(AP) -- Two shuttle astronauts took one last spacewalk at the International Space Station on Friday to finish replacing old batteries and tackle some odd jobs as their visit drew to a close.
Garrett Reisman and Michael Good were eager to get started on the third spacewalk in five days for the Atlantis crew. As the pressure slowly dropped in the air lock, Reisman commented: "It's like standing on your bathroom scale and waiting for the needle to go down."
Within a half-hour, the spacewalkers had plugged in a new jumper cable on the station's sprawling framework. Their next stop was the nest of batteries on the far left side.
Reisman and Good had two fresh batteries to install. Good and another astronaut put in four during Wednesday's spacewalk.
Each battery is about the size of a 3-foot box and weighs 375 pounds.
Atlantis delivered the batteries last weekend along with a new Russian compartment. The chamber was opened Thursday, but had to be sealed again when metal filings were found floating inside. Mission Control said air scrubbers hopefully will clean up everything.
Atlantis will undock from the space station Sunday for the very last time. Only two more shuttle missions are on the books, both of them scheduled for this fall and set aside for NASA's two other shuttles.
NASA and some members of Congress are pushing for one more flight of Atlantis, next June. The Obama administration would have to give its blessing.
President Barack Obama wants to end the shuttle program fairly soon so that NASA has more money to spend on developing the technologies needed to send astronauts to asteroids and Mars. Russian rockets will continue to ferry U.S. astronauts to and from the space station, until commercial companies can perform the job with their own spacecraft.
The space station is expected to keep operating for another 10 years.
Explore further: ISS prepares for a spacewalk and visitors