The primary purpose of the flight is to deliver and install the ISS Airlock. The Joint Airlock is a pressurized flight element consisting of two cylindrical chambers attached end-to-end by a connecting bulkhead and hatch. Once installed and activated, the ISS airlock becomes the primary path for International Space Station space walk entry and departure for U.S. spacesuits, which are known as Extravehicular Mobility Units, or EMUs. In addition, the Joint Airlock is designed to support the Russian Orlan spacesuit for EVA activity. The Joint Airlock is 20ft long, 13ft in diameter and weighs 6.5 tons. It was built at the Marshall Space Flight Center (MSFC) by the Space Station Prime Contractor Boeing. The ISS-airlock has two main components: a crew airlock and an equipment airlock for storing EVA gear and EVA preflight preps. STS-104 also carries a spacelab pallet with four High Pressure Gas Assembly containers that will be attached to the exterior of the airlock. 

Launch Date: July 12, 2001 5:04 a.m. EDT Launch Vehicle: Atlantis Crew: Steven W. Lindsey, Mission Commander Charles O. Hobaugh, Pilot Michael L. Gernhardt, Mission Specialist James F. Reilly, Mission Specialist Janet L. Kavandi, Mission Specialist