ESA astronaut Tim Peake and NASA astronaut Tim Kopra will exit the International Space Station next week to repair a power unit on the outside.

The two Tims arrived at the Space Station on 15 December but this will be their second involvement in a spacewalk: Tim Peake assisted Tim Kopra and Station commander Scott Kelly when they moved an equipment carrier on 21 December.

The new spacewalk will last around six hours on 15 January, with Tim Kopra and Tim Peake working closely together to replace a faulty unit.

The ESA astronaut explains: “Our primary task will be to replace a failed Solar Shunt Unit, which transfers electrical power generated by the solar panels.”

The unit is relatively easy to replace because it is a simple box that can be removed by undoing one bolt. Once done, the spacewalkers will lay cables in advance of new docking ports and reinstall a valve that was removed for the relocation of the Leonardo module last year.

Inside the Station, Scott Kelly will help the spacewalkers into and out of their suits – a major operation in itself.

Before the astronauts leave they will breathe pure oxygen for two hours to purge their bodies of nitrogen. The spacesuit pressure is lower than in the Space Station and the drop could give them the ‘bends’, much like scuba divers rising too quickly to the sea surface.

Donning their spacesuits and safety equipment will take hours before they enter the airlock to reduce the pressure until it is safe to open the exterior hatch.

Tim Peake comments, “I am thrilled at this opportunity for a spacewalk. Right now we are focusing on preparing the tools, equipment and procedures.

ESA press release. Read more..