Zarya - Design

Design

Zarya weighs 19,300 kilograms (43,000 lb), is 12.55 meters (41.2 ft) long and 4.1 meters (13 ft) wide at its widest point.

The module has three docking ports: one axially on the front end at the docking sphere, one on the earth-facing side (nadir) of the docking sphere and one axially on the aft end. Attached to the forward port is the Pressurized Mating Adapter PMA-1, which in turn is connected to the Unity Module – this is the connection between the Russian Orbital Segment (ROS) and the US Orbital Segment (USOS). Attached to the aft port is the Zvezda Service Module. The lower port (nadir) was initially used by visiting Soyuz spacecraft and Progress spacecraft to dock to the ROS; The Rassvet module is now docked semipermanently on the nadir port of Zarya, and visiting spacecraft use Rassvet's nadir docking port instead.

Zarya has two solar arrays measuring 10.67 by 3.35 meters (35.0 by 11.0 ft) and six nickel-cadmium batteries that can provide an average of 3 kilowatts of power – the solar arrays have been however retracted so the P1/S1 radiators of the Integrated Truss Structure could deploy. Zarya has 16 external fuel tanks that can hold over 5.4 metric tons of propellant. Zarya also has 24 large steering jets, 12 small steering jets, and two large engines that were used for reboost and major orbital changes; with the docking of Zvezda these are now permanently disabled. Since they are no longer needed for Zarya's engines, Zarya's propellant tanks are now used to store additional fuel for Zvezda.