Cape Canaveral, Fla. ? Space shuttle Atlantis’ astronauts wrapped up the third and final spacewalk of their flight Friday, completing installation of a 17 1/2-ton piece of the international space station and doing some other fix-it jobs on the outside.

Astronauts Joe Tanner and Heidemarie Stefanyshyn-Piper unpacked a radiator for the space station’s new 240-foot solar arrays during the six-hour, 41-minute spacewalk. The spacewalkers also gathered up a science experiment, replaced an antenna and took video of the space shuttle’s heat shield.

It was the second spacewalk of the mission for both astronauts, who earlier in the week worked like electricians, hooking up wires and cables to the space station’s new addition.

Atlantis is scheduled to undock from the space station Sunday and return home Wednesday after an 11-day flight. The flight marked the first time since the Columbia disaster 3 1/2 years ago that construction on the half-built space station has resumed.