NASA astronauts Chris Cassidy and Bob Behnken will exit the orbital lab on June 26 to continue replacing batteries that store and distribute power collected from the solar arrays. They will work on the outer portion of the truss structure, or the Starboard-6 truss, disconnecting and removing the old nickel hydrogen batteries. Following that, new lithium-ion batteries will be installed in their place and powered up by mission controllers on the ground.