16 large solar panel blocks are attached to the the exterior of the ISS, and it is the solar panels that generates the electricity that is used aboard the space station. A much needed resource that we take for granted down here on Earth with the various choices of supply.
The spacewalk will be the first of its kind in history for a British astronaut and is scheduled precisely at 12:55 GMT to coincide with the ISS being in a solar eclipse as direct sunlight on the solar panels would make the spacewalk too dangerous. The whole spacewalk is expected to last 6 hours in total. Quite a long time to be outside in that vast open space.
The ISS is positioned roughly 250 miles above the Earth, and it orbits the planet at speeds greater than 15,000 mph. Paul Dum; Nasa's lead spacewalk officer has detailed how carefully astronauts will have to move during the spacewalk, in order to carry out the necessary repairs whilst remaining safe and secure.