Encyclopedia Astronautica
LM Guidance


LM Guidance Development Diary

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LM Guidance Chronology


1960 April - .
  • MIT Report on space guidance and control design - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance; LM Source Selection. A study report was issued by the MIT Instrumentation Laboratory on guidance and control design for a variety of space missions. This report, approved by C. Stark Draper, Director of the Laboratory, showed that a vehicle, manned or unmanned, could have significant onboard navigation and guidance capability.

1962 July 1-7 - .
  • Delta V requirements for the Apollo lunar landing mission were established - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance; LM Source Selection. Summary: The delta V (rate of incremental change in velocity) requirements for the lunar landing mission were established and coordinated with NAA by the Apollo Spacecraft Project Office..

1962 July - .
  • Preliminary design of the Apollo lunar landing radar - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance; LM Source Selection. Summary: NAA selected the lunar landing radar and completed the block diagram for the spacecraft rendezvous radar. Preliminary design was in progress on both types of radar..

1962 August 14 - .
  • LEM added to Apollo CSM Statement of Work - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Communications; LM ECS; LM Guidance; LM Hatch; LM Source Selection. The NAA spacecraft Statement of Work was revised to include the requirements for the lunar excursion module (LEM) as well as other modifications. The LEM requirements were identical with those given in the LEM Development Statement of Work of July 24.

    The command module (CM) would now be required to provide the crew with a one-day habitable environment and a survival environment for one week after touching down on land or water. In case of a landing at sea, the CM should be able to recover from any attitude and float upright with egress hatches free of water. Additional Details: here....


1962 November 26 - .
  • Inflight practice at orbital maneuvering said to be essential for lunar missions - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. At a news conference in Cleveland, Ohio, during the 10-day Space Science Fair there, NASA Deputy Administrator Hugh L. Dryden stated that inflight practice at orbital maneuvering was essential for lunar missions. He believed that landings would follow reconnaissance of the moon by circumlunar and near- lunar-surface flights.

1963 January 16 - .
  • Three Apollo operational procedures for the first phase of descent from lunar orbit analyzed - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. The MSC Flight Operations Division's Mission Analysis Branch analyzed three operational procedures for the first phase of descent from lunar orbit:

    1. The first was a LEM-only maneuver. The LEM would transfer to an orbit different from that of the CSM but with the same period and having a pericynthion of 15,240 meters (50,000 feet). After one orbit and reconnaissance of the landing site, the LEM would begin descent maneuvers.
    2. The second method required the entire spacecraft (CSM/LEM) to transfer from the initial circular orbit to an elliptical orbit with a pericynthion of 15,240 meters (50,000 feet).
    3. The third technique involved the LEM's changing from the original 147-kilometer (80-nautical-mile) circular orbit to an elliptic orbit having a pericynthion of 15,240 meters (50,000 feet). The CSM, in turn, would transfer to an elliptic orbit with a pericynthion of 65 kilometers (30 nautical miles). This would enable the CSM to keep the LEM under observation until the LEM began its descent to the lunar surface.
    Comparisons of velocity changes and fuel requirements for the three methods showed that the second technique would use much more fuel than the others and, therefore, was not recommended for further consideration.

    (Apocynthion and pericynthion are the high and low points, respectively, of an object in orbit around the moon (as, for example, a spacecraft sent from earth). Apolune and perilune also refer to these orbital parameters, but these latter two words apply specifically to an object launched from the moon itself.)


1963 January - .
  • Contract to Chance Vought for study of guidance of the Apollo LEM in a lunar landing abort - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: MSC awarded a contract to Chance Vought Corporation for a study of guidance system techniques for the LEM in an abort during lunar landing..

1963 February 26 - .
  • Orbital constraints on Apollo CSM - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Docking; LM Guidance. Two aerospace technologists at MSC, James A. Ferrando and Edgar C. Lineberry, Jr., analyzed orbital constraints on the CSM imposed by the abort capability of the LEM during the descent and hover phases of a lunar mission. Their study concerned the feasibility of rendezvous should an emergency demand an immediate return to the CSM.

    Ferrando and Lineberry found that, once abort factors are considered, there exist "very few" orbits that are acceptable from which to begin the descent. They reported that the most advantageous orbit for the CSM would be a 147-kilometer (80-nautical-mile) circular one.


1963 March - .
  • MSC sent MIT and Grumman radar configuration requirements for the Apollo LEM - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Guidance; LM Guidance. MSC sent MIT and Grumman radar configuration requirements for the LEM. The descent equipment would be a three-beam doppler radar with a two-position antenna. Operating independently of the primary guidance and navigation system, it would determine altitude, rate of descent, and horizontal velocity from 7,000 meters (20,000 feet) above the lunar surface. The LEM rendezvous radar, a gimbaled antenna with a two-axis freedom of movement, and the rendezvous transponder mounted on the antenna would provide tracking data, thus aiding the LEM to intercept the orbiting CM. The SM would be equipped with an identical rendezvous radar and transponder.

1963 May 23 - .
  • Major redesign of the Apollo guidance computer - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Guidance; LM Guidance. Summary: MIT suggested a major redesign of the Apollo guidance computer to make the CM and LEM computers as similar as possible. NASA approved the redesign and the Raytheon Company, subcontractor for the computer, began work..

1963 June 21-27 - .
  • Apollo LEM guidance and navigation system coordination meeting - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MSC met with those contractors participating in the development of the LEM guidance and navigation system. Statements of Work for the LEM design concept were agreed upon. (Technical directives covering most of the work had been received earlier by the contractors.)

1963 June 28 - .
  • RCA named as subcontractor for Apollo LEM electronics subsystems and for engineering support - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Communications; LM Guidance. NASA announced its concurrence in Grumman's selection of RCA as subcontractor for the LEM electronics subsystems and for engineering support. Under the $40 million contract, RCA was responsible for five LEM subsystem areas: systems engineering support, communications, radar, inflight testing, and ground support. RCA would also fabricate electronic components of the LEM stabilization and control system. (Engineers and scientists from RCA had been working at Grumman on specific projects since February.)

1963 July 30-31 - .
  • Installation of the inertial measurement unit and optical telescope in the Apollo LEM discussed - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MIT and Grumman representatives discussed installing the inertial measurement unit and the optical telescope in the LEM. Of several possible locations, the top centerline of the cabin seemed most promising. Grumman agreed to provide a preliminary structural arrangement of the guidance components so that MIT could study problems of installation and integration.

1963 Week of August 22-29 - .
  • Ad Hoc Rendezvous Working Group formed - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Communications; LM Communications; LM Guidance. Summary: An Ad Hoc Rendezvous Working Group was formed at MSC to study the possibility of substituting a unified S-band system for the rendezvous X-band radar on the LEM and CSM..

1963 October 10 - .
  • Results of tests performed by astronauts in the Manned Space Flight Mission Simulator - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Guidance; LM Guidance. LTV announced the results of tests performed by astronauts in the Manned Space Flight Mission Simulator in Dallas, Tex. These indicated that, should the primary guidance and navigation system fail, LEM pilots could rendezvous with the CM by using a circular slide rule to process LEM radar data.

1963 October 18 - .
  • Selection of five organizations for Apollo LEM guidance and navigation equipment - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Guidance; LM Guidance. NASA Headquarters announced the selection of five organizations for contract negotiations totaling $60 million for the development, fabrication, and testing of LEM guidance and navigation equipment: (1) MIT, overall direction; (2) Raytheon, LEM guidance computer; (3) AC Spark Plug, inertial measurement unit, gyroscopes, navigation base, power and servo assembly, coupling display unit, and assembly and testing of the complete guidance and navigation system; (4) Kollsman Instrument Corporation, scanning telescope, sextant, and map and data viewer; and (5) Sperry Gyroscope Company, accelerometers. (All five had responsibility for similar equipment for the CSM as well.)

1963 November 8 - .
  • Go-ahead to RCA to develop the Apollo LEM radar - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Communications; LM Guidance. Grumman issued a go-ahead to RCA to develop the LEM radar. Negotiations on the $23.461 million cost- plus-fixed-fee contract were completed on December 10. Areas yet to be negotiated between the two companies were LEM communications, inflight test, ground support, and parts of the stabilization and control systems.

1963 December - .
  • Ryan selected for Apollo landing radar - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: RCA, contractor to Grumman for the LEM rendezvous and landing radars, chose Ryan Aeronautical Company as vendor for the landing radar. The contract was signed March 16, 1964..

1964 January 15-23 - .
  • Apollo LEM manual orientation 36,600 meters above the moon - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: ASPO asked the Flight Crew Operations Directorate to study whatever was necessary to ensure that the LEM crew could reorient their spacecraft manually in an abort 36,600 meters (120,000 feet) above the moon..

1964 February 11 - .
  • Apollo LEM to use an inertial reference system - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. ASPO directed Grumman to provide an abort guidance system (AGS) in the LEM using an inertial reference system attached to the structure of the vehicle. Should the spacecraft's navigation and guidance system fail, the crew could use the AGS to effect an abort. Such a device eliminated the need for redundancy in the primary guidance system (and proved to be a lighter and simpler arrangement).

1964 February 24 - .
  • Weight and power tradeoff study on the Apollo LEM's radar systems - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. RCA presented results of a weight and power tradeoff study on the LEM's radar systems, which were over Grumman's specification in varying amounts from 100 to 300 percent. RCA proposed that the accuracy requirements be relaxed to cope with this problem. MSC requested Grumman, on the basis of this report, to estimate a slippage in the schedule and the effects of additional weight and power.

1964 February 25 - .
  • Design Engineering Inspection of the Apollo LEM timing equipment - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: MSC conducted a Design Engineering Inspection of the LEM timing equipment at the Elgin National Watch Company..

1964 February 27-March 4 - .
  • Capability of the Apollo LEM landing radar - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. A joint Grumman, RCA, Ryan Aeronautical Company, ASPO, and Flight Crew Support Division (FCSD) meeting was held at Bethpage to review capability of the LEM landing radar to meet FCSD's requirements for ascent and for orbit circularization. A preliminary (unfunded) Ryan study (requested by ASPO earlier in the month) indicated some doubt that those accuracy requirements could be met. RCA advised that it would be possible to make these measurements with the rendezvous radar, if necessary. A large weight penalty, about 38 to 56 kilograms (84 to 124 pounds), would be incurred if the landing radar were moved from the descent to the ascent stage to become part of the abort guidance system. Adding this weight to the ascent stage would have to be justified either by improved abort performance or added crew safety. MSC authorized RCA and Ryan to study this problem at greater length. In the meantime, ASPO and FCSD would analyze weights, radar accuracies, and abort guidance performance capability.

1964 March 12-18 - .
  • Kearfott to build the Apollo LEM rate gyro assembly - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: Grumman completed negotiations with Kearfott Products Division, General Precision, Inc., for the LEM rate gyro assembly, and a contract was awarded later in the month..

1964 March 16 - .
  • RCA to build the Apollo LEM lunar landing radar - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: Ryan Aeronautical Company signed a contract with RCA for the LEM lunar landing radar. Ryan was instructed to design for altitudes of 21,300 meters (70,000 feet) and accuracies of 0.5 percent..

1964 April 2-9 - .
  • Revisions to Apollo's communications requirements - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Communications; LM Guidance. The MSC Operations Planning Division (OPD) reviewed recent revisions by OMSF to Apollo's communications requirements:

    • Elimination of the requirement for continuous tracking of the spacecraft during translunar injection
    • Sequential rather than simultaneous transmission of data from the ground to the two spacecraft (to be compatible with the Manned Space Flight Network)
    • A five-kilometer (three-nautical-mile) communications range on the lunar surface (to be compatible with the design of the portable life support system)
    • Elimination of the requirement for direct transmission to the CSM from an extravehicular astronaut; instead, such transmission would be relayed via the LEM.
    Thus were resolved, OPD reported, a number of conflicting items (i.e., incompatibilities between OMSF's requirements and the capabilities of the two spacecraft). Two other items that OMSF made into firm requirements were already compatible with the design of the spacecraft:

    1. A radar in the CSM capable of tracking the LEM (provided the LEM had a compatible transponder)
    2. Three-way communications between an astronaut on the moon, his fellow crewman inside the LEM, and with mission control.

1964 September 14 - .
  • Ground rules for lunar excursion module guidance and control system firmly defined - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: Ground rules for lunar excursion module guidance and control system firmly defined..

1964 October 1-2 - .
  • Plan for testing the Apollo LEM rendezvous and landing radar - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Representatives from Grumman Aircraft Engineering Corporation, North American Aviation, Inc., and Massachusetts Institute of Technology's (MIT) Instrumentation Laboratory, three of the Manned Spacecraft Center's (MSC) principal contractors, met with radar and guidance and navigation experts from Houston and Cape Kennedy. They formulated a detailed plan for testing and checkout of the lunar excursion module (LEM) rendezvous and landing radar systems both at the factory and at the launch site.

1964 October 8 - .
  • Contract for the Apollo LEM attitude translation control assembly - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Communications; LM Guidance; LM RCS. Radio Corporation of America's (RCA) Aerospace Systems Division received a 9 million contract from Grumman for the LEM attitude translation control assembly (ATCA). The ATCA, a device to maintain the spacecraft's attitude, would fire the reaction control system motors in response to signals from the primary guidance system.

1964 October 8-15 - .
  • Weight of the Apollo LEM rendezvous radar 319.8 kg - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: RCA reduced the weight of the LEM rendezvous radar from 39.9 to 31.98 kg (88 to 70.5 lbs)..

1964 October 12 - .
  • Apollo LEM guidance and navigation ground rules for the coasting phase of the mission - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Guidance; LM Guidance. MSC notified Grumman of several additional LEM guidance and navigation ground rules that were applicable to the coasting phase of the mission. During this portion of the flight, the LEM abort guidance system must be capable of giving attitude information and of measuring velocity changes. Navigational data required to take the LEM out of the coasting phase and to put it on an intercept course with the CSM would be provided by the CSM's rendezvous radar and its guidance and navigation system, and through the Manned Space Flight Network back on earth.

1964 October 15 - .
  • Consequences of eliminating the Apollo CSM rendezvous radar - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Guidance; LM Descent Propulsion; LM Guidance. MSC's Systems Engineering Division reported on the consequences of eliminating the command and service module (CSM) rendezvous radar:

    Coasting period:
    During this phase of the mission, the rendezvous radar on the CSM would be used to track the LEM and the rendezvous radar on the LEM would be used to track the CSM. With the use of Mission Control through the Manned Space Flight Network (MSFN), three sources of information could be used as a vote for guidance system monitoring. Without the CSM rendezvous radar, the monitoring task would become more difficult; however, this was not to imply that it was impossible. The conclusion was that CSM rendezvous radar was highly desirable, but not absolutely necessary.
    Lunar descent and ascent:
    During powered flight, the CSM would be tracking the LEM. This was desirable because if the LEM guidance computer (LGC) failed, it was very doubtful that the astronauts could manually acquire radar lock-on with the CSM. Also, if the LEM rendezvous radar failed, CSM lock-on would be highly desirable. There were several alternative solutions to this problem. First of all, Mission Control through the MSFN could relieve the problem. If this did not satisfy all requirements, it was possible for the LEM rendezvous radar to track the CSM during powered descent and ascent. If the LGC then failed, the tracking acquisition would no longer be a problem. In summary, there did appear to be other ways of fulfilling the functions of the CSM rendezvous radar during the powered phases.
    Lunar surface:
    While the LEM was on the lunar surface, it would be tracked with the CSM rendezvous radar in order to update launch conditions. This could be accomplished by the LEM tracking the CSM and the MSFN.
    Rendezvous:
    This was the most critical phase for the use of the rendezvous radar on the CSM. If the LEM primary guidance system should fail (i.e., the LGC, inertial measurement unit (IMU), and LEM rendezvous radar), navigation information for long-range midcourse corrections would be provided by the rendezvous radar on the CSM. The MSFN, however, could supply this information. The terminal rendezvous maneuver would become a problem if the LEM rendezvous radar failed and there was not a rendezvous radar on the CSM. It had not been established that the MSFN could supply the required terminal rendezvous information. If MSFN could, a restricted mission profile would have to be employed. There were other methods of supplying terminal rendezvous information such as optical tracking. The scanning telescope or sextant on the CSM could be used with the IMU and Apollo guidance computer on the CSM to derive navigation information, meaning that the LEM would require flashing lights. There was a delta-V penalty associated with using angle-only information in place of range range rate and angle information, its importance depending on the accuracy of the angle data and the range/range rate data.

1964 October 15 - .
  • Remote operation of the Apollo CSM's rendezvous radar transponder and SCS not necessary - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Docking; LM Guidance. Remote operation of the CSM's rendezvous radar transponder and its stabilization and control system (SCS) was not necessary, ASPO told North American. Should the CSM pilot be incapacitated, it was assumed that he could perform several tasks before becoming totally disabled, including turning on the transponder and the SCS. No maneuvers by the CSM would be required during this period. However, the vehicle would have to be stabilized during LEM ascent, rendezvous, and docking.

1964 October 16 - .
  • Problem of Apollo CSM stabilization if the crewman disabled - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Docking; LM Guidance. In a letter on August 25, 1964, the LEM Project Office had requested Grumman to define the means by which CSM stabilization and rendezvous radar transponder operation could be provided remotely in the event the CSM crewman was disabled.

    In another letter on October 16, the Project Office notified Grumman that no requirement existed for remote operation of either the rendezvous radar transponder or the stabilization and control system. The letter added, however, that the possibility of an incapacitated CSM astronaut must be considered and that for design purposes Grumman should assume that the astronaut would perform certain functions prior to becoming completely disabled. These functions could include turning on the transponder and the SCS. No CSM maneuvers would be required during the period in which the CSM astronaut was disabled but the CSM must remain stabilized during LEM ascent coast and rendezvous and docking phases.


1964 November 23-25 - .
  • Ground test program for the Apollo LEM guidance and navigation subsystem - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Guidance; LM Guidance. MSC and Grumman reviewed the ground test program for the LEM guidance and navigation subsystem (including radar). All major milestones for hardware qualification would be met by the revised test logic, and both LEM and CSM radar were expected to be delivered on time. The major problem area was permissible deviations from fully qualified parts for pre-production equipment. Since this was apparently true for all LEM electronics equipment, it was recommended that an overall plan be approved by ASPO.

1964 November 26-December 3 - .
  • Leach to supply data storage electronics assemblies for the Apollo LEM - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Grumman selected the Leach Corporation to supply data storage electronics assemblies for the LEM. Conclusion of contract negotiations was anticipated about February 1, 1965. The resident Apollo office at Grumman gave its approval to the selection, with only two conditions:

    1. because of its toxic characteristics, beryllium must not be used in the assemblies; and
    2. Leach should demonstrate the feasibility of the proposed time-voice multiplexing scheme.

1964 December 11 - .
  • Apollo LEM abort guidance section - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MSC directed Grummann to provide a LEM abort guidance section (AGS) having

    • a computer memory of 4096 words
    • the provision for in-flight null bias gyro drift compensation
    • a general purpose input output device
    • Bell 3B accelerometers
    • input registers for rendezvous radar information such that a future interface could be mechanized if desired
    • an interface between the primary navigation and guidance system (PNGS) and the AGS for position and velocity updating of the AGS from the PNGS.

1964 December - .
  • Apollo LEM major subcontractors to revise test programs and hardware schedules - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Descent Propulsion; LM Guidance. Grumman ordered its major subcontractors supplying electronic equipment for the LEM to implement revised test programs and hardware schedules (in line with the new design approach). A similar directive went to RCA to modify the attitude and translation and the descent engine control assemblies as required for the new concept of an integrated assembly for guidance, navigation, and control of the spacecraft.

1965 January 5 - .
  • Study of manual control of the Apollo LEM - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: MSC's Guidance and Control Division conducted a pilot simulation study to determine whether a pilot could take over manual control of the LEM between 4,572 and 3,048 m (15,000 and 10,000 ft) above the lunar surface and satisfactorily land the vehicle.. Additional Details: here....

1965 January 6 - .
  • Apollo program review with MIT - . Nation: USA. Related Persons: Shea. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. ASPO Manager Joseph F. Shea informed Apollo Program Director Samuel C. Phillips that he planned to conduct a program review with MIT during January 1965, similar to the North American, AC Spark Plug, and Grumman program reviews, but with certain differences, since MIT was a non- profit organization and the scope of its work much narrower than the prime hardware contractors. Shea pointed out that 1965 would be the most critical year of the MIT effort; during that year all drawings for the Block I, Block II, and LEM guidance navigation and control programs should be released. Consequently, the program review at MIT would examine only that one year.

    Shea said he would meet with C. Stark Draper on January 14 and discuss with him "where we stand with respect to the MIT work of the past and our concerns for the future." During the week of January 18, MSC would send 14 teams to MIT to meet with their counterparts, and the following week a review board, chaired by R. C. Duncan of MSC, would go over the work of the individual MIT-NASA teams in depth and agree upon the program for 1965. The 14 teams would be: Reliability and Quality Assurance, Field Operations, Documentation and Configuration Management, Systems Assembly and Test, Guidance and Mission Analysis, Simulation, Ground Support Equipment, Optics, Inertial Systems and Sensors, Computer, Radar, Training; Terms, Conditions, Rates and Factors; and Statement of Work Integration.

    Shea felt that the review would give MIT a clearer understanding of their part in the guidance, navigation, and control system development. He recommended that Phillips discuss the general nature of the program review with George E. Mueller and Robert C. Seamans, Jr., so they would both understand ASPO's objectives.

    Phillips forwarded the letter to Associate Administrator for Manned Space Flight George E. Mueller along with his comments on the proposal. He said, "I think it is a good plan and that the results will be beneficial to the program. I urge your support should it become necessary."


1965 January 13 - .
  • Configuration Control Board - . Nation: USA. Related Persons: Maynard. Program: Apollo. Spacecraft: Apollo LM; CSM Block II; LM Guidance; LM Weight. The first meeting of the Configuration Control Board was held at MSC with ASPO Manager Joseph F. Shea as chairman. Approval was given to delete 10 Apollo guidance and navigation systems; and W. F. Rector III was directed to look into the use of computers and prototype units for electronic systems integration. In other actions, a decision on changes to CSM specifications to provide for the heavyweight LEM (a proposed increase from 12,705 to 14,515 kg (28,000 to 32,000 lbs)) was deferred until the next meeting; and Owen Maynard was directed to identify all Block II changes that must be implemented regardless of impact and have them ready for Board action by February 18, 1965.

1965 January 18 - .
  • Alternates considered for Apollo S-band high-gain antenna - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Block II; LM Communications; LM Guidance. MSC was studying several approaches to the problems of automatic thermal control and automatic reacquisition of the earth by the S-band high-gain antenna while the CSM circled the moon. (The Block II spacecraft, MSC had stated, must have the ability to perform these functions wholly on its own. During an extended stay of the LEM on the lunar surface, when the CSM pilot needed uninterrupted sleep periods, antenna reacquisition was absolutely essential for telemetering data back to earth. And although the requirements for passive thermal control were not yet well defined, the spacecraft's attitude must likewise be automatically controlled.)

    Robert C. Duncan, chief of the MSC Guidance and Control Division, presented his section's recommendations for solving these problems, which ultimately won ASPO's concurrence. Precise spacecraft body rates, Duncan said, should be maintained by the stabilization and control system. The position of the S-band antenna should be telemetered to the ground, where the angle required for reacquisition would be computed. The antenna would then be repositioned by commands sent through the updata link.


1965 February 16 - .
  • Specialty areas for 13 astronauts not assigned to Gemini - . Nation: USA. Related Persons: Aldrin; Anders; Bassett; Bean; Cernan; Chaffee; Collins; Cunningham; Eisele; Freeman; Gordon; Schweickart; Scott; Williams, Clifton. Program: Apollo. Spacecraft: Apollo LM; CSM ECS; LM Communications; LM ECS; LM Guidance. MSC announced a realignment of specialty areas for the 13 astronauts not assigned to forthcoming Gemini missions (GT 3 through 5) or to strictly administrative positions:

    Operations and Training
    Edwin E. Aldrin, branch chief - mission planning

    Charles A. Bassett - operations handbooks, training, and simulators

    Alan L. Bean - recovery systems

    Michael Collins - pressure suits and extravehicular activity

    David R. Scott - mission planning and guidance and navigation

    Clifton C. Williams - range operations, deep space instrumentation, and crew safety.

    Project Apollo
    Richard F. Gordon, branch chief - overall astronaut activities in Apollo area and liaison for CSM development

    Donn F. Eisele - CSM and LEM

    William A. Anders - environmental control system and radiation and thermal systems

    Eugene A. Cernan - boosters, spacecraft propulsion, and the Agena stage

    Roger B. Chaffee - communications, flight controls, and docking

    R. Walter Cunningham - electrical and sequential systems and non-flight experiments

    Russell L. Schweickart - in-flight experiments and future programs.


1965 February 17 - .
  • Rendezvous radar delete from Block II Apollo CSMs - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Block II; LM Guidance. MSC directed North American to delete the rendezvous radar from Block II CSMs. On those spacecraft North American instead would install LEM rendezvous radar transponders. Grumman, in turn, was ordered to halt its work on the CSM rendezvous radar (both in-house and at RCA) as well as all support efforts. At the same time, however, the company was directed to incorporate a tracking light on the LEM (compatible with the CSM telescope sextant) and to modify the spacecraft's VHF equipment to permit range extraction in the CSM.

1965 March 9 - .
  • Initial flights of the LLRV - . Nation: USA. Program: Apollo. Spacecraft: Apollo LLRV; LM Descent Propulsion; LM Guidance. Initial flights of the LLRV interested MSC's Guidance and Control Division because they represented first flight tests of a vehicle with control characteristics similar to the LEM. The Division recommended the following specific items for inclusion in the LLRV flight test program:

    • The handling qualities of the LEM attitude control system should be verified using the control powers available to the pilot during the landing maneuver. The attitude controller used in these tests should be a three-axis LEM rotational controller.
    • The ability of pilots to manually zero the horizontal velocities at altitudes of 30.48 m (100 ft) or less should be investigated. The view afforded the pilot during this procedure should be equivalent to the view available to the pilot in the actual LEM.
    • The LEM descent engine throttle control should be investigated to determine proper relationship between control and thrust output for the landing maneuver.
    • Data related to attitude and attitude rates encountered in landing approach maneuvers were desirable to verify LEM control system design limits.
    • Adequacy of LEM flight instrument displays used for the landing maneuver should be determined.
    Guidance and Control Division would provide information as to control system characteristics and desired trajectory characteristics. D. C. Cheatham, a member of the Lunar Lander Research Vehicle Coordination Panel, would coordinate such support.

1965 April 1 - .
  • Systems engineering study of Apollo lunar landing dynamics - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance; LM Landing Gear. Apollo Program Director Samuel C. Phillips told ASPO Manager Joseph F. Shea that Bellcomm, Inc., was conducting a systems engineering study of lunar landing dynamics to determine "functional compatibility of the navigation, guidance, control, crew, and landing gear systems involved in Apollo lunar landing." Phillips asked that he be advised of any specific assignments in these areas which would prove useful in support of the ASPO operation.

    Shea replied, "We are currently evaluating the LEM lunar landing system with the Apollo contractors and the NASA Centers. We believe that the landing problem is being covered adequately by ourselves and these contractors." Shea added that a meeting would be held at Grumman April 21 and 22 to determine if there were any deficiencies in the program, and that he would be pleased to have Bellcomm attend the meeting and later make comments and recommendations.


1965 April 9 - .
  • Recommendation for an up-data system in the Apollo LEM during manned missions - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Guidance; LM Guidance; LM Weight. Systems Engineering Division (SED) reviewed the Flight Operations Directorate's recommendation for an up-data system in the LEM during manned missions. (Currently the LEM's guidance computer received data either from the computer in the CSM or from MSC.) SED concluded that, because the equipment was not essential for mission success, an up-data system did not warrant the cost and weight penalties ($750,000 and 4.54 kg (10 lbs)) that it would entail.

1965 April 20 - .
  • RCA Apollo systems engineering subcontract terminated - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MSC's Systems Engineering Division requested that Grumman be advised to terminate the RCA systems engineering subcontract as soon as possible. It had been determined that this contract was no longer useful. Based on data presented by Grumman during a program review, an immediate and complete termination would save about $45,000.

1965 May 5 - .
  • Communications between the Apollo CSM, LEM, and extravehicular astronauts were reviewed - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Block II; LM Communications; LM Guidance; LM Hatch. In response to a query, Apollo Program Director Samuel C. Phillips told NASA Associate Administrator for Manned Space Flight George E. Mueller that plans to use VHF communications between the CSM, LEM, and extravehicular astronauts and to use X-band radar for the CSM/LEM tracking were reviewed. Bellcomm reexamined the merits of using the Unified S-Band (USB) type which would be installed in the CSM and LEM for communication with and tracking by the earth.

    It was found that no appreciable weight saving or weight penalty would result from an all USB system in the Apollo spacecraft. Also, it was determined there would be no significant advantage or disadvantage in using the system. It was noted, however, that implementation of an all S-band system at that stage of development of the design of the CSM, LEM, and astronaut equipment would incur an obvious cost and schedule penalty.

    Memorandum, Phillips to Mueller, "Use of Only Unified S-Band Communication Equipment in Apollo Spacecraft," May 5, 1965.

    May 6

    After lengthy investigations of cost and schedule impacts, MSC directed North American to incorporate airlocks on CMs 008 and 014, 101 through 112, and 2H-1 and 2TV-1. The device would enable astronauts to conduct experiments in space without having to leave their vehicle. Initially, the standard hatches and those with airlocks were to be interchangeable on Block II spacecraft. During October, however, this concept was changed: the standard outer hatch would be structured to permit incorporation of an airlock through the use of a conversion kit (included as part of the airlock assembly); and when an airlock was installed, an interchangeable inner hatch would replace the standard one.


1965 May 10 - .
  • Proposal to modify Apollo LEM radar programs - . Nation: USA. Program: Apollo. Flight: Apollo 10. Spacecraft: Apollo LM; LM Guidance. Summary: ASPO Assistant Manager William A. Lee heard a proposal to modify the LEM radar programs to reduce FY 1966 costs by $7 million. . Additional Details: here....

1965 May 20-27 - .
  • Radar-aided Apollo powered descent - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. To determine lunar touchdown velocity uncertainties, MIT studied radar-aided powered descent. From MIT's findings, Guidance and Control Division concluded that one or two sensors should provide velocity updates to the guidance system throughout the descent maneuver.

1965 May 24 - .
  • MSC concurred in Grumman's selection of the RF tracking mode for the Apollo LEM's steerable antenna - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: MSC concurred in Grumman's selection of the RF tracking mode for the LEM's steerable antenna..

1965 June 7 - .
  • Revised velocity budgets for Apollo CSM and LM - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Apollo Program Director Samuel C. Phillips approved MSC's request for revised velocity budgets for the two spacecraft. It was understood that these new values would:

    1. still meet the free return trajectory constraint; and
    2. increase (to at least two degrees) the LEM's out-of-plane launch capability. MPAD/FOD provided the analysis and recommendations leading to this decision.

1965 June 16 - .
  • Apollo LEM to be able to telemeter data from the abort electronics assembly (AEA) - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MSC directed Grumman to modify the LEM's pulse code modulation and timing electronics assembly to enable it to telemeter data from the abort electronics assembly (AEA). Thus, if data from the AEA disagreed with those from the spacecraft's guidance computer, the two sets could be reconciled on the ground (using inputs from the Manned Space Flight Network), relieving the astronauts of this chore.

1965 June 16 - .
  • Deviations in the Apollo CSM's roll attitude during docking to be limited to eight degrees or less - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Docking; LM Guidance. Summary: To prevent the CSM's contacting the LEM's radar antenna (a problem disclosed during docking simulations), deviations in the CSM's roll attitude would be limited to eight degrees or less..

1965 June 22 - .
  • Additional functions defined for Apollo LEM's abort guidance computer - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MSC advised Grumman of additional functions for the computer in the LEM's abort guidance section (to be added only if a part of its memory was left over after the basic requirements were digested). These functions, in order of priority, MSC listed as:

    • Midcourse corrections
    • Automatic abort from a coasting descent
    • Display of CSM-LEM range and range rate
    • Automatic terminal rendezvous (with manual velocity control).

1965 June 25 - .
  • Proposed location of the antenna for the radar transponder in the Apollo CSM approved - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Docking; LM Guidance. MSC approved North American's proposed location of the antenna for the radar transponder in the CSM, as well as the transponder's coverage. This action followed a detailed review of the relative positions of the two spacecraft during those mission phases when radar tracking of the LEM was required.

1965 July 22 - .
  • Briefing on the Apollo LEM optical tracker - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Agreements and decisions reached at the MSC briefing on the LEM optical tracker were:

    • Development of the LEM rendezvous radar should be continued.
    • One contractor should be selected for development of the optical tracker with schedules to support installation in early LEMs.
    • A decision on the rendezvous radar versus the optical tracker was deferred.

1965 July 23 - .
1965 July 23 - .
  • Functions defined for the Apollo LEM's abort guidance section - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MSC defined for Grumman the functions that the LEM's abort guidance section (AGS) must perform during earth orbital flights:

    • When both spacecraft were unmanned, the AGS must be able to hold the LEM's attitude during coast or while thrusting; it would not, however, have to control thrusting itself.
    • During manned missions, whether or not the LEM itself actually was manned, the AGS must afford closed-loop control of the vehicle, again both while coasting and thrusting. Thrusting phases of these flights would demonstrate the section's guidance and navigational capabilities.
    The basic lunar mission program still would be used. False position, velocity, and gravity data would be inserted to make the AGS behave as if it were flying around the moon. Finally, MSC emphasized that neither the AGS hardware, its permanent or "hardwired" memory, nor delivery schedules must be altered to meet this earth orbital capability.

1965 August 24 - .
  • Review of the Apollo LEM landing and docking dynamic environments - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM ECS; LM Guidance. MSC requested that Grumman review the current LEM landing and docking dynamic environments to assure: (1) no loss of the abort guidance system attitude reference due to angular motion exceeding its design limit of 25 degrees per second during indicated mission phases; and (2) a mission angular acceleration environment, exceeding the gyro structural tolerances, would not be realized.

1965 September 2-9 - . LV Family: Saturn V. Launch Vehicle: Saturn V.
  • Abort feasibility for the AS-206 mission - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: MSC's Flight Operations Division requested an investigation of the feasibility of performing an abort from an inoperative S-IVB booster on the AS-206 unmanned LEM mission..

1965 September 3 - .
  • Status of the Apollo LEM tracking systems described - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. NASA Associate Administrator for Manned Space Flight George E. Mueller summarized for Administrator James E. Webb the status of the LEM tracking systems. The LEM rendezvous radar system, which had been under development since 1963, was expected to be available when needed for flight missions. Technical studies had shown that an Optical Tracker System offered weight and reliability advantages with no reduction in LEM performance. Hughes Aircraft Company was developing an Optical Tracking System as a back-up to the rendezvous radar.

1965 September 16 - .
  • Apollo LM PCMTEA changes - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance; LM Weight. The Assistant Chief for Electronic Systems notified ASPO that the proposed Grumman plan to repackage the LEM pulse command modulated and timing electronic assembly (PCMTEA) had been discussed and investigated and that the Instrumentation and Electronic Systems Division (IESD) concurred with the proposal. Additional Details: here....

1965 September 20 - .
  • Reducing landing velocity requirements for the Apollo LEM spacecraft - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. On the basis of studies by both MSC and Grumman on LEM landing criteria, Engineering and Development Directorate determined that contractor and customer alike favored reducing landing velocity requirements for the spacecraft. The two did not see eye to eye on how far these requirements should be reduced, however, and MSC would study the problem further.

1965 September 24 - .
  • Critical Design Review (CDR) of the Apollo LEM rescheduled - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Communications; LM Guidance. The Critical Design Review (CDR) of the LEM, tentatively planned during the week of September 27, 1965, at Grumman, was rescheduled as a series of reviews beginning in November 1965 and ending in January 1966. The schedule was to apply with five teams participating as follows: Structures and Propulsion, November 8-11, Team Captain: H. Byington; Communications, Instrumentation, and Electrical Power, December 6-9, Team Captain: W. Speier; Stabilization and Control, Navigation and Guidance, and Radar, January 10-13, Team Captain: A. Cohen; Crew Systems, January 10-13, Team Captain: J. Loftus; and Mission Compatibility and Operations, January 24-27, Team Captain: R. Battey.

1965 October 1 - .
  • Contract to AC Electronics for an optical tracking system for the Apollo LEM (alternative to radar) - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MSC informed Grumman that the Center had awarded a contract to AC Electronics for the development of an optical tracking system for the LEM (as a possible alternative to the rendezvous radar). Until MSC reached a final decision on which mode to use, Grumman should continue building the LEM to accept either of these navigational devices. Flight Crew Operations Directorate requested the decision be deferred pending evaluation of an operational paper.

1965 October 26 - .
  • Apollo Block II CSM to include a luminous beacon compatible with the LEM tracking system - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; CSM Block II; LM Guidance. Summary: MSC authorized North American to modify the Block II CSM design to provide for installation of a luminous beacon compatible with the LEM tracking system. The CSM beacon could replace the rendezvous radar and transponder..

1965 November 4 - .
  • Apollo franslunar flight time reduced to 100 hrs - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: MSC's Configuration Control Board approved the reduction of maximum translunar flight time from 110 hrs to 100 hrs..

1965 November 12-18 - .
  • Ryan to present areas in which weight could be saved on the Apollo LEM landing radar - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: MSC directed Ryan Aeronautical Corporation to present to RCA and Grumman areas in which weight could be saved on the LEM landing radar. Of specific interest was the power supply and the possibility of its overdesign..

1965 November - .
  • Grumman completed negotiations with TRW for Apollo LEM abort guidance system - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: Grumman completed negotiations with Thompson-Ramo-Wooldridge for the LEM abort guidance system..

1965 December 16-23 - .
  • Requirement deleted to use the Apollo LEM rendezvous radar for during powered phases - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Summary: The requirement to use the LEM rendezvous radar for surface or skin track and for tracking in the cooperative mode during powered LEM mission phases was deleted from the Grumman Technical Specification and the Master End Item Specification..

1966 February 1 - .
  • Debate on use of optics versus radar as a primary Apollo LEM rendezvous aid - . Nation: USA. Related Persons: Slayton. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. MSC Assistant Director for Flight Crew Operations Donald K. Slayton said he did not think that current testing or proposed evaluation would do anything to resolve the basic debate between optics versus radar as a primary LEM rendezvous aid. Slayton said, "The question is not which system can be manufactured, packaged, and qualified as flight hardware at the earliest date; it is which design is most operationally suited to accomplishing the lunar mission. The 'Olympics' contribute nothing to solving this problem." He proposed that an MSC management design review of both systems at the earliest reasonable date was the only way to reach a conclusion, adding, "This requires only existing paperwork and knowledge - no hardware."

1966 June 7 - .
  • Series of actions on the Apollo LM rendezvous sensor - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM ECS; LM Guidance. A series of actions on the LM rendezvous sensor was summarized in a memo to the MSC Apollo Procurement Branch. A competition between LM rendezvous radar and the optical tracker had been initiated in January 1966 after discussion by ASPO Manager Joseph F. Shea, NASA Associate Administrator for Manned Space Flight George E. Mueller, and MSC Guidance and Control Division Chief Robert C. Duncan. On May 13, RCA and Hughes Aircraft Go. made presentations on the rendezvous radar optical tracker. The NASA board that heard the presentations met for two days to evaluate the two programs and presented the following conclusions:

    1. both sensors could meet the difficult environmental requirements of the lunar mission with near specification performance,
    2. the tracker had several possible specification deviations,
    3. optical production training represented a difficult schedule problem at Hughes, and
    4. either sensor could be produced in time to meet LM and program schedules.
    The board's evaluation, an analytical presentation by Donald Cheatham, a weight-and-power comparison by R. W. Williams, and a cost presentation by the two contractors were given MSC management May 19. Management recommended that RCA's radar be continued as the main effort and that a backup optical tracker program be continued by Hughes on a greatly reduced level. The recommendations were made to Apollo Program Director Samuel C. Phillips and NASA Associate Administrator George E. Mueller at KSC on May 25. Phillips and Mueller concurred but stipulated that the optical tracker program was to be completed on a fixed-price basis and that MSC would qualify the optical tracker using the facilities of the MSC laboratories. Mueller expressed concern about developmental difficulties and possible production problems in the radar program. RCA representatives visited MSC May 27 and reviewed all developmental difficulties and their potential effect on production.

1967 September 29 - .
  • Apollo spacecraft weight changes - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Communications; LM ECS; LM Guidance; LM Hatch. Because of many questions asked about spacecraft weight changes in the spacecraft redefinition, ASPO Manager George M. Low prepared a memo for the record, indicating weights as follows:

    Lunar Module Significant Weight Changes Lunar module injected weight status March 1, 1967 (ascent and descent less propellant) - 4039.6 kg

    • Material substitution +23.1;
    • decrease clamps and potting, -4.5;
    • government furnished equipment changes (pressure garment assembly, portable life support system, oxygen purge system), +68;
    • plume heating and "fire-in-the-hole" protection, +59.8;
    • redesign umbilical hoses, +2.2;
    • revised oxygen and water requirements, +19.5;
    • provision for ALSEP removal, +11.3;
    • increasing crack resistance of webs, +13.6;
    • additional wiring to provide redundant circuits, +4.9;
    • fuel cask and support increase, +14.9;
    • guidance and navigation equipment, +3.1;
    • instrumentation, +9.9;
    • communications, +1.8;
    • miscellaneous changes, +2.2.
    Net change from March to September was +230.4 kg.

    Lunar module injected weight status September 22, 1967 - 4270.0 kg

    Command Module Significant Weight Changes Command module injected weight status March 1, 1967 - 5246.7 kg

    • New hatch, +114.7;
    • environmental control system and weight management system changes, +103.4;
    • instrumentation and electrical power, +48;
    • wiring and tubing protection, +44.4;
    • crew compartment materials and crew equipment, +101.6;
    • forward heatshield separation, +13.6;
    • earth landing system (larger drogues), +21.7;
    • miscellaneous structural changes, +26.7;
    • ballast for lift-over-drag ratio of 0.35, +175;
    • other, +19.5.
    • Reductions - transfer of portable life support system to LM,-31.2;
    • reduced ballast for lift-over-drag ratio of 0.28, -142.8;
    • other MSC weight reductions, -61.6.
    Net change from March to September was +433.1 kg.

    Command module injected weight status September 22, 1967 - 5679.8 kg


1968 February 8 - .
  • Decision to forego a second unmanned Apollo LM flight using LM-2 - . Nation: USA. Related Persons: Low, George. Program: Apollo. Spacecraft: Apollo LM; LM Descent Propulsion; LM Guidance; LM Landing Gear. Grumman President L. J. Evans wrote ASPO Manager George M. Low stating his agreement with NASA's decision to forego a second unmanned LM flight using LM-2. (Grumman's new position - the company had earlier strongly urged such a second flight - was reached after discussions with Low and LM Manager G. H. Bolender at the end of January and after flight data was presented at the February 6 meeting of the OMSF Management Council.) Although the decision was not irreversible, being subject to further investigations by both contractor and customer, both sides now were geared for a manned flight on the next LM mission. Additional Details: here....

1968 April 10 - .
  • Changes in Apollo lunar mission flight profile - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. The Apollo spacecraft Configuration Control Board (CCB) had endorsed changes in lunar orbit insertion and LM extraction on the lunar mission flight profile, the MSC Director notified the Apollo Program Director. ASPO had reviewed the changes with William Schneider of NASA OMSF the same day and Schneider was to present the changes to George E. Mueller and Samuel C. Phillips for approval.

    The two-burn lunar orbit insertion (LOI) was an operational procedure to desensitize the maneuver to system uncertainties and would allow for optimization of a lunar orbit trim burn. The procedure would be used for lunar orbit and lunar landing missions. The spacecraft lunar-adapter spring-ejection system was required to ensure adequate clearance during separation of the LM/CSM from the S-IVB/instrument unit and would be used on the first manned CSM/LM mission.


1968 June 17 - .
  • Two-burn lunar orbit insertion (LOI) maneuver studied - . Nation: USA. Related Persons: Phillips, Samuel. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Apollo Program Director Phillips wrote MSC Director Gilruth concerning the April 10 proposal for a two-burn lunar orbit insertion (LOI) maneuver and a spring ejection of the LM from the spacecraft-lunar module adapter. Phillips agreed to the two-burn LOI in place of the originally planned one burn if results of an analysis should prove the requirement. He specified that an analysis be made of the tradeoffs and that the analysis include the risk of crash, the assumed risks due to lengthening the lunar orbit time (about four hours), and risks due to an additional spacecraft propulsion system burn, as well as the effect of the lunar gravitational potential on the ability to target the LOI maneuver to achieve the desired vector at the time of LM descent. The proposal for spring ejection of the LM from the SLA was approved with the provision that a failure analysis be made in order to understand the risks in the change.

1968 July 17 - .
  • Review of the Apollo LM program - . Nation: USA. Related Persons: Mueller. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. NASA Associate Administrator George E. Mueller, Apollo Program Director Samuel C. Phillips, and other high-ranking manned space flight officials from Headquarters visited Bethpage for an overall review of the LM program. Greatest emphasis during their review was on schedules, technical problems, and qualification of the spacecraft's principal subsystems. Mueller and Phillips cited several areas that most concerned NASA:

    • Delivery schedules from subcontractors and vendors had slipped significantly during the past year, to the point where many components were only marginally supporting spacecraft deliveries.
    • The large number of hardware changes made during the past year was affecting costs and schedules.
    • Costs forecast for Fiscal Year 1969 exceeded the current LM budget.
    Mueller also suggested that Grumman consider eliminating the LM rendezvous radar to save weight aboard the vehicle. He stated that VHF ranging would be more accurate and would probably be the preferred mode of operation.

1968 August 1 - .
  • Deletion of the rendezvous radar from the Apollo LM discounted - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM Guidance. Howard W. Tindall, Jr., Deputy Division Chief, MSC Mission Planning and Analysis, wrote ASPO Manager George M. Low: "A rather unbelievable proposal has been bouncing around lately. Because it is seriously ascribed to a high ranking official, MSC and Grumman are both on the verge of initiating activities - feasibility studies, procedures development, etc. - in accord with it. . . . The matter to which I refer is the possibility of deleting the rendezvous radar from the LM. The first thing that comes to mind, although not perhaps the most important, is that the uproar from the astronaut office will be fantastic - and I'll join in with my small voice too. Without rendezvous radar there is absolutely no observational data going into the LM to support rendezvous maneuvers. . . . Please see if you can stop this if it's real and save both MSC and GAEC a lot of trouble." On August 9 Low wrote NASA Apollo Program Manager Samuel Phillips that, shortly after Associate Administrator for Manned Space George Mueller had visited Grumman, Low had calls from both C. H. Bolender, MSC, and Joseph Gavin, Grumman, indicating that Mueller had made a suggestion "that we should eliminate the LM rendezvous radar as a weight saving device." He forwarded Tindall's memorandum as the basis for "why we should not consider deleting the radar and why we shouldn't spend any more effort on this work." Low added that MSC was discontinuing "any work that we may have started as a result of George's comments." In a reply on August 28, Phillips told Low, "I am in complete agreement . . . that all work toward deleting the LM rendezvous radar should be discouraged and I have written to George Mueller to that effect."

1968 August 7 - . LV Family: Saturn V. Launch Vehicle: Saturn V.
  • George Low promotes idea of flying Apollo 8 as a lunar orbit mission without the Lunar Module - . Nation: USA. Related Persons: von Braun. Program: Apollo. Flight: Apollo 7; Apollo 8; Apollo 9. Spacecraft: Apollo LM; Apollo CSM; CSM Block II; LM Guidance; LM RCS. On August 7, Low asked MSC's Director of Flight Operations Christopher C. Kraft, Jr., to look into the feasibility of a lunar orbit mission for Apollo 8 without carrying the LM. A mission with the LM looked as if it might slip until February or March 1969. The following day Low traveled to KSC for an AS-503 review, and from the work schedule it looked like a January 1969 launch. Additional Details: here....

1968 November 27 - .
  • Flight-test of manual control of Apollo LM ascent configuration - . Nation: USA. Program: Apollo. Spacecraft: Apollo LM; LM guidance. The need to flight-test manual control of the light LM ascent configuration had been discussed at the October 15 MSC Flight Program Review, MSC Director Robert R. Gilruth informed NASA Apollo Program Director Samuel C. Phillips. There was an implication that a control problem could exist for this configuration. Gilruth said he had stated that MSC should be able to establish manual control handling qualities of the LM through proper simulation and be confident about the adequacy of the control system.

    Subsequently, Gilruth had reviewed the operating characteristics of the LM control system and the status of the simulation program related to manual control of the light ascent stage during docking. He said that the most demanding requirement for precision manual attitude control was the docking maneuver. Docking control had been simulated extensively at MSC, Grumman, and LaRC using functional representation of the control system and these simulations established the capability of docking the LM well within the specified docking criteria. In addition, other LM control tasks had been simulated at MSC and Grumman, and the LM was found to have satisfactory handling qualities for all manual control tasks.


1969 May 27 - .
  • Manual guidance for TLI on Apollo missions - . Nation: USA. Program: Apollo. Flight: Apollo 10; Apollo 11. Spacecraft: Apollo LM; LM Guidance. Summary: Apollo Program Director Sam C. Phillips wrote to MSC regarding a Flight Readiness Review action item on translunar injection (TLI: insertion into a trajectory toward the moon) dispersions after manual guidance for TLI on Apollo missions. . Additional Details: here....

1969 June 23 - .
  • Preparations for the Apollo 11 on schedule - . Nation: USA. Program: Apollo. Flight: Apollo 11. Spacecraft: Apollo LM; LM Guidance. Summary: Preparations for the first manned lunar landing continued on schedule for a July 16 launch of Apollo 11. . Additional Details: here....

1969 August 12 - .
  • Apollo LM-6 (Apollo 12) guidance computer removed and replaced - . Nation: USA. Program: Apollo. Flight: Apollo 12. Spacecraft: Apollo LM; LM Guidance. Summary: During lunar module checkout activities at KSC, the LM-6 (for Apollo 12) guidance computer was removed and replaced because of an unexpected restart during panel revalidation..

1969 November 10 - .
  • Apollo 12 targetting point for Surveyor 3 changed - . Nation: USA. Program: Apollo. Flight: Apollo 12. Spacecraft: Surveyor; LM Guidance. At the request of the Apollo 12 crew, the internal primary guidance and navigational control system targeting for descent was being changed so that the automatic guidance would land LM-6 at Surveyor III rather than at a point offset 305 meters east and 153 meters north as originally planned.

1969 December 1 - .
  • Requirement for a simple lightweight Apollo lunar roving vehicle guidance and navigation system - . Nation: USA. Program: Apollo. Flight: Apollo 12. Spacecraft: Apollo LRV; LM Communications; LM Guidance; LM Weight. The MSC Flight Crew Operations Directorate submitted its requirement for a simple lightweight Rover (lunar roving vehicle) guidance and navigation system that would provide the following displayed information to the crew: vehicle heading and heading to the LM, speed in kilometers per hour, total distance traveled in kilometers, and distance to the LM. Additional Details: here....

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