14 DAY TRIAL // Experts at NASA announced yesterday that they had managed to bring the American-built Carbon Dioxide Removal Assembly (CDRA) air scrubber back online on Sunday, after it broke down on Saturday. While engineers back on Earth are still looking for the original source of the glitch, the 13 astronauts aboard the International Space Station (ISS) are perfectly safe. At no point did the Russian-built Vozdukh show any signs of malfunction. Both of the two air scrubbers have to operate flawlessly, if the station is to support the permanent six-member crew, as well as shuttle astronauts during assembly missions.
According to mission managers, the probable cause was a heater in CDRA, which remained turned on, and triggered a circuit breaker. This is a safety feature of the system, but the problem has been resolved, and experts are currently looking for any other potential threats to the air scrubber. The entire system was placed in manual mode on Sunday, which means that flight engineers back on Earth were required to work around the clock, to keep it running. Usually, its operations are automatic, and NASA hopes to return to that mode as soon as full diagnostics are conducted on the CDRA.
At no point over the weekend did experts even consider the possibility of recalling the space shuttle Endeavor faster to Earth because of the situation. They justified this by showing that several air scrub canisters existed on the two spacecraft, which would have ensured low carbon dioxide concentrations aboard the ISS for the entire scheduled duration of the STS-127 mission. “We're still trying to determine exactly what the root cause of the problem was. But in the meantime, we're doing a great job managing the [situation],” Brian Smith, the ISS flight director, said on Sunday.
With this problem gone, the astronauts can now focus on today's scheduled fifth and final spacewalk of the 16-day mission. Yesterday, they used the station's robotic arm to load a Japanese carrier module – employed at the beginning of the mission to deliver the porch-like Exposed Facility to the Kibo science module – with space parts and debris.
Today, they will install more visual equipment on the Japanese $1-billion module, and will set new covers for the Canadian hand-like Special Purpose Dexterous Manipulator (Dextre) in place. The spacewalk will be conducted by Endeavor Mission Specialists Thomas H. Marshburn and Christopher J. Cassidy, Space informs.
When the shuttle will break off from the ISS on Tuesday, it will most likely have completed all of its mission parameters, despite small glitches. On the return trip, Timothy Kopra's place on Endeavor will be occupied by JAXA Astronaut Koichi Wakata, which concluded his mission as an ISS flight engineer. Kopra will take this position for the next three months, replacing Japan's first long-term astronaut.