Teams on NASA Kennedy Space Center's Launch Pad 39A have disconnected ordinance this evening on space shuttle Endeavour. Once the launch pad is reopened, technicians will return to Endeavour's aft compartment to do some minor work on a cold plate for the power distribution box called a Load Control Assembly 2 (LCA-2). The cold plate is an aluminum plate attached to the box that uses a closed-loop Freon system to cool electronics inside the box.
Following that work, a new LCA-2 will be installed into Endeavour by tomorrow morning. Early this morning, technicians removed the faulty LCA-2 and then transported it to the NASA Shuttle Logistic Depot in Cape Canaveral, Fla., where other technicians began forensic engineering testing to determine what caused the power box to fail. The LCA-2 distributes power to nine various shuttle systems, including heaters on a fuel line for Endeavour's auxiliary power unit-1 (APU-1). The heaters did not work on April 29, prompting the launch team to scrub Endeavour's first launch attempt for its STS-134 mission to the International Space Station.
After the new LCA-2 is installed, technicians will begin testing it and its power distribution system. Managers will continue to evaluate the repair process and make any additional adjustments before scheduling Endeavour's next launch attempt, which remains no earlier than May 10.
Related to the ongoing Endeavour repair work, to move away from any potential launch date next week, managers have decided to retarget shuttle Atlantis' move from its hangar, Orbiter Processing Facility-1, to Kennedy's Vehicle Assembly Building. Atlantis' new "rollover" date now is May 16. The new target date to begin its move to Launch Pad 39A is May 23, depending on when Endeavour actually launches. Atlantis' launch on the final Space Shuttle Program mission, STS-135, remains targeted for June 28.