Astronauts performed their second spacewalk in under a week to replace old batteries outside the International Space Station.
Commander Chris Cassidy and Bob Behnken ventured out to tackle the big batteries.
For every two outdated batteries coming out, a new and improved one goes in to supply power to the station on the night side of Earth.
The two astronauts finished half the work to upgrade the batteries that provide power for one channel on one pair of the station’s solar arrays.
They moved and connected one new lithium-ion battery and its adapter to complete the circuit to the new battery and relocated an ageing nickel-hydrogen battery for future disposal.
The new lithium-ion batteries should last the rest of the space station’s life, according to officials.
They also loosened bolts on nickel-hydrogen batteries that will be replaced when the astronauts return to complete the power upgrade in July.
When Nasa sends the astronauts out on their next spacewalk, they will route power and ethernet cables in preparation for the installation of a new external wireless communications system.
This includes an enhanced HD camera and to increase helmet camera coverage for future spacewalks
Nasa wants the battery work completed before Mr Behnken returns to Earth in August aboard a SpaceX capsule.
He is one of two test pilots who launched on SpaceX’s first astronaut flight in May.
Mr Cassidy and Mr Behnken now have eight spacewalks apiece on their resumes.