Meir will be wearing helmet camera with the number 11 imprinted on it. Koch will be number 18 and her spacesuit has red stripes on it, CNN reported.
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Over the past 35 years, there have been 40 spacewalks done by 12 U.S. female astronauts, but the first woman to ever do a spacewalk was Russian cosmonaut Svetlana Savitskaya in 1984, CNN reported.
Koch and another astronaut, Anne McClain, had been scheduled to do a spacewalk together earlier this year, but that all-female walk was shelved due to equipment issues. NASA didn't have the right-sized space suits for the two women, The New York Times reported.
Then the two were supposed to conduct their spacewalk Monday, to install batteries, but the schedule was moved up when a power controller failed, the Times reported.
This is the seventh spacewalk for 2019.