According to NASA's internal distinction, what officially separates a NASA 'astronaut' from a 'non-astronaut' space flyer?

Answer

Successful completion of formal training and assignment to a mission

NASA maintains that an 'astronaut' is someone who has completed formal training and has been assigned to a mission, implying a specific credentialing process is required.

According to NASA's internal distinction, what officially separates a NASA 'astronaut' from a 'non-astronaut' space flyer?

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What are the qualifications to be called an 'astronaut' ? - YouTube

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