Zarya, also known as the Functional Cargo Block or FGB, is the first module of the International Space Station to have been launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly. With the launch and assembly in orbit of other modules with more specialized functionality, as of August 2021 it is primarily used for storage, both inside the pressurized section and in the externally mounted fuel tanks. The Zarya is a descendant of the TKS spacecraft designed for the Soviet Salyut program. The name Zarya ("Dawn") was given to the FGB because it signified the dawn of a new era of international cooperation in space. Although it was built by a Russian company, it is owned by the United States.

A Pressurized Mating Adapter (PMA) is a spacecraft adapter used on the International Space Station (ISS) to convert a Common Berthing Mechanism (CBM) interface to an APAS-95 docking port. Three PMAs are connected to the US Orbital Segment of ISS. PMA-1 and PMA-2 were launched with the Unity module in 1998 aboard STS-88; PMA-3 was launched in 2000 aboard STS-92. PMA-1 permanently connects the Unity and Zarya modules. IDA adapters have been installed on PMA-2 and PMA-3 which convert them to IDSS docking ports.