Which module did the Bishop Airlock attach to on the ISS?

The Bishop Airlock attached to the Tranquility module on the International Space Station.

Known commercially as the Nanoracks Bishop Airlock, the four-cubic-meter module was launched aboard SpaceX’s CRS-21 cargo mission on 6 December 2020. Canadarm2 berthed it to Tranquility, also called Node 3, on 19 December 2020.

Bishop is different from the ISS’s crew airlocks. It is an external payload airlock used to deploy CubeSats, small satellites and other equipment. Rather than having its own conventional hatches, it can be grappled and moved by Canadarm2 between the station’s berthing port and the Mobile Base System. This makes it a flexible robotic worksite as well as a passage for payloads.

A common mix-up is confusing Tranquility with Unity or Harmony, the station’s other major nodes. Tranquility contains environmental-control equipment, exercise facilities, toilets and the Cupola, and its port side is where Bishop remains attached.