Space shuttle Endeavour's final launch has been scrubbed.
The shuttle was scheduled to launch Friday at 12:47 p.m. Pacific Time. The Associated Press reported the cancelation was due to technical problems.
Launch commentator George Diller told the AP the next try likely would be Monday at the earliest. Officials huddled in launch control, discussing a path forward.
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"They are trying to assess what all is going to be required and how much time we're going to need," Diller said. "We still don't know what's wrong or why these multiple heater failures occurred."
This will be Endeavour's final mission before it comes to Southern California. The shuttle will spend its retirement years at the California Science Center. It's expected to arrive in a new area at the existing Science Center building next year.
The Science Center is preparing online with an #Endeavour Twitter feed.
About a dozen facilities were in the running to land one of the retired shuttles. The shuttle winners were announced April 12.
As for Friday's launch, Endeavour will be commanded Mark Kelly, husband of Rep. Gabrielle Giffords.
It's the shuttle's 25th flight. The six-person crew will remain in space for about 14 days as they bring spare parts to the space station.
After Endeavour lands, it will be prepared as a museum piece. Its flight on the back of a Boeing 747 to Southern California will mark a homecoming -- Endeavour was built at Rockwell International Space Systems facility in Palmdale.
Atlantis will make the final shuttle flight to the space station this summer.
Shuttle Atlantis will stay in Florida. Discovery will be at the Smithsonian's Air and Space Museum.