An instrument that aids spacecraft navigation by measurements using computer-assisted gyroscopes and accelerometers. Connected to the spacecraft by gimbals (swivelling devices), IMUs establish a fixed base from which the spacecraft's attitude in space can be measured. In the Gemini spacecraft, the gyroscopes were mounted at right angles to one another to calculate the vehicle's pitch, yaw, and roll. The accelerometers were mounted in tandem with them to measure the vehicle's reaction to thrusters being fired.
Subjects: Astronomy and Astrophysics.