The Apollo Spacecraft - A Chronology.

Part 2 (M)

Recovery, Spacecraft Redefinition, and First Manned Apollo Flight

June through July 1968

1968 June

1968 July


June 3

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. (Purpose of a total CSM 101 and LM-3 toxicological evaluation was to verify that no toxic contaminants were given off by the nonmetallic materials used in the crew compartments.)

Ltr., Low to R. O. Middleton, KSC, "Toxicological evaluation of CSM 101 and LM-3," June 3, 1968.

June 3

Apollo Program Director Sam Phillips asked ASPO Manager George Low to investigate the value of using freon as a fire extinguishing agent inside the spacecraft. Admittedly, Phillips said, MSC had considered using a freon extinguisher system shortly after the AS-204 accident, but it had been rejected, largely because of toxicity factors and because tests had shown the agent ineffective in extinguishing combustion of polyurethane in a pure oxygen atmosphere. A number of factors now dictated a reevaluation of such an extinguisher system, however:

  • Additional testing of late had indicated a lower toxicity problem than earlier believed.
  • The addition of oxygen masks to the spacecraft now afforded some protection against a toxic atmosphere.
  • Because of post-accident changes inside the cabin, the flammability problem had been reduced to a few specific materials (quite different from polyurethane foam) sited in compartmentalized locations inside the cabin.
  • The oxygen-nitrogen mixed gas had been selected as the prelaunch atmosphere inside the cabin.
In view of these changes, Phillips said, a freon extinguishing system might be better than the present jelled water extinguisher (quicker activation and reduced equipment damage). He asked that Low not overlook this potential improvement in crew safety, which could be of particular value during the high-risk period of launch, when the crew was essentially immobilized by the forces of acceleration.

Ltr., Phillips to Low, "CBrF3 (Freon 1301) as a Fire Extinguishing Agent," June 3, 1968.

June 5

George E. Mueller, Associate Administrator for Manned Space Flight, wrote MSC Director Robert R. Gilruth to express his personal interest in lunar extravehicular activity (EVA) training for the Apollo crews of the F and G missions (i.e., the initial lunar landing and subsequent flights). Because of the complexity of the EVA tasks that the astronauts must perform, Mueller said, crews for those missions should be selected as early as possible. Also, realistic training - including a realistic run-through of many of the lunar surface tasks, especially development of the S-band antenna and the Apollo Lunar Surface Experiments Package and sampling operations - must be conducted to ensure that the crews competently carried out the various scientific experiments and other tasks during their brief stays on the moon.

Ltr., Mueller to Gilruth, June 5, 1968.

June 7

ASPO Manager George M. Low and others from MSC met with Grumman's LM engineering staff, headed by Thomas J. Kelly, to discuss the descent stage heatshield and thermal blanket problems associated with reduced thrust decay of the descent engine at lunar touchdown. Several significant decisions were reached:

  • The touchdown probe was lengthened to 1.6 meters.
  • Effective on LM-5 and later vehicles, Grumman would "beef up" (both structurally and thermally) the base heatshield.
  • Grumman was to conduct a series of tests on overpressure of the descent engine.
  • Grumman would begin design studies of a jettisonable descent engine skirt.
  • Landing stability would be reexamined with the existing thrust tailoff profile (a study to be made either by Grumman or by Boeing; Low asked Maxime A. Faget, Director of Engineering and Development at MSC, to review this proposed test plan and to recommend where it should be conducted, for best cost, schedule, and technical capabilities).
Memo, Low to C. H. Bolender, "LM descent stage base heatshield," June 8, 1968.

June 10

In his weekly progress report to the NASA Administrator, Deputy Administrator for Manned Space Flight George E. Mueller cited several important Apollo events during the first week of June:

  1. On June 1, technicians at MSC completed thermal-vacuum testing on LTA-8 to support LM-3, including 45% hours of manned testing. All spacecraft systems functioned normally, and preliminary results indicated that all significant test objectives had been realized.
  2. Engineers and technicians at KSC completed receiving inspection of CSM 101 on June 3. That inspection revealed fewer discrepancies than had been present on any other spacecraft delivered to the Cape. Pre-mate inspection of CM 101 also was completed, as were leakage and functional tests on the electrical power and reaction control systems. SM 101 was in the altitude chamber being prepared for combined systems testing.
Memo, Mueller to NASA Administrator, "Manned Space Flight Weekly Report - June 7, 1968," June 10, 1968.

June 10

ASPO Manager George M. Low met with Christopher C. Kraft, Jr., and Donald K. Slayton, Directors of MSC Flight and Flight Crew Operations, and several members of their staffs (including astronaut Walter M. Schirra, Jr.) to discuss using the flight combustion stability monitor (FCSM) on the Apollo 7 flight. (The FCSM was a safety device to shut down the service propulsion system [SPS] automatically in the event of rough combustion or instability.) At the insistence of the Propulsion and Power Division, they agreed to use the FCSM for all SPS burns on Apollo 7. On all "noncritical" burns, two attempts to start the engine would be made with the FCSM active. Should the stability monitor shut down the engine on both those attempts, a detailed review of the situation would be made before again attempting to start the engine. On "critical" burns (i.e., the abort-to-orbit and reentry burns), should the FCSM halt the burn the SPS engine would be restarted immediately with the FCSM inactive on the assumption that the shutdown was caused either by an FCSM malfunction or by an engine instability that would not reoccur on the next start.

Low, Kraft, and the others unanimously wanted to eliminate the FCSM before a lunar mission, because on this mission lunar orbit and transearth insertion burns were highly critical and inadvertent shutdowns would cause major trajectory perturbations. Representatives from the Propulsion and Power Division (PPD) contended that, because of the relatively small number of bomb tests carried out on the Block II SPS engine, flight-testing of the engine before the lunar mission would be inadequate to demonstrate engine stability under all conditions. Low therefore asked Engineering and Development Director Maxime A. Faget and PPD Chief Joseph G. Thibodaux, Jr., to plan a ground test program that would give sufficient confidence in the SPS engine to eliminate the FCSM before undertaking lunar missions.

Ltr., Low to Thibodaux, "Use of FCSM on Apollo 7," June 11, 1968.

June 11

Dale D. Myers, Apollo CSM Program Manager at North American Rockwell, advised MSC officials of his company's investigation of two pilot-chute riser failures during recent drop tests of the Block II earth-landing system. Should there be any imperfections in either hardware or assembly techniques, Myers explained, the Block II pilot chute and riser system could be a marginal-strength item. Investigations had determined that early manufacturing processes had allowed a differential length between the two plies of nylon webbing in the pilot-chute riser which caused unequal load distribution between the two plies and low total riser strength. Because of the earlier test failures, Myers said, the pilot chute riser had been redesigned. The two-ply nylon webbing had been replaced by continuous suspension lines (i.e., 12 nylon cords) and the 5.5-millimeter-diameter cable was changed to 6.3-millimeter cable. He then cited a series of recent tests that verified the redesigned pilot-chute riser's strength to meet deployment under worst-case operational conditions.

Ltr., Myers to K. S. Kleinknecht, MSC, June 11, 1968.

June 17

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

Ltr., Samuel C. Phillips, OMSF, to Robert R. Gilruth, MSC, June 17, 1968.

July 3

NASA and contractor technicians successfully conducted the final parachute drop test to qualify the Apollo CSM earth-landing system. The Block II ELS thus was considered ready for manned flight after 12 Block I, 4 Block II, and 7 increased-capability Block II Qualification Tests - that had followed 77 Block I, 6 Block II, and 25 increased-capability Block II Development Drop Tests.

Memo, George E. Mueller, NASA OMSF, to NASA Administrator and Deputy Administrator. "Manned Space Flight Weekly Report - July 5, 1968," July 8, 1968; NASA Technical Note (NASA TN D-7437), "Apollo Experience Report-Earth Landing System."

July 5

ASPO Manager George M. Low asked Aaron Cohen, one of his chief technical assistants, to investigate the ability of the Apollo spacecraft to withstand bending loads imposed by a failure of one or more engines on the Saturn V launch vehicle (as well as actual loads that would be imposed on the spacecraft). During the previous week, Low and the Configuration Control Board had ruled out making any significant design changes to cope with a Saturn V engine failure. Specifically, Low asked how bending loads on the spacecraft were derived; what bending loads were imposed on the spacecraft during the Apollo 6 mission, where two J-2 engines were cut off during the flight; what was the probability - and criticality - of an S-IC engine's failing and thereby imposing high bending loads; and whether abort limits should be established for an engine failure.

Memo, Low to Cohen, "Saturn V single engine out problems," July 5, 1968.

July 10-11

The Apollo Design Certification Review (DCR) Board met in Houston to examine CSM 101 and the Block II CSM for proof of design and development maturity and to certify the designs for flightworthiness and manned flight safety. (Three earlier reviews directly supported this penultimate scrutiny of the vehicle's development: the CSM 101 Design Certification Review March 6-7, the Block II environmental control system and spacesuit DCR May 8, and the DCR covering the CM land and water impact test program June 6.) The board concluded that design certification on CSM 101 was complete. Action and open items were subsequently forwarded to the Centers for resolution, to be closed before the Apollo 7 Flight Readiness Review.

Ltr., Samuel C. Phillips, NASA Hq., to distr., "CSM 101 and Block II CSM Delta Design Certification Review," Aug. 28, 1968.

July 11

ASPO Manager Low informed Apollo Program Director Phillips of several changes in the LM vibration testing program. Before beginning the series of tests, he told Phillips, red line values were established on critical components that were not to be exceeded. However, because of the most recent test effort on LM-2, which resulted from the pogo problem experienced during the flight of Apollo 6, Low was forced to authorize vibration testing beyond the red line values initially set for the spacecraft. This action, in turn, forced an inspection and possible refurbishment of LM-2 to make it available for an unmanned flight, should such a second unmanned LM test mission be required. He then cited MSC's future plans for LM-2:

  • For the planned drop tests with the vehicle, the upper decks would be inspected and repaired or replaced where necessary.
  • Should a LM-2 flight become necessary, all of the descent stage upper decks would probably be replaced.
Phillips approved Low's action immediately. He urged Low to "continue to give priority to that work which is necessary for full and early resolution of the POGO and spacecraft structural dynamics questions."

Ltr., George M. Low to Samuel C. Phillips, July 11, 1968, with handwritten notation by Phillips dated July 11, 1968.

July 13

ASPO Manager George M. Low wrote to Grumman President Llewellyn J. Evans to call his attention to the problem of continued propellant leaks in the LM. "In spite of all of our efforts, last summer" (i.e., with the extensive plumbing rework done on LM-1 after its delivery to Florida), Low said, technicians at KSC found a leak on one of the lines on LM-3, even though no leaks had been observed during checkout at Bethpage. Investigating the problem, Low had learned that Grumman had made some propellant-system design changes that had led to installation of four-bolt flanges with single teflon O-ring seals - despite the fact that during the preceding summer NASA and Grumman had jointly agreed not to use this joint on the LM vehicle. This most recent problem, said Low, again points up the importance of strictest control of all design changes in the spacecraft. Because of the need for maintaining a lunar-configured LM as a design baseline, all spacecraft design changes had to be carried through the Apollo Configuration Control Board before implementation.

Ltr., Low to Evans, July 13, 1968.

July 15

NASA Apollo Program Director Samuel C. Phillips laid down Headquarters and MSC interfaces with the Atomic Energy Commission (AEC) regarding the SNAP-27 radioisotope thermoelectric generator for the Apollo Lunar Surface Experiments Package (ALSEP). The Lunar Surface Program Office at MSC was the field project office responsible for developing the ALSEP system, and the radioisotope generator - as part of the ALSEP - had been assigned to that office for system integration. Thus, the Lunar Surface Program Office served as the AEC's primary contact on the SNAP-27 both for ALSEP program matters and for data pertaining to flight safety and documentation for flight approval. Phillips stressed that all data be fully coordinated with Headquarters before being submitted to the AEC. (Approval for the flight of any nuclear device rested ultimately with the President, but formal documentation had to be concurred in by the NASA Administrator, the AEC Commissioners, the Secretary of Defense, and the National Aeronautics and Space Council.)

Memo, Phillips to George M. Low, ASPO, MSC, "Atomic Energy Commission Interfaces," July 15, 1968.

July 17

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

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

Memo, C. H. Bolender, MSC LM Manager, to Manager, Apollo Spacecraft Program, MSC, "Dr. Mueller's visit to GAEC on July 17, 1968," July 19, 1968.

July 22

In the continuing effort to reduce costs while still maintaining a balanced and viable program, ASPO Manager George M. Low recommended to NASA Hq. that CSM 102 be deleted from the manned flight program. He estimated total savings at $25.5 million (excluding cost of refurbishment after the current ground test program). In addition, he said, during the static structural test program at North American Rockwell, CSM 102 would be subjected to loads that would compromise structural integrity of the vehicle for manned flight.

Ltr., Low to Samuel C. Phillips, "Deletion of CSM 102 from the manned flight program," July 22, 1968.

July 23

Prompted by a request from MSC to increase the Saturn V's performance to 46,070 kilograms for lunar missions, Samuel C. Phillips sought to strike a balance between spacecraft and launch vehicle weight-performance demands. He established as a new payload interface definition at translunar injection a payload of 46,040 kilograms. Should the vehicle per se be incapable of achieving this figure, said Phillips, he would relax certain flight constraints to achieve the best possible balance between the space vehicle and the specific mission to be flown. But he implored both ASPO Manager George M. Low and Lee B. James, Saturn V Program Manager at MSFC, to work toward this balance between spacecraft and launch vehicle and to avoid any hardware changes in the Saturn V solely to meet the new payload interface weight.

Ltr., Phillips to James and Low, "Saturn V Payload Interface Definition," July 23, 1968.

July 30

F. A. Speer, Mission Operations Manager at MSFC, advised NASA Hq. of plans for S-IVB and spacecraft separation and employment of a "slingshot" trajectory following insertion into the trajectory toward the moon. Residuals in the S-IVB, said Speer, could be used to place the stage in a trajectory that would avoid recontact with the spacecraft and impact on either the earth or the moon - with preclusion of spacecraft-launch vehicle collision as the most important priority.

Ltr., Speer to William C. Schneider, Apollo Mission Director, NASA, "Lunar Debris," July 30, 1968.