The International Space Station is facing a $1 billion budget shortfall – separate from President Donald Trump's plans to further cut funding – that will require dropping the number of NASA astronauts on the orbiting platform.

Of NASA's 47 active astronauts, 20 are women. And of the seven astronauts currently living at the space station, McClain and Ayers are the only women. It was the first spacewalk for Ayers, an Air Force major and former fighter pilot, and the third for McClain.

Space exploration and science could take a serious hit as funding is slashed by 24% under Trump's proposed budget.