Discovery's launch pad will be cleared of all but essential personnel at Kennedy Space Center today as NASA and United Space Alliance rig up and test small pyrotechnic devices that will play critical roles in the shuttle's ascent into orbit.
Discovery and seven astronauts remain scheduled to blast off at 7:32 a.m. Feb. 12 on a mission to deliver the fourth and final set of American solar wings to the International Space Station.
An executive-level flight readiness review will be held Tuesday. The STS-119 astronaut crew is scheduled to arrive at KSC at 12:30 a.m. Sunday and a three-countdown to launch will begin at 6 a.m. Monday.
Call-to-stations for final ordnance operations at launch pad 39A will be at 2 p.m. today. NASA and contractor engineers and technicians will rig up small explosive devices that will be used to separate Discovery from its mobile launcher platform, solid rocket boosters and external tank in flight.
Three refurbished gaseous hydrogen flow control valves were installed on the orbiter over the weekend. One of three GH2 valves on sistership Endeavour failed to operate properly during a launch last November, so NASA program managers ordered up the removal and replacement of the valves on Discovery.
The refurbished valves were installed Saturday and then passed electrical checkout. Leak tests are to be performed on the valves today.
Similar to pop-up lawn sprinklers, the poppet valves are critical to keeping pressure within the external tank's liquid hydrogen reservoir at proper levels as the shuttle is thundering toward orbit and propellant in the tank is fed into the orbiter's three main engines.
ABOUT THE IMAGES: Refresh this page to see the latest still images from live video feeds in the Launch Complex 39 area at Kennedy Space Center. The view on the left is from a camera atop the Vehicle Assembly Building. The image on the right is from a camera at launch pad 39A. Click to enlarge either photo. You can see Discovery's external tank poking up over the Rotating Service Structure in the image on the right.
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