Space Station User's Guide

The Joint Airlock (also known as "Quest") is provided by the U.S. and provides the capability for ISS-based Extravehicular Activity (EVA) using either a U.S. Extravehicular Mobility Unit (EMU) or Russian Orlon EVA suits. Before the launch of this airlock, EVAs were performed from either the U.S. Space Shuttle (while docked) or from the Transfer Chamber on the Service Module. Due to a variety of system and design differences, only U.S. space suits could be used from the Shuttle and only Russian suits could be used from the Service Module. The Joint Airlock alleviates this short term problem by allowing either (or both) spacesuit systems to be used.

The Joint Airlock was launched on ISS-7A / STS-104 in July 2001 and was attached to the right hand docking port of Node 1. The Joint Airlock is 20 ft. long, 13 ft. in diameter, and weighs 6.5 tons. The Joint Airlock was built by Boeing at Marshall Space Flight Center. The Joint Airlock will be launched with the High Pressure Gas Assembly. The High Pressure Gas Assembly was mounted on the external surface of the Joint Airlock and will support EVAs operations with breathing gases and augments the Service Module's gas resupply system.

The Joint Airlock has two main components: a crew airlock from which astronauts and cosmonauts exit the ISS and an equipment airlock designed for storing EVA gear and for so-called overnight "campouts" wherein Nitrogen is purged from astronaut's bodies overnight as pressure is dropped in preparation for spacewalks the following day. This alleviates the bends as the astronauts are repressurized after their EVA.

The crew airlock was derived from the Space Shuttle's external airlock. It is equipped with lighting, external handrails, and an Umbilical Interface Assembly (UIA). The UIA is located on one wall of the crew airlock and provides a water supply line, a wastewater return line, and an oxygen supply line. The UIA also provides communication gear and spacesuit power interfaces and can support two spacesuits simultaneously. This can be either two American EMU spacesuits, two Russian ORLAN spacesuits, or one of each design.

Before the crew airlock's hatch is opened to space, the crew airlock is depressurized to 3 pounds per square inch (psi) and then down to zero psi. The atmosphere inside spacesuits is pure oxygen at 4.3 psi. Current spacesuit design requires these lower pressures in order for the suits to be flexible enough to work in. At higher pressures the suits stiffen and are hard to work in for prolonged periods of time. [See EVA for a more detailed discussion]

The Equipment Airlock has stations that assist astronauts and cosmonauts as they get into and out of their spacesuits and to perform periodic maintenance. The Equipment airlock has two racks, one for avionics, the other for cabin air. Batteries, power tools and other supplies are also stored in the Equipment Airlock.

EVA Operations Documents

ISS EVA PLAN 3 March 1999 (Based on Feb. 22, 1999 Assembly Sequence), NASA JSC [Acrobat 100K]

This document presents a description of EVAs for all ISS assembly, resupply, and utilization missions in tabular format.

CTSD Generic EVA Operations Operations Plan, DOC. NO.: CTSD-SH-1017 DATE: April 10, 2000, JSC 33440/D, Crew and Thermal Systems Division, NASA JSC [Acrobat 40K]

"This plan identifies the procedures that will be followed by CTSD and contractor personnel to provide real-time support for Space Shuttle flights that involve scheduled, unscheduled or contingency EVA activities. Interfaces with other supporting contractors or organizations are given. Details involving mission support provided by these organizations must be obtained from the mission support plans, which they generate and publish."

Service Module ORLAN Operations, 25 September 2000, NASA JSC [Acrobat]

This 72 page document contains the procedures required to maintain and operate the Russian ORLAN EVA suit. This documents contains numerous photographs and diagrams describing the ORLAN suit's operation and a series of checklists and procedures used to perform systems checks, trouble shoot, and routine maintenance.

EVA Reference 3A/STS-92 [Acrobat 6.4 MB]

This document contains detailed drawings of the EVA tools, external ISS structures, and other items associated with ISS assembly EVA activity required for ISS mission 3A.

EVA Reference 4A/STS-97 [Acrobat 688K]

This document contains detailed drawings of the EVA tools, external ISS structures, and other items associated with ISS assembly EVA activity required for ISS mission 4A.

EVA Reference 5A/STS-98 [Acrobat 6.4 MB]

This document contains detailed drawings of the EVA tools, external ISS structures, and other items associated with ISS assembly EVA activity required for ISS mission 5A.

ISS EVA Checklist ISS-7A, Mission Operations Directorate, Operations Division, JSC 48538, 27 April 2001, [Acrobat 3.3 MB]

This 411 page document contains detailed operations procedures and checklists for the EVAs conducted on mission ISS-7A. It also contains drawings of the EVA tools, external ISS structures, and other items associated with ISS assembly EVA activity required for ISS mission 7A.