The phrase "the missile knows where it is" originates from a 1997 Air Force training video and refers to how missile guidance systems work by continually determining the missile's position through navigation computations. The missile constantly knows its position by comparing where it is with where it isn't, obtaining a deviation or error used to generate corrective commands to steer the missile to the target. It uses onboard inertial navigation systems, sometimes combined with GPS or celestial navigation, to maintain accurate knowledge of its position and adjust its trajectory accordingly. This allows the missile to guide itself precisely, even when external signals like GPS may be unreliable or jammed. The process involves continuous feedback, subtraction of positional data, and correction of deviations to ensure the missile reaches its intended destination.

How the Missile Knows Where It Is

• The missile's guidance system keeps track of its position by calculating the difference between where it is and where it isn't.
• This deviation generates corrective commands to adjust its flight path.
• The missile also tracks where it was to refine its navigation further.
• Inertial navigation systems (INS), often supplemented by GPS or star fixes (astro-inertial guidance), enable precise self-contained navigation.
• INS is resistant to electronic countermeasures and allows autonomous operation in GPS-denied environments.

Missile Guidance Overview

• Guidance systems combine target location and missile position data to maintain an accurate flight path.
• There are various guidance methods: inertial, command, active, semi-active, and passive.
• INS is critical for long-range missiles and those launched from moving platforms like submarines.
• The missile computing system continuously updates its position and corrects errors by comparing expected and actual positions.

In summary, the concept "the missile knows where it is" reflects the missile's continuous calculation and correction of its location using onboard navigation systems to ensure it can accurately reach its target despite dynamic conditions or disruptions.