NASA term indicating that a spacecraft action is approved. The mission control centre, for example, will inform a space shuttle crew, ‘You are go for deorbit.’ The first crew to land on the Moon in 1969 received such messages as ‘Apollo 11, this is Houston. You are go for TLI’ (translunar injection). When a computer's alarm light proved to be a false alert during the Apollo 11 mission, the message was ‘We're go on that alarm.’