Port Truss with Radiator Unit

Attached to the port side of the Center Truss segment is the Port Truss with Radiator Unit, or P1 Truss segment. This radiates excess heat from the Space Station, along with its mirror Starboard segment.  A refrigerating system using ammonia as its working fluid transports heat from the modules out to this point of the truss where it is radiated into space by the large panels.  Heat is generated inside the modules by the experiments and all the equipment working there.

The Port Truss with Radiator Unit also holds a UHF antenna and external camera sets; it also has tracks for the Mobile Transporter, a moveable base for the space station's robotic arm, are also found in this segment.  The aluminum truss is 45 feet (13.8 meters) long.
