Inside the payload changeout room or PCR at NASA's Kennedy Space Center Launch Pad 39A are open.

Inside the payload changeout room, or PCR, at NASA's Kennedy Space Center Launch Pad 39A, the doors of the payload canister are open. Inside are four carriers holding various equipment for the STS-125 mission aboard space shuttle Atlantis to service NASA’s Hubble Space Telescope. The PCR is the enclosed, environmentally controlled portion of the rotating service structure that supports cargo delivery to the pad and subsequent vertical installation into the shuttle’s payload bay. Launch of Atlantis is targeted for Oct. 10. Photo credit: NASA/Jack Pfaller