What was the first module of the ISS?

The first module of the International Space Station was Zarya, also known as the Functional Cargo Block or FGB. It launched on November 20, 1998, aboard a Russian Proton-K rocket from Baikonur Cosmodrome.

Zarya was built in Russia with NASA funding and provided early power, propulsion, attitude control, and storage for the station. Its launch marked the physical beginning of the ISS in orbit, although the station’s assembly required many later modules and missions.

The U.S.-built Unity module arrived next, on Space Shuttle Endeavour during STS-88 in December 1998. Unity connected to Zarya and became the first major node of the station’s U.S. Orbital Segment. Zvezda, another common answer, arrived in July 2000 and supplied living quarters and important life-support functions.

As the ISS expanded, Zarya’s original propulsion and power duties became less central. It remains attached to the station and is used mainly for storage and propellant-related functions, making it both the station’s starting point and a continuing part of its structure.