Two NASA astronauts are currently outside the International Space Station on the second of several planned spacewalks to replace batteries affixed to the outside of the spacecraft. The duo, Andrew Morgan and Christina Koch, are currently maneuvering around the exterior of the space station as they remove old batteries and attach new, more efficient replacements.

As is often the case, NASA is live streaming the entire event from start to finish, giving us a glimpse at what it takes to walk in space and perform maintenance on one of the most complex pieces of machinery ever sent into space. You can watch it live right here.

The YouTube window below will be broadcasting the entirety of the spacewalk, and it includes commentary from NASA staff to provide some context for what you’re seeing on the screen. You’ll also hear a live feed of the communication between the astronauts and their support staff back on Earth.

The task the pair is carrying out is rather straightforward. The old nickel-hydrogen batteries on the exterior of the space station have to be detached from their mounting points, stowed, and then new lithium-ion batteries have to be installed. The new batteries are much, much more efficient than the old models, meaning that for every two old batteries the team removes, only one new one as to be installed.

The batteries are incredibly important to the functioning of the space station since they hold reserve power for when the space station is in the shadow of the Earth and doesn’t have direct sunlight on its solar panels.

This is the second of a total of five planned spacewalks dedicated to replacing the space station’s batteries. The rest will be carried out on October 16, 21, and 25, based on the current schedule, but since the first spacewalk already put the team ahead of schedule, the plans for later spacewalks could change.