Related Clues:

• Muscle or fat's ultimate check
• Call off a launch
• Cancel, as at NASA
• Op-ending order
• Cancel, at 64 Across
• Nix, at NASA
• Cancel a spaceflight
• Prematurely end
• Stop the launch
• Terminate the mission
• Mission directive
• Cancel, as a space mission
• Scrap, as a mission
• Scrub, in a way
• Cut short, as a flight