A person in a relationship who is being used for sex, friendship or comfort without receiving affection or love in return. Often, the non-astronaut food party is in an unhappy relationship.
The term refers to the packets of food astronauts use for nourishment without any taste or satisfaction.
The term comes from the book "You Don't Love Me Yet" by Jonathan Lethem.
She realized she was only his astronaut food, and didn't mean anything to him.