S.I.D.

The Space Intruder Detector, or S.I.D., is an orbital satellite whose control computer has been programmed with a sufficiently advanced artificial intelligence to communicate with the S.H.A.D.O. MoonBase in a synthesised voice. (BBC newscaster Mel Oxley provided that voice.)

S.I.D., the Space Intruder Detector, in relation to Earth.