Space Shuttle News : STS-129: Stocking the Station

News from nasa space shuttle : The spare parts delivered to the International Space Station by Atlantis during the STS-129 mission will mean spare years on the station’s life once the space shuttle fleet is retired.

“You’ll see this theme in some of the flights that are going to come after ours as well,” said Brian Smith, the lead space station flight director for the mission. “This flight is all about spares – basically, we’re getting them up there while we still can.”

With only one U.S. module left to deliver, the Space Shuttle Program is turning its attention to helping the space station build up a store of replacement parts. There are only half a dozen flights left in the shuttle’s manifest before they stop flying, and as the only vehicle large enough to carry many of the big pieces of equipment into space, several of the flights are devoted to the task. This is the first, however, and as the first this mission is dedicated to taking up the spares of the highest priority.

“We’re taking the big ones,” Smith said. “And not only are they the big ones – they’re the ones deemed most critical. That’s why they’re going up first.”

The spares are going up on two platforms – called external logistics carriers, or ELCs – to be attached on either side of the station’s truss, in hopes that wherever a failure happens, the necessary spare won’t be too far away. The ELCs carried up on STS-129 will be chocked full with two pump modules, two control moment gyroscopes, two nitrogen tank assemblies, an ammonia tank assembly, a high-pressure gas tank, a latching end effector for the station’s robotic arm and a trailing umbilical system reel assembly for the railroad cart that allows the arm to move along the station’s truss system. There’s also a power control unit, a plasma container unit, a cargo transportation container and a battery charge/discharge unit. In all, that’s 27,250 pounds worth of spares to keep the station going long after the shuttles retire.

Some of those spares would be used to replace failed components of the systems that provide the station power or keep it from overheating or tumbling through space. Others, in the case of the latching end effector and reel assembly, are essential parts of the robotics system that allow the astronauts to replace the other parts when they wear out.