Discovery is the oldest shuttle in the fleet, at age 21.

“The hardware doesn’t get mature like people. It just gets older,” said Sieck, who served on a NASA return-to-flight advisory panel. “There’s some hardware that you just can’t subject to realistic tests.”

Down time can also erode the flying form of the shuttle’s 18,000 human parts – flying crew, managers, technicians and support personnel, NASA personnel acknowledged.

Even though the grounding provided extra practice time, it deprived team members of the chance to settle into a rhythm of flight. There was the potential for getting “a little rusty,” Discovery crew member Andrew Thomas said earlier this year.

Before the Columbia disaster, NASA had become accustomed to getting shuttles ready for launch. “The crew down at the Cape was good at it and was doing it regularly. They had good skills, honed skills. We haven’t done that in 2 1/2 years,” Thomas said. However, he predicted a safe flight.

Intensive practice

STS-114 Japanese Mission Specialist Soichi Noguchi, of Yokahama, Kanagawa, Japan, waves to members of the media before flying with some other crew members in the Shuttle Training Aircraft before sunrise Monday at Kennedy Space Center's Shuttle Landing Facility in Cape Canaveral, Fla.

Leaders of this mission say they have used the down time to inspect equipment and practice more intensively.

“It’s very understandable that people would worry about us having lost the edge after not flying for 2 1/2 years, but we worried about that right after the accident,” said flight director Paul Hill.

Hill said managers were concerned last fall that mission operators might be losing their best flight habits and might mishandle the transfer of information from one work shift to another. But he said NASA ran multiday training simulations to sharpen skills. He said NASA’s simulations “feel absolutely real to me – the same adrenaline rush.”

Some astronauts see it a bit differently. “Simulations are never the real thing,” said former astronaut Kathryn Thornton, who also advised NASA on its return to flight. “I think it’s human nature to understand if I mess up today, it’s not fatal.”

She also said that personnel turnover during the flight hiatus means that “people coming on have not witnessed or worked a flight.”

Some former managers said the agency lost too many knowledgeable specialists during the grounding.

“They’re in such a hole now with lack of experience,” said Wetherbee, a one-time deputy director of Johnson Space Center who left NASA in January.

NASA managers disagreed.

“There have been some personnel changes in the past 2 1/2 years,” Nickolenko acknowledged, “but we have verified that everyone supporting the launch is certified, trained and ready to pick up.”

NASA does have one important advantage this time: The agency can draw on previous experience in resurrecting shuttle flights. It overcame an even longer break of two years and eight months after the 1986 Challenger explosion.