The Space Shuttle Atlantis arcs into the black sky over the Atlantic Ocean casting a fiery glow on its way. Atlantis STS-104 launched from Kennedy Launch Pad 39B at 5:03:59 am EDT, headed for the International Space Station (ISS). Its crew of five served as the 10th ISS assembly flight. The primary payload of the mission was the Joint Airlock module which was attached in two space walks. Once installed and activated, the ISS Airlock became the primary path for ISS space walk entry and departure for U.S. space suits, which are known as Extravehicular Mobility Units (EMUs). In addition, it is designed to support the Russian Orlan space suit. The Joint Airlock is 20-feet long, 13- feet in diameter and weighs 6.5 tons. The airlock includes two sections, the larger equipment lock on the left that will store space suits and associated gear, and the narrower crew lock on the right from which astronauts will exit into space for extravehicular activity. It was built at the Marshall Space Flight Center (MSFC) by the Space Station prime contractor Boeing.