“Research has found that this feeling of exclusion can have real, measurable effects. Studies by the National Institute of Mental Health in the 1970s, when NASA first began to recruit women astronauts, showed that women were significantly less likely to apply for jobs with titles that ended in man rather than person. A similar effect was found among men, who avoided professions with feminine-sounding names.”

https://www.theatlantic.com/science/archive/2019/07/manned-spaceflight-nasa/594835/

NASA Style Guide for reference:

“Gender-Specific Language (e.g., Manned Space Program vs. Human Space Program)

In general, all references to the space program should be non-gender-specific (e.g., human, piloted, unpiloted, robotic, as opposed to manned or unmanned).”

https://history.nasa.gov/styleguide.html