Two astronauts are making the fourth and final spacewalk of NASA’s next-to-last space shuttle mission.

Endeavour astronauts Mike Fincke and Gregory Chamitoff floated out of the International Space Station early Friday to install a 50-foot (15-meter) boom.

They are the last shuttle crew members to perform a spacewalk. All future spacewalks will be performed by full-time space station residents.

The Endeavour astronauts used the laser-tipped pole Thursday to survey their ship one last time in orbit. They attached it to the end of a robot arm to check for micrometeorite damage. NASA expects to finish reviewing the 3-D images Friday.

The boom will remain permanently at the space station and assist with future repairs.

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