CAPE CANAVERAL, Fla. -- NASA officials will decide on July 31 if or how they will repair cracks found inside the propulsion system of the nation's space shuttle fleet and when the next shuttle will fly, the program's director said Friday.
"We're very optimistic we're going to get this thing wrapped up soon," said Ron Dittemore, NASA's top shuttle program manager.
At a telecon briefing for the media, Dittemore summarized the decisions made during the past week. Dittemore said the earliest a shuttle might fly is Sept. 26 and that the number of repair options has narrowed from six to three.
It's still possible that engineers will conclude it's safe to fly with the problem first discovered on Atlantis in June, but it's more likely that a repair plan will be approved and then executed during the coming weeks, Dittemore said.
The tiny cracks were found on the surface of metal liners that are inside liquid hydrogen pipes located within each shuttle's rear engine compartment. The flaws are not within the Rocketdyne main engines themselves.
The liners help direct the flow of propellant through the plumbing and past accordion-shaped bellows that give the plumbing needed flexibility for when the supercold fuel causes the pipes to shrink.
The concern is that if the cracks were to grow during a launch and a piece of metal were to break free, the debris would be sent into the engine where it could cause a potentially catastrophic shutdown.
The three options include welding new material over the crack, drilling a tiny hole in front of the crack so it won't grow or removing the crack altogether and creating another slot in the device.
"All three of those are being actively and aggressively reviewed over the coming week," Dittemore said.
The plan is to try to select the one best option on July 24. Analysis will continue until July 29 on whether or not it is safe to fly as is. On July 31 a decision will be made and a launch schedule for the rest of the year laid out.
"Hopefully at that point we'll have a good idea of what we plan to do," Dittemore said.
For now the tentative plan shows either Columbia or Atlantis launching no sooner than Sept. 26, with Endeavour targeted to fly no earlier than Nov. 2.
Columbia's next mission is a 16-day science research flight in low Earth orbit, while both Atlantis and Endeavour are to fly sorties to the International Space Station (ISS).
Complicating the picture of what will fly and when is the fact there are three periods of time between now and the end of the year when a shuttle mission to the ISS cannot be staged.
The periods fall around Oct. 22 because of a Russian Soyuz taxi flight to the station, then Nov. 19 because of the Leonid meteor shower and from about Dec. 7-9 through the rest of the month because of an unacceptable sun angle for a shuttle docked at the orbiting complex.
"So we're trying to fit in these flights in the spaces available," Dittemore said. "We're trying to work the repair options as aggressively as we can. Then we're going to look out of the foxhole and see which piece of the runway is available to us."
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