Astronauts at the International Space Station (ISS) have successfully carried out the first of a series of spacewalks to repair a malfunctioning cooling coil located on the exterior of the space station.

The problem started with a malfunctioning cooling coil installed on one of the trusses of the space station. The coil was located in a section of the station where the solar panels as well as other sensory arrays are installed. The malfunctioning ammonia cooling system was one of a pair and it had to be shut down to keep ammonia from leaking into the space station. However, both the cooling coils are required to keep the station functional and when one of the coils was shut down, the crew was forced to shut off non-essential equipment to keep the remaining functioning cooling coil from getting overloaded. The shutdown also meant that many of the scientific experiments conducted on board the space station had to be stopped temporarily.

The first plan proposed by Johnson Space Center engineers was to bypass a potentially faulty pump using a different valve. However, the initial plan was junked in favor of a spacewalk due to time constraints.

To deal with the problem, two NASA astronauts - Rick Mastracchio and Mike Hopkins - donned their spacesuits to begin the repairs on Saturday. Due to the risk of a water leak, snorkels were installed on the spacesuits to minimize the possible dangers of the mission. This was especially important in light of the last spacewalk where Italian astronaut Luca Parminato almost drowned due to a water leakage that caused water to start filling up his helmet.

The repair process lasted for 5 and a half hours. While the initial repairs were successful, it only constituted the first phase of the entire repair process. The events of the spacewalk were broadcast live on NASA TV as they unfolded. While the successful spacewalk happened without incident, completing the repairs on the cooling system will require two or three more spacewalks in the near future.