Image: Prepping Endeavour

(PhysOrg.com) -- At NASA Kennedy Space Center's Launch Pad 39A, a technician makes his way across a platform in space shuttle Endeavour's aft section as work began to remove and replace the aft load control assembly-2.

Located in the orbiter's aft avionics bay 5, the assembly is believed to have caused heaters on a fuel line for Endeavour's auxiliary power unit-1 to fail April 29, 2011, during the first launch attempt for the STS-134 mission. STS-134 will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station.

The mission also will be the final spaceflight for Endeavour.