Following a technical conference on the LEM electrical power system (EPS), Grumman began a study to define the EPS configuration. Included was an analysis of EPS requirements and of weight and reliability for fuel cells and batteries. Total energy required for the LEM mission, including the translunar phase, was estimated at 61.3 kilowatt-hours. Upon completion of this and a similar study by MSC, Grumman decided upon a three-cell arrangement with an auxiliary battery. Capacity would be determined when the EPS load analysis was completed.
Grumman representatives presented their technical study report on power sources for the LEM. They recommended three fuel cells in the descent stage (one cell to meet emergency requirements), two sets of fluid tanks, and two batteries for peak power loads. For industrial competition to develop the power sources, Grumman suggested Pratt and Whitney Aircraft and GE for the fuel cells, and Eagle-Picher, Electrical Storage Battery, Yardney, Gulton, and Delco-Remy for the batteries.
Meeting in Bethpage, N. Y., officials from MSC, Grumman, Hamilton Standard, International Latex, and North American examined LEM-space suit interface problems. This session resulted in several significant decisions:
MSC reported that two portable life support systems would be stowed in the LEM and one in the CM. Resupplying water, oxygen, and lithium hydroxide could be done in a matter of minutes; however, battery recharging took considerably longer, and detailed design of a charger was continuing.
Grumman selected Pratt and Whitney to develop fuel cells for the LEM. Current LEM design called for three cells, supplemented by a battery for power during peak consumption beyond what the cells could deliver. Grumman and Pratt and Whitney completed contract negotiations on August 27, and MSC issued a letter go-ahead on September 5. Including fees and royalties, the contract was worth $9.411 million.
At a meeting on the LEM electrical power system, Grumman presented its latest load analysis, which placed the LEM's mission energy requirements at 76.53 kilowatt-hours. The control energy level for the complete LEM mission had been set at 54 kilowatt-hours and the target energy level at 47.12 kilowatt-hours. Grumman and MSC were jointly establishing ground rules for an electrical power reduction program.
At a meeting at MSC, Grumman representatives presented 18 configurations of the LEM electrical power system, recommending a change from three to two fuel cells, still supplemented by an auxiliary battery system, with continued study on tankage design. On December 10, ASPO authorized the contractor to proceed with this configuration.
After careful study, Grumman proposed to MSC 15 possible means for reducing the weight of the LEM. These involved eliminating a number of hardware items in the spacecraft; two propellant tanks in the vehicle's ascent stage and consequent changes in the feed system; two rather than three fuel cells; and reducing reaction control system propellants and, consequently, velocity budgets for the spacecraft. If all these proposed changes were made, Grumman advised, the LEM could be lightened significantly, perhaps by as much as 454 kilograms (1000 pounds).
Representatives of Grumman, MSC's Instrumentation and Electronics Systems Division, ASPO, and Resident Apollo Spacecraft Program Office (RASPO) at Bethpage met at Grumman to plan the LEM's electrical power system. The current configuration was composed of three fuel cell generators with a maximum power output of 900 watts each, spiking stabilizing batteries, one primary general-purpose AC inverter, and a conventional bus arrangement. To establish general design criteria, the primary lunar mission of the LEM-10 vehicle was analyzed. This "critical" mission appeared to be the "worst case" for the electrical power system and established maximum power and usage rate requirements.
Those attending the meeting foresaw a number of problems:
North American conducted three tests (4, 20, and 88 hours) on the CSM fuel cell. The third ended prematurely because of a sudden drop in output. (Specification life on the modules was 100 hours.)
During this same week, Pratt and Whitney Aircraft tested a LEM-type fuel cell for 400 hours without shutdown and reported no leaks.
Grumman reported to MSC the current load status and projected load growth for the LEM's electrical power system, requesting a mission profile of 121 kilowatt-hours total energy. The company also presented its latest recommendation for the LEM power generation subsystem configuration: two 900-watt fuel cells, a descent stage peaking battery, an ascent stage survival battery, and four cryogenic storage tanks. To compensate for voltage drops in the power distribution subsystem, Grumman recommended that two cells be added to the current fuel cell stack; however, on March 23 ASPO directed the contractor to continue development of the 900-watt, three-fuel-cell assembly and a five-tank cryogenic storage system. MSC's position derived from the belief that the load growth would make the two-cell arrangement inadequate. Also the three-cell configuration, through greater redundancy, afforded greater safety and chances of mission success: the mission could continue in spite of a failure in one of the cells; should two cells fail, the mission could be aborted on the final power source. The cryogenic tanks should be sized for a usable total energy of 121 kilowatt-hours to permit immediate tank procurement.
ASPO gave Grumman specific instructions on insulating wiring in the LEM: Teflon-insulated wiring was mandatory in a pure oxygen atmosphere. If the standard-thickness Teflon insulation was too heavy, a thin- wall Teflon-insulated wiring with abrasion-resistant coating should be considered. Teflon-insulated wiring should also be used outside the pressurized cabin, wherever that wiring was exposed. Any approved spacecraft insulation could be used within subsystem modules which were hermetically sealed in an inert gas atmosphere or potted within the case.
On the basis of new abort criteria (failure of one fuel cell), extended operating periods, and additional data on fuel cell performance, Grumman recommended a 20.4 kg (45-lb), 1,800 watt-hour auxiliary battery for the LEM. MSC approved the recommendation and Grumman completed the redesign of the electrical power distribution system and resizing of the battery during late October and early November.
NASA conducted a formal review of the LEM mockup M-5 at the Grumman factory. This inspection was intended to affirm that the M-5 configuration reflected all design requirements and to definitize the LEM configuration. Members of the Mockup Review Board were Chairman Owen E. Maynard, Chief, Systems Engineering Division, ASPO; R. W. Carbee, LEM Subsystem Project Engineer, Grumman; Maxime A. Faget, Assistant Director for Engineering and Development, MSC; Thomas J. Kelly, LEM Project Engineer, Grumman; Christopher C. Kraft, Jr. (represented by Sigurd A. Sjoberg), Assistant Director for Flight Operations, MSC; Owen G. Morris, Chief, Reliability and Quality Assurance Division, ASPO; William F. Rector III, LEM Project Officer, ASPO; and Donald K. Slayton, Assistant Director for Flight Crew Operations, MSC.
The astronauts' review was held on October 5 and 6. It included demonstrations of entering and getting out of the LEM, techniques for climbing and descending the ladder, and crew mobility inside the spacecraft. The general inspection was held on the 7th and the Review Board met on the 8th. Those attending the review used request for change (RFC) forms to propose spacecraft design alterations. Before submission to the Board, these requests were discussed by contractor personnel and NASA coordinators to assess their effect upon system design, interfaces, weight, and reliability.
The inspection categories were crew provisions; controls, displays, and lighting; the stabilization and control system and the guidance and navigation radar; electrical power; propulsion (ascent, descent, reaction control system, and pyrotechnics ; power generation cryogenic storage and fuel cell assemblies ; environmental control; communications and instrumentation; structures and landing gear; scientific equipment; and reliability and quality' control. A total of 148 RFCs were submitted. Most were aimed at enhancing the spacecraft's operational capability; considerable attention also was given to quality and reliability and to ground checkout of various systems. No major redesigns of the configuration were suggested.
As a result of this review, the Board recommended that Grumman take immediate action on those RFC's which it had approved. Further, the LEM contractor and MSC should promptly investigate those items which the Board had assigned for further study. On the basis of the revised M-5 configuration, Grumman could proceed with LEM development and qualification. This updated mockup would be the basis for tooling and fabrication of the initial hardware as well.
Grumman completed the fuel cell assembly thermal study and was preparing a specific directive to Pratt and Whitney Aircraft Company which would incorporate changes recommended by the study. These changes would include the cooling of electrical components with hydrogen and the shifting of other components (water shutoff valves, and oxygen purge valve) so that they would operate at their higher design temperatures.
Testing of the first flight-weight 15-cell stack of the LEM fuel cell assembly began. Although the voltage was three percent below design, the unit had a 980-watt capability. Earlier, the unit completed 150 hours of operation, and single cell life had reached 662 hours.
ASPO officials completed a preliminary evaluation of the design and weight implications of an all-battery electrical power system (EPS) for the LEM. Investigators reviewed those factors that resulted in the decision (in March 1963) to employ fuel cells; also, they surveyed recent technological improvements in silver-zinc batteries.
At about the same time, Grumman was analyzing the auxiliary battery requirements of the spacecraft. The contractor found that, under the worst possible conditions (i.e., lunar abort), the LEM would need about 1,700 watt-hours of auxiliary power. Accordingly, Grumman recommended one 1,700 watt-hour or two 850 watt-hour batteries (23 and 29.5 kg [50 and 65 lbs], respectively) in the spacecraft's ascent stage.
MSC analyzed Grumman's report on their program to resize the LEM. On the basis of this information, ASPO recommended that the propellant tanks be resized for separation and lunar liftoff weights of 14,742 and 4,908 kg (32,500 and 10,820 lbs), respectively. Studies should investigate the feasibility of an optical rendezvous device and the substitution of batteries for fuel cells. And finally, engineering managers from both Grumman and MSC should examine a selected list of weight reduction changes to determine whether they could immediately be implemented.
MSC was giving serious thought to using radioisotope generators to power the Apollo lunar surface experiments packages. If some method could be found to control waste heat, such a device would be the lightest source of power available. Accordingly, the Center asked Grumman to study the feasibility of incorporating it into the LEM's scientific payload. The company should analyze thermal and radiological problems, as well as methods of stowage, together with the possibility of using the generator for power and heat during the flight. To minimize the problem of integration, Grumman was allowed much flexibility in designing the unit. Basically, however, it would measure about 0.07 cu m (2.5 cu ft) and would weigh between 13 and 18 kg (30 and 40 lbs). Its energy source (plutonium 238) would produce about 50 watts of electricity (29 volts, direct current).
Grumman and LEM Project Office representatives met to discuss the split bus distribution system. They decided there would be two circuit breaker panels similar to those of Mockup 5. All power distribution system controls would be located on the system engineer's center side console with remote controls and valves on the commander's center side console.
By improving filling and preparation procedures and by using nickel foil in the oxygen electrode, Pratt and Whitney eliminated both short- and long-term plugging in the LEM's fuel cell assembly. Since then, Pratt and Whitney had consistently operated single cells for over 400 hours and - as far as the company was concerned - felt this settled the matter.
In September 1964, Hamilton Standard, manufacturer of the portable life support system (PLSS), had established a 108-watt-hour capacity for the system's batteries. And on the basis of that figure, Grumman had been authorized to proceed with the development of the LEM's battery charger. (The size of the charger was determined by several factors, but primarily by the size of the battery and time limits for recharging.)
During November, however, Hamilton Standard and Crew Systems Division (CSD) engineers advised the Instrumentation and Electronic Systems Division (IESD) that the PLSS's power requirements had increased to about 200 watt-hours. (CSD had jurisdiction over the PLSS, including battery requirements; IESD was responsible for the charger.) Hamilton Standard placed most of the blame on the cooling pump motor, which proved far less efficient than anticipated, as well as on the addition of biosensor equipment. ASPO Manager Joseph F. Shea, reviewing the company's explanation, commented that "this says what happened . . . but is far from a justification - this is the type of thing we should understand well enough to anticipate." "How can this happen," he wondered, ". . . in an area which has been subjected to so much discussion and delay?"
Representatives from Grumman and Hamilton Standard, meeting at MSC on December 17, redefined PLSS battery and charging requirements, and Grumman was directed to proceed with the development of the battery charger. This episode was accompanied by some sense of urgency, since Grumman had to have firm requirements before the end of year to prevent a schedule slippage.
ASPO approved the technique for LEM S-IVB separation during manned missions, a method recommended jointly by North American and Grumman. After the CSM docked with the LEM, the necessary electrical circuit between the two spacecraft would be closed manually. Explosive charges would then free the LEM from the adapter on the S-IVB.
ASPO evaluated Grumman's proposal for an "all battery" system for the LEM descent stage. ASPO was aiming at a 35-hour lunar stay for the least weight; savings were realized by lessening battery capacities, by making the water tanks smaller, and by reducing some of the spacecraft's structural requirements.
ASPO and the MSC Instrumentation and Electronic Systems Division (IESD) formulated a program for electromagnetic compatibility testing of hardware aboard the CSM and LEM. The equipment would be mounted in spacecraft mockups, which would then be placed in the Center's anechoic chamber. In these tests, scheduled to begin about the first of September, IESD was to evaluate the compatibility of the spacecraft in docked and near-docked configurations, and of Block I spacecraft with the launch vehicle. The division was also to recommend testing procedures for the launch complex.
MSC decided in favor of an "all-battery" LEM (i.e., batteries rather than fuel cells in both stages of the vehicle) and notified Grumman accordingly. Pratt and Whitney's subcontract for fuel cells would be terminated on April 1; also, Grumman would assume parenthood of GE's contract (originally let by Pratt and Whitney) for the electrical control assembly. MSC ordered an immediate cessation of all other efforts involved in the fuel-celled configuration. During the next several weeks, Grumman issued study contracts to Yardney Electric and Eagle-Picher for cost proposals. On April 1, the spacecraft manufacturer presented its proposal for an all-battery LEM; MSC's concurrence followed two weeks later.
A portable life support system (PLSS) battery charger would no longer be required, but three additional nonrechargeable PLSSs would be carried to provide for extravehicular activities. This change would now require a total of six nonrechargeable batteries.
On this same date, MSC ordered Grumman to end its work on a supercritical helium system for the LEM's ascent stage, and to incorporate an ambient mode for pressurization. All work on a supercritical system for the stage should be halted. However, Grumman should maintain the supercritical approach for the descent stage, while continuing parallel development on the ambient system. To permit the incorporation of either approach into the final design of the descent stage, components must be interchangeable.
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.
MSC notified Grumman that a device to recharge the portable life support system's (PLSS) batteries was no longer required in the LEM. Instead, three additional batteries would be stored in the spacecraft (bringing the total number of PLSS batteries to six).
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.
Grumman officials presented their findings on supercritical versus gaseous oxygen storage systems for the LEM [supercritical: state of homogeneous mixture at a certain pressure and temperature, being neither gas nor liquid]. After studying factors of weight, reliability, and thermal control, as well as cost and schedule impacts, they recommended gaseous tanks in the ascent stage and a supercritical tank in the descent stage. They stressed that this configuration would be about 35.66 kg (117 lbs) lighter than an all-gaseous one. Though these spokesmen denied any schedule impact, they estimated that this approach would cost about 2 million more than the all-gaseous mode. MSC was reviewing Grumman's proposal.
During the latter part of the month, Crew Systems Division (CSD) engineers also looked into the several approaches. In contrast to Grumman, CSD calculated that, at most, an all-gaseous system would be but 4.08 kg (9 lbs) heavier than a supercritical one. CSD nonetheless recommended the former. It was felt that the heightened reliability, improved schedules, and "substantial" cost savings that accompanied the all-gaseous approach offset its slim weight disadvantage.
During late April, MSC ordered Grumman to adopt CSD's approach (gaseous systems in both stages of the vehicle). [Another factor involved in this decision was the lessened oxygen requirement that followed substitution of batteries for fuel cells in the LEM.]
The change from LEM fuel cells to batteries eliminated the need for a hard-line interstage umbilical for that system and the effort on a cryogenic umbilical disconnect was canceled. The entire LEM pyrotechnic effort was redefined during the program review and levels of effort and purchased parts cost were agreed upon.
MSC ordered Grumman to halt development of linear-shaped charge cutters for the LEM's interstage umbilical separation system, and to concentrate instead on redundant explosive-driven guillotines. By eliminating this parallel approach, and by capitalizing on technology already worked out by North American on the CSM umbilical cutter, this decision promised to simplify hardware development and testing. Further, it promised to effect significant schedule improvements and reductions in cost.
William F. Rector, the LEM Project Officer in ASPO, replied to Grumman's weight reduction study (submitted to MSC on December 15, 1964). Rector approved a number of the manufacturer's suggestions:
Grumman presented to MSC its recommendations for an all-battery electrical power system for the LEM:
MSC requested that Grumman evaluate the possibility of furnishing power for the pre-separation checkout of the LEM wholly from that module's power supply. This procedure would obviate the CSM's supplying that power during the initial 60 min of the checkout. This would simplify the electrical connections between the two spacecraft and eliminate the possible requirement for an additional battery charger in the CSM. The Center advised North American, however, that such a charger might still be needed on Block II CSMs.
The Apollo Program Director, Samuel C. Phillips, informed the Associate Administrator for Manned Space Flight, George E. Mueller, that action was underway by Grumman to terminate all Pratt & Whitney LEM fuel cell activity by June 30, 1965. Pratt & Whitney would complete testing of LEM fuel cell hardware already produced and one complete LEM fuel cell module plus spare parts would be sent to MSC for in- house testing.
North American's Space and Information Systems Division would continue development at Pratt & Whitney on the CSM fuel cell for 18 months at a cost not to exceed $2.5 million, to ensure meeting the 400-hour lifetime requirement of the CSM system.
MSC would contract directly with Pratt & Whitney for CSM cell development followed by complete CSM module testing for a 1,000-hour CSM module at a cost of approximately $2.5 million. Grumman was scheduled to propose to ASPO their battery contractor selection on April 29, 1965.
As a result of the decision for an all-battery LEM, MSC advised Grumman that power for the entire pre- separation checkout of the spacecraft would be drawn from that module's batteries (instead of only during the 30 minutes prior to separation). This change simplified the electrical mating between the two spacecraft and obviated an additional battery charger in the CSM. From docking until the start of the checkout, however, the CSM would still furnish power to the LEM.
TWX, James L. Neal, MSC, to GAEC, Attn: R. S. Mullaney. April 30, 1965.
During the Month
Grumman reported two major problems with the LEM's descent engine:
Grumman advised MSC that it had selected the Eagle-Picher Company as vendor for batteries in both stages of the LEM. At the same time, because a proposal by Yardney Electric Company promised a sizable weight saving, this latter firm would produce "pre-production" models for the ascent stage.
MSC instructed Grumman to negotiate award of a contract to supply batteries for the ascent and descent stages of the LEM with Eagle-Picher Company. Grumman had solicited and received proposals from Eagle-Picher and Yardney Electric Corporation. The bids, including fees, were: Eagle-Picher, $1,945,222; and Yardney, $1,101,673. Grumman evaluated the bids; made presentations to MSC personnel; and proposed on May 6 that they negotiate with Eagle-Picher for ascent and descent batteries; and with Yardney for development of a lighter ascent battery at a cost of approximately $600,000. MSC instructed Grumman not to place the proposed development contract with Yardney, stating that such work could be more appropriately done by MSC work with Yardney or other battery vendors.
The Resident ASPO at Grumman approved three vendor selections by the LEM manufacturer:
William A. Lee, ASPO Assistant Manager, asked Systems Engineering Division to study the feasibility of an abbreviated mission, especially during the initial Apollo flights. Because of the uncertainties involved in landing, Lee emphasized, the first LEMs should have the greatest possible reserves. This could be accomplished, he suggested, by shortening stay time; removing surplus batteries and consumables; and reducing the scientific equipment. Theoretically, this would enable the LEM pilot to hover over the landing site for an additional minute; also, it would increase the velocity budgets both of the LEM's ascent stage and of the CSM. He asked that the spacecraft's specifications be changed to fly a shorter mission:
Crew Systems Division reported that, as currently designed, the environmental control system (ECS) in the LEM would not afford adequate thermal control for an all-battery spacecraft. Grumman was investigating several methods for improving the ECS's thermal capability, and was to recommend a modified configuration for the coolant loop.
Samuel C. Phillips, Apollo Program Director, noted MSC request for support from Goddard Space Flight Center on LEM battery development as well as Goddard's agreement to furnish limited support.
Phillips suggested to ASPO Manager Joseph F. Shea that since MSFC had much experience in the design, development, and operational aspects of battery systems, it was important to use their experience and recommended MSFC be contacted if such action had not already occurred.
The Weekly Activity Report for the period indicated that
Grumman reported the status of its effort to lighten the LEM. Despite some relief afforded by recent program changes (e.g., revised velocity budgets and the replacing of fuel cells with batteries), the contractor admitted that significant increases resulted as the design of the spacecraft matured. Grumman recommended, and MSC approved, a Super Weight Improvement Program (SWIP) similar to the one that the company had used in its F-111 aircraft program. By the end of the month, the company reported that SWIP had trimmed about 45 kg (100 lbs) from the ascent and about 25 kg (55 lbs) from the descent stages of the spacecraft. Grumman assured MSC that the SWIP team's attack on the complete vehicle, including its equipment, would be completed prior to the series of LEM design reviews scheduled for late in the year.
Grumman advised that prelaunch heat loads on LEM-1 exceeded the capability of the spacecraft's prelaunch Freon boiler. That boiler had originally been designed for loads anticipated from fuel-celled LEMs. When batteries replaced fuel cells, MSC had recommended deleting the boiler; Grumman had urged that the item be retained on LEM-1, however, because that spacecraft would have optional equipment onboard at launch. "It appears," Crew Systems Division (CSD) reported, "that the number of items of equipment required to be on [LEM-1] at earth launch has snowballed": the boiler's maximum capability was about 900 Btus per hour; the spacecraft's heat load was estimated at something like 6,000. "GAEC is presently investigating what can be done to reduce these loads," CSD said.
MSC requested Grumman and North American to study the possibility of taking the guillotine that Grumman had developed for the LEM's interstage umbilical and using it as well to sever the two umbilicals linking the LEM to the adapter. In this manner, North American's effort to develop these cutters might be eliminated; LEM-adapter interface would be simplified; and a significant monetary savings could be effected without schedule impact.
The development mission planning panel met to discuss the general constraints for missions AS-206 and AS-207. AS-206 spacecraft and operational constraints and mission rules were checked for compatibility. An investigation of the AS-207 preliminary mission profile showed that the ascent power requirements far exceeded the capacity of the ascent stage batteries. A modification to the mission profile was developed which would enable the mission objectives to be accomplished within the LEM battery capabilities. A tentative procedure for negotiating MSFC launch vehicle constraints was established between MSC and MSFC.
A manned lunar mission metabolic profile test was run in the Hamilton Standard Division altitude chamber using the development liquid-cooled portable life support system (PLSS). The system was started at a chamber altitude of over 60,906 m (200,000 ft), and the subject adjusted the liquid bypass valve to accommodate the programmed metabolic rates which were achieved by use of a treadmill. Oxygen was supplied from an external source through the PLSS bottle and oxygen regulation system. This procedure was used because bottle qualification was not complete, so pressure was limited to 2,068 kilonewtons per sq m (300 psig). An external battery was used for power because the new batteries that were required by the change to the all-battery LEM were not yet available. The thermal transport system including the porous plate sublimator was completely self-contained in the PLSS. All systems operated within specification requirements and the test was considered an unqualified success.
MSC notified Grumman that all electrically actuated explosive devices on the LEM would be fired by the Apollo standard initiator. This would be a common usage item with the CSM and would be the single wire configuration developed by NASA and provided as Government-furnished equipment.
The LEM electrical power system use of the primary structure as the electrical ground return was approved after Grumman presentations were made to ASPO and Engineering and Development personnel. The descent-stage batteries would not use a descent-stage structure ground to preclude current flow through the pyrotechnic interstage nut and bolt assemblies. The ascent and descent stage batteries would be grounded to primary structure in the near vicinity of the ascent-stage batteries. In addition, several selected manually operated solenoids would ground. All other subsystems would remain grounded to the "single-point" vehicle ground. This change would be implemented by Grumman with no cost or schedule impact and would effect a weight savings of approximately 7.7 kg (17 lbs).
Hamilton Standard Division was directed by Crew Systems Division to use a 2.27-kg (5-lbs) battery for all flight hardware if the power inputs indicated that it would meet the four-hr mission. The battery on order currently weighed 2.44 kg (5.4 lbs). This resulted in an inert weight saving of l.45 kg (3.2 lbs) and a total saving on the LEM and CSM of 5.44 kg (12 lbs).
The Service Module Disposition Panel (No. 21) report accepted by the Apollo 204 Review Board said test results had failed to show any SM anomalies due to SM systems and there was no indication that SM systems were responsible for initiating the January 27 fire.
Panel 21 had been charged with planning and executing SM activities in the Apollo 204 investigation, beginning at the time the Board approved the command module demate. The task was carried out chiefly by Apollo line organizational elements in accordance with a plan approved by the Board and identifying documentation and control requirements.
The panel's major activities had been:
An investigation at Grumman compared flammability characteristics of blankets representative of the external LM vehicle insulation with those of unshielded mylar blankets. When subjected to identical ignition sources, the mylar specimens burned during all phases of testing. Localized charring and perforation were the only visible signs of degradation in specimens simulating the LM shielding. The conclusion was that the protection of mylar blankets by H-Film in the LM configuration effectively decreased the likelihood of ignition from open flame or electrical arcing.
Circuit breakers being used in both CSM and LM were flammable, MSC ASPO Manager George Low told Engineering and Development Director Maxime A. Faget. Low said that although Structures and Mechanics Division was developing a coating to be applied to the circuit breakers, such a solution was not the best for the long run. He requested that the Instrumentation and Electronics Systems Division find replacement circuit breakers for Apollo - ideally, circuit breakers that would not bum and that would fit within the same volume as the existing ones, permitting replacement in panels already built. On July 12 Low wrote Faget again: "In light of the work that has gone on since my May 5, 1967, memo, are you now prepared to propose the use of metal-jacketed circuit breakers for Apollo spacecraft? If the answer is affirmative, then we should get specific direction to our contractors immediately. Also, have you surveyed the industry to see whether a replacement circuit breaker is available or will be available in the future?" Low requested an early reply.
George M. Low, Manager of the Apollo Spacecraft Program, notified NASA Hq. that Grumman was committed to a June 28 delivery for lunar module 1 (LM-1). This date included provisions for replacement of the development flight instrumentation harness with a new one. Low's assessment was that the date would be difficult to meet.
Grumman Aircraft Engineering Corp.'s method of building wiring harness for the lunar module was acceptable, George Low, MSC Apollo Spacecraft Program Office Manager, wrote Apollo Program Manager Samuel C. Phillips at NASA Hq. Low had noted on a visit to Grumman on May 9 that many of the harnesses were being built on two-dimensional boards. In view of recent discussions of the command module wiring, Low requested Grumman to reexamine their practice and to reaffirm their position on two-versus three-dimensional wiring harnesses.
In his May 31 letter to Phillips, Low enclosed Grumman's reply and said that, in his opinion, Grumman's practice was acceptable because
Although the LM-1 wiring harness had been accepted by the Customer Acceptance Readiness Review Board it was not clear that the harness would also have been accepted for manned flight, ASPO Manager George M. Low told Apollo Systems Engineering Assistant Chief R. W. Williams. Low asked Williams to assign someone to prepare a plan of actions needed to ensure that the harnesses in LM-2 and subsequent vehicles would be acceptable.
The RTG Review Team - established to investigate the relation of the radioisotope thermoelectric generator's fuel-cask subsystem to Apollo mission safety and success - submitted a preliminary report. Apollo Program Director Samuel C. Phillips had established the team after concern was expressed over the design and safety of the subsystem at a June 1 review at NASA Hq. of the Apollo Lunar Surface Experiments Package (ALSEP).
The team's preliminary report was based on data received and observations of the LM at Grumman that indicated the interface of the RTG, LM, and spacecraft-LM adapter (SLA) presented a potential problem to the Apollo mission. The most serious hazard was the presence of the 530-640 K (500-700 degrees F) RTG fuel cask in the space between the LM and the SLA, where leaks were possible during fuel unloading or in the mechanical joints of the LM fuel system.
Plans were to fuel the LM four days before launch and to pressurize the LM fuel system at T (time of launch) minus 16 hours. The RTG fuel element was to be loaded into the graphite cask, which was mounted on the LM at T minus 12 hours and the system secured. All work would be completed on the ALSEP by T minus 10 hours. If a condition occurred that required unloading fuel from the LM after installation of the fuel element in the cask, the hot cask would be a partial barrier to reaching one of the fuel unloading points and also would be a potential fire hazard. No mechanism was available to remove the entire cask system rapidly. Other potential problems were:
MSC Director of Flight Operations Christopher C. Kraft, Jr., raised questions about lunar module number 2: Would it be possible for LM-2 to be a combined manned and unmanned vehicle; that is, have the capability to make an unmanned burn first and then be manned for additional activities? Would additional batteries in the LM provide greater flexibility for earth-orbital missions? Mission flexibility would be worthwhile only if it allowed deletion of a subsequent mission, at least on paper.
A cooling design to keep heating effects of the radioisotope thermoelectric generator (RTG) below 450 kelvins (350 degrees F) was being sought for the Apollo Lunar Surface Experiments Package. Studies had shown that the RTG could be a fire hazard when the ALSEP was carried in the lunar module, heating temperatures up to 590 kelvins (600 degrees F) unless cooling was provided. Temperatures from 460 to 465 kelvins (370 degrees F to 380 degrees F) were hazardous with the fuels in the LM.
Bethpage RASPO Business Manager Frank X. Battersby met with Grumman Treasurer Pat Cherry on missing items of government property. The Government Accounting Office (GAO) had complained of inefficiency in Grumman property accountability records and had submitted a list of some 550 items of government property to Grumman. After nine weeks of searching, the company had found about 200 items. The auditors contended the missing items amounted to $8 million-$9 million. Cherry said he believed that all the material could be located within one week. Battersby agreed to the one-week period but emphasized that the real problem was not in locating the material but rather in establishing accurate records, since GAO felt that too often the contractor would be tempted to go out and buy replacement parts rather than look for the missing ones.
Twist-and-solder wire splices were evaluated for ASPO Manager Low by Systems Engineering Division. The evaluation stated that twist-and-solder wire splices with shrink sleeve tubing had been used for many years and when properly done were adequate. It then listed three advantages and six disadvantages of this kind of splice. In summary, it stated that the splice could be phased into the LM program but was not recommended by the division because:
In response to a query from MSFC, MSC took the position that primary batteries as opposed to secondary (rechargeable batteries) should be used to power the lunar roving vehicle. Concern was expressed that a solar array recharge assembly would introduce an extra complexity into the LM payload packaging and the roving vehicle servicing requirements and would contribute to a loss in effective EVA time because astronauts would need time to deploy the solar array and connect it to the rover.
Major items of discussion during the Manned Space Flight Management Council meeting in Washington were the Apollo 15 anomalies. These included parachute collapse during landing, lunar module descent battery, lunar surface drill, and steering mechanism on the LRV. Also discussed were the Apollo 16 preparations and the feasibility of TV coverage of the lunar rover during traverse.
The most likely cause of the parachute collapse was damage from burning raw RCS fuel (monomethyl hydrazine) being expelled during depletion firing. Corrective action included landing with reaction control system propellants on board for a normal landing and biasing the propellant load to a slight excess of oxidizer and increasing the time delay inhibiting the rapid propellant dump, to avoid fuel contacting the parachute riser and suspension lines during low-altitude-abort land landings.