Space Shuttle mission STS-88 delivered the Unity module to orbit.
Endeavour launched STS-88 on December 4, 1998, carrying Unity, the first U.S.-built component of the International Space Station, along with two Pressurized Mating Adapters. The mission was designated ISS assembly flight 2A and became the first shuttle mission dedicated to assembling the station.
During the flight, the crew used Endeavour’s robotic arm to capture the Russian-built Zarya control module, which had launched on a Proton rocket two weeks earlier. They then connected Zarya to Unity and conducted three spacewalks to attach cables, antennas, handrails, and other equipment.
STS-92 is a common distractor because it later delivered the Z1 truss and Pressurized Mating Adapter 3. STS-96 also visited the station, but it delivered logistics and equipment rather than Unity. STS-88 therefore marks the mission that physically joined the first two major ISS elements in orbit.