Orbital Cargo Launch Delayed While NASA Works to Solve ISS Malfunction

NASA and the aerospace firm Orbital Sciences Corp. announced the delay of an unmanned resupply mission to no earlier than Dec. 19 while engineers continue to work to solve an equipment failure aboard the International Space Station.

Originally planned for Dec. 18, the mission is designed to carry more than 2,700 pounds of cargo to the orbiting lab, nearly 1,000 pounds of which is science and research equipment.

The launch will be the first following a successful trial round carried out in September as part of a $1.9 billion contract with the space agency, and is still contingent on NASA's ability to resolve a malfunction in one of the station's two external cooling loops.

The glitch occurred when the pump model on one of the loops shutdown automatically after reaching its preset temperature limit.

Both the crew and lab are in stable condition, the space agency said, although several non-critical systems were powered down while teams work to solve the problem.

"Everything we can do is being done," ISS Mission Operations Integration Manager Kenny Todd said in a statement Thursday. "The system is good and stable. The crew is in good shape. All the right folks on the ground are looking at the problem and trying to assess exactly what the root cause is and what our options are to continue moving forward."

The station's cooling is currently being managed through a second cooling loop as it orbits the Earth every 90 minutes, experiencing a 400 degree Fahrenheit shift in temperature as it moves in and out of the night side of the planet.

The latest pump failure differs from one that took place in 2010, Todd explained.

"That was a failure to be able to move the ammonia," he said. "Here we have a failure in controlling the temperature of the ammonia. The valve is basically a mixing valve, which helps regulate the temperature of the circulating ammonia. While it's in the same pump module, it's in a different area."