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:

- Parawing and other earth landing systems instead of parachutes
- The "skip" reentry technique
- HF beacon as recovery aid
- Radar altimeter from CSM communication system
- Crew recreational equipment
- Engineering and Development Test Plan

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 :

• The first docking maneuver would take place as soon after S-IVB burnout as possible and hard docking would be within 30 minutes after burnout.
• The docking methods to be investigated would include but not be limited to free fly-around, tethered fly-around, and mechanical repositioning.
• The S-IVB would be stabilized for four hours after injection.
• There would be no CM airlock. Extravehicular access techniques through the LEM would be evaluated to determine the usefulness of a LEM airlock.
• A crewman would not be stationed in the tunnel during docking unless it could be shown that his field of vision, maneuverability, and communication capability would substantially contribute to the ease and reliability of the docking maneuver.
• An open-hatch, unpressurized CM docking approach would not be considered.
• The relative merit of using the CM environmental control system to provide initial pressurization of the LEM instead of the LEM environmental control system would be investigated.

The first formal inspection and review of the LEM test mockup TM-1 was held at Grumman. TM-1 allowed early assessment of crew mobility, ingress, and egress. It was a full-size representation of crew stations, support and restraint systems, cabin equipment arrangement, lighting, display panels and instrument locations, and hatches. The TM-1 evaluation became the basis for the final LEM mockup, TM-5, from which actual hardware fabrication would be made.

The TM-1 Review Board (comprising Chairman Owen E. Maynard, Maxime A. Faget, Donald K. Slayton, and William F. Rector III, all of MSC; and Tom J. Kelly and Robert M. Carbee of Grumman) approved 28 requests for change; 15 others were marked for further investigation.

MSC Crew Systems Division representatives attended a demonstration at Grumman of Apollo Phase B and Gemini space suits using the LEM TM-1 mockup and a mockup portable life support system. Tests demonstrated ingress egress capability through the forward and top hatches, operation of controls and displays, and methods of getting out on the lunar surface and returning to the spacecraft. Generally, the A7L Space Suit proved sufficiently mobile for all these tasks, though there was no great difference between its performance and that of the Gemini suit during these trials.

Representatives from a number of elements within MSC (including systems and structural engineers, advanced systems and rendezvous experts, and two astronauts, Edward H. White II and Elliot M. See, Jr.) discussed the idea of deleting the LEM's front docking capability (an idea spawned by the recent TM-1 mockup review). Rather than nose-to-nose docking, the LEM crew might be able to perform the rendezvous and docking maneuver, docking at the spacecraft's upper (transfer) hatch, by using a window above the LEM commander's head to enable him to see his target.

A good many factors pointed to the merit of this approach:

- A rectangular window 18 by 38 centimeters (seven by 15 inches) above the commander's head could readily be incorporated into the LEM's structure, with only minimal design changes. The weight penalty would be between 4.5 and 6.8 kilograms (10 and 15 pounds) (excluding possible effects on the vehicle's environmental control system). On the other hand, eliminating the front docking mechanism would save about 11 or 14 kilograms (25 or 30 pounds). A docking aid on the CM was essential, but the device "would pay for itself in increased reliability and decreased design load requirements and fuel requirements." Additionally, instead of two docking aids on the LEM (as currently envisioned), only the upper one would be needed.
- The top-only docking arrangement would simplify the docking operation per se. The crew would no longer have to transfer the drogue from the top to the front hatch prior to rejoining the CM. [The need for depressurizing the spacecraft to perform this task thus was obviated.] As an additional "fringe benefit," the front hatch could possibly be reconfigured to make it easier for the crewmen to get out of and back into their craft while on the moon.
- The overhead window would enable the LEM commander to see the moon during powered descent and ascent portions of the flight, and thus would afford the crew a visual attitude and attitude reference.

There existed, naturally, some offsetting factors: the pilot's limited view of his target (thought to be of "no major consequence"); and his being unable quickly to scan his instrument panel (which was not essential). Also, the maneuver called for the pilot to fly his vehicle, for a considerable period, in a rather strained physical position (i.e., with his head tossed backward). But because of the many inherent advantages, the group concluded, LEM-active docking at the upper hatch was acceptable as a backup method for docking. (CM-active docking still would be the normal procedure, because that vehicle could "perform the docking maneuver more easily and more reliably than can the LEM . . . Deletion of the front docking capability on [the] LEM will not alter this relationship, therefore the LEM should be required to dock only when the CSM or the crew member inside is incapacitated. If the CSM is incapacitated returning to it is of questionable importance.") They recommended that Grumman be directed to proceed with this concept for the LEM.

After reviewing the requirement for extravehicular transfer (EVT) from the LEM to the CM, MSC reaffirmed its validity. The Center already had approved additional fuel for the CM, to lengthen its rendezvousing range, and modifications of the vehicle's hatch to permit exterior operation. The need for a greater protection for the astronaut during EVT would be determined largely by current thermal tests of the pressure suit being conducted by NASA and Hamilton Standard. While the emergency oxygen system was unnecessary during normal transfer from one vehicle to the other, it was essential during EVT or lunar surface activities.

To make it easier to get in and out of the spacecraft, Grumman modified the LEM's forward hatch. During mobility tests on the company's mockup, a hinged, trapezoidal-shaped door had proved superior to the original circular hatch, so the earlier design was dropped.

After further design studies following the M-5 mockup review (October 5-8, 1964), Grumman reconfigured the boarding ladder on the forward gear leg of the LEM. The structure was flattened, to fit closer to the strut. Two stirrup-type steps were being added to ease stepping from the top rung to the platform or "porch" in front of the hatch.

MSC and Grumman reviewed the requirement for a backup mode of entering and leaving the LEM while on the moon. The new rectangular hatch was deemed "inherently highly reliable," and the only failure that was even "remotely possible" was one of the hatch mechanism. The proposal to use the top (or transfer) hatch was impractical, because it would cost 13.6 kg (30 lb) and would impose an undue hazard on both the crew and the spacecraft's thermal shield.

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.

Representatives from North American, Grumman, Hamilton Standard, and MSC discussed the problem of stowing the portable life support systems (PLSS).

Current specifications called for two PLSSs under the crew couch in the CM at launch, one of which would be brought back to earth. This location presented some serious problems, however.

MSC officials laid down several ground rules for the discussions:

• The capability for extravehicular transfer must be maintained.
• During translunar flight, the capability must exist for general extravehicular activity from the CM.
• And upon landing, the PLSS must not interfere with the sweep of the crew couch.

During the next few weeks, MSC concluded that, at earth launch, one PLSS would be stowed in each spacecraft. With the help of Hamilton Standard engineers, North American and Grumman designers worked out a stowage volume acceptable to all concerned. Hamilton Standard agreed to repackage the PLSS accordingly. MSC ordered North American to provide for stowage of one PLSS beneath the side hatch of the CM, again stressing that the system must not interfere with the crew couch during landing impact; also, the Center directed Grumman to plan for PLSS stowage in the LEM and to study ingress and egress with the reshaped backpack. (Studies by the Crew Systems Division had already indicated that, from the standpoints of compatibility and mobility, the new shape probably would be acceptable.)

MSC Director of Flight Crew Operations Donald K. Slayton pointed out to ASPO Manager Joseph F. Shea that LM-to-CSM crew rescue was impossible. Slayton said

1. there was no way for the portable life support system and crewman to traverse from the LM front hatch to the CSM side hatch in zero-g docked operations, because there was no restraint system or tether attach points in the vicinity of the CSM hatch to permit the crewman to stabilize himself and work to open the hatch; and
2. there was no way to control the Apollo inner hatch (35-43 kilograms) to ensure that it would not inadvertently damage its seals, the spacecraft wiring, or the pressure bulkhead.

Slayton added that several spacecraft changes, additional training hardware for valid thermal testing, zero-g simulator demonstration, and crew training effort would be required to permit extravehicular crew rescue from LM to CSM. Until this total rescue capability was implemented, manned LM to CSM operations would constitute an unnecessary risk for the flight crew.

Donald K. Slayton said there was some question about including extravehicular activity on the AS-503 mission, but he felt that, to make a maximum contribution to the lunar mission, one period of EVA should be included. Slayton pointed out that during the coast period (simulating lunar orbit) in the current flight plan the EVA opportunity appeared best between hour 90 and hour 100.

Two primary propulsion system firings would have been accomplished and the descent stage of the LM would still be attached.

Slayton specified that EVA should consist of a crewman exiting through the LM forward hatch and making a thorough orbital check of the LM before reentering through the same hatch. He said EVA on AS-503 would provide:

- flight experience and confidence in LM environmental-control-system performance during cabin depressurization;

- flight confidence in the Block II International Latex Corp. pressure garment assemblies;

- orbital time-line approximation of cabin depressurization times, forward hatch operation, flight crew egress procedures, and LM entry following a simulated lunar EVA;

- visual inspection and photography of LM landing gear for possible damage during withdrawal from the S-IVB stage;

- external inspection and photography of the LM to record window and antenna contamination caused by SLA panel pyrotechnic deployment;

- inspection and photography of descent engine skirt and adjacent areas for evidence of damage from two descent propulsion system firings;

- inspection and photography of possible damage to the upper LM caused by the SM reaction control system during withdrawal;

- possible additional data regarding EVA metabolic rates, etc., as applied to the Block II pressure garment assembly; and

- additional orbital confidence in the portable life support system operational procedures.

MSC submitted requirements to KSC that TV signals from cameras inside the LM and CM be monitored and recorded during manned hazardous tests, with hatch open or closed, and tests in the Vehicle Assembly Building, launch pads, and altitude chambers. A facility camera was to monitor the propellant-utilization gauging system during propellant loading. MSC specified that the field of view of the TV camera should encompass the shoulder and torso and portions of the legs of personnel at the normal flight stations in both the CM and the LM.

ASPO Manager George Low in a letter to Dale Myers of North American Aviation, emphasized that the spacecraft weight situation was the single most serious problem in the entire Apollo program.

An example of the weight estimating problem was the spacecraft hatch. When the decision was made in March 1967 to incorporate a new hatch, the net weight increase was estimated at 185 kilograms, but calculations indicated that this increase was actually 558 kilograms. Neither of these numbers included the additional ballast, which doubled the required weight. Clearly weight estimates were inadequate, making a workable weight control program impossible. North American was requested to take immediate action to bring the weight problem under control. A letter in a similar vein was sent by C. H. Bolender, ASPO LM Manager, to J. G. Gavin, Jr., Grumman Aircraft Engineering Corp.

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.

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.

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

ASPO Manager George Low, commented on control of Apollo spacecraft weight. Following the January 1967 spacecraft fire at Cape Kennedy, there had been substantial initial weight growth in the CSM. This was attributed to such items as the new CSM hatch, the flammability changes, and the additional flight safety changes. In mid-1967 the CSM weight stabilized and from then on showed a downward trend. The LM weight stabilized in mid1968 and since that time had remained fairly constant. Conclusions were that the program redefinition had caused a larger weight increase than expected, but that once the weight control system became fully effective, it was possible to maintain a weight that was essentially constant. Low told Caldwell C. Johnson, Jr., of the MSC Spacecraft Design Division that the weight control was in part due to Johnson's strong inputs in early 1968. Johnson responded, "Your control of Apollo weight growth has destroyed my reputation as a weight forecaster - but I'm rather glad."

Microscopic examination of dust particles collected from the spacecraft after the Apollo 10 mission and of samples collected from the inside of nine garments worn by the Apollo 10 astronauts confirmed preliminary findings that the itching experienced by the astronauts was due to the insulation in the tunnel hatch of the command module.

Investigation showed the fiberglass insulation had flaked off during LM pressurization. Review of thermal conditions indicated the insulation was not essential and it was eliminated from future vehicles.

During the Apollo 11 management debriefing, the ASPO Manager noted a number of items requiring investigation.

During separation from the S-IVB stage, the CSM autopilot apparently had difficulty determining direction of rotation. After the CSM hatch removal, there was a strong odor of burnt material in the tunnel. The leveling device on one of the experiment packages did not work. The closeup stereo camera was hard to operate and tended to fall over. The temperature in the lunar module was too cold during sleep periods. The biological isolation garment was uncomfortably hot and its visor fogged. The crew observed flashes at the rate of about one per minute in the command module at night.