Apollo Abort Guidance System

Apollo LM Abort Guidance System; left to right: Abort Sensor Assembly (ASA), Data Entry and Display Assembly (DEDA), Abort Electronic Assembly (AEA)
Abort Guidance System keypad (DEDA) in Apollo 11 Lunar Module (LM-5) on the way to the Moon.

The Apollo Abort Guidance System (AGS, also known as Abort Guidance Section) was a backup computer system providing an abort capability in the event of failure of the Lunar Module's primary guidance system (Apollo PGNCS) during descent, ascent or rendezvous. As an abort system, it did not support guidance for a lunar landing.[1]

The AGS was designed by TRW independently of the development of the Apollo Guidance Computer and PGNCS.

It was the first navigation system to use a strapdown Inertial Measurement Unit rather than a gimbaled gyrostabilized IMU (as used by PGNCS).[2] Although not as accurate as the gimbaled IMU, it provided satisfactory accuracy with the help of the optical telescope and rendezvous radar. It was also lighter and smaller in size.

  1. ^ "Chapter Two - Computers On Board The Apollo Spacecraft". Computers in Spaceflight: The NASA Experience (Report). NASA. Retrieved December 11, 2022.
  2. ^ Computers in Spaceflight: The NASA Experience -- Chapter Two: Computers On Board The Apollo Spacecraft