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Airlock and gas system in Space Shuttle (NASA)

Release: 01-224

Space Shuttle to deliver new 'doorway to space', Marshall Center experiment to Space Station

Space walkers soon will leave the International Space Station more easily through a new "doorway to space" when the Space Shuttle Atlantis delivers to the Station an airlock built and tested at NASA's Marshall Space Flight Center in Huntsville, Ala.

In addition to the airlock, the next Shuttle mission, STS-104, set for launch on July 12, will carry a crystal growth experiment sponsored by Marshall's Biotechnology Program. It will be making its third trip to the Station. And Atlantis will lift-off with a new, improved Space Shuttle Main Engine, developed under the Marshall Center's direction.

"We're ready to fly," said Todd May, the airlock element manager in Marshall's Flight Projects Directorate. "The Joint Airlock Module will provide a critical capability for the Space Station by allowing space walks in U.S. spacesuits without relying on the Space Shuttle and its airlock."

The U.S. Joint Airlock will make it easier for crews to perform Extravehicular Activities, know as EVAs or space walks, and allow both Russian and American spacesuits to be worn when the Shuttle is not docked with the Space Station. Currently, American suits will not fit through Russian airlocks. The third EVA during STS-104 will be staged out of the new airlock and will be the first space walk from the Station using a U.S. suit.

In addition to the Joint Airlock Module, a new high-pressure gas system - also manufactured at the Marshall Center -- will be carried into orbit on a double Spacelab Pallet that fits inside the Shuttle's cargo bay.

"It's great to see hardware that did such a good job supporting Spacelab science payloads continue the tradition by carrying major components to our newest space research facility," said Elaine Flowers Duncan, the project manager for the Spacelab Pallet in Marshall's Flight Projects Directorate.

By reusing the Spacelab Logistic Pallet and Marshall's 20 years of successful experience integrating and operating unpressurized carriers, the Flight Projects Directorate is making it less expensive to transport Space Station components. Duncan's team of MSFC and Boeing engineers was instrumental in performing the analytical integration required to carry the Space Station's high-pressure gas system into orbit.

"We performed all the engineering, including design, development, test and evaluation of the flight support equipment and the pallet to carry the equipment safely on the Shuttle to the Space Station," said Duncan.

The Spacelab Pallet team will support the mission from the Huntsville Operations Support Center Engineering Support Room at the Marshall Center.

The high-pressure gas system includes two oxygen and two nitrogen tanks to be mounted on the outside of the airlock. The oxygen and nitrogen in the tanks will be used to repressurize the airlock after space walks, replenishing the Station's air when small amounts are lost during EVAs and normal operations and augmenting the Station's current gas resupply system.

Building and testing the new airlock, high-pressure gas tanks and Spacelab pallet was a team effort involving more than 12 contractors from two countries, as well as three NASA centers - Marshall, the Johnson Space Center in Houston, Texas, and the Kennedy Space Center in Florida. The Boeing Company, the Space Station prime contractor, built the 6.5-ton (5.8 metric ton) airlock and several other key Space Station components in the same Marshall Center building where the Saturn V rocket was built that carried people to the Moon.

"It's been a tremendous pleasure to watch the NASA and Boeing team transform an empty shell into a flight-worthy component of the Space Station," said May.

The Joint Airlock Module is spindle-shaped, consisting of two cylindrical, pressurized chambers. It is 18 feet (5.49 meters) long and has a diameter of 13 feet (3.96 meters). Inside the large chamber attached directly to the Unity node, astronauts from every participating nation can suit up for space walks to assemble the Station, perform maintenance or install experiments.

In the large chamber, several crew members don suits and perform other activities to prepare for extravehicular activities. Just before the start of a space walk, crew members close a hatch and move to the smaller part of the airlock. Here, pressure is reduced, so the crew can safely go outside and work in the vacuum of space.

Before the airlock was shipped to the Kennedy Center in September 2000, several tests were conducted at the Marshall Center to ensure it would work safely in orbit. A full-suit checkout test in August 1999, and an oxygen systems test in March 2000, were critical to the airlock's performance.

Tests of both Russian and U.S. spacesuits included checking communications between systems in the suits and the airlock, fluid checks of cooling loops and battery checks. The airlock has its own environmental control system, which was evaluated by closing the hatch and measuring temperature and humidity control and carbon dioxide removal capability.

"Communications and acoustics testing, thermal and structural analysis, mechanical evaluation and testing, and safety are just a few of the areas Marshall team members have supported," said May. "Marshall also provided manufacturing facilities and performed program-critical tasks."

During the upcoming Atlantis mission, the Space Station's new robot arm, delivered to the Station in April, will be used to pick up the airlock and attach it to Unity. Unity also was built and tested at the Marshall Center -- a primary NASA center for Space Station construction.

The arm will be used to grab each of the four gas tanks from the Spacelab pallet and place them near the airlock. Astronauts performing an extravehicular activity using the Shuttle airlock will attach the four tanks to the outside of the large part of the airlock using mechanisms tested by Marshall engineers. During the STS-104 mission, astronauts will conduct three extravehicular activities to complete airlock activation operations.

On their way to the Station, the Space Shuttle crew can expect an even safer ride into orbit, thanks to completion of a new Space Shuttle Main Engine. This is the first flight of the engine -- called the Block II configuration - developed under Marshall Center direction. The engine has a new high-pressure fuel turbopump and other features that enhance its reliability. The main engines operate for about eight-and-one-half minutes during liftoff and ascent, and shut down just before the Shuttle reaches low-Earth orbit - the address of the International Space Station.

While the Shuttle is docked with the Station, the crew will transfer a biotechnology experiment from the Shuttle middeck to the orbiting laboratory. Students and teachers from elementary, middle and high schools throughout Alabama, California and Tennessee helped prepare biological solutions inside the experiment container.

During a one-month stay in space, the solutions will form crystals that help scientists and the students learn how biological substances carry out important functions in humans, animals and plants. This hands-on education and science experiment will join seven other experiments, already on the Station, sponsored by the Microgravity Research Program at Marshall -- NASA's lead center for flying experiments that take advantage of low gravity inside the Space Station.