14 DAY TRIAL // Officials with the American space agency say that efforts aimed at fixing an error that affected the cooling system aboard the International Space Station a few days ago are currently unsuccessful. Engineers at NASA believe that at least a spacewalk may be necessary to address the issue.
Last week, a malfunction in Loop A on the space lab's cooling system forced astronauts with the Expedition 38 crew to shut the loop down, and move all essential systems to Loop B. This is a safe procedure to perform, but it does entail some risks of overloading the second loop over prolonged use.
On Sunday, December 15, engineers at NASA continued to relay instructions to astronauts in orbit, in a bid to mitigate some of the damage Loop A suffered. Their end goal is to restore at least partial functionality to this segment of the cooling system.
The affected part is a flow control valve, located in a cooling pump on the station’s starboard truss. This means that the component is only available from the exterior of the lab, and must be accessed during an extravehicular activity (EVA).
The valve is responsible for controlling the flow of ammonia through the cooling system. Last Wednesday, the component failed to position itself properly, so unregulated ammonia flows caused a temperature swing in Loop A. Some of the support systems on the ISS had to be shut down.
“Efforts overnight to fine-tune the position of an isolation valve associated with the flow control system in the Pump Module into a 'sweet spot' to assist the faulty Flow Control Valve in regulating the affected cooling loop’s temperatures were still being evaluated as engineers continue to review the data, valve positioning techniques and additional methods of temperature management in the loop,” NASA said in a statement.
A similar error occurred on the ISS in August 2010, when the situation was more severe. At that time, there was even talk of evacuating the six astronauts aboard the space lab. Eventually, a series of three EVA fixed the issue, and normal operations resumed.
In case of emergency, ISS crewmembers can easily evacuate the station by boarding the two Russian-built Soyuz space capsules attached to the space lab for this exact contingency. Each group of three astronauts that flies to space takes off and lands in its own spacecraft.
The situation is not that severe yet. NASA experts are currently taking all possible steps to fix the issue without a spacewalk. If efforts fail, an EVA might be scheduled for this week or the next.