NASA officials are working with the International Space Station crew to address a malfunction that occurred Wednesday in one of the station's two external cooling loops.
The crew and orbiting lab are both in stable condition, the space agency said, reassuring the public that neither were ever in any danger. However, the glitch "does remove redundancy, which could make a second failure a far more serious concern," NASA officials wrote in a statement.
"Everything we can do is being done," ISS Mission Operations Integration Manager Kenny Todd said. "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."
Several non-critical systems have been powered down while teams work to solve the problem.
Far more than simply keeping the station crew comfortable, ISS temperature control ensures that the the orbiting lab remains livable and scientific equipment located onboard functional.
The two external loops work by circulating ammonia outside the station through giant radiators in order to keep it cool during the 400 degree Fahrenheit fluctuation the ISS experiences during its orbit around the Earth. The system is responsible for acquiring and removing excess heat from all of the US and international partner modules except the Russian modules.
The glitch occurred when the pump model on one of the loops automatically shutdown after reaching a pre-set temperature limit. NASA officials deffered deciding whether or not they will postpone the launch of the Orbital Sciences' Cygnus cargo craft scheduled for Dec.18 in light of the issue.
The International Space Station orbits the Earth in just over 90 minutes, during which time it undergoes a temperature shift of 200 degrees Fahrenheit when exposed to the Sun, to 200 degrees below zero while over the night side of the planet.
When comparing the latest pump failure to one that took place in 2010, Todd said: "That was a failure to be able to move the ammonia. 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."