Anne McClain, one of the NASA astronauts supposed to participate in the agency's first all-female spacewalk, has spoken out amid the wave of backlash directed at the agency since it canceled the assignment over concerns with safety and speed.

McClain said in a tweet on Wednesday morning that the decision, which came from a lack of accommodating spacesuits, was based on her recommendation.

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“Safety of the crew and execution of the mission come first,” McClain said.

NASA also responded to criticism over canceling what would have been its first all-female spacewalk on Tuesday.

NASA previously suggested in a statement on Monday that only one of the correct-size astronaut suits would have been available for McClain and Christina Koch, one of the other NASA astronauts who was scheduled for the Friday assignment.

"Mission managers decided to adjust the assignments, due in part to spacesuit availability on the station," the statement read.

"McClain learned during her first spacewalk that a medium-size hard upper torso – essentially the shirt of the spacesuit – fits her best. Because only one medium-size torso can be made ready by Friday, March 29, Koch will wear it."

The cancellation of what would have been a historic spacewalk for NASA was met with a wave of criticism this week.