noun. A female naturally skilled and trained during childhood in the art of being an unreasonably sassy drama queen
and self-entitled. Sasstronauts will often evade responsibility for their own dramatic actions that were caused by their unreasonable sassiness.
Alysin pissed off every one of her coworkers by being an unbearably cunty
A person who is being exceptionally sassy, and maybe beginning to get an attitude but you don't want to hit in the face because they're your friend.
Friend A is being bitchy. Friend B, "dude, why are you being such a sasstronaut?"