The International Space Station (ISS) has been having some problems with a coolant pump stored on the exterior of the craft. However, engineers has proposed a method to repair the problem, which means that the resupply mission scheduled to begin this week may receive the go signal for launch.

If the coolant pumps are not repaired in time, NASA will have to postpone the resupply mission to allow enough time for astronauts on board the ISS to repair the coolant pump on a spacewalk mission. Accessing the erring pump may prove to be difficult due to the fact that the pump is located on the space station's scaffolding. The said scaffolding is about the length of an entire football field and it supports many of the space station's equipment such as radiators and solar panels.

The cooling pump problems first started last Dec. 11 when NASA controllers noticed anomalies in the temperature readings from the station's sensors. The sensors detected an unusual lowering of the ammonia in one of the station's cooling loops. The problem needs to be repaired as soon as possible since it could freeze water used in the station's heat exchanger. This could lead to a domino effect that can damage the heat exchanger and cause ammonia to leak into the interior of the space station. 

As a temporary measure, NASA controllers have rerouted the coolant to the space station's other external cooling loop. However, the measure required the crew to turn off all non-mission critical equipment in order to reduce the load on the remaining functional cooling loop.

According to NASA engineers, the problem started due to a malfunctioning valve that normally adjusts the rate of flow of the ammonia coolant. To remedy the problem, engineers have devised more temporary measures that will allow the aforementioned resupply mission to commence without further delays. The added short-term measure involves manipulating the settings of an isolation valve in the coolant path. While this valve is either open or closed in a given time, adjusting the valve's open or closed position variably could help produce the same effect as the original malfunctioning control valve. While engineers are still trying to solve the problem, the astronauts are readying their spacesuits for a possible space walk.