NASA Office of Logic Design

NASA Office of Logic Design

A scientific study of the problems of digital engineering for space flight systems,
with a view to their practical solution.

Apollo Guidance, Navigation, and Control

Some of the documents on this page are posted here courtesy of MIT and are for the use of researchers, engineers, historians, and interested readers.  Thus, not all documents are not in the public domain and distribution must be approved by MIT. 

I have organized the documents, extracted abstracts, and will maintain them and improvements to the quality of documents.  Please send comments and suggestions to


Apollo Guidance and Navigation Lunar Module Student Study Guide

AC Electronics Division of General Motors
15 January 1967

The intent of this study guide is to give the student an understanding of the basic utility programming concepts associated with the LM computer. The programs described in this study guide are utility programs which, for the most part, are used in conjunction with all computer operations and include the basic executive routines, input/output routines and miscellaneous service routines along with basic programming techniques.
     This study guide is organized in the sequence of instruction of the course and is divided into four major sections. Each of these sections is associated with the LM peculiar programs.
     The objectives of this study guide are to provide the student with:
     a. Course materials organized in the sequence of classroom presentation for
     b. A familiarity of the overall utility programs associated with the LM

Astronauts' Guidance and Navigation Course Notes

E-1250, December, 1962
MIT Instrumentation Laboratory

This report reviews briefly the overall functions and operation of the Apollo Guidance and Navigation System, defining its major subsystems and the means by which these subsystems accomplish the necessary guidance and navigation system functions.
Section Title
  1. Functional view of Apollo G&N system
  2. Gyro Principles
  3. Stabilization
  4. Electromagnetic navigation
  5. Midcourse navigation and guidance
  6. Re-entry guidance
  7. Optics

More Apollo Guidance Flexibility Sought

Aviation Week & Space Technology
November l6, 1964

Washington - Apollo guidance, navigation and control concepts have undergone a number of evolutionary changes intended to improve mission flexibility and reliability and to save weight and space in the spacecraft. Some of these changes have resulted from more detailed studies of alternative solutions, while others stem from technical advances and experience gained since the Apollo program was launched several years ago.

Guidance System Operations Plan, AS - 278: Vol. 1, CM GNCS Operations

October 1966

This plan governs the operation of the Command Module Guidance, Navigation and Control System and defines its functional interface with the spacecraft, flight crew, and ground support systems on Apollo Mission AS-278.

Jim Lovell at G&N station


Original Reference to JSC was 404 Page Not Found

Apollo Command and Service Module Reaction Control by the Digital Autopilot

Robert Crisp and D. Keene
May 1968

An Apollo Guidance Computer Program developed to control the reaction jets of the Service Module of the Apollo spacecraft is described. Design philosophy is discussed, although the main design restraints are the existing hardware design, and maneuver requirements evolved at the implementation meetings for Apollo Block II CSM G&C systems. In general, the translation and rotation manual controls are implemented in the same way as the Block I SCS except simultaneous translation and rotation accelerations are possible. Automatic maneuver and attitude hold are instrumented in such a way as to conserve reaction control propellants.
     The maneuver instrumentation was designed and evaluated using a flexible vehicle model with no propellant motion. Current slosh models look on propellant motion as a source of disturbing torques. However, analog simulations have been made with new slosh models where the propellant motion is coupled with vehicle response.
     A theoretical study has been made of propellant utilization in generalized automatic maneuvers, and is compared with figures from three-degree-of-freedom digital simulations. The theoretical figures give a good estimate of the simulated propellant utilization.
     Conclusions are made regarding the current design, future work, and simulation plans.

Guidance, Navigation and Control

Space History Division
1999 not found at the Air and Space Museum www site.

Space Navigation Guidance and Control. Volume I.

C. S. Draper, W. Wrigley, D. G. Hoag, R. H. Battin, J. E. Miller, D. A. Koso, A. L. Hopkins, and W. E. Vander Velde

     The material in this book was assembled to support a series of lectures to be given by the authors in Europe in June 1965, under the sponsorship of the Advisory Group for Aerospace Research and Development, an agency of NATO.
     The general subject of Space Vehicle Control Systems is the subject of discussion with particular application to the present Manned Lunar Landing Program. The man-machine interaction along with requirements of the mission are first described. These mission requirements in terms of specific hardware along with the performance requirements and underlying reasons for choice are next explained. Lastly, the theoretical background, the system analysis and the derivation of the control functions to integrate the hardware into a precision guidance, navigation and control system are discussed. The book is organized into seven sections following the pattern of the lectures.

Space Navigation Guidance and Control. Volume II.

C. S. Draper et al.

not found on the HRST site.

Human Performance During a Simulated Apollo Mid-Course Navigation Sighting

Charles M. Duke Jr., Captain, U.S. Air Force S. B., U.S. Naval Academy
Michael S. Jones, Captain, U.S. Air Force S.B., U.S. Military Academy
June 1964

Abstract (excerpt)
This is an investigation into the effects of certain variables on the performance of man doing a precise superposition task. This simulates the task that the Project Apollo navigator will be required to perform during the mid-course (translunar and transearth) phases of the proposed lunar excursion. For this investigation, the Apollo Sextant Simulator located at the M.I.T. Instrumentation Laboratory, Cambridge, Massachusetts was used. The variables were (1) Rate of spacecraft motion, (2) Magnification of sextant telescope, (3) Orientation of landmark, and (4) Star-landmark contrast ratio. In order to determine the effect of each variable individually, only one was varied at a time.

The Evolution of Flight Control of the Apollo Mission

Maxime A. Faget

The purpose of this paper is to recount how the various Apollo flight control techniques and systems were first conceived and how they evolved. However, as I started tracing early events and attempted to recall to memory the motivation for the things we did and didn't do, it became increasingly clear that the question at the time was not how man may fly to the Moon, but could it be done with adequate safety.  And one of the dominant considerations concerned the feasibility of navigation and flight control. Thus, the evolution of flight control of the Apollo mission is best seen as part of the history of American manned space flight.

Hybrid Simulation of the Apollo Guidance Navigation and Control System

Philip G. Felleman
December, 1966

     The MIT Instrumentation Laboratory has the responsibility for the design of the Guidance and Navigation System for the Block I Apollo Spacecraft and the further responsibility of the design of the primary control system for the Block II spacecraft and LEM. This results in both a hardware design and on-board computer programs for each mission. The purpose of this hybrid simulation laboratory is to verify these programs in a real-time simulation which utilizes G&N flight hardware. With these simulators, crew procedures are examined and programs can be modified to allow a better interface between the flight crew and the G&N system. The simulator also becomes a part task trainer with the addition of a cockpit mockup.
     The facility uses an analog/digital general-purpose computer, flight hardware such as the onboard computer, coupling data units, and special purpose simulators for the inertial measurement unit and accelerometers. The facility is designed to allow rapid changeover from Block I to Block II simulations.

Computer-Aided Inertial Platform Realignment in Manned Space Flight

James A. Hand
May 1968

     Manually conducted star sighting necessary to realign an inertial platform during long-term manned space flights are, at best, a time consuming task.  At worst, these sightings can be critically time consuming since they are prerequisite to accurate spacecraft guidance and control functions; e.g. reentry maneuvers.
     Through establishment of logical communications between a star tracker, a computer and a previously aligned inertial platform, it has been shown practical to bypass the manual sighting function and execute optics pointing, search moding, target acquisition and data processing such that a completely automatic realignment is accomplished.  The technology represented by the Apollo Guidance and Navigation system is the foundation for developing this automatic inertial platform realignment capability.  The new capability is being considered for an Apollo Applications Program experiment to be conducted from low earth orbit.

Apollo Navigation, Guidance, and Control Systems: A Progress Report.

David G Hoag
April 1969

The status of certain aspects of the Apollo navigation, guidance, and control systems in the command module and lunar module are examined on the basis of experience with the first eight development flights.  Covered in this paper are facets of the inertial, optical, and computer hardware operation.  The application of these hardware subsystems to the digital autopilots, rendezvous navigation, midcourse navigation, and entry are examined.  The systems are judged to be fully ready to help a crew of astronauts land on the moon.

The History of Apollo On Board Guidance and Navigation

David G Hoag
September 1976
P- 357

When Apollo astronauts finally walked on the moon, thousands of engineers, scientists, managers, and technicians of many disciplines and specialties shared in the glorious accomplishment of an extraordinary national goal.  This is the story of an essential part of that endeavor -- that of the development and execution of the guidance, navigation, and control systems which, on-board Apollo along with the astronauts, made essential measurements of the motions of the spacecrafts and directed necessary maneuvers for the mission.

LEM Guidance Computer Programs to be Supplied by MIT

David G. Hoag
November 1965
AG: 937 -65

Introduction (excerpt)

This document is being submitted by MIT for approval by the Apollo Guidance Software Control Panel.  The document defines the test programs which will be supplied by MIT to support checkout of the LEM flight vehicle system, GAEC radar integration tests, and GAEC flight control integration tests.  These programs will be incorporated into the basic Block 2 computer service program designated as AURORA by MIT.  It was agreed at NASA Coordination Meeting # L18A and GAEC/MIT Checkout Work Group Meeting #14 that these programs, which were outlined in the above meetings, would satisfy all of the LGC program requirements for the above checkout and integration tests.


Description and Performance of the Saturn Launch Vehicle's Navigation, Guidance, and Control System

Walter Haeussermann
George C. Marshall Space Flight Center
July 1970
TN D-5869

   A review of the navigation, guidance, and control system of the Saturn launch vehicle includes the system analysis and design, signal flow diagrams, redundancy, and self-checking features used to obtain extreme reliability for crew safety.
   The iterative path adaptive guidance mode , featuring flight path optimization, is explained and presented in its computational form. Following the analytical considerations, the main guidance and control components are described. The navigation and control information is obtained inertially by a gyro-servo-stabilized, three-gimbal platform system with three mutually orthogonal pendulous-integrating gyro accelerometers; the single-degree-of-freedom gyros as well as the accelerometers use externally-pressurized gas bearings. Rate gyroscopes provide attitude stabilization; some vehicle configurations require additional accelerometer control to reduce wind loads. The digital computer system serves as the computation, central data, and onboard programming center, which ties in with the ground computer system during the prelaunch checkout of the overall system. The control signals are combined, shaped, attenuated, and amplified by an analog type control computer for engine actuator control.
   Results from recent launchings of Saturn V vehicles are presented to confirm the adequacy of the navigation, guidance, and control system and its overall performance even under extreme flight perturbations.

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