Quest airlock

The Quest Joint Airlock, previously known as the Joint Airlock Module, is the primary airlock for the International Space Station. Quest was designed to host spacewalks with both Extravehicular Mobility Unit (EMU) spacesuits and Orlan space suits. The airlock was launched on STS-104 on July 14, 2001. Before Quest was attached, Russian spacewalks using Orlan suits could only be done from the Zvezda service module, and American spacewalks using EMUs were only possible when a Space Shuttle was docked. The arrival of Pirs docking compartment on September 16, 2001 provided another airlock from which Orlan spacewalks can be conducted.

The Quest Airlock consists of two segments, the "Equipment lock" that stores spacesuits and equipment, and the "Crew Lock" from which astronauts can exit into space. It was derived from the Space Shuttle airlock, although it was significantly modified to waste less atmospheric gas when used. It was attached to the starboard CBM of the Unity during STS-104. It has mountings for four high-pressure gas tanks, two containing oxygen and two containing nitrogen, which provides for atmospheric replenishment to the American side of the space station, most specifically for the gas lost after a hatch opening during a space walk.

Quest was necessary because American suits will not fit through a Russian airlock hatch and have different components, fittings, and connections. The airlock is designed to contain equipment that can work with both types of spacesuits, however, it is currently only able to host American spacewalks because the equipment necessary to work with Russian space suits has not been launched yet, which required the Expedition 9 crew to take a circuitous route to a worksite because of problems with the American space suits.

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