A Change of Course for Apollo

Scientific investigations highlighted the last three Apollo missions. The cold war competition that had put men on the moon was fading. Congress and the American public now wanted tangible benefits from space expenditures. NASA adjusted its manned programs to the new climate. Skylab, the post-Apollo manned program, would focus on practical applications, most of them earth-oriented. Apollo, reduced by funding cuts to three more missions, would emphasize lunar exploration. Missions 15-17 did not disappoint American scientists; indeed those missions proved a fitting climax to one of the nation’s great achievements.

NASA’s plans for the concluding Apollo missions were announced on 2 September 1970. Modifications to the spacecraft and astronaut support systems would double the time the astronauts could stay on the moon. The weight devoted to lunar surface experiments would also double. A lunar rover vehicle - an appropriate gift to the moon from an America-on-wheels-would more than double the distance the astronauts could travel on the surface. Other new equipment included a lunar communications relay unit, which enabled the crew to maintain contact with earth while exploring beyond the lunar module’s horizon. Transmissions from the portable relay station to Houston included voice, TV, and telemetry. Although the suitcase-sized device was normally mounted on the front of the rover, it could be detached and carried by an astronaut - a feature that ensured the crewmen a means of communication if they had to walk back to their spacecraft. The rover also mounted television cameras that were operated by remote control from Houston.¹

The command-service module’s lunar orbiting experiments, while less dramatic, were a vital part of the last missions. The scientific instrument module (SIM) in Apollo 15’s service module included three spectrometers - gamma-ray, x-ray fluorescence, and alpha-particle - to measure the composition and distribution of the lunar surface. A mass spectrometer would measure the composition and distribution of the lunar atmosphere. A subsatellite, ejected from the SIM bay into lunar orbit, would beam earthward information about solar winds, lunar gravity, and the earth’s magnetosphere and its interaction with the moon. Other equipment in the SIM, two cameras and a laser altimeter, would map about 8% of the lunar surface, in all some three million square kilometers.²

The extended missions on the moon required major modifications to the lunar module. Supplies of water, oxygen for the portable life support system, and electrical power were increased. Grumman enlarged the capacity of the propellant tanks by 7% and redesigned the descent stage to make room for the lunar rover. Altogether, the lunar module modifications and the SIM additions added about 2,270 kilograms to the Apollo 15 spacecraft, bringing its total weight to over 48 metric tons.³ This put a burden on Saturn engineers. Marshall and its contractors met the payload increase through minor hardware changes in the S-IC stage and by revising the Saturn V’s flight plan. The hardware modifications reduced the number of retrorocket motors, rebored the orifices on the F-1 engines, and set the burning time for the outboard engines nearer LOX depletion. Better use of the Saturn’s thrust was achieved by launching the AS-510 rocket in a more southerly direction (changing the launch azimuth limits from 72-96 degrees to 80-100 degrees) and by using an earth parking-orbit of 166 rather than 185 kilometers. Apollo 15 also stood to gain some advantage from the July launch date, when temperature and wind effects would be favorable.⁴

Interfaces with the First SIM

Apollo 15 launch operations got off to a slow start, impeded by spacecraft modifications. Checkout of the lunar module began in mid-June 1970, about the time the Apollo 13 review board announced its findings. Service module modifications, recommended by the board, delayed the launch date by five months. The September decision to enlarge the final missions brought further hardware changes. Spacecraft operations resumed in November with the arrival of the modified stages of the lunar module. Initial testing concentrated on the propulsion systems. Early in the new year Grumman engineers added three equipment pallets to the descent stage and brackets for the lunar rover. The new command-service module arrived in mid January and went almost immediately into the altitude chambers.⁵

January also brought the first instruments for the scientific instrument module. By that time the Experiments Section had been at work on the SIM for more than a year. Preparations for the lunar orbiting experiments included the construction of a laboratory in the operations and checkout building and development of ground support equipment. When testing began, the 7-man Experiments Section supervised 25 engineers representing 8 contractors. An occasional visit from an experiment’s scientist-author further complicated the three-shift operations. The contractor representatives proved invaluable from a logistical standpoint, securing minor design changes and spare parts. They did not always, however, seem to appreciate the need to meet a launch date.

From the very beginning the test engineers faced a familiar problem - hardware designed for use under conditions of zero gravity could not stand up to the rigors of earth gravity. The 7.5-meter extendable booms, which would deploy the mass and gamma-ray spectrometers, were built by North American for zero gravity. They could not support the spectrometers on Merritt Island, Earth. North American designed a long rail to help carry the load for test purposes. The operation was generally unsatisfactory, however, since it introduced problems that would not occur in zero g.

The SIM work crew joined North American’s spacecraft operation in late February and placed the SIM, with its eight experiments, inside the service module. Interface problems between the scientific instruments and the service module appeared almost immediately. The alpha spectrometer’s data stream failed to synchronize with the spacecraft data-relay system. The Experiments Section had more trouble with the gamma-ray and mass spectrometer booms. When the engineers extended the boom, they received no indication that signals were being received. Investigation indicated that diodes in the boom circuitry were blocking the signal. North American subsequently modified the spectrometer booms.⁶

Test procedures caused nearly as much trouble as the hardware:

The SIM bay complicated the checkout flow in every major procedure we ran. In some cases the vendors got the scientific instruments to us late. In other cases they would want to conduct a last-minute check at a very inconvenient time. Every time we powered up the ship for a major test somebody would come down with a special requirement for their instrument.⁷

The initial requirements for the calibration of the gamma-ray spectrometer called for halting all motor vehicles within 16 kilometers. NASA and the contractor negotiated the matter for several weeks, agreeing finally to a late night test with a traffic ban in nearby parking lots and roads. Following the weekend calibration exercise, the Experiments Section tested all SIM systems on 15 March and returned them to the factory for a month’s rework by the responsible contractors.

The instruments arrived back at KSC in mid-April. While there were some minor problems, e.g., the mapping camera would not turn off, the test team closed out the SIM bay temporarily in late April for the move to the pad. When the subsatellite arrived a month later, the Experiments Section installed its batteries, checked out the transmitter, and tested the interface with the mechanism that would eject the subsatellite into a lunar orbit. Technicians entered the space vehicle stack on 9 June and added the subsatellite to the SIM bay.⁸

The Moon Gets an Automobile

For the public, the big feature of the Apollo 15 mission was its little lunar rover. Americans immersed in an automobile age contemplated with no small joy the beginnings of a stop-and-go traffic jam on the moon. And the rover was worthy of its homeland; it boasted bucket seats and power steering. The 207-kilogram vehicle would run for 65 kilometers on its two 36-volt batteries. As a safety precaution, NASA restricted travel to a 9.5-kilometer radius from the lunar module, the limit of the astronauts’ ability to walk home. The rover’s payload allowed about 363 kilograms for the two astronauts and their portable life support systems, 54 kilograms for scientific and photographic equipment, the same for communications equipment, and 27 kilograms to bring home lunar samples. All weights, of course, would be reduced by five-sixths when the little car operated in lunar gravity. To meet space limitations inside the lunar module, the rover folded into a wedge-shaped package less than half its operating size.⁹

The Boeing Company and its prime subcontractor, the Delco Electronics Subdivision of General Motors, designed and built the first lunar rover in 18 months - one of the major rush jobs of the Apollo program. While the forced schedule contributed to the $12.9 million cost, the high price was principally a result of the rover’s unique engineering requirements. The harshness of the lunar environment - its extremes in temperature, lack of atmosphere, one-sixth gravity, and rough yet silt-soft surface - posed design problems in vehicle propulsion, stability, control, and wheel-soil interaction. Special wheels made of woven spring steel wire with titanium chevrons for traction were developed to meet the launch weight restrictions and still provide the support and mobility required on the moon. Each wheel had its own electric drive motor. The vehicle had independent steering motors for front and rear wheels so the driver could use front, rear, or both.

The two crewmen sat side by side on the vehicle. Control was provided by a T-bar “joy-stick” mounted on a console in the center. The joystick provided acceleration, brake, and steering control through complex electrical circuitry. It could be operated by either crewman. The console also provided electrical system control, monitor, and alarm capabilities.

Since a magnetic compass could not be used to indicate direction on the moon and because of other problems - such as having to go around craters - a special navigation system was built around a directional gyroscope, odometers, and a small computer. The system used the distance and direction traveled to determine range and bearing from the lunar module. With this information the astronauts could easily determine the shortest course back at any time. The navigational system also provided data for the location and placement of scientific equipment on the lunar surface.¹⁰

The launch team started preparing for the rover in late 1970 when the requirements document arrived from Marshall Space Flight Center. Arthur Scholz, Boeing’s rover project manager at KSC, drew up the test and checkout plan describing the sequence of operations. The first events on the flow chart involved reception and inspection, activation, and calibration of the rover’s ground support equipment. Meanwhile, Boeing engineers began preparing test procedures for the rover. They relied first on preliminary design data from the Seattle plant and then on the formal requirements document from Marshall. In January 1971 R. Dale Carothers, KSC’s manager for rover operations, and a group of Boeing and government engineers journeyed to Seattle where they took part in the last two months of factory tests.

The action switched to KSC in mid-March when the rover arrived at the Cape’s skid strip^* aboard a C-130 Hercules aircraft. The first rover spent two days in the operations and checkout building undergoing inspections, first in its folded and then in its unfolded condition. During the next three days technicians installed simulators for the two 36-volt batteries and checked out the vehicle’s power. The second week was taken up with electrical systems tests including front and rear wheel steering, the four drive motors, and the alarm system. During the tests the rover had to rest on a pedestal while the wheels turned in mid-air. The pedestal also supported the chassis when an engineer or astronaut entered the rover. The vehicle could support its own weight on earth, but no more. On one or two occasions, with the rover mounted on the pedestal, the test team witnessed a strange sight - the front wheels moving forward and the rear wheels in reverse. Boeing engineers said the drive motors were out of synchronization and that the phenomenon could not occur on the moon, where the wheels would be touching the lunar surface.

On 26 March the prime and backup crews went through the Crew Fit and Function Test, known in KSC parlance as CF squared. The test marked the astronauts’ first opportunity at KSC to work with the rover. There were several operations: removing the rover’s communication, television, photographic, and data-gathering equipment from the pallets in the spacecraft, placing the equipment in its proper place aboard the rover, and selecting items from the rover for further operations. The task was made more difficult by bulky gloves, the only part of their life support system the astronauts wore for the test. The exercise revealed a number of small problems such as recalcitrant strap fasteners and poorly fitting safety belts. As the rover’s stowage date was only a month away, Scholz and Carothers sought immediate modifications. The paperwork took more time than the physical changes. Coordinating design modification with contractors and other NASA centers was always a slow process. On this occasion a money dispute threatened further delays. Marshall did not want to authorize additional funds to accomplish the changes. Houston wanted the modifications but did not want to finance the work. In the end, the astronauts’ wishes prevailed; program managers from Marshall, Houston, KSC, and Boeing approved the proposed modifications and the work was under way in two weeks. The changes did not affect the stowage schedule.

The third week of rover testing began with a navigational systems check. The rover was mounted on the work stand, the wheels started turning in mid-air, and an engineer moved the steering handle. The test team observed the computer’s performance as it assimilated driving data from the odometers and gyroscope. The following day the launch team tested the rover’s mechanical brakes. Wheel and fender replacements and the closing out of discrepancy records took the remainder of the week. During Easter week technicians completed most of the modifications. A silicone-oil leak from the shock absorbers caused several days’ concern before the test team declared the shock absorbers “acceptable for flight.” On 16 April Boeing undertook one of the more difficult tasks - loading the rover aboard the lunar module. Technicians successfully deployed the rover the following day, using a landing platform to reduce the distance it fell, so that the impact was equivalent to what would be experienced under lunar gravity.

A second CF squared test inaugurated the last week of operations. The exercise provided a check on the various modifications that had been made since the first test. The rover group joined Grumman engineers the next two days for the electromagnetic compatibility test. As its name implied, this test was to detect interference, primarily with the lunar communications systems. With radios, computers, radars, even the rover’s wheels operating, no problems developed in the lunar communications relay unit. The launch team then moved on to the climax - simulated mission runs with the two astronaut crews.

The simulated missions gave Test Conductor Herman Widick some uneasy moments. Whereas lunar module tests usually attracted little attention, the novelty of the rover drew a large crowd of Apollo officials. The simulation involved a number of organizations: a Hamilton Standard representative for the portable life support system, NASA spacesuit technicians, Grumman engineers for the lunar module and rover storage, RCA and Goddard Space Flight Center communications experts, and Houston observers. While Widick had worked with most of these men, the Boeing engineers were new. Matters were complicated by two communications systems. The test conductor talked with the crew by radio through the portable life support system; communications with the rest of the test team were over the operational intercommunication system. The astronauts, their vision limited by the spacesuits, unwittingly interrupted Widick on several occasions. Spacecraft engineer Ernest Reyes had tried for several days to give the rover a sportier look, but Widick rejected every suggestion. As the test was about to begin, Commander David Scott pulled a fox tail from his spacesuit and attached it to the rover’s low gain antenna.

The setting for the simulated mission resembled a science-fiction film of the 1940s. Sunlight gleamed off the lunar module’s aluminum foil covering. Antennas stretched along the wall of the operations and checkout building’s high bay. In the center of the scene the rover, fully deployed, rested on its pedestal. The astronauts, dressed in the lunar surface version of their Apollo spacesuits, completed the picture. Since the test employed the communications equipment within the portable life support system, the 38-kilogram unit was strapped to each astronaut’s back. A reasonable load on the moon, it was too heavy to carry on earth, so a dolly with an overhead cantilevered arm supported the equipment. A technician guided each dolly as it moved behind the astronaut.

The mission simulation began with a communications check. While the astronauts stood in front of the rover, a test engineer switched on the drive motors. The wheels were noisy but produced no electrical interference. Technicians then removed the life support system from each astronaut’s back and placed the packs on the rover seats. The crew moved to the back of the vehicle where they engaged the equipment pallet pin and disengaged the rear steering pin. The latter operation, a difficult maneuver, was only for emergencies. If the rear steering mechanism failed on the moon, the astronauts could lock the rear wheels in place and steer with only the front wheels. After these tests, the astronauts seated themselves in the rover. A wedge was placed between the life support system and the seat to give the astronaut the feel of lunar gravity with the pack. Wearing pressurized suits, the astronauts had considerable trouble with the seat belts. Finally ready, the astronauts began their lunar ride - simulating specific distances and directions until they returned to the lunar module. The astronauts also checked the TV signal that would return to earth over the relay unit.

After successful mission simulations with both crews, Boeing technicians folded the rover and reinstalled it. Two days of rover deployment followed. The exercise included possible malfunctions and appropriate responses. (On subsequent missions the launch team rigged various deployment malfunctions in the rover trainer and lunar module simulator.) On 25 April the launch team placed the rover inside the lunar module. The spacecraft joined the Saturn stack two weeks later.¹¹

The rover was stowed away but not forgotten. On 5 May the training vehicle was demonstrated for the press. Scott and Irwin answered newsmen’s questions and then drove the one-gravity rover trainer to the lunar simulation area. A few fortunate reporters tried their hand at the T-bar handle controls. The reporters, with instructors at their side, drove the rover through the astronauts’ crater-pocked sandpile. Their enthusiastic response carried over to the next day’s newspapers.¹²

Lunar Module Problems and More Lightning

The SIM and rover were the newest, but not necessarily the biggest, problems on Apollo 15; February and March 1971 were difficult months for the lunar module team. A combined systems test ran for ten days in February as test engineers attempted to resolve a series of discrepancies. Problem areas included the rendezvous radar, a frequent source of trouble in the past. The NASA-Grumman team discovered a malfunction in the radar’s rangefinding circuitry and called Bethpage for a replacement on the 24th. It arrived on the 26th and went immediately to the boresight range. Weekend tests disclosed another deficiency: the radar would not slew from its normal straight-ahead position to directly overhead, which would be needed for tracking the command-service module from the lunar surface. The fault was apparently in the mode position switch. On 1 March KSC asked Bethpage to send another radar. It arrived the following day and passed inspection at the boresight range; the self-tests (internal checks of electrical circuits), range determinations, and angle readout checks were all satisfactory. The angle readouts told what direction the radar was pointing and therefore the azimuth and elevation of the target. After installation, tests of the third radar looked all right except for some ambiguous range sensings. Then a technician reported an unusual grinding sound in the gyroscope assembly. The noise increased; a bearing had gone bad. With its fourth radar installed on 13 March, the launch team had a satisfactory rendezvous system.¹³

Herman Widick’s test team uncovered more problems when the lunar module began altitude chamber runs in late March. During an unmanned run on the 26th, engineers noted unsatisfactory conditions in the communications system and the environmental control system. The radio problem involved extraneous noise from the transceiver. With no crew on board, the radios operated in a relay mode, i.e., signals went to the lunar module on the VHF uplink and came back immediately over the S-Band downlink. Harold Cockran’s engineering team traced the problem to an improper setting on the VHF receiver squelch circuit.¹⁴

The possible malfunction in the environmental control system concerned a relief valve on the suit circuit assembly. Two demand regulators controlled the oxygen pressure to the assembly.^* The relief valves protected the suit circuit from overpressurization. On the test of the 26th, the regulator’s maximum pressure and the relief valve’s minimum line were closer than the prescribed tolerance. It was realized, however, that the regulator pressure would drop somewhat during the manned runs. On the 29th, as the backup crew prepared for an altitude run, a technician inadvertently applied too much pressure to the commander’s oxygen umbilical, damaging the hose. The rescheduled test failed when both demand regulators continued to pressurize the suit circuit after reaching the acceptable limit. Technicians removed the regulators the following day. Finally, on 6-7 April, the test team managed successful altitude runs with the prime and backup crews.¹⁵

The problems prompted James Irwin, Apollo 15’s lunar module pilot, to speak out publicly. At a press conference in Houston, Irwin singled out the difficulties with the lunar module’s environmental control system, the landing radar, and the rendezvous radar. Irwin attributed some of the problems to the extended shelf life of the Apollo equipment. Due to the stretchout of Apollo flights, equipment was remaining in storage longer than manufacturers had expected. Irwin also noted that a lot of trained people were leaving the Cape and said, “I think maybe morale is slipping perhaps.” Apollo 15’s other two astronauts, David Scott and Alfred Worden, disagreed. Worden remarked: “I think the people there are more fired up about 15 than they have been before.”¹⁶ Concern about the lunar module lessened after the successful altitude runs.

Lightning strikes were the most significant events after the Saturn V was moved to the pad in early May. During the flight readiness test on 14-15 June, lightning struck the mobile service structure and mobile launcher. Although there was no apparent harm to the space vehicle, some ground support equipment was damaged. Schedules were revised to permit retesting of all spacecraft systems. On 25 June, the day following the flight readiness review, lightning struck again with the same results. Damaged electrical components were replaced and the spacecraft systems checked once more. Pad A experienced a third strike on the evening of 2 July during hypergolic loading. While there was no apparent damage, some tests were repeated during the countdown demonstration test. Minor problems during the countdown demonstration test, 7-14 July, were corrected before the start of the countdown on 20 July. When more lightning struck LC-39A during countdown week, Kapryan delayed moving the service structure from the pad until the evening of the 25th.¹⁷ Apollo 15 lifted off the next morning at 9:34 a.m. Commander Scott radioed back from space: “As we watch the S-IVB drift away here, how about passing along to Jim Harrington [Apollo 15 space vehicle test conductor] at the Cape congratulations from the crew to the launch team for a superior job.”¹⁸

Apollo 16 Operations

While astronauts Scott and Irwin motored around Hadley Rille, KSC officials turned their attention to the Apollo 16 mission scheduled for March 1972. In early August, North American mated the command and service modules. Three weeks later Grumman joined the two LM stages for their altitude tests. September saw the start of lunar rover checkout and the erection of the S-IC stage. In October the launch vehicle team stacked the Saturn stages. Meanwhile the astronauts went through the crew compartment fit and functional tests and the altitude chamber runs. The spacecraft modules moved out of the chambers in November and landing gear was installed on the lunar module. In December the spacecraft team mated the Apollo spacecraft to the lunar adapter and moved the combination to the assembly building. Twelve days before Christmas Apollo 16 rolled out to the pad.¹⁹

The launch team had made relatively few changes to the Apollo 16 spacecraft during the first five months of launch operations. Malfunctions on Apollo 15 prompted two command module changes: replacing panel switches for the spacecraft propulsion system and replacing the main parachutes. One of the three main parachutes had failed to open for the splashdown of Apollo 15, and NASA officials suspected hydrogen embrittlement in the connector links of the suspension lines. After replacing the suspect parts with steel alloy links, North American shipped a new set of parachutes to KSC in mid-November. That same week the launch team replaced the water glycol accumulators in two fuel cells of the service module. When the fuel cells converted oxygen and hydrogen to electricity and water, considerable heat was produced. As it transferred this heat to a series of radiators, the glycol expanded and the excess liquid accumulated in reservoirs. The accumulators had been damaged in September when technicians overpressurized the glycol system during a vacuum-purging test.²⁰

One of the few problem areas in the Saturn operations involved the engine actuators on the S-IC stage. These hydraulic actuators, 1.5 meters in length, swivelled the four outboard F-1 engines to change pitch, yaw, and roll. Actuator tests included the calibration of a recorder in the launch control center. As the actuators swivelled the F-1 engines, a potentiometer sent a voltage to the recorder indicating the direction and amount of movement. During November tests, excessive noise in one actuator interfered with the signal to the control center; the actuator was replaced on the 25th. The following week Boeing engineers inspected the S-IC LOX and RP-1 tanks for stress corrosion but found no problem.²¹

Early in the new year a spacesuit alteration and two spacecraft problems delayed the Apollo 16 launch to 16 April. Grumman engineers had increased the capacity of the lunar module batteries and wanted more time to gather test data. At Downey technicians discovered that an explosive device used to separate the command-service and lunar modules would malfunction under certain conditions; modification required additional time. The delay proved a godsend for KSC in late January when a fuel tank in the command module’s reaction control system ruptured.²²

The hypergolic propellants of the reaction control system, which controlled the attitude of the command module during reentry, were forced from their tanks by high pressure helium gas. Within each fuel tank, the fuel was inside a teflon bladder. As gas entered the tank, outside the bladder, rising pressure squeezed the bladder and forced the hazardous fuel from its tank. The flow of helium was tested during the integrated systems test. The primary and secondary regulators were checked to guarantee that an accurate flow was maintained, that the regulator shut off properly, and that after shutoff the pressure did not creep up, which would indicate internal leakage.

Problems with ground support equipment had put the launch team about two shifts behind schedule on 25 January when technicians completed the fuel-tank relief-valve checks and moved to the regulator tests. For these tests, the bladders were filled with helium gas instead of the hazardous monomethyl hydrazine. Human error brought the team grief: a technician failed to fully engage a quick-disconnect valve that controlled the flow of helium to a pressure regulator. Pressure inside a fuel tank, but outside the filled bladder, dropped quickly, and the bladder ruptured.²³

The seriousness of the problem stemmed from its location. Replacement of the fuel tank involved removing the command module’s aft heatshield, an operation that had to be conducted in the operations and checkout building. KSC faced a roll-back of the space vehicle from the pad to the assembly building - the first time this had happened since a hurricane threatened 500-F in June 1966. At first glance the accident seemed to preclude the April launch, and NASA officials announced a possible second month’s delay; but after reviewing the work needed to replace the damaged fuel tank, Kapryan and Petrone concluded that the launch team could recover in time for the 16 April launch. The space vehicle was returned to the assembly building on 27 January. The following day the launch team transferred the spacecraft to the operations and checkout building where both fuel tanks were replaced, along with the descent propulsion system regulators. By working overtime and weekends,^* KSC had Apollo 16 back on the pad in less than two weeks.²⁴

While operations resumed their smooth course for most of the KSC team, the propellants section experienced more headaches. The spacecraft was undergoing another integrated systems test on 17 February when a leak developed in a quick-disconnect test point. A North American engineer closed off test points improperly and excessive pressure ruptured discs on both oxidizer tanks. While the launch team waited for replacements to arrive, the program office rescheduled the remaining propulsion tests. New burst discs were emplaced and x-rayed on the 22nd, and propulsion tests resumed the following day.²⁵

Spacecraft Stowage

Stowing equipment on the Apollo spacecraft grew more complicated with the lunar exploration missions. The SIM bay and the rover have been described. The modularized equipment storage assembly occupied another quadrant of the descent stage. These cargo pallets provided room for tools, the lunar communications relay unit, various cameras including the color television equipment, and other items to be mounted aboard the rover. Inside the command and lunar modules the astronauts required more of nearly all supplies: food, clothing, film, and life support items. During the latter missions the Manned Spacecraft Center placed a number of experiments aboard the command module, e.g., Apollo 16 carried 60 million microbial passengers in a small rectangular container, a light flash detector, a biostack,^* and a Skylab food package.²⁶

The launch team stowed the spacecraft cabins on three separate occasions during the Apollo 16 operations: first, in the chambers prior to the astronauts’ altitude runs, a second time for the crew compartment fit and function test; and finally the day before launch. KSC had dropped the practice of stowing the cabin for the countdown demonstration test; instead technicians placed empty lockers inside the command module to give the astronauts the appearance of a flight-ready cabin. A team of nine normally stowed the command module. Inside the cabin two technicians secured each item in its proper place. A KSC quality control representative observed their work. Outside, two technicians unpacked the flight articles. A North American quality representative and engineers from Houston, KSC, and North American completed the team. While the six “outside members” of the team found the white room of the mobile service structure confining, they preferred it to the occasional use of the ninth swing arm from the umbilical tower, which had to be used in changing flight articles when Swigert replaced Mattingly on Apollo 13. Carrying equipment across a catwalk a hundred meters above the ground unnerved some members of the group. During the countdown, stowage of the command module began about 24 hours before launch and ran for seven hours. If no problems arose, the team could finish with several hours to spare.

The stowage exercise culminated two weeks of intensive preparations for KSC’s Anne Montgomery. Her group checked many of the flight articles such as cameras, communications equipment, and the lithium hydroxide canisters. The items were tested individually and then in conjunction with other flight articles and command module systems. Some items required special packaging; all were weighed and recorded by serial number. Every flight article received a detailed quality inspection and each mission disclosed a number of discrepancies.

James McKnight directed a similar activity for the lunar module, the final stowage of which began just before the start of the formal countdown. At T-55 hours Grumman technicians placed most of the articles aboard and checked out the lunar equipment conveyor. The astronauts relied on this moving clothesline to carry heavy items such as rocks inside the lunar module. The group completed stowage at T-30 hours. After placing a portable life support system on the cabin wall and another on the floor, the technicians took pictures of their work and then sealed the hatch.

Houston prepared the stowage plans for each mission; these took into consideration when and where the astronauts would use a particular flight article. Emergency items received first consideration. The Manned Spacecraft Center was also responsible for the contents of the crew preference kits, the bags in which astronauts carried their personal mementos. Following the incident with unauthorized postal covers on Apollo 15, NASA tightened its restrictions on what the astronauts could take to the moon.²⁷

After a successful flight readiness test on 1 March, officials met for the launch readiness review. The session covered all major aspects of Apollo 16 operations - range safety, operations safety, base support, Eastern Test Range support, Goddard’s communications network support, the central instrumentation facility, technical support, and the status of the space vehicle. Despite the problem with the reaction control system fuel talk, Apollo 16 had been KSC’s smoothest Apollo operation yet.²⁸

One month before the scheduled liftoff, John Young, Apollo 16 commander, and Charles M. Duke, lunar module pilot, briefed KSC employees on the upcoming mission. Although 1,500 attended the meeting, the crowd appeared insignificant inside the assembly building. Young and Duke discussed the problems they anticipated on landing in the high, rugged Descartes region. They outlined the goals of their extravehicular activities and explained the flight plan. After answering questions from the audience, Command Module Pilot Thomas K. Mattingly and Young circulated through the crowd, shaking hands and signing autographs. The briefing was one of the astronauts’ last public appearances before the launch, as they began their three-week preflight quarantine on 26 March. This crew had special reason to appreciate the restriction; Mattingly’s potential measles on Apollo 13 had prompted the quarantine and in January 1972 Duke had spent a week at the Patrick Air Force Base hospital with bacterial pneumonia.²⁹ The last month of operations saw few hardware changes. The actual countdown went without a hitch. Liftoff came on a hot Sunday afternoon, 16 April, at 12:54.³⁰

Apollo 17 Launch Operations

The Kennedy Space Center team saved its most spectacular liftoff for the last Apollo mission. Apollo 17, launched on a dark December night, lit up the Florida sky for miles. Despite its early hour (12:33 a.m.), the launch attracted nearly 500,000 watchers in the immediate vicinity. Where clouds did not obstruct the view, thousands more saw the ascending Apollo-Saturn from as far away as 800 kilometers. Of course there was television coverage: the Florida launch site had become familiar to millions of viewers.

Other aspects of the Apollo 17 mission reawakened the interest of the American public. It represented man’s last journey to the moon for an indefinite period. Apollo 17 would carry more scientific equipment than any previous mission and would number among its crew the first scientist-astronaut, Harrison Schmitt. The mission also marked the end of a dramatic and controversial program. Appropriately for Apollo, the last mission met acclaim and success.³¹

The first launch vehicle stages for Apollo 17 arrived at KSC in late 1970 during preparations for the Apollo 14 flight. Spacecraft operations got under way in March 1972. During the next four months John Williams’s directorate conducted the normal sequence of tests. Spacecraft engineers ran into some typical problems. In May Grumman engineers determined that the rendezvous radar assembly had received too much voltage during the tracking and pointing test at the boresight range. A new radar was installed on the 24th. A month later the landing radar began locking up intermittently and it was replaced. The lunar rover required several changes including replacement of forward and aft steering motors.³²

The biggest change in command-service module operations concerned the scientific instrument module, which gained three new experiments: a lunar sounder, an infrared scanning radiometer, and a far ultraviolet spectrometer. The sounder was essentially a radar that could determine the physical properties of the lunar crust to a depth of 1.5 kilometers. This data, coupled with information gathered from cameras, the laser altimeter, and surface measurements, would allow the construction of a detailed topographical profile of the moon. The radiometer provided data from which scientists could prepare an accurate thermal map of the lunar surface. The new spectrometer measured compositional and density variations of the lunar atmosphere.³³

The new experiments, particularly the lunar sounder, caused considerable headaches. For testing the sounder, the lunar surface had to be simulated. The sounder recorded the returning signals with an advanced optical recorder that required a special data reduction machine. After the launch team completed a lunar sounder test, the results were sent to the University of Kansas for interpretation. As the head of the Experiments Section recalled, “It would take weeks sometimes to get the results back and they might come back and say, ‘You have nothing on the tapes.’” North American had trouble integrating the new experiments with the service module hardware.³⁴

The stacked vehicle emerged from the assembly building on 28 August. Although another Saturn V would make the slow journey for Skylab, area residents reacted as if this were the last one. Five thousand spectators watched Apollo 17 creep toward pad A. The astronauts (Eugene Cernan, Ronald Evans, and Harrison Schmitt) joined the Bendix crew aboard the crawler for part of the trip.³⁵

Launch operations during the next three months followed the routine established in earlier missions. The few changes in hardware went smoothly. There was one scare in late-September, again involving the command module’s reaction control system. While conducting a leak check, a technician overpressurized one of the oxidizer tanks. KSC officials feared the worst - the rupture of the bladder and the spacecraft’s return to the operations and checkout building. At a press conference a few hours after the accident, NASA Administrator James Fletcher announced the possibility of a month’s delay in the launch. Further tests, however, indicated that the teflon bladder was all right, and Apollo 17 stayed on schedule.³⁶

In the outside world, there was an ill omen. A NASA request for 21 hours of Public Broadcasting Service network time to cover Apollo 17 stirred little excitement among the stations. Of some 70 replies, ten were favorable, ten opposed, and 50 expressed serious reservations. While this was blamed on a fear of governmental interference in programming, the commercial networks were no more enthusiastic. The prelaunch word was that they planned to cover only highlights of the flight.³⁷

The morale at the spaceport remained generally high. For most companies, KSC contracts continued through Skylab and the Apollo-Soyuz flight. Apollo 17, however, marked the end of the road for the 600 members of the Grumman team. During its years at Merritt Island, Charles Kroupa’s group had earned an excellent reputation with NASA counterparts and fellow contractors. The men working for test supervisor Ray Erickson wanted to assure the astronaut crew of their continued support. The result was a large poster at the lunar module working level of the mobile service structure. Signed by Grumman’s employees, it read: THIS MAY BE OUR LAST BUT IT WILL BE OUR BEST. Fletcher said the slogan “should be the watchword for the entire Apollo team.”³⁸

The last Apollo mission was the first Saturn V launched after dark. As dusk approached, thousands of cars poured across the causeways leading onto Merritt Island. In front of the headquarters building, children threw footballs while the parents talked and listened for the progress of the countdown. The December weather did justice to Chamber of Commerce claims; in the mid-80s during the day, the temperature was 72 degrees at launch.

The countdown proceeded. At T-82 minutes launch control reported the cabin purge had been completed, and the booster protective cover closed. The spacecraft was pressurized and checked for leaks. Houston tested its command signals to the launch vehicle, and the first-motion signal was checked out with Houston and the Eastern Test Range; the next time, it would bring them word of liftoff. The last weather balloon was released to determine wind direction.

In the meantime the C-band and Q-ball tests were in hand. The first was used in tracking to report range velocity during the powered phase. The Q-ball, perched above the launch escape system, would warn the spacecraft commander of deviations in the first stages of flight. Cernan reported things looking good “up here.” His next task was to check out the emergency hand control for the service module engine, normally operated by a computer. Far below him, little white wisps marked the topping off of the propellant loads.

At T-1 hour, the close-out crew had secured the white room and was clearing the pad area. The elevators were set at the 96-meter level, for the astronauts’ use in an emergency. At T-50 minutes the launch control center initiated the power transfer test, switching the vehicle momentarily onto its own battery power and then restoring external power. Some five minutes later, swing arm 9 - the access arm to the spacecraft - retracted 12 degrees to a standby position. Range safety test signals were flashing to the still unarmed destruct receivers.³⁹

At T-30 minutes, reports came from around the circuit. The water system was ready to flush the pad two seconds after liftoff. Final propulsion checks were completed, the C-band tests repeated, and the reaction control systems armed on the service module. The recovery helicopters were on station, and the weather looked good - a major front remaining well to the west. The launch control center began chilling the second- and third-stage propulsion systems to condition them for the final flow of cryogenic propellants. Swing arm 9 was coming back to a fully retracted position. With the swing arm back, the launch escape system, with twice the power of a Redstone, could loft the astronauts to parachute deployment height. At T-3 minutes and 7 seconds, the automatic sequencer took over.

This sequencer, the oldest and most reliable piece of automation on LC-39, chose this moment in the launching of the last Apollo to cause trouble. At T-30 seconds it went into an automatic cutoff indicating that one of the essential operations leading to the launch of the space vehicle had not been properly completed. Besides halting the countdown, the cutoff started a series of “safing” procedures which included the return of swing arm 9 to a standby position.⁴⁰

As Launch Director Walter Kapryan explained in a postlaunch press conference:

At two minutes, 47 seconds, the countdown sequencer failed to output the proper command to pressurize the S-IVB LOX tank. The control room monitors noted it and immediately took steps to perform that pressurization manually. This was done, and at the time that we had the cutoff, we were up to pressure and everything was normal. The problem was that since the Terminal Count Sequencer did output the command, the logic circuitry said that we really didn’t complete all of the launch preparation for the S-IVB stage. And we didn’t have an interlock in our countdown circuitry that precludes the retracting of Swing Arm #1 which occurs at T-30 seconds, and this is the reason for the cutoff. Now, it didn’t take us very long to determine that we should bypass this command failure and go through the pressurization manually and go through the rest of the countdown.⁴¹

With the count returned to (and held at) T-22 minutes the launch team installed jumpers that took the countdown around the faulty relays. The fix was verified on Huntsville’s Saturn breadboard, the two centers making good use of the launch information exchange facility. The work took about an hour, and Marshall’s confirmation took somewhat longer. Finally the launch team was satisfied that there was no problem. In Kapryan’s words: “We picked up the count and went on our merry way.”⁴²

Apollo 17 lifted off into space at 12: 33 a.m., 7 December. The flames, exploding into the darkness, made KSC momentarily as light as day. The launch was expected to be visible as far away as Montgomery. Miami observers saw a red streak crossing the northern sky, but Tampa was blacked out by a heavy ground fog and much of the Orlando area was under cloud cover.

During three days in the Taurus-Littrow valley on the moon, Cernan and Schmitt set up their multimillion-dollar array of scientific experiments, using the lunar rover to get them about the crater-pocked landscape. They took three excursions for a total of more than 32 kilometers in the rover, gathering rock samples and taking gravity measurements. Upon return to the command module, the team orbited the moon for nearly two more days of experimentation. They left the last of the Apollo lunar surface experiment packages. With four previously established nuclear-powered stations, the Apollo 17 equipment would allow scientists to monitor the moon’s heat flow, volcanic activity, meteor impacts, and other phenomena. Also left behind were eight time bombs scheduled to go off after the astronauts started their return to earth. With the lunar module ascent stage, which was jettisoned into the moon, the bombs were expected to create artificial moonquakes that could be measured by seismometers and perhaps reveal more secrets of the moon’s structure.⁴³ The Apollo program was leaving the moon with nine bangs and no whimpers.