The term SCRUB A NASA MISSION is a crossword solution which refers to the process of aborting a mission. Aborting a mission is the act of cancelling or ending a mission before it has been completed. This is usually done in order to protect the safety of the astronauts and the spacecraft. In the case of NASA missions, aborting a mission is a last resort option and is only used when there is an imminent danger to the crew or the spacecraft.