British astronaut Tim Peake prepares to exit the ISS airlock. NASA pic.
On Friday, Jan. 15, astronauts Tim Kopra (USA) and Tim Peake (UK) took a spacewalk (EVA-35) to replace a Sequential Shunt Unit (SSU) which regulates electrical voltage from the Solar Arrays. It was the third EVA for Kopra, and the first for Peake. It was also a record as the first spacewalk for a British astronaut. There had been previous spacewalks by British astronauts when they worked for NASA, but this flight was the first time an astronaut representing the UK was performing an EVA.
Tim Peake enjoying the first British Spacewalk.
The replacement was scheduled to take place during one of the night portions of the station's orbit. Engineers did not want to risk removing the SSU during a sunlit period when the solar panels would be charged up and transmitting electricity. The astronauts moved out along the Truss and during a dark period changed out the failed unit with the spare SSU. They then moved back to the airlock area to prepare for using the rest of the EVA for some other minor tasks.
Tim Peake moving along the side of the US Lab module.
Tim Kopra had completed the re-installation of a waste valve on Node 3 when he reported to NASA that he was experiencing a tiny amount of water leak in his helmet. Due to the experience astronaut Luca Parmitano had with a leaky water line that could have drowned him on EVA-23, ground Mission Control Director Royce Renfrew immediately cancelled the rest of the EVA and the two astronauts safely returned to the airlock. The leak in Kopra's helmet was not nearly as dangerous as the earlier incident, but no one was about to take any chances. No doubt the astronauts will be closely examining the problem and working with engineers to make repairs. The remaining tasks of this EVA will be left to another time.