Payload Changeout Room Supports Last Shuttle Cargo

After 29 years of supporting space shuttle missions, the payload changeout room, or PCR, at NASA Kennedy Space Center's Launch Pad 39A has been used for the last time to install cargo into a shuttle's payload bay.

The canister containing the Raffaello multi-purpose logistics module, or MPLM, was hoisted into the PCR on June 17 and the MPLM transferred into space shuttle Atlantis on June 20.

As part of the rotating service structure, or RSS, the PCR is an enclosed, environmentally controlled area that supports payload delivery and servicing at the pad and mates to the shuttle's cargo bay for vertical payload installation. Clean-air purges help ensure that payloads being transferred from a payload canister into the PCR are not exposed to the open air.

Although there was a PCR on both Launch Complex 39 pads, the first 24 shuttle missions lifted off from pad A while pad B was being transitioned from an Apollo to a shuttle pad.

The payload for the STS-4 mission was the first shuttle cargo to be installed from a PCR, arriving at the pad May 22, 1982, a few days before shuttle Columbia's rollout on May 26.

Greg Henry, United Space Alliance, or USA, deputy director of solid rocket booster manufacturing operations, was the pad's first payload move director and supported the first payload transfer from the PCR, which was for the STS-4 mission.

"STS-4 carried a primary Department of Defense payload, DoD 82-1," Henry recalled, "which was a classified instrumentation pallet."

The STS-4 cargo manifest also included the first university student experiments, known as Get Away Specials, and the first commercial experiment, which utilized the Continuous Flow Electrophoresis System, or CFES.

"At the pad, the payload canister is lifted and mated to the PCR," Henry explained. "The PCR and canister doors then are opened and the payload is transferred to the payload ground-handling mechanism, or PGHM, a movable payload handling mechanism that is supported by overhead rails in the PCR."

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