Meanwhile, Fischer, making the second spacewalk of his career, installed a pair of antennas on the US Destiny Laboratory module to enhance wireless communication capability for future spacewalks.
It was unclear what caused the MDM to fail.
The unit had just been installed in March during a spacewalk by Whitson and Expedition 50 commander Shane Kimbrough.
Nor was it the first time an MDM unit failed.
"A similar MDM replacement spacewalk was conducted in April 2014 by Expedition 39 crewmembers Steve Swanson and Rick Mastracchio of NASA," the US space agency said.
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Whitson is the most experienced female spacewalker in the world, and during the spacewalk she leapt to third place for the most time spent doing spacewalks.
She now has a total of 60 hours, 21 minutes over 10 career walkabouts in space.
The world record holder for spacewalking is Russian cosmonaut Anatoly Solovyev, who completed 16 spacewalks totaling 78 hours, 21 minutes.
In second place is Spanish-American astronaut Mike Lopez-Alegria, who has done 10 spacewalks totaling 67 hours and 40 minutes.
Tuesday's spacewalk was the 201st in support and maintenance of the ISS.
The $100 billion football-field sized orbiting laboratory has been continuously occupied by global astronauts since 2000.
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