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.
The service propulsion system would now provide all major velocity increments required for translunar midcourse velocity corrections, for placing the spacecraft into a lunar orbit, for rendezvous of the command and service modules CSM with the LEM on a backup mode, for transfer of the CSM from lunar orbit into the transearth trajectory, and for transearth midcourse velocity corrections for lunar missions.
Three FIST-type drogue parachutes would replace the original two called for in the earth landing system.
The CM camera system was revised to require one for monitoring the crew, displays, and spacecraft interior; the other for lunar photography and stellar studies. The latter camera could be used in conjunction with the telescope or independently at the crew's discretion.
A new communication concept was described in which all voice, telemetry, television, and ranging information for near-earth and lunar distances would be transmitted over a unified frequency system.
All references to the lunar landing module and space laboratory module were dropped. Among other deletions from the previous Statement of Work were:
Apollo Spacecraft Project Office requested NAA to perform a study of command module-lunar excursion module (CM-LEM) docking and crew transfer operations and recommend a preferred mode, establish docking design criteria, and define the CM-LEM interface. Both translunar and lunar orbital docking maneuvers were to be considered. The docking concept finally selected would satisfy the requirements of minimum weight, design and functional simplicity, maximum docking reliability, minimum docking time, and maximum visibility.
The mission constraints to be used for this study were :
MSC released a sketch of the space suit assembly to be worn on the lunar surface. It included a portable life support system which would supply oxygen and pressurization and would control temperature, humidity, and air contaminants. The suit would protect the astronaut against solar radiation and extreme temperatures. The helmet faceplate would shield him against solar glare and would be defrosted for good visibility at very low temperatures. An emergency oxygen supply was also part of the assembly.
Four days earlier, MSC had added specifications for an extravehicular suit communications and telemetry (EVSCT) system to the space suit contract with Hamilton Standard Division of United Aircraft Corporation. The EVSCT system included equipment for three major operations:
Grumman met with representatives of North American, Collins Radio Company, and Motorola, Inc., to discuss common usage and preliminary design specifications for the LEM communications system. These discussions led to a simpler design for the S-band receiver and to modifications to the S-band transmitter (required because of North American's design approach).
Grumman representatives met with the ASPO Electrical Systems Panel (ESP). From ESP, the contractor learned that the communications link would handle voice only. Transmission of physiological and space suit data from the LEM to the CM was no longer required. VHF reception of this data and S-band transmission to ground stations was still necessary. In addition, Grumman was asked to study the feasibility of a backup voice transmitter for communications with crewmen on the lunar surface should the main VHF transmitter fail.
NASA Headquarters, MSC, Jet Propulsion Laboratory, MSFC, North American, and Grumman agreed that the LEM and CSM would incorporate phase-coherent S-band transponders. [The S-band system provides a variety of communications services. Being phase-coherent meant that it could also provide Mission Control Center with information about the vehicle's velocity and position, and thus was a means of tracking the spacecraft.] Each would have its own allocated frequencies and would be compatible with Deep Space Instrumentation Facilities.
Christopher C. Kraft, Jr., of the MSC Flight Operations Division, urged that an up-data link (UDL) be included on the LEM. In general, the UDL would function when a great deal of data had to be transmitted during a time-critical phase. It would also permit utilization of the ground operational support system as a relay station for the transmission of data between the CM and LEM. In case of power failure aboard the LEM, the UDL could start the computer faster and more reliably than a manual voice link, and it could be used to resume synchronization in the computer timing system.
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.]
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.
The MSC Operations Planning Division (OPD) reviewed recent revisions by OMSF to Apollo's communications requirements:
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.
A number of outstanding points were resolved at a joint MSC-Grumman meeting on LEM communications. Most significant, the VHF key mode was deleted, and it was decided that, during rendezvous, voice links must have priority over all other VHF transmissions. Further, the echo feature of the current configuration (i.e., voice sent to the LEM by the ground operational support system, then relayed back via the S-band link) was undesirable.
Engineers from Grumman and the MSC Instrumentation and Electronics Systems Division (IESD) reviewed the coverage requirements for the LEM's S-band radio and the incompatibility of those requirements with the present location of the steerable antenna. Most observers felt that a deployable boom was the only feasible solution. The two groups therefore recommended that IESD verify with ASPO the S-band coverage requirements and that Grumman analyze the design effects of such a boom. In the meantime, Dalmo-Victor, the antenna vendor, should continue its design effort on the basis of the current location.
Representatives of MSC's Information and Electronic Systems Division, Flight Operations Division, Flight Crew Operations Division, Guidance and Control Division, Astronaut Office, and ASPO, Goddard Space Flight Center, and Bellcomm, Inc., met to discuss communications during LEM and CSM rendezvous.
Capability of the Manned Space Flight Network (MSFN) to provide data for rendezvous was studied. Aaron Cohen of ASPO stated sufficient data could be collected, processed, and transmitted via MSFN to the LEM to achieve rendezvous. Dr. F. O. Vonbun of Goddard showed that MSFN data did little to improve data already available in the LEM before launch. Although five tracking stations would communicate with the LEM during ascent and the first 10 minutes of orbit, there would be only a slight improvement in spacecraft position and motion data over the data already contained in the LEM computer. No decision was made concerning the MSFN's capability.
Alternate rendezvous methods were discussed.
MSC evaluated the VHF communications requirements and determined that there was no requirement for the LEM to communicate simultaneously over VHF with:
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.
The MSC-MSFC Mechanical Integration Panel discussed the possibility that, when deployed, the LEM adapter panels might interfere with radio communications via the S-band high-gain antenna. On earth-orbital missions, the panel found, the S-band antenna would be rendere useless. They recommended that MSC's Instrumentation and Electronic Systems Division investigate alternative modes for communications during the transposition and docking phase of the flight. During lunar missions, on the other hand, the panel found that, with panels deployed at a 45 degree angle, the high-gain antenna could be used as early as 15 minutes after translunar injection. Spacecraft-to-ground communications during transposition and docking could thus be available and manual tracking would not be needed. North American was informed that the high-gain antenna would be used during this maneuver, and was directed to fix the panel deployment angle for all Block II spacecraft at 45 degrees.
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:
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.
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.
To eliminate interference between the S-IVB stage and the instrument unit, MSC directed North American to modify the deployment angle of the adapter panels. Originally designed to rotate 170 degrees, the panels should open but 45 degrees (60 degrees during abort), where they were to be secured while the CSM docked with and extracted the LEM.
But at this smaller angle, the panels now blocked the CM's four flush- mounted omnidirectional antennas, used during near-earth phases of the mission. While turning around and docking, the astronauts thus had to communicate with the ground via the steerable high gain antenna. For Block II spacecraft, therefore, MSC concurrently ordered North American to broaden the S-band equipment's capability to permit it to operate within 4,630 km (2,500 nm) of earth.
Preliminary investigation by Grumman indicated that, with an all-battery LEM, passive thermal control of the spacecraft was doubtful. (And this analysis did not include the scientific experiments package, which, with its radioisotope generator, only increased the problem. Grumman and MSC Structures and Mechanics Division engineers were investigating alternate locations for the batteries and modifications to the surface coatings of the spacecraft as possible solutions.
In November 1964, MSC asked Grumman to conduct a study on the feasibility of carrying a radioisotope power supply as part of the LEM's scientific equipment. The subsequent decision to use batteries in the LEM power system caused an additional heat load in the descent stage. Therefore, MSC requested the contractor to continue the study using the following ground rules: consider the radioisotope power supply a requirement for the purpose of preliminary design efforts on descent stage configuration; determine impact of the radioisotope power supply - in particular its effect on passive thermal control of the descent stage; and specify which characteristics would be acceptable if any existing characteristics of the radioisotope power supply had an adverse effect. The radioisotope power was used only to supply power for the descent stage.
MSC requested that Grumman incorporate in the command list for LEMs 1, 2, and 3 the capability for turning the LEM transponder off and on by real-time radio command from the Manned Space Flight Network. Necessity for capability of radio command for turning the LEM transponder on after LEM separation resulted from ASPO's decision that the LEM and Saturn instrument unit S-band transponders would use the same transmission and reception frequencies.
A LEM/CSM interface meeting uncovered a number of design problems and referred them to the Systems Engineering Division (SED) for evaluation: the requirement for ground verification of panel deployment prior to LEM withdrawal; the requirement for panel deployment in earth orbit during the SA-206 flight; the absence of a backup to the command sequencer for jettisoning the CSM (Flight Projects Division [FPD] urged such a backup signal); and Grumman's opposition to a communications link with the LEM during withdrawal of the spacecraft (FPD felt that such a link was needed through verification of reaction control system ignition). SED's recommendations on these issues were anticipated by April 22.
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.
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.
MSC informed Grumman it believed it would be beneficial to the LEM development program for MSC to participate in the manned environmental control system tests to be conducted in Grumman's Internal Environment Simulator. The following individuals were suggested to participate: Astronaut William A. Anders or an alternate to act as a test crewman for one or more manned runs; D. Owen Goons or an alternate to act as a medical monitor for the aforementioned astronaut; and John W. O'Neill or an alternate to monitor voice communications during the test and record astronaut comments.
Representatives from Motorola, RCA, Grumman, and MSC held the first design review on the S-band transponder for the LEM. Several areas were pointed out in which the equipment was deficient. Motorola was incorporating improved circuitry to ensure that the transponder met specifications.
Apollo Program Director Samuel C. Phillips listed the RE communications systems envisioned by NASA Headquarters on the first three R&D LEMs and requested ASPO Manager Joseph F. Shea's comments.
The first three LEMs (LEM-1, LEM-2, and LEM-3) would be equipped with communications equipment in addition to that required in the LEM for lunar missions to provide:
Systems Engineering Division chief, Owen E. Maynard, reported to the Instrumentation and Electronic Systems Division (IESD) the results of a study on a LEM communications problem (undertaken by his own group at IESD's request). During phases of powered descent to certain landing sites (those in excess of 20 degrees east or west longitude), the structure of the spacecraft would block the steerable antenna's line of sight with the earth. Communications with the ground would therefore be lost. Maynard concurred with IESD that the problem could best be solved by rotating the LEM about its thrust axis.
MSC officially notified Grumman that, as part of the Apollo scientific program, an experiments package would be left on the moon by the crewmen of the LEM. The Center outlined weight and storage requirements for the package, which would be stored in the descent stage of the vehicle along with the lunar geological equipment. And MSC emphasized the need for dissipating waste heat given off by the system's radioisotope generator. (The radioisotope generator was a firm requirement, despite the fear voiced by many scientists that the radiation it gave off would disrupt the experiments.)
NASA announced plans to install Apollo Unified S-Band System equipment at its Corpus Christi, Tex., tracking station. The Unified S-Band equipment included a 9-m (30-ft) diameter parabolic antenna and would enable handling of seven different types of communications with two different vehicles, the CM and the LEM. The communications would: track the spacecraft; command its operations and confirm that the command had been executed; provide two-way voice conversation with three astronauts; keep a continuous check on the astronauts' health; make continuous checks on the spacecraft and its functions; supply a continuous flow of information from the Apollo onboard experiments; and transmit television of the astronauts and the exploration of the moon.
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.
The Instrumentation and Electronic Systems Division (IESD) proposed that the LEM's inflight VHF antenna might be used as a link to astronauts on the surface of the moon as well. (LEM communications had to provide VHF contact with the crew outside the spacecraft at ranges up to three nautical miles. The VHF antenna, however, had been designed only for the flight portions of the mission, and to meet this communications requirement another antenna was being added to the LEM at a cost of between 1.36 and 2.26 kg [3 and 5 lbs].) IESD offered to study the coverage and range of the inflight antenna while on the lunar surface, and suggested that the three-mile range requirement might be relaxed. The additional VHF antenna might thereby be obviated.
Also, IESD attended a preliminary design review at Autonetics on the signal conditioning equipment (SCE) for the Block II CSM. IESD concurred in several modifications to the Block I design (adding a redundant power supply; hermetic sealing of equipment; and repackaging to fit the equipment bay in Block II CMs). These changes reduced the SCE's weight from 22 to 19 kg (47.5 to 41 lbs) and, because of more efficient power supply, lowered its power consumption from 65 to 35 watts. North American was studying ways of perhaps lightening the SCE even further.
John D. Hodge, Chief of MSC's Flight Control Division, proposed that time-critical aborts in the event of a service propulsion system failure after translunar injection (TLI; i.e., insertion on a trajectory toward the moon) be investigated. Time-critical abort was defined as an abort occurring within 12 hours after TLI and requiring reentry in less than two days after the abort.
He suggested that if an SPS failed the service module be jettisoned for a time-critical abort and both LEM propulsion systems be used for earth return, reducing the total time to return by approximately 60 hours. As an example, if the time of abort was 10 hours after translunar injection, he said, this method would require about 36 hours; if the SM were retained the return time would require about 96 hours.
He added that the LEM/CM-only configuration should be studied for any constraints that would preclude initiating this kind of time-critical abort. Some of the factors to be considered should be:
Handling and installation responsibilities for the LM descent stage scientific equipment (SEQ) were defined in a letter from MSC to Grumman Aircraft Engineering Corp. The descent stage SEQ was composed of three basic packages:
Bendix Corp. demonstrated the operation of a sliding boom concept to prove that the Apollo Lunar Surface Experiments Package (ALSEP) could be removed from the LM at various attitudes. MSC representatives viewing the demonstration at Ann Arbor, Mich., were Aaron Cohen, Don Weissman, Paul Gerke, Don Lind, and Harrison Schmitt. Cohen reported that the mockup was crude but indicated that the concept was satisfactory to both Grumman and NASAL Design refinement, qualification, and effect on LM structure would have to be looked into. It was believed an additional seven kilograms of weight would be added to the LM descent stage. Two interface problems were defined at the meeting:
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
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
Command module injected weight status September 22, 1967 - 5679.8 kg
Reflecting the climate of scientific thinking at his Center, MSC Director Robert R. Gilruth responded to inquiries from Homer E. Newell, NASA Associate Administrator, concerning vocal communications during exploration of the lunar surface. While he termed continuous talking undesirable, Gilruth stated an astronaut's running comment would in effect form a set of field notes that a geologist might ordinarily keep during a field exercise. This normal vocal narrative, he told Newell, would keep ground control informed of mission progress and would ensure a maximum scientific return from the flight.
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. Requirements were based on the assumptions that the landing area was as well known as for Apollo 12, all traverses were preplanned, accurate photo maps were available, and there was MSFN support through voice communications. The Directorate emphasized that it had no requirements for a display of pitch and roll, X and Y coordinates, or time.