NASA is still hoping to launch the shuttle Endeavour in early February as engineers scramble to repair broken hoses on the new space station module set to ride aboard the orbiter.
Endeavour is slated to launch the new Tranquility module to the International Space Station on Feb. 7 from Kennedy Space Center in Florida. But two of the module's four ammonia coolant hoses have failed standard pre-launch checks, forcing engineers to come up with a repair plan while others try to build new hoses from scratch, station managers said Monday.
"Folks are working really hard to get the hoses checked out, completed, certified [and] tested," said Pete Hasbrook, NASA manager for the Expedition 22 mission aboard the space station. "We are still working toward the Feb. 7 launch date."
The Tranquility module will provide additional living space for the crew on board the space station.
Broken hoses
The new module, like other space station rooms, uses liquid ammonia as a coolant to keep its computers and other electronic equipment cool in space. The coolant hoses are routed on the exterior of the space station and must function at a pressure of 3,000 pounds per square inch (psi) to keep the ammonia supply liquid and moving, Hasbrook said.
But the two broken coolant hoses on Tranquility failed at a pressure of only 1,500 psi or so, apparently due to a defect in the exterior braided-metal sheath covering the flexible hose, Hasbrook said. The metal braids began separating from the hose connector during the test, he added.
The test was performed in Florida where the shuttle Endeavour is waiting atop its seaside launch pad for the delivery of Tranquility, a seven-window observatory port called the Cupola and other supplies to be launched to the station.
Tranquility was initially slated to be attached to an Earth-facing berth on the station's main Unity connecting node. However, the misalignment of ammonia coolant lines on that node led managers to move the new module to an open berth on Unity's port — or left — side. To attach Tranquility there, engineers built the four "jumper" lines to route vital ammonia coolant from Unity to the new module. The hoses are custom-made and each 14 feet (4.2 meters) long – longer than typical station hoses.
"We haven't used anything that long before," station flight director David Korth told reporters. "So that may be a contributing factor."
Repairs under way
Hasbrook said station engineers have successfully tested a "beefed-up" version of the coolant hoses using an extra layer of braided metal in Florida, though the final approval on the repair is still under review. Meanwhile, another team at Marshall Space Flight Center in Huntsville, Ala., is working to modify spare station hoses to replace the damaged ones in case they don't pass muster, he added.
Still another option is to launch Endeavour and the Tranquility module as planned, but to delay the space room's full activation until March or later, when new hoses could be launched on a different shuttle flight, Hasbrook said.
That option would require spacewalking astronauts to install extra heaters on Tranquility that would allow astronauts to install the module and power up some systems temporarily. The module would feel more like a dark, cool cellar until the new hoses arrive later and allow for the full activation, Hasbrook said.
"That's about a Plan C," he added. "The other two options are looking pretty good."
Endeavour's STS-130 mission will mark the first of NASA's five final shuttle missions scheduled to fly this year. The agency plans to retire its three space shuttles in the fall to make way for their replacement — the Orion capsules and their Ares rockets.
Those new vehicles are expected to be ready to launch astronauts into space no earlier than 2015, and possibly later, experts have said.
This week, the five astronauts living aboard the International Space Station plan to move a huge shelf of spare parts from one end of the outpost to the other using its robotic arm. Two Russian cosmonauts also plan to perform a six-hour spacewalk early Thursday to work on a new science module called Poisk to activate its docking port.