MSC reported that crew systems engineers at the Center were assessing feasibility of having the LEM crew stand rather than sit. MSC requested Grumman also to look into having the crew fly the vehicle from a standing position. The concept was formally proposed at the August 27 crew systems meeting and was approved at the NASA-Grumman review of the LEM M-1 mockup on September 16-18.
MSC and Grumman assessed crew visibility requirements for the LEM. The study included a series of helicopter flights in which simulated earthshine lighting conditions and LEM window configurations were combined with helicopter landings along representative LEM trajectories. These flights simulated the LEM's attitude, velocity, range, and dive angle in the final approach trajectory.
MSC directed North American to concentrate on the extendable boom concept for CSM docking with the LEM. The original impact type of docking had been modified:
Grumman presented the results of a study on LEM visibility. A front-face configuration with triangular windows was tentatively accepted by MSC for the ascent stage. Further investigation would be directed toward eliminating the "dead spots" to improve the configuration's visibility.
MSC received proposals for the visual displays for the LEM simulator. Because of the changed shape of that vehicle's windows, however, Grumman had to return those proposals to the original bidders, sending revised proposals to MSC in December. Farrand Optical Company was selected to develop the display, and the Center approved Grumman's choice. Negotiations between Grumman and Farrand were completed during March 1964.
At MSC, the Spacecraft Technology Division reported to ASPO the results of a study on tethered docking of the LEM and CSM. The technology people found that a cable did not reduce the impact velocities below those that a pilot could achieve during free flyaround, nor was fuel consumption reduced. In fact, when direct control of the spacecraft was attempted, the tether proved a hindrance and actually increased the amount of fuel required.
Based on the LEM mockup review of September 16-18, 1963, MSC established criteria for redundancy of controls and displays in the LEM crew station. Within the framework of apportioned reliability requirements for mission success and crew safety, these guidelines applied:
MSC's Center Medical Office was reevaluating recommendations for LEM bioinstrumentation. The original request was for three high-frequency channels (two electrocardiogram and one respiration) that could be switched to monitor all crew members. Grumman wanted to provide one channel for each astronaut with no switching.
Studies on the LEM's capability to serve as the active vehicle for lunar orbit docking showed the forward docking tunnel to be the best means of accomplishing this. ASPO requested Grumman to investigate the possibility of this docking approach and the effect it might have on the spacecraft's configuration.
ASPO decided upon transfer through free space as the backup mode for the crew's getting from the LEM back to the CM if the two spacecraft could not be pressurized. North American had not designed the CM for extravehicular activity nor for passage through the docking tunnel in a pressurized suit. Thus there was no way for the LEM crew to transfer to the CM unless docking was successfully accomplished. ASPO considered crew transfer in a pressurized suit both through the docking tunnel and through space to be a double redundancy that could not be afforded.
In simulated zero-g conditions aboard KC-135s, technicians evaluated a number of different devices for restraining the LEM crewmen. These trials demonstrated clearly the need for a hip restraint and for a downward force to hold the astronaut securely to the cabin floor. In mid-February a second series of flights tested the combination that seemed most promising: Velcro shoes that would be used together with Velcropile carpeting on the cabin floor of the spacecraft; a harness that enveloped the astronaut's chest and, through an intricate system of cables and pulleys, exerted a constant downward pressure; and a waist strap that secured the harness to the lighting panel immediately facing the crewman. These evaluations permitted Grumman to complete the design of the restraint system.
Initial development testing of LEM restraint systems was completed. Under zero-g conditions, investigators found, positive restraints for the crew were essential. While the system must be further refined, it consisted essentially of a harness that secured the astronaut's hips (thus providing a pivot point) and held him firmly on the cabin floor.
A device to maintain the spacecraft in a constant attitude was added to the LEM's primary attitude control system (ACS). The feature brought with it some undesirable handling characteristics, however: it would cause the vehicle to land long. Although this overshoot could be corrected by the pilot, and therefore was not dangerous operationally, it would require closer attention during final approach. The attitude hold, therefore, hardly eased the pilot's control task, which was, after all, its primary function. Instead of moving the device to the backup ACS (the abort section), the Engineering Simulation Branch of MSC's Guidance and Control Division recommended that the system be modified so that, if desired, the pilot could disengage the hold mechanism.
MSC, North American, and Grumman reviewed the results of Langley Research Center's LEM-active docking simulation. While the overhead mode of docking had been found to be acceptable, two items still caused some concern: (1) propellant consumption could exceed supply; and (2) angular rates at contact had occasionally exceeded specifications. Phase B (Grumman's portion) of the docking simulations, scheduled to begin in about two weeks, would further investigate these problems. Langley researchers also had evaluated several sighting aids for the LEM and recommended a projected image collimated (parallel in lines of direction) reticle as most practicable. Accordingly, on March 9, MSC directed Grumman to incorporate this type of sighting device into the design of their spacecraft.
On the basis of in-house tests, Grumman recommended a scheme for exterior lighting on the LEM. The design copied standard aeronautical practice (i.e., red, port; green, starboard; and amber, underside). White lights marked the spacecraft, both fore and aft; to distinguish between the two white lights, the aft one contained a flasher.
MSC decided upon a grid-type landing point designator for the LEM. Grumman would cooperate in the final design and would manufacture the device; MIT would ensure that the spacecraft's guidance equipment could accept data from the designator and thus change the landing point.
AC Spark Plug officials presented to MSC their evaluation of bidders to design an optical rendezvous sensor for the LEM. Because three different approaches were planned, AC gained Guidance and Control Division's approval to let three subcontracts. The firms chosen were Perkin-Elmer, Hughes Aircraft, and the Itek Corporation.
At an implementation meeting at MSC on the LEM's guidance and control system, Grumman again made a pitch for its concept for the landing point designator (i.e., scale markings on the vehicle's window). On September 13, the company received MSC's go-ahead. Grumman was told to coordinate closely with both MSC and MIT on the designator's design to ensure that the scale markings would be compatible with the spacecraft's computer.
Grumman completed an analysis of radiation levels that would be encountered by the LEM-3 crew during their earth orbital mission. Grumman advised that doses would not be harmful. To lessen these levels even further, the contractor recommended that during some parts of the mission the two astronauts climb back into the CM; also, the planned orbit for the LEM (556 by 2,500 km (300 by 1,350 nm)) could be changed to avoid the worst part of the Van Allen Belt.
MSC and Grumman representatives reviewed Grumman's timeline analysis for the intravehicular LEM crew activities subsequent to lunar landing. This timeline was being rewritten for a test program to be conducted to determine what crew mobility problems existed within the LEM so that they could be better evaluated at the Certification Design Review.
Grumman was directed by MSC to provide for the disposition and bacteriological control of the LEM urine containers by off-loading all containers to the lunar surface immediately prior to LEM ascent, locating them so their physical integrity would be assured during ascent stage launch. Incorporation of an appropriate germicide in all LEM urine containers would effectively sterilize the internal part of the container and the contained urine.
Grumman and MSC reached agreement to continue with Freon for prelaunch cooling of LEM-1. By changing to a different Freon the additional heat sink capability was obtained with minor changes to flight hardware. The ground support equipment for supplying Freon had to be modified to increase the flow capability, but this was not expected to be difficult. Plans were to use the same prelaunch cooling capability for LEM-2 and LEM-3.
Contractor personnel began an exercise to identify problem areas associated with activity within the LEM. Subjects using pressurized suits and portable life support systems ran through various cockpit procedures in the LEM mockup. Evaluations would continue during the week of January 10, using astronauts. The purpose of the exercise was to identify and gather data on problem areas in support of the Critical Design Review scheduled to be held at Grumman in late January.
Mission requirements for AS-503 were reviewed to determine if the LEM test objectives which caused the crew to be in the LEM at high altitudes (3,704 to 12,964 km (2,000 to 7,000 nm)) could be deleted. The reason for keeping the crew out of the LEM at those altitudes was the possibility they might be exposed to a total radiation dose which might prevent them from flying a later lunar mission.
The LEM Configuration Control Panel approved Grumman's request for government-furnished-equipment (North American Aviation-manufactured) optical alignment sights (OAS) for installation in the LEM. A total of 21 OAS units would be required (including 2 spares). Detailed interface requirements between the OAS and LEM would be negotiated between North American and Grumman and delivery dates would be specified during negotiations.
Langley Research Center reported on its November study of visibility from the CSM during extraction of the LM from the S-IVB stage. The study had been made in support of the AS-207/208A mission, with assistance of MSC and North American Aviation personnel, to
MSC Director Robert R. Gilruth asked LaRC Director Floyd Thompson to conduct a study at Langley to familiarize flight crews with CM active docking and to explore problems in CM recontact with the LM and also LM withdrawal. MSC would provide astronaut and pilot-engineer support for the study. Apollo Block II missions called for CM active docking with the LM and withdrawal of the LM from the S-IVB stage, requiring development of optimum techniques and procedures to ensure crew safety and to minimize propellant utilization. LM withdrawal was a critical area because of clearances, marginal flight crew visibility, and mission constraints. Previous simulations at LaRC indicated the possibility of using the Rendezvous Docking Simulator.
The Flammability Test Review Board met at MSC to determine if the M-6 vehicle (a full-scale mockup of the LM cabin interior) was ready for test and that the ignition points, configuration, instrumentation, and test facility were acceptable for verifying the fire safety of LTA-8 and LM-2 vehicles. Additional Details: here....
ASPO Manager George Low advised Apollo program officials at KSC that, to collect adequate data for evaluating any potential toxicological hazard inside the spacecraft, collection of gas samples of the cabin atmosphere must be made for 12 hours during the unmanned altitude chamber test with all systems operating. Low asked that this requirement be included in the spacecraft test procedures. Additional Details: here....
During integrated testing of the Apollo spacecraft, a well-qualified test pilot accidentally threw two guarded switches marked "CM/SM Separation" instead of the intended adjacent switches marked "CSM/LM Final Sep" to separate the lunar module from the command and service modules. Had the error occurred in a lunar flight, the CM would have separated from the SM, with a high probability of leaving the crew stranded in lunar orbit. Studies of methods to preclude such an accident in actual flight led later to provisions for visual differences in switch covers.