The decision to press ahead with the launch of space shuttle Discovery next month without fixing the foam problem came down to whether six months would be too long to wait for repairs, NASA's chief engineer said Wednesday.

Chief Engineer Christopher Scolese said that during a meeting of top NASA officials over the weekend, he wanted to fix the problem first and launch later. He estimated the job would take six months, which he called "a reasonably short amount of time."

But those in favor of a July 1 liftoff worried that a six-month delay would not leave enough time to launch all the shuttles necessary to finish the space station by 2010, Scolese said Wednesday in a teleconference with reporters.

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Ultimately, NASA Administrator Mike Griffin decided to go ahead with a launch.

The debate concerned the risks of foam flying off the shuttle's massive external fuel tank and potentially punching a hole in the spacecraft's protective skin. Falling foam blew a hole in Columbia in 2003, causing the shuttle to disintegrate during re-entry and killing seven astronauts.

On Discovery's flight last year, foam also struck the shuttle and caused minor heat-protection damage that still worries engineers.

• Click here to read why NASA's top safety official thinks Discovery shouldn't be allowed to fly.

Scolese said the launch decision came down to how realistic the repair was, saying: "I believe we should repair it and we have a path to repair it."

The head of spaceflight for NASA said the repair plans were not ready and could take a long time, although he used the same six-month estimate.

• Click here to read about a female astronaut being tapped to command the Discovery mission.

Also, launching a shuttle without fixing the foam problem — and then photographing what goes on in flight — will help engineers better design ways to fix the foam, said Bill Gerstenmeier, NASA's associate administrator for space operations.

"There's a reason to go fly; it helps the engineering community" Gerstenmeier said. "We're taking some risk; and the risk we're taking is to give us some data."

"The risk, although not overall desirable, is still tolerable," he said.

Chief Safety Officer Bryan O'Connor also opposed the launch decision but characterized the risk as "just barely into the unacceptable risk area."

Even though they voted not to fly, O'Connor and Scolese said if the shuttle is damaged, the crew could take refuge in the space station. That option made them more comfortable with the decision to launch.

"We have plenty of capability" for rescue, O'Connor said.