The first US module to be delivered to the International Space Station (ISS); also known as Node 1. The Unity Node is a cylinder 5.5 m long and 4.6 m in diameter. It is attached to the station's Zarya Control Module and acts as connecting passageway to living and work areas of the ISS. Unity was delivered by the space shuttle Endeavour on the STS-88 mission in December 1998.