English: Cargo Transportation Container (CTC)
ELC 3 will carry a Cargo Transportation Container (CTC) 2 that will contain 10 Remote Power Controller Modules (a large circuit breaker box) and 11 RPCM ORU Adapter Kits (OAKs) – basically brackets installed in the CTC to hold the ORUs. The empty RPCM OAK is used for a “fast swap” as the RPCM has a limited thermal clock, this allows the arm to remove the bad RPCM first, open the lid, place that in the blank spot, grab the replacement and install it in the shortest amount of time.
In addition, the CTC will contain an Arm Computer Unit (ACU) ORU. The ACU is the heart of the computer subsystem of Canadarm2 – the station’s Canadian-built robotic arm. The ACU is programmed to receive and process commands from the station crew or from ground control for moving Canadarm2. The ACU is being launched on STS-134 to add to the inventory of Canadian pre-positioned spares in orbit.
Orbital Sciences Corporation delivered five CTCs to NASA for use in conjunction with the resupply of the International Space Station. Each CTC measures about 4 feet by 3 feet by 3 feet. The CTC weighs in at 809 pounds. (680 pounds is the weight of the box only). Depending on internal configuration it can weigh up to a total of 1,300 pounds, for this mission it is coming in at a total of 1,050 pounds.
The CTCs can be opened and their contents retrieved either through robotic methods or by astronauts performing extravehicular operations.