Copyright © 2022, Columbia University Press. The Columbia Electronic Encyclopedia, 6th ed.
Too sudden a change of pressure may cause decompression sickness. Great care must be exercised in passing workmen through an air lock, so that the change of atmospheric pressure takes place gradually. The reverse of this procedure takes place on leaving the working chamber. After the outer door is closed, compressed air is admitted to raise pressure in the air lock to the level of the pressure in the working chamber, and the inner door can be opened. When the outer door of the air lock is opened, men or material may be admitted into the compartment. It is also used at the head of tunnel excavations underwater. By its means access can be gained to the working chamber without loss of pressure. An airlock was the point of entry to a space station or starship which allowed ingress and egress to empty space or another vessel which had docked at the. A more common example is the air lock between the outer atmosphere and the working chamber of a caisson. Space capsules have air locks to enable astronauts to move between the pressurized cabin and the near vacuum of space. As an astronaut enters the crew lock, it is closed to prevent decompression in the equipment lock.Ĭrew lock – Once an astronaut has put on their EMU (spacesuit), they exit the equipment lock into the crew lock.Įxtravehicle hatch – Only when the crew lock has been totally depressurised does this hatch open, allowing the astronaut to venture into space.Air lock, compartment connecting two different environments, usually at different pressures, that enables personnel to transfer from one environment to the other. Intravehicle hatch – This provides a sealed barrier between the equipment and crew locks. Gas tanks – Nitrogen and oxygen tanks replenish gas lost during hatch opening for any spacewalk. Power supply assembly – The entire airlock is powered from a central power supply assembly located in the equipment lock. It provides a kitting-up area and a chance for astronauts to acclimatize to the EMU. Airlock in a space shuttleĮquipment lock – The equipment lock stores the airlock’s power supply and the spacesuits. Nitrogen and oxygen are supplied and replenished via four externally mounted gas tanks, which ensures that the lock does not need to draw upon the host ISS’s own gas supplies.
This ensures that astronauts avoid decompression sickness in the low pressure experienced within the pure-oxygen atmosphere of the spacesuit. Importantly, before any spacewalk is attempted, astronauts must ‘camp out’ within the equipment chamber of the airlock in a reduced-nitrogen environment in order to purge nitrogen from their blood stream. When the crew lock is fully depressurised, an external hatch becomes operational, providing an exit for the astronaut to enter space. This provides a sealed environment for the suited astronaut and allows depressurisation to proceed. Once inside this section, the interior hatch between the equipment lock and the crew lock is shut. It also supplies a staging area where astronauts can prepare for a spacewalk -namely get in and out of their spacesuits.Ĭonnected to the equipment compartment is the crew lock, a smaller cylindrical chamber into which astronauts enter prior to any spacewalk. The former connects to the ISS and supplies an auxiliary holding bay for any essential equipment, such as Extravehicular Mobility Units (EMUs – or spacesuits), as well as other key gear. The Quest airlock of the ISS is split into two main sections: an equipment chamber and crew lock chamber.
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