( CNN ) -- Launch of the space shuttle Discovery has been delayed at least a week , NASA has announced . Discovery moves atop the crawler transporter in Cape Canaveral , Florida , on January 14 . The shuttle will now lift off no earlier than February 19 because of concern over a valve in the main engine . A decision on the launch date will be made February 12 , after more analysis and testing of the part . NASA said Tuesday night : `` The valve is one of three that channels gaseous hydrogen from the engines to the external fuel tank . One of these valves in shuttle Endeavour was found to be damaged after its mission in November . As a precaution , Discovery 's valves were removed , inspected and reinstalled . '' This will be the shuttle 's 28th mission to the international space station . The mission will deliver the final set of solar arrays needed to complete the station 's complement of electricity-generating solar panels . They will help support the station 's expanded crew of six in 2009 . `` More crew means that we 'll have to run more life support equipment , more crew support equipment -- toilet facilities , water processing equipment and all of that stuff , '' Kwatsi Alibaruho , the lead space station flight director for the mission , said on NASA 's Web site . `` We 'll have to run more of all of that , so we need additional power . '' The expanded capacity will mean more hands to perform science experiments . The mission also will include four spacewalks .
Discovery will lift off no earlier than February 19 , NASA says . Space agency concerned about a valve in the main engine . This will be the shuttle 's 28th mission to the international space station . The mission will deliver the final set of solar arrays for the station .