From the Orlando Sentinel..... NASA officials on Friday again postponed the final flight of the space shuttle Endeavour -- this time until May 16 at the earliest. The reason: a nagging electrical problem that engineers worry could lead to a major malfunction when the orbiter tries to land after its last trip to the International Space Station. While engineers have fixed the problem, by replacing an electrical switch box, they're still trying to figure out what caused the failure. Technicians discovered the glitch last week just hours before Endeavour's scheduled April 29 takeoff. President Barack Obama and his family had flown into Kennedy Space Center to watch the launch, along with wounded U.S. Rep. Gabrielle Giffords of Arizona, whose husband, Mark Kelly, is Endeavour's commander. On Friday, NASA also extended the length of Endeavour's mission to the space station from 14 to 16 days." A NASA official said that neither the delay in Endeavour's launch nor the extension of the mission would – at least for the moment -- affect the agency's plans for the last shuttle flight, the launch of Atlantis now tentatively set for June 28. "Managers will evaluate any possible affects Endeavour's launch delay may have on Atlantis. For now, the 135 launch still is targeted for June 28," said NASA spokeswoman Candrea Thomas. Since Endeavour's launch was scrubbed just hours before liftoff last week, NASA had postponed setting a new date as engineers worked to fix the problem in an electrical switch box that connects several systems. Among them: heaters that prevent fuel lines from freezing while the orbiter is in space. These lines help power the hydraulics system that runs essential functions, such as the orbiter's landing gear. A failure in the heater circuit is what initially tipped NASA to the problem. That this mission is even close to launching, however, is somewhat of a minor miracle. After the 2003 Columbia accident, NASA leaders decided to reduce the remaining scheduled flights of the aging orbiter. One of the launches they cut was this one -- a transport mission that is scheduled to haul a $1.5-billion physics experiment called the Alpha Magnetic Spectrometer to the International Space Station. Only after congressional intervention, and Obama's consent, did NASA agree to add this extra flight.