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

Apollo Guidance Computer and Other Computer History


luminary1.jpg (174681 bytes)   Sample AGC Code (courtesy of Gary Neff).

Red => In my collection.

Teal => On order

Apollo 13 Guidance, Navigation, and Control Challenges

John L. Goodman, United Space Alliance
AIAA Space 2009 Conference & Exposition
September 14-17, 2009
Pasadena, California
AIAA 2009-6455

Abstract: Combustion and rupture of a liquid oxygen tank during the Apollo 13 mission provides lessons and insights for future spacecraft designers and operations personnel who may never, during their careers, have participated in saving a vehicle and crew during a spacecraft emergency. Guidance, Navigation, and Control (GNC) challenges were the reestablishment of attitude control after the oxygen tank incident, re-establishment of a free return trajectory, resolution of a ground tracking conflict between the LM and the Saturn V S-IVB stage, Inertial Measurement Unit (IMU) alignments, maneuvering to burn attitudes, attitude control during burns, and performing manual GNC tasks with most vehicle systems powered down. Debris illuminated by the Sun and gaseous venting from the Service Module (SM) complicated crew attempts to identify stars and prevented execution of nominal IMU alignment procedures. Sightings on the Sun, Moon, and Earth were used instead. Near continuous communications with Mission Control enabled the crew to quickly perform time critical procedures. Overcoming these challenges required the modification of existing contingency procedures.

Lunar Module Interface Control Drawings

Introduction (excerpt)
This ICD defines and unless otherwise stated, controls the electrical signal interface between the LM Guidance Computer (LGC), including the DSKY, and LM Spacecraft subsystems. Electrical requirements for the interface through which spacecraft prime power is supplied to the LGC are included for reference only. The controlling document for prime power is LIS-390-10002.

Space Transportation System As Seen by an Astronaut

Fred W. Haise, Jr.
October 4, 1974
AIAA Paper 74-1287

The astronaut's role in space transportation is embodied in the Space Shuttle and its associated payload operations. This next-generation spacecraft represents the man-in-space system through the 1980's. A discussion of man's role in the Space Shuttle Program requires some reference to previous manned programs, as many tasks have foundations in the past. Generally, the work astronauts perform can be divided into piloting, experiments/payloads, and "other duties asassigned," which includes such tasks as systems management, extravehicular activity, and housekeeping. The emphasis on man's role will alter somewhat as the Shuttle system progresses from the initial test phase to the operational phase. The Shuttle is designed for automatic guidance, navigation, and control (GN&C), and the need for active piloting will decrease with system maturity. With the shift to onboard autonomous operation, the system management role will expand. Direct tasks with delivery/recovery and laboratory/observatory payloads will continue to expand throughout the program. The Shuttle assures man a role in space through the 1980's. The specific tasks include those involved with previous manned spacecraft as well as some new ones that are primarily associated with payloads. There will be a shift in emphasis regarding the astronaut's tasks as the Shuttle system matures.

The Space Shuttle -- A Future Space Transportation System

Robert F. Thompson
November 1974
AIAA Paper 74-1286

The objective of the Space Shuttle Program is to achieve an economical space transportation system. This paper provides an introductory review of the considerations Which led to the Government decisions to develop the Space Shuttle. The role of a space transportation system is then considered Within the context of historical developments in the general field of transportation, followed by a review of the Shuttle system, mission profile, payload categories, and payload accommodations which the Shuttle system will provide, and concludes with a forecast of the systems utilization for space science research and payload planning activity.

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.

James E. Webb’s Letter to President Kennedy of 30 November 1962

Requested by the President at Our Meeting on 21 November 1962

Author's (Robert C. Seamans) Notes (Excerpt)Memo
The discussion with President Kennedy on 1 November revolved around the issue of a $400-million supplemental request for fiscal year 1963. Brainerd Holmes recommended the supplemental as a means for advancing the lunar landing date from 1967 to 1966. Mr. Webb, Dr. Dryden, and I were strongly opposed. In 1961, we had gained approval from Congress for an FY 1962 budget increase from $1.1 billion to $1.8 billion, and Congress had appropriated $3.7 billion for FY 1963. In our view, Congress would balk at a still further increase, and we didn’t feel that NASA could efficiently sustain still further growth.
The Gemini MOCR A picture of the Gemini MOCR.

Picture of MOCR with personnel identified.

This material courtesy of Sy Liebergot.

NASA Electronics Research Center



The Apollo Guidance Computer: A User's View

David Scott, NASA Astronaut
Document and Photo Courtesy of Eldon C. Hall




Apollo Guidance Computer Documents


A collection of documents about the Apollo Guidance Computer.

Apollo Experience Reports

Index to documents from the NASA Technical Reports Server

AGC NOR Gate Specifications


The documents below, courtesy of Eldon C. Hall, are the specifications and related documents for the AGC's NOR gate (flat pack, dual 3-input NOR version).

AGC Integrated Circuit Packages


The documents below, courtesy of Eldon C. Hall, discuss issues with moving to the flat package for the Block II Apollo Guidance Computer, a dual 3-input NOR microcircuit.

AGC - Saturn V LVDC Comparison


The documents below, courtesy of Eldon C. Hall, discuss an evaluation of the Apollo Guidance Computer and its potential replacement with the Saturn V Launch  Vehicle Digital Computer.

Miscellaneous Apollo Memos and Documents


The documents below are courtesy of Eldon C. Hall.

Apollo Spacecraft

George M. Low
NASA Manned Spacecraft Center
AIAA 6th Anual Meeting and Technical Display
Anaheim, California, October 20-24, 1969

The flawless performance of the five manned Apollo flights is attributed to reliable hardware; thoroughly planned and executed flight operations; and skilled, superbly trained crews.  Major factors contributing to spacecraft reliability are simplicity and redundancy in design; major emphasis on tests; a disciplined system of change control; and closeout of all discrepancies.  In the Apollo design, the elimination of complex interfaces between major hardware elements was also an important consideration.  The use of man, in flying and operating the spacecraft, evolved during the course of the program, with a tendency to place more reliance on automatic systems; however, the capability for monitoring and manual takeover was always maintained.  The spacecraft test effort was increased during the 18 months preceding the first manned flight with emphasis on environmental acceptance testing.  This test method screened out a large number of faulty components prior to installation.

Tales from the Lunar Module Guidance Computer

Don Eyles
27th Annual AAS Guidance and Control Conference
February 4-8, 2004, Breckenridge, Colorado
Paper # AAS 04-064


The Apollo 11 mission succeeded in landing on the moon despite two computer- related problems that affected the Lunar Module during the powered descent. An uncorrected problem in the rendezvous radar interface stole approximately 13% of the computer's duty cycle, resulting in five program alarms and software restarts. In a less well-known problem, caused by erroneous data, the thrust of the LM's descent engine fluctuated wildly because the throttle control algorithm was only marginally stable. The explanation of these problems provides an opportunity to describe the operating system of the Apollo flight computers and the lunar landing guidance software.

Historical Perspectives on Apollo

Eugene M. Emme
NASA Headquarters
AIAA 4th Annual Meeting and Technical Display
Anaheim, CA, October 23-27, 1967

Abstract (excerpt)
Launching from preceding papers and other examples of turning points in the history of aerospace technology, this paper focuses upon the major elements culminating in mid-l96l with a national decision to broaden and to accelerate the American space program. It examines the influential factors, such as the pace of large rocket booster development, which determined the assessment of the national effort in space. It supports the totality of this assessment of the space program and the portents for the future made in mid-l96l was a strategic decision largely confirmed by subsequent events bringing across-the-board space competence to the United States. Important prerequisites for a sound decision -- technological feasibility, basic program definition, and active development of major components -- were existent before Yuri Gagarin -- first orbited the earth in Vostok I on April 12, 1961. On April 12, such a decision had political feasibility at the highest level as well as with the general public. The Apollo-dramatized request for a national decision by President Kennedy on May 25, endorsed by the Congress and public opinion, required no fundamental alteration of the national goals, governmental structure, or operational basis of the American space program as it had been instituted via the national decision in 1958 after Sputnik.

Edgar M. Cortright: Oral History


The following interview of Dr. Edgar Cortright was conducted on August 20, 1998, Langley Research Center in Virginia

The "Bug" Heard 'Round the World

Jack Garman
NASA, Johnson Space Center
ACM Software Engineering Notes
October, 1981, pp. 3-10.

Introduction (excerpts)
Discussion of the software problem which delayed the first Shuttle orbital flight.

On April 10, 1981, about 20 minutes prior to the scheduled launching of the first flight of America's Space Transportation System, astronauts and technicians attempted to initialize the software system which "backs-up" the quad-redundant primary software system ......and could not.  In fact, there was no possible way, it turns out, that the BFS (Backup Flight Control System) in the firth onboard computer could have been initialized properly with the PASS (Primary Avionics Software System) already executing in the other four computers.

The Prologue, A Look at Apollo and Apollo/Soyuz

C.M. Lee and A.S. Lyman

AIAA Life Sciences and Systems Conference
Arlington, Texas, November 6-8, 1974
Paper No. 74-1284

Abstract (excerpt)
   During the past decade there has been much discussion of the relative merits of manned versus unmanned space activities.
   With the advent of Shuttle, the distinction between the manned and unmanned missions becomes blurred as they come together into a unified approach for carrying out our total space objectives.  Shuttle will be the launch vehicle for transporting almost all automated as well as manned missions into space.
   As we progressed from Mercury to Gemini to Apollo to Skylab and not to the Apollo/Soyuz Test Project (ASTP) and Shuttle, the role of man has become more important and his capabilities have been increasingly exploited.  During this period, we were learning that man could survive and function normally in a space environment, we demonstrated that man could live and effectively work in space, we extended our knowledge of our planet earth through space observation and experimentation, in Apollo, a giant step was taken in exploiting man's capabilities in space, and in ASTP we will lay the groundwork for possible international space rescue and future joint missions.

Memory Requirements for the Launch Vehicle Digital Computer (LVDC)

J.J. Rocchio, Bellcomm, Inc.
April 25, 1967

Abstract (excerpt)

The Launch Vehicle Digital Computer (LVDC) has a modular memory system with a maximum capacity of eight modules. Each module has 16 sectors, for a total of 28 sectors (64 duplexed sectors) in all.  At this time, expected reserve capacity in the LVDC memory is about 18% (12.9 sectors duplex) of total capacity for AS 501, and only 11% (6.9 sectors duplex) for AS 504. This is considered insufficient to provide an adequate margin for new requirements and contingencies.


F.J. Bailey, Jr., NASA Manned Space Center
AIAA Space Flight Testing Conference
Cocoa Beach, Florida, March 18-20, 1963

   The papers presented so far in this session have described specific measures taken in preparing the launch vehicle and spacecraft for Mercury missions.  the purpose of the present paper is to review, in somewhat more general terms, some of the more significant lessons learned in the Mercury program, to see where changes or additional measures may be desirable in future programs.
   The lessons that have been learned fall broadly into two main areas, the first applying to program planning, the second to detailed design.

Product Assurance Program Planning - Some Lessons Learned from Apollo

Gerald Sandler, Grumman Aerospace Corporation
AIAA Paper No. 72-247
AIAA Man's Role in Space Conference
Cocoa Beach, Florida, March 27-28, 1972


Over the past decade we have developed the technical and programmatic approaches needed to provide the levels of reliability required for manned space missions. The combination of design, test and control or assurance programs used on Apollo have proven very effective. In the design approach we have learned how to minimize the number of potential single-point failures that could result in mission failure. In test and product assurance areas, screens and controls were established that effectively prevented a. latent defect from filtering through the system and occurring in flight. The cost of these combined efforts, however, have been a large percentage of total program costs. The challenge of this decade, I believe, is how to achieve the same or improved levels of reliability at lower program costs.

The area of primary concentration, at this time, should be failures that are "human oriented" rather than "design oriented". Our engineering techniques have gone a long way in reducing the latter problem area. on Apollo half or more of the failures that occurred in the test programs were classified as workmanship, procedural or quality-oriented problems. We have learned how to screen them out by test; what we have to do now is to prevent them from occurring or catch them earlier. In addition, recognizing that failures will always occur in our test programs, the cost challenge is to design units and systems for maintain- ability, rework and proper isolation, so that we can minimize the extent of retesting for adequate confidence.

Mission Control of Lunar Orbiter I

J.C. Graves, The Boeing Company
Dalton D. Webb, NASA Langley Research Center
AIAA Paper No. 67-278
AIAA Flight Test, Simulation and Support Conference
Cocoa Beach, Florida, Feb. 6-8, 1967

For those unmanned spacecraft that have so far ventured into space beyond the Earth's immediate influence, Earth-based mission control systems have taken the place of the on-board crew. The Lunar Orbiter mission control system is comprised of long-range tracking, telemetry, radio command, and computing equipment plus a team of skilled flight control engineers. After spacecraft separation from the Atlas-Agena launch vehicle, mission control was transferred from the Eastern Test Range to the Space Flight Operations Facility at Pasadena, California, where three crews of flight controllers worked around the clock for 35 days analyzing millions of data samples and originating over 4500 commands to the spacecraft to control its flight path, attitude, and photographic activities. During the flight of Lunar Orbiter I during August 1966, a number of nonstandard events occurred. All of these situation were detected and properly analyzed by the flight control team, and, with the exception of a camera shutter control problem, work-around procedures were developed for all anomalies encountered. A second camera in the spacecraft did, however, successfully provide extensive and informative photographic coverage of the lunar surface. This important contribution to Apollo and to science is surpassed only by the highly successful second flight recently concluded this past December.

Apollo Rendezvous Navigation

Richard Phillips and Peter Kachmar
27th Annual AAS Guidance and Control Conference
February 4-8, 2004, Breckenridge, Colorado
Paper # AAS 04-063

Abstract (excerpt)
     The Apollo guidance, control and navigation system was designed by Draper Laboratory (nee the MIT Instrumentation Laboratory) during the mid to late '60's, but was the legacy of a series of earlier studies of Mars photographic reconnaissance missions which had been sponsored by the Air Force Ballistic Missile Division. The development of rocket engines and inertial measurement instruments was basic to turning the dream of poets into the reality of a trip to the moon, but on a narrower scale the development of practical guidance and navigation algorithms was enabled by the development of programmable digital computers and of higher order programming languages. In this paper we will focus in particular on navigation and guidance associated with the rendezvous of the Lunar Module with the Command Module as they orbited the moon.


Sherman M. Seltzer
27th Annual AAS Guidance and Control Conference
February 4-8, 2004, Breckenridge, Colorado
Paper # AAS 04-061


     The purpose of this paper is to describe the SATURN Launch Vehicle that successfully launched the manned APOLLO spacecraft into Earth orbit and thence onto a trans-lunar trajectory to the moon. It will then describe the SATURN G&C system that enabled this to occur.
     Using a "building block" approach, the NASA Marshall Space Flight Center (MSFC), under the direction of Wernher von Braun, achieved 33 successful launches out of33 attempts. This included:
  • Ten unmanned SATURN I "multiple engine development flights," seven of which were orbital;
  • Ten orbital SATURN IB "APOLLO hardware development flights," five of which were manned; and
  • Thirteen manned APOLLO Saturn V missions, seven of which were lunar.

     This is the only major rocket development program ever to be completed without a catastrophic in-flight failure. The SATURN V, with its 34.7-million N (7.5-million pounds) of thrust in its first stage, lofted 96,000 kg (212,000 lb) of payload into Low Earth Orbit [213 km (115 nautical miles)]. The SATURN 3rd stage then went on to place a 48,500 kg (107,350 lb) payload onto a trans-lunar trajectory. This paper will describe how NASA MSFC was successful in developing and implementing this system. It will describe the SATURN G&C system, including its genesis and associated trade studies. The techniques will be described to show how this feat was accomplished: engineering leadership; the extensive "building block approach; and the integrated design analysis, simulations, and testing.

Collective Knowledge Gained from Gemini

Charles W. Mathews
NASA Manned Spacecraft Center
AIAA Paper No. 66-1027
AIAA Third Annual Meeting, Boston, MA, Nov. 29-Dec. 2, 1966.

The Gemini Program has comprised 12 space flights, 10 of which were manned operations.  The information gained is difficult to summarize within a brief paper, but more detailed information has and will continue to be made available to those who have an interest in it.  With minor exceptions, the objectives of the program were met, having been expanded well beyond original concepts and examined in considerably more depth than expected.  Gemini leaves a legacy of results that, hopefully, will further accelerate man's efforts to explore and utilize the frontier of space.

Summary of Gemini Rendezvous Experience

Glynn S. Lunney
NASA Manned Spacecraft Center
AIAA Paper No. 67-272
AIAA Flight Test, Simulation and Support Conference
Cocoa Beach, Florida, Feb. 6-8, 1967

A significant portion of the Gemini program was devoted to the rendezvous problem. One of the major objectives was to establish a base of operational experience and confidence in the required techniques. In this paper, the planning and flight test cycle is reviewed to provide an outline of the Gemini results. Many various considerations were studied and several of the more important factors are discussed as to their influence on the different choices and subsequent operations. The flight test results are summarized according to technique and performance such as propellant costs, satisfaction of conditions, et cetera. Overall, the conclusion is that the base of experience has been established, the rendezvous sequence is practical, the systems and the management of these systems have been satisfactory in accuracy and performance. Further study and a continued, detailed preparation will be the key to the future uses of rendezvous.

Gemini: Mercury Experience Applied

Jerome B. Hammack and Walter J. Kapryan
NASA - Manned Spacecraft Center
Houston, Texas


     It is the intent of this paper to show how the Gemini program has attempted to draw upon and profit from Mercury experience.
     The Gemini Project has evolved as a NASA space program with its prime mission of providing a flexible space system that will enable us to gain proficiency in manned space flight and to develop new techniques for advanced flights, including rendezvous.  To achieve these objectives, we must have a space vehicle with substantially greater capability than the Mercury spacecraft.  This increased capability will include provisions for two men, instead of one, as in the Mercury spacecraft and for space missions of up to two weeks' duration.  It is the intent of the Gemini Project to build upon the experience gained from Mercury so that most of the energies of the new program can be devoted to the solution of the problems associated with achieving its primary mission objectives and not have to fight its way through a swelter of old problems.

Block I Apollo Guidance Computer (AGC): How to build one in your basement

This report describes my successful project to build a working reproduction of the 1964 prototype for the Block I Apollo Guidance Computer. The AGC is the flight computer for the Apollo moon landings, with one unit in the command module and one in the LEM.

Electrical Systems in Missiles and Space Vehicles

H. J. Fichtner
Astrionics Division
George C. Marshall Space Flight Center
National Aeronautics and Space Administration
Huntsville, Alabama

Commemorating the Fiftieth Birthday of Wernher von Braun, March 23, 1962
Edited by: Ernst Stuhlinger, Frederick I. Ordway, III, Jerry C. McCall, and George C. Bucher

Introduction (excerpt)
     Now that space operations have become a reality, it is appropriate to review the accomplishments of the past and to discuss what must be done in the future to insure the operational readiness of our large carrier vehicle systems. Well-planned overall systems engineering is the key to this task, with electrical systems engineering playing a major subsidiary role.
     When missiles were introduced on a relatively large scale some 25 years ago overall electrical systems engineering did not exist as such, although with theV2 missile the systems approach was being utilized for the first time. In those days the designers of the propulsion system provided for the system's electrical needs by maintaining the required start and cutoff sequence. The designers of the guidance and control system worked their own electrical system and took care of the electrical equipment needed for the checkout and launch operations.

Special Instrumentation for Apollo Developmental Spacecraft

Alfred B. Eickmeier
NASA Manned Spacecraft Center, Houston Texas
Aerospace Instrumentation, Volume 4
Proceedings of the Fourth International Aerospace Symposium, 1966, Edited by M.A. Perry

Introduction (excerpt):
The recent advent of space exploration and manned space flight has provided aerospace technologists and engineers with many challenging problems in instrumentation development and application  Capabilities for accurate determination of inflight spacecraft performance and external environmental parameters have steadily increased from early missile flights, which required only a few relatively simple measurements, to present-day programs such as Apollo, which require in excess of several hundred independent and individual measurements.

"Apollo Reaction Control Systems"

Chester A. Vaughan
Manned Spacecraft Center, Houston Texas
Paper No. 68-566
AIAA 4th Propulsion Joint Specialist Conference
Cleveland, Ohio
June 10-14, 1968

Descriptions of the reaction control systems for the Apollo command module, service module, and lunar module are presented. Major problems encountered during the development and qualification of the engines for these systems are discussed. These systems are pressure fed, bipropellant, hypergolic propulsion systems utilizing nitrogen tetroxide as the oxidizer and the hydrazine group of fuels. A total of 44 reaction control system engines are installed in the three modules. The Apollo reaction control system must satisfy many unique environmental requirements ranging from zero-gravity propellant feed to operation with the reaction control system engine in a gravitational field firing vertical up. Operational requirements range from short on-off to long on-off firing times. Total impulse requirements from a single firing range from 0.4 to 50 000 pound-seconds. Ten thousand firings may be required of some engines. Three Apollo command module and service module flights and one lunar module flight have been made. In each flight, the reaction control system performed its required functions successfully.

Apollo -  A Program Review

SP-257: National Aeronautics and Space Meeting
Los Angeles, 1964


Checkout Criteria and Requirements for Manned Spacecraft

Rolf W. Lanzkron and William C. Fischer
National Aeronautics and Space Administration
AIAA Paper No. 65-284
AIAA/AFLC/ASD Support for Manned Flight Conference
Dayton, Ohio, April 21-23, 1965

Abstract (excerpt)
The basic criteria for checkout of manned vehicles can be stated as follows, quoted from the "Apollo Checkout Criteria":
  1. Provide for astronaut safety and assure the accomplishment of mission objects.
  2. Demonstrate that no malfunction exist within the vehicle at the time of launch
  3. Provide for monitoring and analysis of critical functions in such a manner that anomalies can be recognized and assessed in time for remedial action
  4. Demonstrate to the maximum extent practicable operational suitability of vehicles and their associated ground support equipment.

These statements summarize the basic Apollo Checkout Criteria.

Apollo Guidance Computer

from Wikipedia, the free encyclopedia

The Apollo Guidance Computer (AGC) was the first recognizably modern embedded system. It was developed for the Apollo program by the MIT Instrumentation Laboratory under Charles Stark Draper, with hardware design led by Eldon C. Hall (see References). Based upon MIT documents, early architectural work seems to come from J.H. Laning Jr., Albert Hopkins, Ramon Alonso, and Hugh Blair-Smith. The actual flight hardware was fabricated by Raytheon, whose Herb Thaler was also on the architectural team.

NASA History Office Publications


All publications:

Online publications:

Notes on Comments by a Panel of Apollo Astronauts with U.S. Navy Backgrounds

11th Annual Naval Aviation Symposium
The National Museum of Naval Aviation
Pensacola, Florida

May 18, 1997

Panel of Apollo Astronauts:

  • Armstrong, Neil A. (Mr.)

  • Cernan, Eugene A., Captain, USN (ret.)

  • Lovell, James A., Captain, USN (ret.)

  • Schirra, Walter M., Captain, USN (ret.)

  • Shepard, Alan B., Rear Admiral, USN (ret.)


  • Roy Neal, aerospace correspondent, NBC News (ret.)


  • Jack Fetterman, Vice Admiral, USN (ret), President and CEO, Naval Aviation Museum Foundation

  • Patricia Tracey, Vice Admiral, Director, Naval Training, and Chief, Naval Education and Training, U.S. Navy

"25 Years Ago"

Fred Martin, MIT/IL

25 years ago it happened, the first Lunar Landing, Apollo 11 - July 20,1969. It was an exciting, exhilarating time of total focus and dedication. Current and alumni Intermetrics employees were intimately involved with the project since its inception in 1960 (John Miller, Jim Miller, Ed Copps, Jim Flanders, Dan Lickly, Joe Saponaro, Bill Widnall, John Green, Alex Kosmala, Ray Morth, Steve Copps and me, Fred Martin). The most memorable part of the flight for me, aside from the landing and the moonwalk itself, was the descent from lunar orbit to the surface. I'd like to present a personal remembrance and perspective.

Special Message to the Congress on Urgent National Needs

President John F. Kennedy
Delivered in person before a joint session of Congress
May 25, 1961

First, I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish.



  • Guy Thibodaux -- NACA rocket propulsion expert, later Division Chief in Propulsion Systems at JSC
  • Max Faget--member of the Space Task Group (STG), designer of the Mercury and Apollo capsules and the shuttle, considered the father of spacecraft design, later Head of Engineering at JSC
  • Paul Purser-- hired Thibodaux and Faget at Langley during NACA days, member of STG, later Deputy Administrator of JSC under Bob Gilruth
  • Clotaire Wood--former Special Assistant to Hugh Dryden, Deputy Administrator of NASA
  • Harry Finger--former nuclear propulsion expert from Lewis, early Associate Administrator for NASA
  • Adelbert O. Tischlier--propulsion engineer, in the early days of Lewis, member of the STG
  • Josephine Dibella-- former secretary for Hugh Dryden and the STG
  • Guy Thibodaux, Max Faget, and Paul Purser



Title, Author, and Reference


LEM Electronics Reliability

J. B. Friedenberg, J.J. Landers, and P. Marcellos
LEM Program Management Office
Aerospace Systems Division, Burlington, Mass.

The LEM Program at RCA pp. 16-20 A brief description of the wide range of reliability tasks implemented under the Lunar Excursion Module (LEM) reliability program illustrates the vital role of reliability in all phases of the program, from conceptual design of a circuit to delivery as flight hardware. Analytical techniques and hardware aspects of reliability are discussed.

Distributed Processing on the Space Shuttle:
A Case Study

P. 5. Schoonmaker
McDonnell Douglas Technical Services Co., Inc.
Houston, Texas
AIAA Paper 81-2140

This paper describes a study of centralized vs. distributed processing approaches to the design and integration of a new Space Shuttle Orbiter subsystem -- the Power Extension Package (PEP), a 25-kw solar array. The objective of this study was to determine the "best" a l location of PEP monitoring and control functions between the existing Orbiter Systems Management (SM) computer and an autonomous PEP processor. Four candidate functional configurations were defined, and a subjective, life-cycle assessment of the re1ative merits o f these candidates was performed by the study team. We concluded that the optimum configuration will (a) include substantial processing "intelligence" in the PEP processor, and (b) make use of SM computer "standard services".

Airborne Computer Technology

W. T. Chow
IBM Electronics Systems Center
Owego, New York

Proceedings of the Tenth Space Congress
Cocoa Beach, Florida
April 11-13, 1973
pp. 4-19 through 4-28


The development of airborne digital computer has been greatly influenced by rapid technological advances.  This paper provides an overview of the present status and the direction of further evolution.  It discusses the changes that are taking place in the areas of hardware, software, and computer organization; and suggests a number of approaches towards a broadened usage of airborne computer to take advantage of its increasing capability and decreasing cost.

Skylab Attitude Control System

T. R. Coon, J. E. Irby
IBM Journal of Research and Development
Volume 20, Number 1, Page 58 (1976)


The attitude stabilization and control system for Skylab evolved from an analog controller into a fully digital processing system. Features of this system include a software-determined attitude reference to provide general maneuvering ability, an in-orbit programming capability, the use of large control moment gyros for attitude control, and the use of vehicle maneuvers to desaturate gyro momentum. The objectives, requirements, and implementations of the control system software are described, along with the rationales for certain design decisions and discussion of some system dynamics and actual performance.

EXPLORER I: A New Look at America's First Satellite

Matt Bille (AIAA Senior Member)
Booz, Allen & Hamilton
Colorado Springs, CO

Erika Lishock
Colorado Springs, CO

Paper AIAA 2002-0313
40th AIAA Aerospace Sciences Meeting Reno, NV January 14-17, 2002.

In October 1957, the first race into space ended with the launch of the Soviet Union's Sputnik 1. As America's official satellite program, Vanguard, struggled through technical difficulties, Wernher von Braun and his Army Ballistic Missile Agency team successfully pressed for permission to launch their own satellite. The result was Explorer 1, which, despite its hurried construction and diminutive size, restored American prestige while making a major scientific discovery. This paper draws on recent scholarship, declassified documents, and new interviews conducted by the authors to clarify the technology and the politics surrounding America's first satellite. The genesis of Explorer 1 involved science, interservice rivalry, Cold War politics, and some truly ingenious engineering. In the modern era, where satellite programs may cost billions of dollars and take decades to carry out, the achievements of the tiny Explorer spacecraft convey lessons which should be preserved.

NOTSNIK: The Secret Satellite

Matt Bille (AIAA Senior Member)
Booz, Allen & Hamilton
Colorado Springs, CO

Erika Lishock
Colorado Springs, CO

Paper AIAA 2002-0314
40th AIAA Aerospace Sciences Meeting Reno, NV January 14-17, 2002.

In the late 1950s, the entire world became aware of the successes and failures of the first Earth satellite projects - Sputnik, Explorer, and Vanguard. Only a handful of people knew there were actually four such projects, not three. In the California desert, Navy engineers and scientists in 1958 were engaged in a classified crash program to develop the world's first aircraft-launched satellite. Against an impossible deadline, with limited resources, they may just possibly have succeeded. This paper examines the now-declassified story of the "NOTSNIK" satellite booster, a five-stage improvisation using a concept decades ahead of its time. In the frantic days after Sputnik, personnel at the Naval Ordnance Test Station in China Lake conceived a project to put rapid, all-aspect access to orbit in the hands of naval forces worldwide. From approval to orbit, they had four months to design and build a complete space system. Their one-kilogram test satellites may or may not have made orbit, but the project stands as a fascinating demonstration of ingenuity, determination, and imagination in the first year of the Space Race.


"Some Aspects of the Logical Design of a Control Computer: A Case Study"

R.L. Alonso, H. Blair-Smith, and A.L. Hopkins, Instrumentation Laboratory, MIT, Cambridge, Mass.
IEEE Transactions on Electronic Computers, December 1963, pp. 687-697


     Some logical aspects of a digital computer for a space vehicle are described, and the evolution of its logic design is traced.  The intended application and the characteristics of the computer's ancestry form a framework for the design, which is filled in by accumulation of the many decisions made by its designers.  This paper deals with the choice of word length, number system, instruction set, memory addressing, and problems of multiple precision arithmetic.
     The computer is a parallel, single address machine with more than 10,000 words of 16 bits.  Such a short word length yields advantages of efficient storage and speed, but at a cost of logical complexity in connection with addressing, instruction selection, and multiple-precision arithmetic.

"Primary Processor and Data Storage Equipment for the Orbiting Astronomical Observatory"

Thomas B. Lewis, IBM Corporation, Space Guidance Center, Owego, NY.
IEEE Transactions on Electronic Computers
December 1963, pp. 677-687

     Telescopes in space will soon permit astronomers to observe the heavens in more detail than ever before.  The Orbiting Astronomical Observatory (OAO) is a space vehicle designed to place these telescopes in orbit beyond the earth's atmosphere and to telemeter the collected data back to earth.
     To aid the orbiting observatory in the fulfillment of its scientific mission, a low-power, long-life, high-density command and memory system has been designed and is currently undergoing qualification testing.  The digital command storage and processing element will permit reprogramming of spacecraft orientation and astronomical experiments on each orbit, even when the satellite is not in contact with the ground, while the core memory element will permit storage of experiment data for subsequent transmission to the ground.
     In the following paper, the functional design of the satellite command and memory system is discussed in detail.  In addition, the power conservation methods, reliability design techniques and environmental performance considerations which influenced the design of this equipment are reviewed.


"Mission Influences on Advanced Computers"

Gene A. Vacca, NASA Office of Advanced Research and Technology, Philip L. Phipps, UNIVAC Div., Sperry Rand Corp., and Thomas E. Burke, NASA Electronics Research Center
Astronautics & Aeronautics
April 1967, pp. 36-40

     Future spaceflight and advanced SST and Jumbo Jet operations help define mainstream trends in computers and promote design concepts.


"Flight Computer Hardware Trends"

Ramon L. Alonso, MIT, and Glenn C. Randa, IBM Corp.
Astronautics and Aeronautics
April 1967, pp. 30-34


     Increasingly powerful integrated-circuit technology - promising new flight programs, controls, and displays - now challenges the foresight of the system designers.

Proceedings - Conference on Spaceborne Computer Engineering

Anaheim, California
October 30-31, 1962


"Computer Design Problems for the Space Environment"

Dr. Joseph F. Shea, Deputy Director of Manned Space Flight (for Systems), NASA
Proceedings - Conference on Spaceborne Computer Engineering

October, 1962, pp. 1-8

The performance of complex manned and unmanned space missions requires considerably sophisticated on-board computers to perform a variety of tasks.  This paper examines, in some detail, the functional and environmental requirements for such units.

"Two Approaches to the Design of Spacecraft Data Handling System"

R. C. Baron, R. W. Waller, Computer Control Company, Inc.
Proceedings - Conference on Spaceborne Computer Engineering

October, 1962, pp. 9-18

The Systems described in this paper were developed by Computer Control Company for the Jet Propulsion Laboratory (NASA) for use in the Mariner Interplanetary exploration program.  On board the Mariner Spacecraft are a number of instruments which perform experiments designed to further man's knowledge concerning the scientific properties of the planets and deep space.  Two spacecraft scientific data handling and control systems were designed for this program and are discussed here.  Both systems are similar in that they act as a buffer between all scientific experiments and telemetry.  They differ substantially in their implementation of this function.   One system, the Science Data Conditioning System (SDCS) is a real time, fixed sampling sequence and control system.  The other, the Science Data Automation System (SDAS), is a more versatile programming system which uses standard digital computer techniques to provide buffer data storage, variable experiment sampling sequences, and modified programs during the course of a mission.  The hardware used to build these two systems is described and the logic, circuit, and packaging marriage problems are discussed.

"A Multiaperture Digital Memory Having Nondestructive Sensing"

Proceedings - Conference on Spaceborne Computer Engineering
October, 1962, pp. 65-68

A ferrite sheet memory featuring nondestructive read operation and a short read cycle time has been developed.  The nondestructive read is accomplished by sampling the complex flux pattern in a selected bit position on the ferrite sheets.   The use of the ferrite sheet has resulted in considerable saving in wiring complexity as compared to previous systems having nondestructive read ability.

A small prototype memory was built, and has achieved read cycle times of one microsecond, information access times of 0.3 microseconds, and a write time of 4 microseconds.   The currents involved are easily obtainable with transistor drivers.


"Logic Organization of the UNIVAC ADD-1000 Aerospace Computer"

D.C. Morse, B.J. Jansen, and R.P. Blixt, UNIVAC Division of Sperry Rand Corporation
Proceedings - Conference on Spaceborne Computer Engineering

October, 1962, pp. 69-82

This report emphasizes the logical design of the ADD-1000 which is the first airborne computer to utilize a thin-film magnetic memory.

The computer operates in the binary, parallel mode employing two's complement fractional arithmetic.  The logic design is based on the use of a random-access moderate speed memory.  For example, assigned memory addresses in the scratch-pad memory are used in place of the several arithmetic registers such as A, Q, and X, and counters, such as velocity and incremental accumulators required by conventional computers.

A highly flexible repertoire of over 950 useful instructions is achieved by means of a sequential phase-field method of execution described in detail later.  The inherent flexibility of the instruction logic provides an effective saving in program memory capacity of more than fifty per cent over single address drum computers, and a smaller but significant saving over indirectly addressed computers, that is, computers without extensions or switching.

Other special features found in the computer include interrupt features; variable-length multiply and divide operations; capability to increment of decrement the content of any scratch-pad memory location without modifying the content of the accumulator; double-word-length shift instructions; 16 input and 16 output addressable channels (with an almost unlimited umber of direct inputs available); priority options; and on-line self-loading of program instructions and constants.

The computer represents a signifant achievement in meeting the requirement for a data processor which is small, light, rugged, and low in power consumption, while possessing at the same time the qualities of speed, large modular storage capacity, and high reliability.

Note: This "low power" machine had a peak power consumption of 262 watts peak, with performance measured in 10's of kips.  Along with the reference to the drum memory in the introduction, above, the I/O section of the computer, along with being tailored for missle control, had an interface to a paper tape reader and punch.


"The Arma Micro Computer for Space Applications"

E. Keonjian, Inertial Guidance Department, J. Marx, Arma Division, American Bosch Arma Corporation
Proceedings - Conference on Spaceborne Computer Engineering

October, 1962, pp. 103-116

The Arma Micro Computer is a serial binary, stored program computer, capable of calculating at the rate of 36000 operations on a 22 bit word per second.   Additoin or subtraction requires 27 x 10-6 seconds, including access to memory; multiplication requires 135 x 10-6 seconds; division requires 324 x 10-6 seconds; square root, depending on the precision required, up to 584 x 10-6 seconds.  Although it is a serial machine, computation rates are enhanced by access to memory in parallel while multiplication, division and square root processes in quasi-parallel, using unusual algorithms for minimization of hardware.  In addition, higher effective speed is obtained because the operations add or subtract, and multiply or divide or square root may be processed simultaneously.

The Micro Computer is designed, primarily, for versatility in handling such problems as guidance, on-board data evaluation and monitoring, system checkout and information telemetering for a missle or spacecraft.   It is the third in three generations of airborne computers designed and built by Arm Division of American Bosch Arma Corporation.


"The D210 Magnetic Computer"

Eugene T. Walendziewicz, Burroughs Corporation
Proceedings - Conference on Spaceborne Computer Engineering

October, 1962, pp. 117-127

The Burroughs D210 is a general-purpose, parallel, synchronous, digital computer using predominantly magnetic circuit techniques.  It is particularly well suited for use as a control element in applications which require operation in stressed environments, which require a computer of high reliability, and which call for equipment of small size, low weight, and low power consumption.  The D210 is capable of performing the computations required in missle and satellite systems for guidance, control, and system checkout.

The D210 overcomes the traditional speed limitations of magnetic systems, without resorting to the use of unconventional components, by means of a new organization.  Its unique logic permits relatively fast operations (30-microseconds add, for example) with a clock of only 100 kc, and requires minimal power consumption and a fraction of the compnents ordinarily required.

Power consumption is proportional to the computation rate, with essentially no standby power required.  Under program control, the clock rate can be varied to match the real-time needs of each task, thus minimizing drain on the primary power supply and extending component life through reduced dissipation.  With these characteristics, it is reasonable to predict an unattended computer life expectancy of up to several years for many applications.

Note: For those travelling here from the programmable logic pages, the logic used in this computer may be interesting.  The core-rope memory4 is described first and then a detailed explanation of their logic implementation follows.  The core-rope was used on the AGC, for example, for read only memories and had essentially a fixed AND plane and a programmable OR plane.  The programming of the OR plane was accomplished by threading or not threading a sense wire through the selected core, with 2n cores, each implementing a fixed AND function of all of the inputs.  The logic elements in the D210 were implemented by providing programmable AND and OR planes.   First, each input was complemented, making both senses of each input available.   Then, for each term involved in the AND function, either the true or complement was threaded through a single a core (it actually decoded when all inputs were a logic '0').   A sense line was then wound through all of the desired AND cores to finish implementation of the logic equation.  This is quite similar to a PLA.  Since large numbers of wires could be threaded through a core, the gates had a very high fan in to go along with their high fan out.

4R. Alonso and J.H. Laning, Jr., "Design Principles for a General Control Computer"(R-276, Instrumentatin Laboratory, MIT, April, 1960).


"HCM-202 Thin Film Computer"

M. M. Dalton, Hughes Aircraft Company
Proceedings - Conference on Spaceborne Computer Engineering

October, 1962, pp. 129-135

The HCM 202 is the latest in a family of high performance parallel computers for aerospace applications.  There are two major features which distinguish the HCM 202 from other aerospace digital computers.  First of all, the HCM 202 has been designed to fulfill the exacting requirements of a wide variety of aerospace applications with a minimum of redesign effort.  This flexible or modular design approach has been necessitated by an expanding market for small quantities of digital computers to fulfill the specific requirements of advanced aerospace systems.  The second unique feature of the HCM 202 is its advanced thin film construction.  The basic objectives of this thin film microelectronic fabrication method has been to greatly improve the reliability of the digital computer and to reduce the fabrication cost.   A further advantage of the construction technique used in the HCM 202 is a unique and highly flexible interconnection technique which has solved one of the major stumbling blocks to effective thin film construction of complex digital computers.

Note: For those travelling here from the programmable logic pages, the interconnection technique used in this computer may be interesting. On the back of the wafer, there's a two level grid of metal interconnect put down.  "By the simple selective etching of the upper or lower interconnection layers, virtually any given wiring configuration can be achieved. ... the unique arrangement required for each circuit  wafer need not be applied   ... is very nearly through its fabrication cycle."  This sounds similar to the more recent Chip Express devices.,


"Radiation Environment at High Orbital Altitudes"

Peter W. Higgins, Joseph C. Lill, and Timothy T. White, Space Physics Division, Science and Applications Directorate, NASA Manned Spacecraft Center.
Gemini Summary Conference

February 1-2, 1967, Manned Spacecraft Center, Houston, Texax, pp. 149-157

The Gemini X and XI space flights were highlighted by high-altitude apogees achieved by firing the Primary Propulsion System of the Gemini Agena Target Vehicle.  In both flights, the docked spacecraft target-vehicle combinations were carried much higher into the Van Allen trapped radiation belt than ever before in manned space flight.

This paper deals with the radiation environment at these altitudes and the effect of the environment on the two missions.  An attempt will be made to describe the premission radiation planning for the flights, the inflight radiation measurements, the results of the postflight data analysis, and the preliminary conclusions.

Radiation Dosimetry on the Gemini and Apollo Missions

Carlos S. Warren1, Joesph C. Lill2, Robert B. Richmond3, and William G. Davis4

NASA Manned Spacecraft Center, Houston, Texas
1Technical Assistant, Space Physics Division
2Assistant Chief, Radiation and Fields Branch
3Head, Radiation Environment Section
4[can't read] Technologist, Radiation Environment Section

Journal of Spacecraft, Vol. 5, No. 2., February 1968, pp. 207-210


U.S. astronauts are equipped with radiation-dose recording instrumentation.  This paper describes the dosimetry used on Gemini and that designed for use on Apollo.  Radiation doses received by Gemini crews varied between less than 10 mrad on the Gemini VIII mission (Neil A. Armstrong and David R. Scott) and 779 mrad on the Gemini X mission (Michael Collins).  Particle spectrometers were flown on the Gemini IV and VII missions in order to compare dose calculations to measurements.  Radiation instrumentation for Apollo consists of a particle spectrometer, rate-meters, integrating dosimeters, and passive dosimeters.   The rationale for each instrument is discussed.  Calculated doses in the Apollo vehicle are presented for intense events in the last solar cycle.


"Core Rope Memory"

Computer Design
June, 1963



"Computer Memories - A Survey of the State-of-the-Art"

Jan A. Rajchman, RCA Labs., Princeton, N.J.
Proceedings of the IRE

January, 1961, pp. 104-127

Summary - Computer memory developments of the last decade, the present state, and efforts for improvements are surveyed.  The following topics are included: principles of storage and selection of random-access memories; principles and engineering considerations of current-coincident-driven core memories; magnetic decoding and load-sharing switches; word-organized one-core and two-core-per-bit memories; fast and impulse switching; transfluxor memories; non-destructive read-out memories; ferrite apertured plates; twistors; fixed read-only memories; thin magnetic film memories - dots, sheets, coated wires and rods; present operational memories typically with capacities of 10E5 and 10E6 bits and read-write cycles of 2 to 15 usec; likelihood of the order of 100-nsec read-write cycle times attainable with ferrite and thin film memories; consideration relating to large capacities; ferroelectric memories attempts; cryoelectric superconductive memories - principle, superconductive films, Crowe cells, continuous sheets, systems, and the outlook for large capacities; tunnel diode memories which promise a read-write cycle of the order of 10 nsec; and outlook for content addressable memories.

Saturn V Launch Vehicle Digital Computer and Data Adapter

M. Dickinson, J. Jackson, and G. Randa, IBM Space Guidance Center
Proceedings - Fall Joint Computer Conference

1964, pp. 501-516

This paper describes the IBM Space Guidance Center's part in the Saturn V Program and the digital computer and data adapter being developed for the Saturn V booster.   This work is being performed under contract to NASA under direction of the Marshall Space Flight Center, Huntsville, Alabama.

The computer and data adapter are located in the Saturn V Instrument Unit and integrated into the total guidance system of the booster.   The computer interfaces only with the data adapter, which in turn presents the interface to the rest of the system.  Basically, during boost guidance, the computer evaluates in-flight changes in booster speed and position derived from an inertial platform and develops signals to control the rocket engines so as to keep the booster on course.  The data adapter takes analog inputs from sensors and converts them to digital form of the computer; it also takes the computer digital outputs, converts some of them to analog form, and sends corrections to the appropriate controls.


"Testing the Man-Rated Launch Vehicle"

Francis X. Carey
Martin Company

Proceedings of the Third Space Congress
"The Challenge of Space"

1966, pp. 332-341

Although manned space flight is still in its infancy, testing of launch vehicles has progressed to a high degree of sophistication.

As of December 1965, the Martin-built Gemini launch vehicle has launched seven Gemini spacecraft successfully out of seven attempts.  This remarkable record was made possible by two facts:

  1. The basic reliability of the hardware
  2. The test program.

This paper briefly describes the Gemini launch vehicle noting the major differences between it and the Tital II and discusses the test program.  It is not proposed that this is the only method of testing a man-rated launch vehicle; however, it is a successful one.

The Gemini launch vehicle is a basic Air Force Tital II which has been modified in certain areas to achieve man-rating.

What Is a Man-Rated Booster?

A.J. Kullas
Martin Company
Journal of Spacecraft and Rockets
VOL. 3, NO. 3
February 1966, p. 270-273

   The primary purpose of this note is to change the approach to the design of launch vehicles destined to carry man into space. The proposal consists of adding to today's state of the art the interconnection of systems coupled with much greater utilization of the astronaut's judgment and more extensive systems flight test in order to get the most out of the man-machine combination. A brief history of actions taken to produce today's man-rated booster is offered to show that a uniform approach does not exist. A basic definition of man-rating consistent with the previous intent is offered:
   A booster is considered as man-rated when its design permits an astronaut alternate equipment choices and alternate capabilities through participation in the propulsion and guidance control functions and, in addition, in the course of the booster flight test development, it is as deliberately as possible exposed to the critical design conditions to assure its capability to perform adequately in the real mission environment.
   The actions involved in "man-rating" Atlas Mercury, Titan Gemini, Saturn, and Titan III can be classified into six general headings: 1) motivation of engineers and technicians to be more careful in their work, 2) hardware changes for increased booster and spacecraft reliability, 3) hardware changes to enhance mission success, 4) hardware changes for astronaut personal safety, 5) special handling and selection of parts, and 6) astronaut training. The specific actions applied to each of the boosters is markedly different. No fundamental criteria form the basis for all of the actions taken. Each is considered as man-rated in its own inimitable way.

Modular Computer Research

Edward H. Bersoff
Frank f. C. Tung, Member, IEEE
NASA Electronics Research Center
Cambridge, Mass. 02139

Margaret Elaine Hope
United Aircraft
Hamilton Standard System Center
Farmington, Conn.

IEEE Transactions on Aerospace and Electronic Systems
Vol. AES-6, No. 1, January 1970 pp. 29-36


This paper discusses one area of research being carried out at the NASA/Electronics Research Center in strapdown guidance technology.   In particular, the task of determining the characteristics of the onboard computer is examined.  Strapdown calculations impose unique constraints on the computational requirements of the flight computer.  In addition, this computer should be suitable for prolonged unmanned missions, which involves system reliability.  A description of this ideal system is followed by a description of the first implementation of this approach, the modular computer breadboard.

Improved Centaur Computer Operating System

Samuel W. Matthews
Senior Guidance Analysis Engineer
Convair Division of General Dynamics
San Diego, CA

AIAA Aerospace Computer Systems Conference
Los Angeles, California
September 8-10, 1969



The Improved Centaur computer assimilates hardware functions of the Centaur vehicle that can be performed by a digital computer. The resulting Centaur electronics module embodies a computer-controlled guidance and flight control system with lower variable cost, increased reliability, and the flexibility to accommodate without hardware modifications most vehicle and payload configurations. Functional tasks currently assigned to the computer are navigation, guidance, flight attitude control, vehicle sequencing, propellant utilization, and telemetry format control of computer parameters.

To obtain a manageable system for implementing the computer's tasks, the precepts of large-scale computer systems were adapted to produce a state-of-the-art aerospace software system. The operating system consists of the task scheduling algorithm, task table, re-entrant storage techniques, task/executive communication routines, and hardware interrupt processors. Individual functional tasks are classified and structured as modules, which can be easily tested and replaced to accommodate mission-peculiar requirements. The real-time, multiprogram, execution control consists of a combination of hardware priority interrupts and a real-time software technique that extends indefinitely the priority interrupt structure under executive program control. The system provides flexibility, permits any degreee of modularity, permits individual functional tasks to be coded independently without detailed timing considerations, and permits independent control of preflight tasks by a ground computer which overlays a portion of airborne computer memory. These advantages result In reduced programming and checkout costs.



Title, Author, and Reference


What Made Apollo A Success?

A series of eight articles reprinted by permission from the March 1970 issue of Astronautics & Aeronautics, a publicaion of the American Institute of Aeronautics and Astronautics.


  1. Introduction. George M. Low.

  2. Design Principles Stressing Simplicity. Kenneth S. Kleinknecht.

  3. Testing to Ensure Mission Success. Scott H. Simpkinson.

  4. Apollo Crew Procedures, Simulation, and Flight Planning. Warren J. North and C. H. Woodling.

  5. Flight Control in the Apollo Program. Eugene F. Kranz and James Otis Covington.

  6. Action on Mission Evaluation and Flight Anomalies. Donald D. Arabian.

  7. Techniques of Controlling the Trajectory. Howard W. Tindall, Jr.

  8. Flexible Yet Disciplined Mission Planning. C. C. Kraft, Jr., J. P. Mayer, C. R. Huss, and R. P. Parten.

Apollo 13: Houston We've Got a  Problem



Unmanned Space Project Management: Surveyor and Lunar Orbiter

NASA SP-4901
Erasmus H. Kloman

Introduction (excerpt)
One of the valuable byproducts of the U S. space program is the body of knowledge concerning management of large complex development project activities. The brief span of years since the formation of NASA has witnessed the rapid evolution of a variety of systems and techniques for directing the combined efforts of thousands of individuals cooperating in closeknit programs in which Government, university, and private industry play mutually reinforcing roles. Many of the major learning experiences, such as those in the Apollo management system, have been applied to other activities within NASA. There has been only limited effort, however, to distill the generalized management experience gained in other NASA projects for application outside the space agency itself.

Note: NASA commissioned the National Academy of Public Administration to undertake this study to look at its innovative management techniques on these complex technological projects.

Computers Take Flight: A History of NASA’S Pioneering Digital Fly-By-Wire Project

James E. Tomayko

The NASA History Series
NASA SP-2000-4224


Foreword (excerpt)

This history of the F-8 Digital Fly-By-Wire Project at NASA’s Dryden Flight Research Center by Dr. James E. Tomayko of Carnegie Mellon University is important for a number of reasons. Not the least of these is the significance of the program itself. In 1972 the F-8C aircraft used in the program became the first digital fly-by-wire aircraft to operate without a mechanical backup system. This fact was important in giving industry the confidence to develop its own digital systems, since flown on military aircraft such as the F-18, F-16, F-117, B-2, and F-22, as well as commercial airliners like the Boeing 777. Flying without a mechanical back-up system was also important in ensuring that the researchers at Dryden were working on the right problems.

The F-8 Digital Fly-By-Wire Project made two significant contributions to the new technology: (1) a solid design base of techniques that work and those that do not, and (2) credible evidence of good flying qualities and the ability of such a system to tolerate real faults and to continue operation without degradation. The narrative of this study captures the intensity of the program in successfully resolving the numerous design challenges and management problems that were encountered. This, in turn, laid the groundwork for leading, not only the U.S., but to a great extent the entire world’s aeronautics community into the new era of digital fly-by-wire flight controls. The book also captures the essence of what NASA is chartered to do—develop and transfer major technologies that will keep the U.S. in a world leadership role as the major supplier of commercial aviation, military, and aerospace vehicles and products. The F-8 project is an example of how advanced technology developed in support of the agency’s space program, in this case the Apollo endeavor, can be successfully transferred to also address the agency’s aeronautics research and development goals, greatly multiplying payoff on taxpayer investments and resources. It is truly an example of what NASA does best.

Manned Lunar-Landing Through Use of Lunar-Orbiting Rendezvous



In the course of conducting research on the problem of space rendezvous and on various aspects of manned space missions, Langley Research Center has evolved what is believed to be a particularly appealing scheme for performing the manned lunar landing mission. The key to the mission is the use of lunar rendezvous, which greatly reduces the size of the booster needed at the earth.

More definitely the mission may be described essentially as follows: A manned exploration vehicle is considered on its way to the moon. On approach, this vehicle is decelerated into a low-altitude circular orbit about the moon. From this orbit a lunar lander descends to the moon surface, leaving the return vehicle in orbit. After exploration the lunar lander ascends for rendezvous with the return vehicle. The return vehicle is then boosted into a return trajectory to the earth, leaving the lander behind.

The significant advantage brought out by this procedure is the marked reduction in escape weight required; the reduction is, of course, a direct reflection of the reduced energy requirements brought about by leaving a sizable mass in lunar orbit, in this case, the return capsule and return propulsion system.

This report has been prepared by members of the Langley Research Center to indicate the research that has been conducted, and what a complete manned lunar landing mission using this system would entail. For further reference, main contacts are John D. Bird, Arthur W. V oge1ey, or John C. Houbolt.

October 31,1961

Apollo 13 Review Board (Cortright Commission)


     The Apollo 13 accident, which aborted man's third mission to explore the surface of the Moon, is a harsh reminder of the immense difficulty of this undertaking.
     The total Apollo system of ground complexes, launch vehicle, and spacecraft constitutes the most ambitious and demanding engineering development ever undertaken by man. For these missions to succeed, both men and equipment must perform to near perfection. That this system has already resulted in two successful lunar surface explorations is a tribute to those men and women who conceived, designed, built, and flew it.
     Perfection is not only difficult to achieve, but difficult to maintain. The imperfection in Apollo 13 constituted a near disaster, averted only by outstanding performance on the part of the crew and the ground control team which supported them.
     The Apollo 13 Review Board was charged with the responsibilities of reviewing the circumstances surrounding the accident, of establishing the probable causes of the accident, of assessing the effectiveness of flight recovery actions, of reporting these findings, and of developing recommendations for corrective or other actions. The Board has made every effort to carry out its assignment in a thorough, objective, and impartial manner. In doing so, the Board made effective use of the failure analyses and corrective action studies carried out by the Manned Spacecraft Center and was very impressed with the dedication and objectivity of this effort.
     The Board feels that the nature of the Apollo 13 equipment failure holds important lessons which, when applied to future missions, will contribute to the safety and effectiveness of manned space flight.


"We choose to go to the moon...."

" is there, and we're going to climb it."

Special Message to the Congress on Urgent National Needs

May 25, 1961

First, I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish. (Full Text)   (Kennedy Library)

(med_res   high_res)

September 21, 1962

JFK at Rice University

Audio (mp3)
Audio (wav)

Video Part 1
Video Part 2
Video Part 3
Video Part 4


jsc_mirror A large number of history documents.  A mirror of the public JSC pages.

Stages to Saturn

A Technological History of the Apollo/Saturn Launch Vehicles


SP-4213 THE HUMAN FACTOR: Biomedicine in the Manned Space Program to 1980

Apollo Training
Structures and Mechanical Subsystems
Course Number A-512S

April 1, 1966


AGC4 Basic Training Manual, Vol. I of II

Document No. E-2052
Bernard I. Savage, Alice Drake
MIT Instrumentation Laboratory
January, 1967

     This manual contains a concise description of that which a computer programmer should know about the Apollo Guidance and Navigation Programming System to be useful.  That is we answer the following questions: What are the pertinent machine characteristics?  What programming languages and conventions exist for my use?  What systems subroutines may I rely on?  How do I communicate with the system subroutines which I need?  This manual does not concern itself with the Mission Programming System or that which an engineer or mathematician must know to adequately program a phase of the mission after he has an adequate knowledge of the system.
     This manual attempts to be thorough while brief.  It does not try to exhaust all there is to know about a subject nor does it try to make the reader an expert on any subject.  It is designed so that someone fairly new to the subject may acquire a practical understanding of it within the shortest time.  Whenever a detailed and complete understanding is required the reader should consult the program listing and/or other technical documents.
     This manual is divided into four sections.  Section I discusses the AGC4 and how to program it in Assembly Language.  Section II describes the Interpreter and how to program in Interpretive Language.  Section III describes the System Software subroutines and how to interact with them.  Section IV contains an outline and suggestions for teaching sections I-III.  Each section has a table of contents.


The Apollo Guidance Computer

Document No. R-416
Ramon L. Alonso and Albert L. Hopkins
MIT Instrumentation Laboratory
August, 1963

     The general logical structure of the on-board Apollo Guidance Computer is presented, and the developments of fixed and erasable memory are described.  Particular attention is given to the methods of input and output.


Computers in Spaceflight: The NASA Experience

James E. Tomayko, Wichita State University, NASA Contractor Report CR-182505, National Aeronautics and Space Administration, Scientific and Technical Information Division, 1988, 417 pages.


Notes: This book examines the computer systems used in actual spaceflight or in close support of it. Each chapter deals with either a specific program, such as Gemini or Apollo onboard computers, or a closely related set of systems, such as launch processing or mission control. Also published in Volume 18 of the "Encyclopedia of Computer Science and Engineering", as published by Marcel Dekker, New York. All references can be found in the Special Collections of Ablah Library, Wichita State University, Wichita, Kansas.


Astrionics System Handbook: Saturn Launch Vehicle

International Business Machines Corp., NASA-CR-102371 (MSFC-IV-4-401-1, IBM-68-996-0002),   International Business Machines Corp., November 1968, 399 pages

Notes: This describes the Saturn V avionics and computer systems.

Apollo Lunar Descent and Ascent Trajectories

Floyd V. Bennet
NASA, Manned Spacecraft Center
Houston, Texas
January, 1970


A description of the premission planning, real-time situation, and postflight analysis for the lunar descent and ascent phases of the Apollo 11 mission, the first manned lunar landing, is given.  Actual flight results are shown to be in agreement with premission planning.  Based on Apollo 11 postflight analysis, a navigation correction capability was provided for Apollo 12.  A preliminary postflight summary of the descent for Apollo 12, the first pinpoint landing, is also included.

NASA Space Vehicle Design Criteria
(Guidance and Control)

Spaceborne Digital Computer Systems

NASA SP-8070


W. Hoffman, Aerospace Systems , Inc.
A. Hopkins, Jr., MIT
J. Green, Jr., Intermetrics, Inc.

March, 1971

As space vehicle missions have become more complex, the use of onboard digital computers has become more prevelant.  The functions which these computers are assigned to perform are also expanding in number and magnitude.  As a result, the problem of specifying and designing digital computers for space vehicles has increased in complexity.

Although most spaceborne digital computers are of the type often referred to as "general purpose," they have been in fact special-purpose machines in that a particular choice of design must reflect the requirements of the particular mission application.  Thus, the program manager must be aware of the capabilities and limitations of spaceborne computer systems and the design tradeoffs which might affect his application.

The flight performance of spaceborne digital computer systems has generally been successfull.  However, a number of recurring problems have been experienced during the design, development, and testing of these machines.  Previous systems have been very costly, have required major redesigns, and have caused significant schedule delays.   Most difficulties have resulted from 1) lack of adequate capacity and flexibility to accommodate expanded requirements, 2) poorly defined subsystem and interface specifications, 3) the impact on software of changing mission requirements, and 4) reliability demands.

This report is divided into three major sections:

  1. State of the Art
  2. Design Criteria
  3. Recommended Practices

It also includes an excellent set of references.


A Perspective on the Human-Rating Process of U.S. Spacecraft: Both Past and Present

NASA Special Publication 6104

B. Zupp, Editor
Lyndon B. Johnson Space Center

February, 1995

Historically, the methods of implementing human-rating vary as a function of program, across the systems and subsystems that are components of a program or project, and sometimes across mission phases within a program.  Although details of specific implementations have varied, the top-level, fundamental process has remained constant.  That invariant process is as follows:
  • The program establishes processes and procedure for human-rating early in the definition phases and constantly reviews these processes and procedures as the program matures.
  • Historically, the human-rating process can be collected into three fundamental components: human safety, human performance, and human health management and care.1
  • The human-rating process evaluates and balances the components of human-rating with cost, schedule, risk, benefit, and performance.

As used here, human-rating implementation refers to a specific approach to ensuring that the space system is human-rated.  For example, capsule separation and jettison is an implementation approach that provides the required level of human safety during launch.  However, an abort system carries risks of malfunction which can affect otherwise normal missions.  Quad-redundancy and high reliability are other implementation approaches that can satisfy a required level of human safety.

Similarly, as used here, the human-rating process is that set of procedures and methods that not only estimates and evaluates the combined components of human-rating along with cost, schedule, risk, benefit, and performance, but also maintains an active consistency of decisions.

1The human rating process for Mercury, Gemini, and Apollo Programs was centered on human safety.  The Skylab and Shuttle Programs added to this an emphasis on human performance and health management.

Design Principles for a General Control Computer

S.M.F. Fund Paper No. FF-29

R. Alonso and J.H. Laning, Jr.

April, 1960

A condensed version of this paper was presented at the Institute of Aeronautical Sciences National Specialists Meeting on Guidance of Aerospace Behicles, May 25,27, 1960.

This report was prepared under Project DSR 52-156 sponsored by the Ballistic Missle Division of the Air Research and Development Command through USAF Contract AF04(647)-303 and Project DSR 53-138, Division of Sponsored Research, Massachusetts Institute of Technology, sponsored by the Bureau of Ordnance, Department of the Navy, under Contract NOrd 17366.


A set of techniques is described which permits the design of computers particularly well suited for outer space and other airborne control applications.  These techniques are unified by reference to a representative computer.

Some of the properties of the computer are: variable speed, power consumption proportional to speed, relatively few transistors, relatively large storage for program and constants, and parallel transfer of words.  Certain features of the input system permit automatic incrementing of counters and automatic interruption of normal computer processes upon receipt of inputs.

The program and constants are stored in a wired-in form of memory which permits unusually high bit densities.

Table of Contents

Chapter I General Organization of Storage
   A.        The Core Rope (Wired-in Memory)
   B.        Erasable Storage Registers
   C.        The Erasable Storage System
   D.        The Complete Memory System
Chapter II Execution of Computer Instructions
   A.        Central Registers and Overall Organization
   B.        The Sequence Generator
   C.        Representative Order Code System
   D.        Addition and Multiplication
Chapter III Input-Output System
   A.        Introduction
   B.        The Priority Circuit
   C.        The Automatic Interrupt
   D.        State Inputs
   E.        Counter Inputs
   F.        Output Devices
Chapter IV General Remarks
   A.        Sizes and Weights
   B.        Reliability Problems
   C.        Practical Experience to Date
   D.        Power and Speed

Managing the Moon Program
Lessons Learned From Project Apollo

Proceedings of an Oral History Workshop

Monographs in Aerospace History
Number 14
July 1999

Conducted July 21, 1989.
Moderator: John M. Logsdon

Howard W. Tindall
George E. Mueller
Owen W. Morris
Maxime A. Faget
Robert A. Gilruth
Christopher C. Kraft



In a spring 1999 poll of opinion leaders sponsored by leading news organizations in the United States, the 100 most significant events of the 20th century were ranked.  The Moon landing was a very close second to the splitting of the atom and its use during World War II.  "It was agonizing," CNN anchor and senior correspondent Judy Woodruff said of the selection process.  Probably, historian Arthur M. Schlesinger, Jr., best summarized the position of a large number of individuals polled.  "the one thing for which this century will be remembered 500 years from now was: This was the century when we began the exploration of space."  He noted that Project Apollo gave many a sense of infinite potential.  "People always say: If we could land on the Moon, we can do anything," said Maria Elena Salinas, co-anchor at Miami-based Spanish-language cable television Univision, who also made it her first choice.

End excerpt.

Roger D. Launius
Chief Hisorian
National Aeronautics and Space Administration
April 18, 1999

Apollo Reliability and Quality Assurance Program Plan

Office of Manned Space Flight
Apollo Program
NHB 5300.1A
July 1966

Table of Contents

Section 1: Introduction
Section 2: Reliability and Quality Assurance Requirements
Section 3: Reliability and Auality Assurance Plans
Section 4: Mission Reliability Analysis
Section 5: Reliability and Quality Assurance Status Reporting
Section 6: Reliability and Quality Assurance Auditing
Section 7: Parts, Materials and Components Program
Section 8: Identification for Traceability
Section 9: Nonconforming Material Control



Title, Author, and Reference


The Apollo Guidance Computer: Architecture and Operation

Frank O'Brien
Springer Praxis Books

Description: The Apollo Guidance Computer: Architecture and Operation is the first comprehensive description of the Apollo computer, beginning with its internal organization to its user interface and flight software. Particular emphasis is placed on the instruction set, Executive capabilities, the Interpreter and the detailed procedures for mission application software. Launch, landing on the Moon and entry back on Earth are explained in rich detail and show how the computer was an integral part of the spacecraft operation.

Expanding the Envelope:
Flight Research at NACA and NASA

Michael H. Gorn
2001 by The University Press of Kentucky
ISBN 0-8131-2205-8



  1. Early Flight Research

  2. Flight Research Takes Off

  3. Necessary Refinements

  4. First Among Equals

  5. A Lap Out of Water

  6. Slower and Cheaper

  7. A Tighter Focus

  8. New Directions


Aiming at Targets:
The Autobiography of Robert C. Seamans, Jr.

The NASA History Series
Stock number 033-000-01175-0.


Foreword: Willis H. Shapley
Preface and Acknowledgements

  1. Liftoff
  2. The NASA Years
  3. The Air Force Years
  4. Reentry

Appendix A: Selected Documents
Appendix B: Biographical Appendix
Appendix C: Chronology for Robert C. Seamans, Jr.

Spaceflight and the Myth of Presidential Leadership

Edited by Roger D. Launius and Howard E. McCurdy

University of Illinois Press
1997 by the Board of Trustees of the University of Illinois
ISBN 0-252-02336-6 -- 0-252-06632-4 (pbk)


Introduction: The Imperial Presidency in the History of Space Exploration, Roger D. Launius and Howard E. McCurdy

  1. The Reluctant Racer: Eisenhower and U.S. Space Policy, David Callahan and Fred I. Greenstein
  2. Kennedy and the Decision to Go to the Moon, Michael R. Beschloss
  3. Johnson, Project Apollo, and the Politics of Space Program Planning, Robert Dallek
  4. The Presidency, Congress, and the Deceleration of the U.S. Space Program in the 1970s, Joan Hoff
  5. Politics Not Science: The U.S. Space Program in the Reagan and Bush Years, Lyn Ragsdale
  6. Presidential Leadership and International Aspects of the Space Program, Robert H. Ferrell
  7. National Leadership and Presidential Power, John M. Logsdon

Epilogue: Beyond NASA Exceptionalism, Roger D. Launius and Howard E. McCurdy

First Man

James R. Hansen
Simon & Schuster
2005 by James R. Hansen
ISBN 0-7432-5631-X

Prologue: The Launch
PART ONE: AN AMERICAN GENESIS: The Strong of Arm; The Strong of Spirit
PART TWO: TRANQUILITY BASE: First Child; The Virtues of Smallville; Truth in the Air; Aeronautical Engineering;
PART THREE: WINGS OF GOLD: Class 5-49; Fighter Squadron 51; Fate Is the Hunter; The Ordeal of Eagles
PART FOUR: THE REAL RIGHT STUFF: The Research Pilot; Above the High Desert; At the Edge of Space; The Worst Loss; Higher Resolve; I've Got a Secret
PART FIVE: NO MAN IS AN ISLAND: Training Days; In Line for Command; Gemini VIII; The Astronaut's Wife; For All America
PART SIX: APOLLO: Out of the Ashes; Wingless on Luna; Amiable Strangers; First Out; Dialectics of a Moon Mission
PART SEVEN: ONE GIANT LEAP: Outward Bound; The Landing; One Small Step; Return to Earth; For All Mankind
PART EIGHT: DARK SIDE OF THE MOON: Standing Ground; To Engineer Is Human; The Astronaut as Icon; Into the Heartland
Acknowledgments; Notes; Bibliography; Index

Apollo EECOM: Journey of a Lifetime

Sy Liebergot with David M. Harland
An Apogee Books Publication
2003 Apogee Books and Sy Liebergot
ISBN 1-89-6522-96-3

Forwards: Ron Howard and Clint Howard
Mission Control Center
Prologue: 1936 World Events

Part One: The Early Years and Decisions
Part Two: Mission Control
Part Three: Life After Mission Control
Epilogue: Reflections

Apollo: The Race to the Moon

Charles Murray & Catherine Bly Cox
Simon and Schuster
1989 by Cox and Murray, Inc.
ISBN 0-67161101-1

BOOK I. GATHERING: 1. That famous Space Task Group is akin to the Mayflower; 2. I could picture the astronauts looking down at it with binoculars; 3. Those days were out of the Dark Ages; 4. He would rather not have done it; 5. We're going to the moon.

BOOK II. BUILDING: 6. The flight article has got to dominate; 7. We had more harebrained scheme than you can shake a stick at. 8. Somewhat as a voice in the wilderness ... 9. What sonofabitch thinks it isn't the right thing to do?  10. It aged me, I'm sure.  11. It sounded reckless. 12. Hey, it isn't that complicated.  13. We want you to go fix it.  14. Did he say 'fire'? 15. The Crucible.  16. You've got to start biting somewhere.  17. And then on launch day it worked.

BOOK III. FLYING: 18. We're going to put a guy in that thing and light it.  19. There will always be people who want to work in that room.  20. The flight Director may take any necessary action.  21. There was no mercy in those days.  22. You've lost the engines?  23. It was darn scary.  24. We .. we're go on that, Flight.  25. Well, let's light this sumbitch and it better work.  26. I think we need to do a little more all-weather testing.  27. You really need to understand that the C.S.M. is dying.  28. You don't have time to worry.  29. I hope the guys who thought this up knew what they were doing.  30.  We drank the wine at the pace they handed it to us.

Epilogue: Twenty Years after the First Landing
Apollo as History

The Depths of Space
The Story of the Pioneer Planetary Probes

Mark Wolverton
Joseph Henry Press, Washington, D.C.
2004 by Mark Wolverton
ISBN 0-309-09050-4


Forward by James A. Van Allen
Introduction - Message in a Bottle

  1. Embarkation
  2. Reaching into the Void
  3. Something Man Has Never Done Before
  4. The Sole Selection
  5. Countdown and Controversy
  6. Spring at the Cape
  7. Twelve Generations from Galileo
  8. Filling in the Gaps
  9. A Jewel in the Night
  10. Planet of Clouds
  11. Whispers Across the Abyss
  12. Lone Survivor

The Secret of Apollo - Systems Management in American and European Space Programs

Stephen B. Johnson
2002 The Johns Hopkins University Press
ISBN 0-8018-6898-X

New Series is NASA History - Roger D. Launius, Series Editor


Introduction: Management and the Control of Research and Development
  1. Social and Technical Issues of Spaceflight
  2. Creating Concurrency
  3. From Concurrency to Systems Management
  4. JPL's Journey from Missiles to Space
  5. Organizing the Manned Space Program
  6. Organizing ELDO for Failure 154
  7. ESROs American Bridge across the Management Gap
  8. Coordination and Control of High-Tech Research and Development

Essay on Sources 277 Index 283

How does one go about organizing something as complicated as a strategic-missle or space-exploration program?  Stephen B. Johnson here explores the answer -- systems management -- in a groundbreaking study that involves Air Force planners, scientists, technical specialists, and, eventually, bureaucrats.  Taking a comparative approach, Johnson focuses on the theory, or intellectual history, of "systems engineering" as such, its origins in the air force's Cold War ICBM efforts, and its migration to not on NASA but the European Space Agency.

Exploring the history and politics of aerospace development and weapons procurement, Johnson examines how scientists and engineers created the systems management process to coordinate large-scale technology development, and how managers and military officers gained control of that process.  "Those funding the race demanded results," Johnson explains.  "In response, development organizations created what few expected and what even fewer wanted - a bureaucracy for innovation.  To begin to understand this apparent contradiction in terms, we must first understand the exacting nature of space technologies and the concerns of those who create them."

Prescription for Disaster
From the Glory of Apollo to the Betrayal of the the Shuttle

Joseph J. Trento with reporting and editing by Susan B. Trento
Crown Publishers Inc., New York
ISBN 0-517-56415-7

Table of Contents

The Great Space Race
The Kennedy Years
Shooting the Moon
Flight of the Sun God
The Dark Side of Space
Carter - The Man Who Paid the Piper
Fly Now, Pay Later
The Contractors and the Congress
The Politics of Space
Death of a Dream
Notes on Sources and Interviews

Beyond the Limits: Flight Enters the Computer Age

Paul E. Ceruzzi, MIT Press, June 1989, 270 pages, ISBN 0-26203143-4 (hard bound), ISBN 0-26253082-1 (soft bound)

Notes: Describes how computer technology affected the theory and practice of engineering and operations of aircraft and spacecraft from 1945 to 1988.

Computers in Space

Allen L. Wold, New York: Franklin Watts, 1984, 122 pages, ISBN 0-531-04847-0. "Computers in Space: Journeys with NASA", James E. Tomayko, Indianapolis IN: Alpha Books, March 1994, 197 pages, ISBN 1-56761-463-9 (soft cover).

Notes: A lay person's historical guide to flight and ground computers as used for many NASA space programs. Galileo and Shuttle systems are used for many examples.

Journey to the Moon: The History of the Apollo Guidance Computer

Eldon C. Hall, Reston VA: American Institute of Aeronautics and Astronautics, 1996, 221 pages, ISBN 1-56347-185-X (softbound).

Notes: Details history and design of the computer that enabled Apollo astronauts to land on the moon. Written for experts as well as lay persons. Contents: History, Computer Hardware, Computers, MIT Instrumentation Laboratory, Apollo Hardware, Requirements, In the Beginning-Apollo Computer, Winds of Change were Blowing, Block I Computers, System Integration, Naysayers and Advice from Outside Experts, Next Generation-Block II, Naysayers Revisited, Reliability, Apollo Software, Software Development, Mission Software, and Finale.

Annotations to Eldon Hall's Journey to the Moon.

In February of 1997, Hugh Blair-Smith wrote a series of annotations to Eldon Hall's book about the history of the AGC.

The Untold Story of the Computer Revolution

G. Harry Stine, New York: Arbor House, 1985.


Understanding Computers: Space

Editors of Time-Life Books, part of the multiple volume series "Understanding Computers", Time-Life Books, Alexandria, Virginia, 1993, 128 pages, ISBN 0-8094-7590-1 (hardbound).

: James E. Tomayko was a technical contributor to "Understanding Computers: Space"; a condensed version of "Computers in Spaceflight: The NASA Experience"

List of Books

List of books from Jacqmans Spaceflight History Homepage

NASA Engineers and the Age of Apollo

NASA SP-4104
Sylvia Doughty Fries
The NASA History Series


Chapter 1 Beginnings, 1918-1932
Chapter 2 Beginnings, 1932-1948
Chapter 3 What Goes Up
Chapter 4 Journeys
Chapter 5 Scientists, Engineers, and Managers
Chapter 6 Changes
Appendix A NASA Managers Solicited for Names of "Representative" NASA Engineers
Appendix B Demographic Tables
Appendix C Education and Military Service of NASA Apollo Era Engineers Interviewed

A Man on the Moon
The Voyages of the Apollo Astronauts

Andrew Chaikin
Foreward: Tom Hanks

Chaikin, 1994
Foreword Hanks, 1998

ISBN 0-670-81446-6 (hc)
ISBN 0 14 02.7201 1 (pbk)



Boook One

Chapter 1: "Fire in the Cockpit!"
Chapter 2: The Office
Chapter 3: First Around the Moon (Apollo 8)
I: The Decision
II: A Hole in the Stars
III: "In the Beginning ... "
IV: "it's All Over but the Shouting"
Chapter 4: "Before This Decade is Out"
I: The Parlay
II: "We Is Down Among 'Em!"
III: Down to the Wire
Chapter 5: The First Lunar Landing (Apollo 11)
I: The Eagle Has Landed
II: Magnificent Desolation
III: "Before This Decade is Out"

Book Two

Chapter 6: Sailore on the Ocean of Storms (Apollo 12)
I: The Education of Alan Bean
II: Shore Leave
III: In the Belly of the Snowman
Chapter 7: The Crown of an Astronaut's Career (Apollo 13)
I: A Change of Fortune
II: The Moon Is a Harsh Mistress
III: The Chill of Space
Chapter 8: The Story of a Full-up Mission (Apollo 14)
I: Big Al Flies Again
II: To the Promised Land
III: Solo
IV: The Climb

Book Three

Chapter 9: The Scientist
Chapter 10: A Fire to Be Lighted
Chapter 11: To the Mountains of the Moon (Apollo 15)
I: "Exploration at Its Greatest"
II: High Point
III: The Spirit of Galileo
IV: The Final Selection
Chapter 12: The Unexpected Moon (Apollo 16)
I: Luna Incognita
II: "You Just Bit Off More Than You Can Chew"
III: "... Or Wherever Geologists Go"
Chapter 13: The Last Men on the Moon (Apollo 17)
I: Sunrise at Midnight
II: Apollo at the Limit
III: Witnesses to the Earthrise

Epilogue: The Audiences of the Moon
Appendix A: astronaut Biuographical Information
Appendix B: Persons Interviewed
Appendix C: Apollo Mission Data
Author's Notes

Red Star In Orbit

James E. Oberg
Random House, New York

1981, Oberg

ISBN 0-394-51429-7


Forword by Tom Wolfe
1. At Home in Orbit
2. The Birth of Sputnik
3. The Nedelin Catastrophe
4. Man and Woman in Space
5. The Voskhod follies
6. Death and Disaster
7. The Moon-Race Cover-up
8. The Long Climb Back
9. Secret Space Cities
10. The Salyut-6 Breakthrough
11. Guests in Space
12. Through the Zero-G Barrier
13. Things to Come


Guest Cosmonauts
Soviet Man-Related Space Shots
Annotated Bibliography
Sources of Current Information
Open Questions

Moon Shot
The Inside Story of America's Race to the Moon

Alan Shephard and Deke Slayton
with Jay Barbree and Howard Benedict

Introduction by Neil Armstrong

Turner Publishing, Inc., Atlanta

1994 by Shepard, Slayton, Barbree, Benedict.

ISBN 1-878685-54-6



Chapter 1: The Landing
Chapter 2: The Beginning
Chapter 3: The Pilots
Chapter 4: The Astronauts
Chapter 5: Training
Chapter 6: The Selection
Chapter 7: The Cape
Chapter 8: First in Space
Chapter 9: Freedom Seven
Chapter 10: NASA is Made
Chapter 11: Mercury: Messengers from Space
Chapter 12: Houston
Chapter 13: Space Walk
Chapter 14: Gemini: The Little Spaceship That Could
Chapter 15: I've Got a Fire in the Cockpit
Chapter 16: Aftermath
Chapter 17: apollo 8 and a Russian Push to the Moon
Chapter 18: Getting There, Getting Back
Chapter 19: Lifeboat!
Chapter 20: Apollo 14: All or Nothing
Chapter 21: No Turning Back
Chapter 22: Moon Walk
Chapter 23: Last Apollo Out
Chapter 24: Salt and Vodka
Chapter 25: Soyez and Apollo Are Shaking Hands
Chapter 26: Deke Slayton: Astronaut

Apollo 13
(Lost Moon: The Perilous Voyage of Apollo 13)

Jim Lovell & Jeffrey Kluger

Pocket Books
1994 Lovell and Kluger

ISBN: 0-671-53464-5


U.S. Manned Space: From Mercury to the Shuttle

Donald K. "Deke" Slayton
with Michael Cassutt

A Tom Hoherty Associates Book, NY
1994 by the Estate of Donald K. Slayton and St. Croix Production
ISBN 0-312-85918-X


1. Beginnings
2. Flying
3. Combat
4. The Pacific
6. Boeing
7. Air Force
8. Test Pilot
9. Project Astronaut
10. Mercury
11. First in Space
12. Delta Seven
13. Chief Astronaut
14. Flight Crew Operations
15. Delays
16. Gemini
17. Operational
18. Fire
19. Apollo
20. The Moon
21. Steps
22. Landing
23. Changes
24. Return to Flight
25. Apollo-Soyuz
26. Orbit
27. Shuttle
28. Racing
29. Space Services

Failure Is Not an Option
Mission Control From Mercury to Apollo 13 and Beyond

Gene Kranz
Simon & Schuster
2000 by Gene Kranz

ISBN 0-7432-0079-9


1. The Four-Inch Flight
2. "Liftoff; the Clock is Running"
3. "God Speed, John Glenn"
4. The Brotherhood
5. The Making of a Rocket Man
6. Gemini - The Twins
7. White Flight
8. The Spirit of 76
9. The Angry Alligator
10. A Fire on the Pad
11. Out of the Ashes
12. The X Mission
13. The Christmas Story
14. 1969 - The Year of Apollo
15. SimSup Wins the Final Round
16. "We Copy You Down, Eagle"
17. "What the Hell Was That?"
18. The Age of Aquarius
19. Coming Home
20. Shepard's Return
21. What Do You Do After the Moon?
22. The Last Liftoff
Where They Are
Appendix: Foundations of Mission Control
Glossary of Terms



Computers in Spaceflight
The NASA Experience

James E. Tomayko
Wichita State University
Wichita, Kansas



The 25th Anniversary of STS-1


On April 12, 1981, 30 years worth of concepts and research into space-capable aircraft took flight from the Kennedy Space Center.  The Space Shuttle Columbia, which lifted off into orbit on her maiden voyage that day, was unlike anything that had flown in space before.  Before this time, conventional spacecraft were blunt-shaped capsules that could only be used once due to the intense heat produced by reentry into the Earth's atmosphere.  But the Shuttle was different; this new craft would be launched into space, glide to a landing on a conventional runway, and be refurbished for more trips into orbit.

National Advisory Committee for Aeronautics (NACA)

The NASA History Division is pleased to unveil a new Web site devoted to the 90th anniversary of the National Advisory Committee for Aeronautics, the predecessor organization to NASA. It is online at on the Web and contains biographical sketches, images, movie clips, key documents, and more. Special thanks to Liz Suckow of the History Division for putting together this content and to Todd Messer of the HQ Printing and Design Office for designing this informative and attractive site.

Virtual AGC


The purpose of this project is to provide an emulation of the Apollo guidance computer, along with some ancillary items needed to make the emulation do something interesting. "Interesting" is, of course, a subjective notion, and there are plenty of additional components one might want to add to the simulation to make it more interesting. (Click here for examples.)

NASA History Series Publications On-Line

Apollo Guidance Computer

The Apollo Guidance Computer

The Apollo Guidance Computer (AGC) provided reliable real-time control for the Apollo spacecraft that carried US astronauts to the moon, 1969-1972. It was designed by the MIT Instrumentation Laboratory and manufactured by Raytheon Corporation.

The AGC was significant for its tight coupling of human and machine, its early use of integrated circuits, and its reliable, mission critical software. The history of the AGC project provides a window into the history of technology in America during the space race and the Cold War.

Mr. Wen Tsing Chow, 1919 - 2001. Excerpt from a memorial www site for W.T. Chow.  He is the author of a number of important papers on this site, having played a critical role in the development of aerospace computers.  -- rk

Mr. Chow applied his remote-control weapons system design expertise to the immediate problem of finding fire control
solutions to counter the superior speed and maneuverability of the Japanese Zero fighter planes and later worked on weapons control systems design for the B-36 bomber.

During the 1950s and early 1960s, Mr. Chow was Program Director for Atlas ICBM Guidance (Project 107A) for the American Bosch Arma corporation and worked in the development of inertial guidance systems, and "all-inertial" guidance systems for the U.S. Air Force Atlas and Titan intercontinental ballistic missile programs. He pioneered the use of digital computers in missile guidance, and the use of photochemical circuitry, allowing for the miniaturization of the guidance system components and production of reliable digital circuits.

He personally formulated the design of the first all solid state, high reliability, space-borne digital computer and established the basic systems approach and mechanization of this country's ICBM guidance systems. His work led directly to the feasibility of using digital computers in missile guidance systems. This was a novel, controversial, and untried concept at the time.

After his work with Bosch Arma, Mr. Chow was responsible for advising the U.S. Air Force on all technical work for all electronic systems for ballistic missiles including the Air Force's massive Minuteman ICBM project. Specifically, responsible for guidance and control, radar and communications, command and control, computer and data processing efforts for U.S. strategic weapon systems.

From the late 1960s to the late 1970s, Mr. Chow worked for IBM, responsible successively for IBM efforts in Strike Avionics Systems, including those for the B-52 and B-1 bomber systems, Space Data and Control Systems (military satellites), and as an advisor on the IBM Space Advisory Council, on the promotion of high reliability technologies such as magnetic bubble memory and fiber optics. Mr. Chow also worked on the development of fault tolerant on-board digital computers and systems for space vehicles and satellites, including those used on the U. S. Space Shuttle.




Welcome to the Great Images in NASA library of images.

GRIN is a collection of over a thousand images of significant historical interest scanned at high-resolution in several sizes. This collection is intended for the media, publishers, and the general public looking for high-quality photographs. Please note that downloading these image files may take some time, although searching and browsing should be relatively quick.

Project Apollo Gallery The Project Apollo Archive presents the Apollo Image Gallery
NASA's History Office  
The Apollo Saturn Reference Page  
Cradle of Aviation Museum at Mitchel Center  
Going to the Moon Block I Computer at the American Computer Museum, Bozeman, MT
Apollo 15 Flight Journal  
Historic Space Systems - Exhibits That Launch Imaginations  
A Field Guide to American Spacecraft  
Jim Scotti's Apollo page  
Phill Parker's Apollo Tools & Experiments Site  
Gemini IMU The NASA Gemini spacecraft programme was announced on the 3 January 1962 to extend the US manned spacecraft effort by development of a two manned spacecraft.Prime objectives were to provide a logical follow-on to the Mercury one manned spacecraft,to subject two astronauts and equipment to long duration spaceflight,to effect orbital rendezvous and docking with another space vehicle,to effect extra vehicular activity (EVA) and to perfect methods of re-entry and landing. This was in an effort to develop and master these techniques in preparation for the more ambitious NASA Apollo Lunar Landing programme in the late 1960's and early 1970's.

Paramount to the rendezvous and docking manoeuvres was the availability of an Inertial Measurement Unit (IMU) and this web page discusses this latter unit.
Space History Notes  
The Project Apollo Archive  
Nedelin disaster

R-16 Family: Nedelin Disaster

It took almost three decades before the first publication in the official Soviet press shed the light on what really happened in October 1960. In 1989, Ogonyok magazine, a mouthpiece of Gorbachev's "perestroika," run a story called "Sorok Pervaya Ploshadka," (or Site 42 in English). The article revealed to the Soviet people that Nedelin died in the explosion of a ballistic missile in Tyuratam along with numerous other nameless victims.

Some interesting excerpts:

To make matters worse, several minutes after the membranes blew up, pyrotechnic devices on the valves of one of three engines in the first stage fired spontaneously.

The commission concluded that the management of the testing was overly confident in the safe performance of the complex vehicle, which resulted in the decisions taken without thorough analysis.

(Added 10/9/01)

Space History Notes Sven's Space Place

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