Category Paving the Way for Apollo 11

AS-201 was the first in a series of test flights to ‘man rate’ the Saturn IB and the Apollo spacecraft.8 It lifted off from Pad 34 at 16:12:01 GMT on 26 February 1966. After the booster cut off, the S-IVB stage separated cleanly and attained the planned suborbital arc. In releasing CSM-009, the stage splayed its four panels to an angle of 45 degrees to allow the service propulsion system engine an unobstructed exit. The spacecraft had neither a guidance and navigation system nor an S-Band transmission system. It was powered by batteries instead of fuel cells, had a 20 per cent propellant load, and an ad hoc electromechanical control sequencer. It began by firing its RCS thrusters for 18 seconds to withdraw from the S-IVB. Upon peaking at an altitude of 226 nautical miles, the spacecraft fired its thrusters again to provide ullage to settle the propellants in their tanks, then fired the service propulsion system. However, 80 seconds into the planned 184-second burn the thrust chamber pressure started to decline owing to inadvertent helium ingestion, and by the time the engine shut down the pressure had declined to 70 per cent. The thrusters were immediately fired for ullage and the engine was reignited for a 10-second burn, during which the chamber pressure oscillated from 70 per cent down to 12 per cent.

At this point, CSM-002 was the only production-line spacecraft to have flown – it was launched on 20 January 1966 at the White Sands Missile Range by a Little Joe II booster as a high-altitude abort test.

Although the manoeuvres on the descending side of the arc were designed to drive the spacecraft into the atmosphere at a speed significantly faster than a normal orbital entry, it was still not as fast as a trajectory returning from the Moon. Several seconds later, the thrusters began a pitch manoeuvre at a rate of 5 degrees per second for 18 seconds to yield a 90-degree change in attitude. On separating, the command module used its own thrusters to continue this pitch rotation for an additional 82.5 degrees and then rolled 180 degrees in order to orient its heat shield for atmospheric entry. The plan was to subject the heat shield to a high heating rate – meaning a high temperature for a comparatively short time – but the velocity at entry was 782 ft/sec slower than the planned 29,000 ft/sec and the flight path was 0.44 degree shallower, with the result that the heating rate was less than that intended. Although the deceleration peaked at 14.3 g rather than 16.0 g, it was still much greater than on an operational mission. A fault in the electrical power system ruled out aerodynamic steering, and the ‘rolling’ entry which resulted was 40 nautical miles short. Some 37 minutes after launch, the command module splashed into the South Atlantic. It was recovered 2.5 hours later by USS Boxer. To allow the time to diagnose and rectify the fault in the service propulsion system, AS-202 was rescheduled to follow AS-203, which, as an S-IVB development flight, would not carry a spacecraft.

The docking by Gemini 8 with its Agena target vehicle on 16 March lent support to the decision to try the AS-207/208 dual mission. On 21 March NASA announced that Gus Grissom was to command the first Apollo mission. He would fly CSM-012 with Ed White and Roger Chaffee. They were to be backed up by James McDivitt, David Scott and Rusty Schweickart respectively. In each case, the commander and senior pilot were Gemini veterans and the third man was a rookie. Deke Slayton earmarked Grissom for this role immediately after the Gemini 3 test flight in March 1965. After commanding Gemini 4 in June 1965, McDivitt was reassigned to back up Grissom. White, who flew with McDivitt on Gemini 4, backed up Gemini 7 in December 1965 and then joined Grissom’s crew. Although Slayton was introducing a ‘rotation’ for Gemini in which a pilot could progress through backup to command a later mission, after flying Gemini 8 Scott was immediately assigned to McDivitt’s crew to enable them to obtain early experience of Apollo training prior to attempting the AS-207/208 dual mission. If CSM-011 demonstrated that the problems suffered by CSM-009 had been fixed, then AS-204 would launch CSM-012 in the last quarter of 1966 on an ‘open ended’ mission of up to 14 days ‘‘to demonstrate spacecraft and crew operations and evaluate spacecraft hardware performance in Earth orbit’’, but if there were significant issues outstanding then CSM-012 would be modified for a third unmanned test.

On 4 April 1966 the Manned Spacecraft Center revised its senior management job titles, replacing ‘assistant director for’ with ‘director of’ in order to make explicit the fact that the post had primary rather than subordinate responsibility for that activity. Thus, for example, Kraft ceased to be the Assistant Director for Flight Operations and became the Director of Flight Operations. On 12 May NASA deleted the word ‘Excursion’ from ‘LEM’, to make the lander the Lunar Module ‘LM’. On 25 May, precisely 5 years after President Kennedy made his speech to Congress calling for a lunar landing, a diesel-powered crawler carried the 500-F engineering model of the

Apollo-Saturn V at a maximum speed of 1 mile per hour from the vast cube of the Vehicle Assembly Building a distance of 3.5 miles on a special causeway to Pad 39 on the Merritt Island Launch Area in order to verify the ground facilities and assist in the development of training procedures. It was an awesome demonstration of the ‘mobile launcher’ concept.

AS-203 lifted off from Pad 37 at 14:53:17 GMT on 5 July 1966 and the S-IVB inserted itself into the desired circular orbit at an altitude of 100 nautical miles. As it did not have a spacecraft, an aerodynamic nose cone was used. At orbit insertion the liquid hydrogen was ‘settled’ by a combination of tank baffles and deflectors and by ullage induced by venting liquid oxygen. A TV camera in the fuel tank then verified that continuous venting of liquid hydrogen could hold the fluid in this condition during a coasting phase that approximated a flight heading for translunar injection. The fact that the rise in the liquid hydrogen pressure in orbit was greater than predicted gave data on the heat transfer properties of the tank that would be applied in planning Saturn V missions. Radar tracking by ground stations monitored how the parameters of the orbit were changed by the thrusting effect of continuous venting. A simulated restart of the J-2 engine verified the charging of the restart bottles at orbital insertion cutoff, the fuel recirculation chill – down, the fuel antivortex screen, and the liquid oxygen recirculation chill-down. A subcritical cryogenic nitrogen experiment carried in the nose cap successfully maintained pressure control, with a progressive decrease in the fluid quantity indicating that vapour was being uniformly delivered from a two-phase mixture. To save weight, the S-IVB had been designed such that its propellant tanks shared a bulkhead. This sophisticated structure had to cope with the normal difference in pressure between the tanks and also insulate the liquid oxygen at -172°C from the liquid hydrogen at -253°C to preclude the oxygen solidifying. After the ullage trial of the first revolution, the hydrogen valves were closed and the oxygen valves opened to space in order to place an inverse pressure on the common bulkhead and assess its predicted failure point – when this occurred early on the fifth revolution it caused the vehicle to break up.

On 13 July 1966 Deke Slayton and Chris Kraft jointly wrote to Joseph Shea, the Apollo Spacecraft Program Manager: ‘‘A comprehensive examination of the Apollo missions leading to the lunar landing indicates there is a considerable discontinuity between the missions AS-205 and AS-207/208. Both missions AS-204 and AS-205 are essentially long-duration system validation flights. AS-207/208 is the first of a series of very complicated missions. A valid operational requirement [therefore] exists to include an optical equi-period rendezvous on AS-205.’’ If this Block I flight were to include a rendezvous with its spent S-IVB, it would offer an opportunity to evaluate the control dynamics, visibility, and piloting techniques for the rendezvous phase of AS-207/208. By this point, every spacecraft on Grumman’s production line through to LM-4 was late. The focus, of course, was on LM-1, but late shipments by subcontractors were impeding its assembly. Nevertheless, the ‘rate of slippage’ was slowing, and on 6 October Shea reported his expectation that the company would be able to deliver LM-1 early in 1967. By the end of 1966 LM-1 and LM-2 were in test stands, and LM-3 through LM-7 were in various stages of assembly, but by the end

of January 1967 it was clear that LM-1 would not be able to be shipped on schedule in February.

As its designation suggests, AS-202 was intended to be the second Saturn IB test, but it slipped behind AS-203 as a result of delays involving the spacecraft. CSM-011 was a fully functional Block I spacecraft, minus the crew equipment. But it carried a more sophisticated ad hoc sequencer than on AS-201, a 60 per cent propellant load, a variety of flight qualification instrumentation and four film cameras. It lifted off from Pad 34 at 17:15:32 GMT on 25 August 1966. A key objective was to verify the emergency detection system in closed-loop configuration. At cutoff, the S-IVB was at an altitude of 120 nautical miles and climbing on a ballistic arc. Eleven seconds after separating, the spacecraft fired its service propulsion system in order to place itself on a higher trajectory that would result in entry over the Pacific. As a thermal test, the spacecraft then turned to aim its apex towards the Earth and maintained this attitude through the peak altitude of 618 nautical miles above Africa. On descending over the Indian Ocean it realigned its apex to the velocity vector, then fired its main engine for 89.2 seconds to accelerate for atmospheric entry and concluded by firing it briefly twice more in rapid succession as a demonstration of rapid restart.

In contrast to the ‘rolling’ entry made by AS-201, this time the command module controlled its attitude to fly a trajectory that ‘skipped’ off the atmosphere to trace a ballistic arc which led to a second contact and full entry. A similar profile was to be used on returning from the Moon. The double peak in the heating rate was designed to expose the shield to low heat rates with high heat loads – lower temperatures, but applied for longer – than a ‘straight in’ lunar return. Although the temperature at the base of the shield peaked at 1,482°C, the cabin did not exceed 21 °C. After a flight of 93 minutes, the command module splashed into the Pacific and adopted the apex-up flotation attitude. But the flight path angle at entry of-3.53 degrees was steeper than the desired -3.48 degrees and the lift-to-drag ratio of 0.28 ( + 0.02) was less than the predicted 0.33 ( + 0.04), causing it to fall short by 205 nautical miles. It was 8 hours before USS Hornet recovered the capsule. The planners would have to take into account the lower than expected lift-to-drag ratio of the command module. This qualified the heat shield for Earth orbital missions, but additional tests would be required for a lunar return. Both the Saturn IB and the Block I spacecraft were declared ready for the first manned mission.

As 80 per cent of the objectives specified for CSM-002, CSM-009 and CSM-011 had (between them) been met, AS-204 was released for the manned Apollo 1.

As William Herschel was passing sunlight through a prism in 1800, he found that heat was refracted just beyond the red end of the visible spectrum, so he named this infrared radiation. The Estonian physicist Thomas Johann Seebeck discovered in 1821 that if two wires of different metal are made into a loop by soldering their ends together, then an electric current will flow if the joins are at different temperatures. In 1856 Charles Piazzi Smyth utilised such a thermocouple to detect solar infrared reflecting off the Moon. Laurence Parsons inherited the 72-inch reflecting telescope built by his father at Birr Castle in Ireland. ft was the largest telescope in the world at that time. The common view was that since the airless lunar surface was exposed to the intense cold of space, it simply must be covered by ice. fn fact, S. Ericsson of Norway had proposed in 1869 that the lunar landscape was shaped by glaciation. fn 1870 Parsons equipped his telescope with a thermocouple and found that at lunar noon the temperature of the equatorial zone – where the Sun would pass close to the zenith – exceeded that of the boiling point of water, which indicated that the surface could not be ice. Measurements of the angle of polarisation of the surface published by M. Landerum in 1890 confirmed that it could not be ice. Despite the measured high temperatures at lunar noon, P. J.H. Fauth in Germany endorsed the idea that the landscape was shaped by glaciation, and in 1913 he and Hans Horbiger announced the highly unorthodox theory that ice was the essence of the cosmos! However, the vapour pressure of ice would cause it to sublime in the vacuum. ff ice were indeed present, it would have to be subterranean. fn 1916 Pierre Puiseux in Paris pointed out that if ice were present in the amounts claimed by Fauth, then it should be most evident at high latitudes where the Sun did not rise far above the horizon – yet there were no polar caps. Nevertheless, W. H. Pickering speculated that there might be ice at the summits of lunar peaks. The outcome of these studies was therefore that the majority of the surface was not ice.

fn 1930 Edison Pettit and Seth B. Nicholson put a thermocouple on the 100-inch reflector on Mount Wilson, which at that time was the largest telescope in the world, and discovered that the surface temperature in the equatorial zone varied by several hundred degrees during the monthly cycle. At the onset of a lunar eclipse in 1939 they measured the temperature plunge by 120°C in the space of an hour as the Moon entered the Earth’s shadow. This implied that the material on the surface was poor at retaining heat. On making more sophisticated measurements, they found that at the equator the temperature was +101°C at noon, fell to -39°C at sunset and -160°C at midnight. fn 1948 A. J. Wesselink in Holland inferred from these cooling rates that the Moon could not be exposed solid rock but must be covered by a blanket of loose material.

After the Second World War, the Moon was investigated at radio wavelengths. fn 1946 Robert H. Dicke and Robert Beringer in America detected thermal emission from the Moon at a microwave wavelength of 1.25 cm. Using the same wavelength, in 1949 J. H. Piddington and H. C. Minnett in Australia measured the temperature of the whole disk at a variety of phases over three lunations. The variation proved to be less extreme than it was at infrared wavelengths. The fact that the radio temperature lagged behind the optical phase of the Moon by 3.5 days suggested the presence of a thin insulating layer with low thermal conductivity. fn 1950 John Conrad Jaeger in Australia matched materials to the microwave observations made by Piddington and Minnett. Agreeing with Wesselink’s inference of loose material, Jaeger argued for a layer of ‘dust’, typically only several millimetres thick, resting on top of a granular material. Observations of lunar eclipses on 29 January 1953 and 18 January 1954 at microwave wavelengths by the US Naval Research Laboratory implied that only the uppermost part of the surface underwent a large variation in temperature. This was consistent with a thin layer of dust on a loose granular material. In 1962 J. F. Denisse in France announced that for wavelengths exceeding 30 cm there was no variation in temperature over the monthly cycle.

Taken together, these investigations indicated that whereas an optical telescope fitted with a thermocouple measured the temperature of the surface itself, the radio temperatures were averages for granular material to depths corresponding to several times the wavelength. The constancy at wavelengths greater than 30 cm implied that the material in the uppermost metre or so was such a poor conductor of heat that even when the Sun was at the zenith its heat did not penetrate that far. And at night, although the surface rapidly radiated away the heat it had gained during the day, the poor conductivity of the deeper material served to insulate it. The temperature at a depth of about one metre was estimated to be a constant -40°C. Candidates for the uppermost metre of material were a porous volcanic rock like pumice or a granular conglomerate. A colloquium held in Dallas, Texas, in 1959 concluded that the fine dust that formed the actual surface was probably of meteoritic origin. It was initially believed that the Moon is particularly bright at its ‘full’ phase due to there being no shadows in view – the objects at the centre of the disk cast no shadows, and objects away from the centre mask their shadows to terrestrial observers. But the absence of appreciable darkening of the limb proved to be a result of the fact that the surface ‘scatters’ more light back towards its source than it does in other directions. It was inferred from this that the material at the surface was a porous vacuum-sintered dust, and that sunlight which penetrated a ‘cavity’ was not absorbed but reflected back out towards its source.

In 1955 Thomas Gold, an astronomer with a wide-ranging interest who was then at the Royal Greenwich Observatory in England, proposed that particles of dust on the lunar surface would become electrically charged by the harsh ionising ultraviolet radiation from the Sun, and that in making the grains of dust repel each other this would cause them to flow remorselessly ‘down hill’ and collect in low-lying areas. Tests using powdered cement in a vacuum had shown that this tended to form fragile ‘fairy castle’ structures full of voids, which was consistent with the inference that the surface material was porous. Gold claimed that the maria were accumulations of dust, possibly several kilometres thick, and were of low albedo because the dust had been darkened through exposure to radiation. But whilst dust moving down hill could bury craters in low-lying terrain, it could not explain the missing ‘seaward’ wall of a crater such as Le Monnier on the margin of Mare Serenitatis, nor the dark floors of Archimedes sitting on elevated terrain or Plato embedded in the lunar Alps.

A. Deutsch in Leningrad suggested in 1961 that there might be life in the granular material where the temperature was constant, and that it lived off gases leaking from the interior. Expanding on this, Carl Sagan in America speculated that if the granular material were tens of metres deep, then it might contain a considerable amount of ice and organic material.

As the space age dawned, therefore, there were already interesting insights and speculations into the nature of the lunar surface material.

When on 25 May 1961 President Kennedy challenged his nation to land a man on the Moon before the decade was out, the sky scientists were unimpressed but the geologists were delighted.

On 8 June Hugh Dryden advised the Senate Committee on Aeronautics and Space Sciences that NASA intended to make use of automated spacecraft to strengthen the manned lunar program. In particular, it was essential to find out whether the surface would support the weight of the Apollo lander. As Dryden put it, ‘‘We want to know something about the character of the surface on which the landing is to be made, and obtain as much information as we can before man actually gets there.’’ Following up, Abe Silverstein provided some details. For a start, Ranger would be extended by four Block III missions. Congress authorised the funding for these missions several weeks later.

Clifford Cummings, JPL’s Lunar Program Director, visited NASA on 21 June and told Edgar Cortright and Oran Nicks, the two managers in Silverstein’s office who were responsible for Ranger, that the greatest single contribution this project could make to Apollo would be to provide high-resolution imagery to enable the nature of the lunar surface to be characterised to provide the information needed to design the landing gear of the Apollo lander. For this, the Block III would replace the surface package subassembly with a TV system that was more sophisticated than that made for the Block II. In the interim, some insight would be provided by the Block II radar altimeter and the accelerometers of the surface capsule as this impacted and rolled to a halt.

JPL recommended that the contract to develop the high-resolution TV system go to the same company that supplied the camera for the Block II, and this was agreed.

On 5 July 1961 JPL discussed the design of the system with the Radio Corporation of America, and it was decided to use a shutter (which was not a standard feature on a continuous-scan TV system) to define a ‘frame’ on a vidicon tube. The contract was signed on 25 August. Responsibility for the design, fabrication and testing of the system was delegated to the company. Harris Schurmeier’s Systems Division would monitor the work. On 31 August, Cummings appointed Allen E. Wolfe as the Ranger Spacecraft Systems Manager to assist James Burke with the increased work. Wolfe had replaced Gordon Kautz as Project Engineer in the Systems Division when Kautz was made Burke’s deputy. Wolfe’s first responsibility would be to steer the remaining Block II spacecraft through all phases of assembly and testing, and then supervise the development of the Block III.

The design of the high-resolution TV subsystem was finished in September 1961. It had three major assemblies: a tower superstructure incorporating a thermal shield to stand on the top of the hexagonal bus; a central box to house the main electronics; and, above, a battery of six cameras and their individual electronic systems. It used two types of camera. The ‘A’ type had a lens with an aperture ratio of f/1 and a focal length of 25 mm. The ‘B’ type had an f/2 lens with a focal length of 75 mm. There were two ‘A’ cameras and four ‘B’ cameras. The vidicons were all the same, but the entire 11-mm square image would be used for the full (F) frame and only the central 3-mm square for the partial (P) frame. One ‘A’ and one ‘B’ camera would operate a 5.12-second cycle in which the shutter fired to expose its vidicon and this was read out over an interval of 2.56 seconds, then erased over the next 2.56 seconds. They were to operate out of phase so that a frame was taken every 2.56 seconds. The other cameras would require 0.2 second to fire the shutter and perform the readout, and 0.6 second to erase. The faster cycle time for these cameras was because a smaller

area was to be scanned. They were to be cycled to take a frame every 0.2 second, in the hope that one camera would be able to provide a close-up picture just prior to impact. The cameras were mounted at angles designed to provide overlap to enable the relationship of one frame to be related to those preceding and following. The TV subsystem would have its own battery, independent of the bus, and a pair of 60-watt transmitters. Unlike the Block II, whose flow of pictures would conclude when the separation of the surface package caused the high-gain antenna to lose its lock on Earth, the Block III would continue to send pictures until it hit the surface. In all, the high-resolution TV subsystem would be 160 kg.6

As in the case of the Block I, the low-gain antenna would be in a fixed position at the top of the tower. The designers of the Block III had the luxury of being able to exploit the full payload capacity of the Atlas-Agena B, and this allowed some degree of redundancy in the basic systems.

On 19 September 1961 NASA announced that the Block IIIs were to be launched in January, April, May and August 1963 – certainly they were to be over before the first soft-landing Surveyor, which was expected in 1964.

On 25 June 1963 Floyd Thompson went to Washington to define the terms of the request for proposals. In particular, he did not wish it to be stated that the spacecraft should be spin stabilised; he wished to see what the bidders proposed. It was agreed to say only that the primary requirement was photographic data at medium and high resolution in order to facilitate the selection of sites for Surveyor and Apollo landers. The secondary objectives were to provide information on the size and shape of the Moon and the properties of its gravitational field. Information would also be sought on conditions near the Moon, including the micrometeoroid flux and total exposure to energetic particles and gamma rays – the latter having been shown by Ranger 3 to exist. A key requirement of the photographic system was that it identify the altitude of the orbiter at the time of an exposure, the orientation of the line of sight (relative to lunar north) and the angle of the Sun to the surface. In particular, it was desired to be able to determine the location of any surface feature to an accuracy of 1 km.

On 23 August Lee Scherer presented the request for proposals to Oran Nicks and Edgar Cortright, who duly reviewed it with Robert Seamans. The Project Approval Document signed by Seamans on 30 August officially initiated Langley’s first deep – space project. It was given the mundane name of Lunar Orbiter. The Lunar Orbiter Project Office was set up at Langley, with Clifford H. Nelson as Project Manager,2 William J. Boyer as Operations Manager and Israel Taback as Spacecraft Manager. In Newell’s office, Lee Scherer was appointed as Lunar Orbiter Program Director, Leon J. Kosofsky as Program Engineer and Martin J. Swetnick as Program Scientist.

On 30 August 1963 NASA invited bids from industry. In September the Lunar Orbiter Project Office established a Source Evaluation Board chaired by Eugene C. Draley of Langley. Five bids were received. The evaluations began in October and ran to late-November.

A key factor in the requirements was that, where possible, off-the-shelf hardware be used to minimise the development effort. The Hughes Aircraft Company, which was prime contractor for Surveyor and would have built the 3-axis-stabilised orbiter for that project, proposed a spin-stabilised spacecraft that would use a solid rocket

In October 1964 Langley recruited James S. Martin from Republic Aviation as Assistant Project Manager.

Boeing wins 147

motor to enter lunar orbit. The Space Technology Laboratories submitted a refined version of its spin-stabilised design. The Martin Company, which supplied the Titan missile to the Air Force but had limited experience of spacecraft systems, offered a 3- axis-stablised design. The Lockheed Missile and Space Company, which had built the Agena as a 3-axis-stablised vehicle and integrated various payloads into it for the Air Force, including reconnaissance cameras, suggested that the Agena be adapted to operate in lunar orbit. Eliminating the need to develop a new vehicle satisfied the desire for off-the-shelf hardware, but the operational concept was flawed because it would require a lot of propellant to insert such a heavy rocket stage into lunar orbit. The Boeing Company’s expertise was aircraft, but it wished to gain experience with spacecraft systems. It proposed a 3-axis-stabilised spacecraft with a mass of 360 kg that would enter lunar orbit using a liquid rocket (just developed by Marquardt as an attitude control thruster for the Apollo spacecraft) and be powered by solar panels. The Source Evaluation Board was particularly impressed by Boeing’s plan to use a lightweight form of a photographic system developed by Eastman Kodak in I960 for a reconnaissance satellite. The camera used two lenses in a configuration that would take wide-angle and narrow-angle frames simultaneously and interleave them onto a single strip of film.[27] The film would be developed and fixed using the ‘semi-dry’ Bimat process introduced by Kodak in 1961, as this obviated the complication of handling ‘wet’ chemicals in weightlessness.[28] The clinching argument in favour of Boeing was the proposal to use Kodak SO-243 fine-grain aerial film to obtain the required high resolution. This film had an exceedingly ‘slow’ rating of 1.6 ASA, whereas the other bidders intended to use ‘fast’ film. In the case of the spin – stabilised designs, a high-speed film was essential. But adding up the time spent flying to the Moon, the time spent in orbit preparatory to imaging, the 10 days spent imaging, and the time spent scanning and transmitting the film, a mission might last up to a month. During this time there was a fair chance of the particle radiation from a solar storm ‘fogging’ a high-speed film, and the heavy shielding to protect it would be prohibitive. Boeing’s proposal to use slow film showed that the company had a better understanding than its competitors of the mission requirements. The Source Evaluation Board strongly recommended in favour of Boeing, and this was accepted. On 20 December 1963 James Webb announced that the contract would be awarded to Boeing of Seattle, Washington.

Boeing appointed Robert J. Helberg to manage the development of Lunar Orbiter. George H. Hage was Chief Engineer. Carl A. Krafft, the Business Manager, led the contract negotiations that began on 6 January 1964 and involved both Langley and the merged Office of Space Sciences and Applications. Boeing subcontracted Kodak to provide the photographic system, and the Radio Corporation of America for the communications system. In March, Boeing

suggested that the photographic data be processed into pictorial format at Kodak in Rochester, New York, where there was already the necessary equipment, but NASA decided that the processing, handling and distribution of all scientific data provided by Lunar Orbiter should be done at Langley – in the case of photographic data by utilising equipment and technicians supplied by Kodak. Langley appointed Calvin Broome as Chief of the Photographic Subsystem Section.

The plan called for five Lunar Orbiter missions to be launched by Atlas-Agena D, with the first in either late 1965 or early 1966. They were to photograph the lunar surface from a perilune of 40 km. As in the case of Ranger at JPL, Langley would be responsible for overall systems integration of the spacecraft and the launch vehicle, as well as the necessary ground support, but, significantly, by this point NASA had gained control of both the procurement of launch vehicles and of launch operations. Because JPL had established the Deep Space Network to track and communicate with spacecraft, the Lunar Orbiters would be run from the Space Flight Operations Facility. In April 1964, Langley discussed this collaboration with Eberhardt Rechtin. This was the first time that JPL had provided another NASA centre with deep-space support, and so, in effect, a ‘contract’ had to be negotiated to define what JPL would do. But since trajectory design was closely related to the design of the spacecraft’s communications system, and JPL had neither the manpower nor the computer time available to involve itself in this, the transit trajectory and operations in lunar orbit

would have to be planned by Langley and Boeing after JPL had educated Boeing’s engineers in the capabilities and procedures of the Deep Space Network.

Langley and Boeing signed the detailed contract on 16 April 1964. It was sent to NASA headquarters for ratification. James Webb agreed on 7 May, and the formal contract was signed on 10 May.

When NASA decided in 1962 that Apollo would use the lunar orbit rendezvous mission mode, many people doubted that orbital rendezvous would be feasible. The primary objective of the Gemini program was to explore the issues. The ten manned missions flown between March 1965 and November 1966 not only established that rendezvous and docking was feasible, by testing a variety of techniques it gave the Apollo planners the flexibility of options. This inspired a workaround to the fact that the combined Apollo vehicles exceeded the payload capacity of the Saturn IB, in the form of the dual AS-207/208 rendezvous. Gemini also showed that astronauts could endure the space environment for longer than any Apollo mission would require. Given that the longest American space flight at the time of President Kennedy’s commitment to Apollo was Al Shepard’s 15-minute suborbital arc, on which he was weightless for only a couple of minutes, this was welcome news. The fuel cells that were to power the Apollo spacecraft were tested on Gemini, as were a fully inertial reference platform for guidance and navigation, a spaceborne radar, a state-of-the-art digital computer to process the radar data for rendezvous, and bipropellant ablative thrusters. Gemini established that a spacecraft could be steered through re-entry for recovery at a specific location. This increased confidence in the ‘atmospheric skip’ manoeuvre that was to be used by an Apollo spacecraft returning from the Moon. By enabling astronauts to learn how to operate outside a spacecraft, Gemini inspired a rescue option for the crew of an Apollo lunar module that was unable to dock with its mothership. And, of course, by training a cadre astronauts and flight controllers Gemini allowed Apollo to get off to a running start.

As Robert Gilruth, Director of the Manned Spacecraft Center, observed: ‘‘In order to go to the Moon, we had to learn how to operate in space. We had to learn how to manoeuvre with precision to rendezvous and to dock; to work outside in the hard vacuum of space; to endure long-duration in the weightless environment; and to learn how to make precise landings from orbital flight – that is where the Gemini program came in.’’

EARLY IDEAS ABOUT LUNAR CRATERS

In 1662 Robert Hooke was made curator of the recently formed Royal Society of London. He was charged with devising demonstration experiments. As an extremely skilled technical artist, in 1665 he published Micrographica, which was profusely illustrated with his own observations using a telescope and a microscope. Although he included a detailed drawing of the lunar crater Hipparchus, which is at the centre of the Moon’s disk, he had no desire to map the Moon. However, he undertook a series of experiments to investigate how craters may have formed. First he dropped heavy balls into tightly packed wet clay, and examined the imprints that they made. He also heated alabaster until it bubbled, and then let it set so that the last bubbles to break the surface produced craters. However, just as Hooke could not imagine where the projectiles could have come from to scar the Moon so intensively, nor could he conceive how the surface could have been sufficiently hot to blister on such a scale.

Following the discovery of the first two asteroids in 1801 and 1802, Marshal von Bieberstein in Germany suggested that lunar craters were created by the impact of such bodies. This was reiterated independently in 1815 by Karl Ehrenbert von Moll. In 1829 Franz von Gruithuisen agreed. However, the idea was rejected by those who supported the anti-catastrophist paradigm of uniformitarianism in terrestrial geology which was developed in the 1830s and 1840s.[4] In 1873 Richard A. Proctor published The Moon. Although this book was largely devoted to the motions of the Moon, he revived the idea that the craters marked impacts. But when the second edition of the book was issued in 1878 this section had been deleted. What puzzled the nineteenth century proponents of the impact hypothesis was that the lunar

craters are almost all circular, whereas the majority of bodies must have struck at an oblique angle and, it was presumed, produced elliptical craters.

In 1874 James Nasmyth and James Carpenter in England published The Moon, in which they attempted to explain how the surface features may have formed. As had Hooke two centuries earlier, they made model craters in experiments. They came to the conclusion that the lunar craters were produced by ‘fountains’ of material. In the early part of an eruption, when the velocity of the material ejected from the vent was great, the material would spray out in an umbrella-shaped plume and fall back some distance away to build up a concentric ring that became the wall of the crater. In many cases, as the eruption declined the fallout formed a succession of terraces interior to the wall. They presumed that in some cases the final phase of the eruption either built up the central peak, or in the case of craters with dark floors and no peak, switched to fluid lava that was confined to the cavity and buried the vent. In view of the weak gravity and absence of an atmosphere, it seemed plausible that this process could have produced very large structures.

Other explanations were offered for the origin of lunar craters. In 1854 the Danish astronomer Peter Andreas Hansen argued that the Moon bulged towards Earth, that its centre of gravity was displaced 50 km towards the far-side, and that this had drawn all the air and water on the surface around to the far-side, to where the inhabitants had relocated. In 1917 D. P. Beard suggested that the Moon was once immersed in a deep ocean, that the craters were limestone structures similar to coral reefs, and they were left exposed when the water flowed to the far-side.

On 24 September 1961 NASA announced that the Manned Spacecraft Center to be built near Houston, Texas, would supersede the Space Task Group. It would not only design, develop, evaluate and test manned spacecraft, but also train astronauts and manage mission operations. Robert R. Gilruth, head of the Space Task Group, was made Director of this new centre.

On 1 November, NASA restructured its headquarters. As part of this review, the offices of Space Flight Programs and Launch Vehicle Programs were wrapped up, and new program offices were created for Manned Space Flight, Space Sciences, and Applications. This raised Manned Space Flight to office status, as opposed to a subdivision of Space Flight Programs. The effect was to put the administration of all the agency’s activities (some of which were aeronautical) on a par with the Office of Manned Space Flight, although that office had fully three-quarters of the budget. In effect, James Webb had gathered the power of decision-making into headquarters, since the directors of all the ‘offices’ and ‘centres’ would report to Robert Seamans, the Associate Administrator who, as the agency’s ‘general manager’, would have budgetary control.

The obvious candidates to be Director of the Office of Manned Space Flight were Abe Silverstein and Wernher von Braun, but because their relationship was stormy Webb had sought an outsider, and on 21 September hired Dyer Brainerd Holmes. As general manager of the Major Defense Systems Division of the Radio Corporation

Specifically, the cameras were designated Fa (25-mm), Fb (76-mm), P1/P2 (76-mm) and P3/P4 (25-mm).

of America, Holmes had built the Ballistic Missile Early Warning System on time and on budget, which was no mean feat.7 Silverstein returned to the Lewis Research Center, this time as its Director.

Homer Newell was promoted from Silverstein’s deputy to become Director of the Office of Space Sciences. Edgar Cortright became Newell’s deputy, and Oran Nicks superseded Cortright as Director of the Lunar and Planetary Programs Division. As one of his first acts, Nicks established individual offices in the Lunar and Planetary Programs Division for Ranger and Surveyor, and also for the Mariner interplanetary program. For Ranger, William Cunningham was Program Chief, Walter Jakobow – ski was Program Engineer and Charles Sonett served in an interim capacity as Program Scientist. James Burke at JPL was delighted with this structure, because it integrated engineering and science in a single program office and greatly simplified his relationship with NASA headquarters.

Holmes promptly assigned Joseph F. Shea, a systems engineer who had run the development of the inertial guidance system for the Titan intercontinental-range ballistic missile, to resolve the protracted debate about how Apollo would fly to the Moon – the ‘mission mode’ issue.

On 28 November, NASA announced that North American Aviation of Downey, California, had been awarded the contract to develop the Apollo spacecraft. On 21 December, Holmes set up the Manned Space Flight Management Council. Drawing on senior managers at headquarters and the field centres, this would set policy for manned space planning. At its first meeting, the Council decided on a launch vehicle which would become known as the Saturn V. A single launch would be capable of dispatching an Apollo circumlunar mission. It might even be possible to undertake a lunar landing with a single launch. A landing mission involving Earth orbit rendezvous could certainly be done using just two launches.

On 20 February 1962, America finally inserted a man into orbit, with John Glenn riding an Atlas missile to circle the globe three times. On 7 June NASA decided on lunar orbit rendezvous as the mode for Apollo. On 7 November, it announced that the Grumman Aircraft Engineering Corporation of Bethpage, New York, had been awarded the contract to develop the Apollo lunar module.

By the end of 1962, therefore, NASA had taken all the key decisions that defined how it would address Kennedy’s challenge.

BMEWS used large radar stations in Alaska, Greenland and England to provide the US with the famous ‘‘fifteen minute’’ warning of a Soviet ICBM strike over the north pole.

On 12 May 1964 the Office of Space Sciences and Applications announced how Lunar Orbiter would satisfy Apollo’s requirements for maps of the Moon, as agreed with William B. Taylor of the Advanced Manned Missions Program Directorate of the Office of Manned Space Flight. The Manned Spacecraft Center in Houston was interested primarily in the near-side within 5 degrees of latitude of the equator, and had specified stringent requirements for accuracy of selenodetic and topographic data in the vicinity of selected landmarks to assist in navigation in orbit and landing site selection. The US Geological Survey was to produce a variety of maps based on Lunar Orbiter photography.

Oran Nicks suggested to Sam Phillips on 23 September 1964 that the Office of Manned Space Flight should make a study of how Lunar Orbiter could best support Apollo. This would aid the Lunar Orbiter Project Office in developing guidelines for mission planning. Bellcomm was asked to make this study, and on 25 January 1965 Douglas D. Lloyd and Robert F. Fudali submitted the report Lunar Orbiter Mission Planning. This discussed the relative merits of clockwise and anticlockwise orbits of the Moon aligned near the lunar equator. It was confirmed that to achieve the specified 1-metre resolution in the H frames the pictures could be taken from an altitude no greater than 46 km. A strategy of obtaining contiguous high-resolution coverage of multiple targets was recommended. To avoid the possibility of orbital instability as a result of such a low perilune, it was recommended that the initial inclination of the orbit should not exceed 7 degrees to the lunar equator (because gravity perturbations would tend to increase the inclination) and that the spacecraft should have sufficient propellant to perform corrective manoeuvres. Bellcomm followed up on 30 March with Apollo Lunar Site Analysis and Selection, which recommended that the Office of Manned Space Flight and the Office of Space Sciences and Applications form a Site Survey Steering Committee with responsibility for choice of measurements and their relative priorities and instruments, target selection, launch schedules, control of data handling, and methods of data analysis for the Lunar Orbiter and Surveyor missions. On 10 May Bellcomm further recommended that the Office of Manned Space Flight and the Office of Space Sciences and Applications create a joint Lunar Surface Working Group to coordinate mutual planning activities concerning site survey requirements and the means by which these should be satisfied.

In May the Surveyor/Orbiter Utilisation Committee was formed. It was chaired by Edgar Cortright, and its membership comprised senior representatives of these two programs and their project offices: Oran Nicks of Lunar and Planetary

Programs, Urner Liddel of Lunar and Planetary Science, Lee Scherer of the Lunar Orbiter Program, and Benjamin Milwitsky of the Surveyor Program, all of whom were from the Office of Space Sciences and Applications; Israel Taback of the Lunar Orbiter Project Office at Langley; Victor Charles of the Surveyor Project Office at JPL; Sam Phillips, the Apollo Program Director and Everett E. Christensen of Manned Operations, both at the Office of Manned Space Flight; and William A. Lee of the Apollo Spacecraft Project Office and William E. Stoney of Data Analysis, both at the Manned Spacecraft Center. The Committee was to coordinate the Surveyor and Lunar Orbiter projects for their mutual benefit and in support of Apollo. In July, the Apollo Site Selection Board was established in the Office of Manned Space Flight. Although the Surveyor/Orbiter Utilisation Committee would gather engineering and science information and assess proposals for Lunar Orbiter imaging coverage and for Surveyor landing sites, and later recommend landing sites for Apollo, the Apollo Site Selection Board chaired by Sam Phillips would make the decisions.

The Surveyor/Orbiter Utilisation Committee’s first meeting on 20 August 1965 discussed four Lunar Orbiter mission options which had been developed by Langley and Boeing in response to Bellcomm’s report. In order of priority they were: type 1, to photograph ten evenly distributed target areas near the equator, each of which would be covered stereoscopically with both M and H frames; type 2, to photograph four areas in order to ‘screen’ for possible Surveyor landing sites near the equator; type 3, to photograph using H frames an area containing a landed Surveyor in order to study its context; type 4, to obtain topographic data which would not otherwise be obtained. It was decided to start with the type 1 mission, in order to provide as soon as possible the data that was required by the Apollo planners. If the Office of Space Sciences and Applications had not been obliged to support Apollo, the preferred first mission would have been to enter a high circular polar orbit for a global survey at a resolution better than that obtainable using a terrestrial telescope and, significantly, to view the limbs from a vertical perspective.5 In 1963, when the Office of Manned Space Flight began to specify its requirements for Apollo in terms of surface slopes, Gene Shoemaker had hired Jack McCauley to develop methods of photoclinometry. In June 1965 the Surveyor project asked McCauley to use this technique to suggest possible landing sites for their landers. He formed a small team and compiled a list of 74 sites. Owing to uncertainty in the accuracy of Surveyor’s approach trajectory, the sites were specified in terms of ‘target circles’ 25, 50 and 100 km in radius. After factoring in vertical descent and illumination constraints, they selected only circles of 25 and 50 km radius. McCauley presented the final list to the Surveyor/Orbiter Utilisation Committee on 20 August. There were 24 sites with 50-km-radius circles on the maria, and seven in the highlands. There were also 13 ‘scientific’ targets with 25-km-radius circles that would require greater landing accuracy.6

As yet, the only images of the far-side had been provided by Luna 3 in October 1959 and Zond 3 in July 1965.

In fact, all Surveyors except the last would be sent to sites on McCauley’s list.

Mission objectives 151

On 8-9 September 1965 Langley hosted a meeting which (in part) drew up lists of photographic targets judged compatible with Apollo, Surveyor and Lunar Orbiter constraints. James Sasser of the Apollo Spacecraft Project Office in Houston argued for distributed coverage which ‘sampled’ different types of terrain near the equator, although with the emphasis on apparently smooth areas. Lawrence Rowan of the US Geological Survey described an analysis based on a map produced by the Air Force Chart and Information Center on a scale of 1:1,000,000. This analysis identified the types of terrain available for ‘sampling’ by Lunar Orbiter: namely an ordinary mare, a dark mare, mare ridges, mare rays, crater rims, deformed crater floors, and several different types of terrain in the highlands. These discussions led to the ‘A’ mission plan which was formally presented to the Surveyor/Orbiter Utilisation Committee on 29 September. This called for a type 1 mission to inspect a number of areas in the ‘Apollo zone’ – defined as being within 5 degrees of the equator and 45 degrees of the central meridian – to assess their suitability for Apollo and Surveyor landings. It would start with test pictures taken in the high-perilune initial orbit of sites between 60°E and 110°E. Although not in the Apollo zone, these pictures would show a vertical perspective of the limb region in which landmarks would later be selected for Apollo orbital navigation. After the perilune had been lowered, ten sites, mostly in the zone, would each receive a single photographic pass timed to maintain a given angle of illumination as the terminator advanced westward. The targets would cover a variety of terrains, including the Flamsteed Ring in Oceanus Procellarum, which was the favoured site for the first Surveyor. In May, a team of photo-interpreters led by Lawrence Rowan had been created by the US Geological Survey to suggest sites for Apollo. Each site was subjected to a detailed analysis, drawing in data from all sources. This work continued through the Summer Study on Lunar Exploration and Science held 19-31 July 1965 in Falmouth, Massachusetts. Rowan presented a list of ten potential Apollo landing sites to the Surveyor/Orbiter Utilisation Committee on 29 September (just over a month after the Committee received McCauley’s list of candidate Surveyor sites – some sites were on both lists). The meeting approved the ‘A’ mission proposal with nine primary (P) sites, including several that were not on the smooth maria.

The Planetology Subcommittee of the Space Sciences Steering Committee met on 21-22 October to discuss the ‘A’ mission plan. The meeting was chaired by Urner Liddel, who was a member of the Surveyor/Orbiter Utilisation Committee. Harold Masursky of the US Geological Survey explained how the methods of structural and stratigraphic geological mapping would be applied to the pictures supplied by Lunar Orbiter. Liddel then wrote to Oran Nicks on 5 November to emphasise the merit of developing a Lunar Orbiter Block II for a multifaceted scientific study of the Moon to obtain the data which would be required to plan ‘advanced’ Apollo missions.[29]

The Apollo Site Selection Board held its inaugural meeting on 16 March 1966. Although the only materials available were telescopic studies and their interpretation on the basis of close-up views of three sites provided by the Ranger project, several potential areas were identified in the expectation that it would prove possible to land the first Apollo mission at one of them.

On 4 April Leonard Reiffel, representing Apollo, informed Oran Nicks of another Apollo requirement. The original plan had been to store all the data returned by the Lunar Orbiter missions on film, but magnetic tape had a greater dynamic range and was more readily processed by computer, and NASA wished the process of analysis to be as automated as possible – in particular the photoclinometry by which the US Geological Survey was to measure the slopes. Nicks duly ordered that state-of-the – art recorders be purchased to enable the data to be written directly onto tape.

By the time of the Apollo Site Selection Board’s second meeting on 1 June 1966, Surveyor 1 had landed on the Moon and the first Lunar Orbiter was soon to attempt to photograph it to provide a sense of context which would allow the ‘ground truth’ from the lander to be applied more generally.

On 26 August 1966 the command module of CSM-012 arrived at the Cape in a container prominently labelled ‘Apollo One’.

North American Aviation was to have shipped it several weeks earlier, but the failure of a glycol pump in the environmental control system had led to the exchange of this unit with its CSM-014 counterpart. Although the customer acceptance review identified other ‘‘eleventh-hour problems’’ associated with the environmental control system, NASA had taken receipt.

The Office of Manned Space Flight held the AS-204 design certification review on 7 October, and declared that the launch vehicle and the spacecraft ‘‘conformed to design requirements’’ and would be flightworthy once a number of deficiencies had been overcome. Sam Phillips issued a list of these deficiencies to Lee B. James at the Marshall Space Flight Center, Joseph Shea at the Manned Spacecraft Center, and John G. Shinkle, Apollo Program Manager at the Kennedy Space Center, requiring speedy compliance. On 11 October Phillips was informed by Carroll Bolender of a report he had received the previous day from Shinkle detailing increasing delays in the preparation of CSM-012. When the spacecraft was delivered, 164 ‘engineering orders’ had been identified as ‘open work’ – despite the fact that the accompanying data package had listed only 126 such items. By 24 September the list had grown to 377, and Shinkle ventured that about 150 of the 213 additional orders ought to have been identifiable by the manufacturer prior to the customer acceptance review. The issues included the environmental control system (which had failed again), problems with the reaction control system, a leak in the service propulsion system, and even design deficiencies with the couches that had obliged the company to send engineers to the Cape. On 12 October Phillips wrote to Mark E. Bradley, Vice President of the Garrett Group, whose AiResearch Division had supplied the environmental control system under subcontract to North American Aviation, explaining that its reliability threatened a “major delay” to the AS-204 mission. To Phillips, the problems seemed “to lie in two categories: those arising from inadequate development testing, and those related to poor workmanship”. A replacement was delivered on 2 November, and testing resumed as soon as it was in place. However, the unit malfunctioned and had to be returned to the company.

On 25 October the propellant tanks of the service module for CSM-017, assigned to AS-501, failed catastrophically in a test at North American Aviation. The normal operating pressure was 175 psi, but it had failed after 100 minutes at the maximum requirement of 240 psi. The test had been ordered following the discovery of cracks in the tanks of CSM-101, assigned to AS-207. The failure was particularly puzzling because the tanks of CSM-017 had been subjected to 320 psi for several minutes in ‘proof testing’. ASPO set up an investigation, which was to report by 4 November. As SM-012 had been through the same test regime, Shea grounded it pending this report. The problem was determined to be stress corrosion in the titanium resulting from the use of methyl alcohol as a test liquid. The point of the test was to verify the integrity of the tanks, and because the hydrazine and nitrogen tetroxide propellants were toxic another fluid had been used – and unfortunately this had caused damage! The remedy was to switch to a fluid that was compatible with titanium, and it was decided to use freon in the oxidiser tank and isopropyl alcohol in the fuel tank, with the additional stipulations that the systems must not have been previously exposed to the actual propellants and that after the tests the system must be purged by gaseous nitrogen. With the issue resolved, the tanks of SM-012 were removed for inspection and confirmed to be free of cracks.

The crew for the CSM-014 mission was announced on 29 September 1966. Wally Schirra would be in command, flying with Donn Eisele and Walt Cunningham. They would be backed up by Frank Borman, Tom Stafford and Michael Collins. Schirra was the only experienced man of the prime crew, but all the backup astronauts were veterans. In fact, Deke Slayton had given Schirra and Borman these assignments in March, on their return from an international ‘goodwill tour’ after the rendezvous of Gemini 6/7. Stafford and Collins had been assigned following Gemini 9 in June and Gemini 10 in July, respectively. Slayton had actually earmarked the rookies Eisele and Chaffee to Grissom’s crew, but in late 1965 Eisele had injured his shoulder in weightlessness training in a KC-135 aircraft and dropped out of training, prompting Slayton to swap Eisele with Ed White, whom Slayton had earmarked for Schirra’s crew. This Apollo 2 mission was to be a straightforward rerun of Apollo 1 to further evaluate the spacecraft’s systems.

In early December 1966, accepting that Apollo 1 would not fly that year, George Mueller postponed it to February 1967 and also deleted the Block f reflight in order to prevent the slippage of CSM-012 from impacting the Block II missions scheduled for later in 1967. Schirra had hoped to put his crew first in line for the dual mission, but Slayton imposed a rule that the man who would operate the CSM alone while his colleagues flew the LM must be experienced in rendezvous, since if the LM were to become crippled he would have to perform a rescue. Eisele was a rookie but Scott had performed a rendezvous on Gemini 8, so Slayton exchanged Schirra’s crew with McDivitt’s crew. Schirra was not pleased at being given the backup role, but Slayton had always intended to assign McDivitt the dual mission.

On the new schedule, AS-206 would launch LM-1 for an unmanned test as soon as possible after Apollo 1, and if this was satisfactory McDivitt’s crew would fly the dual mission (which was now AS-205/208 because deleting CSM-014 had released AS-205) as the revised Apollo 2 in August. This revision was publicly announced on 22 December, together with the assignment of Tom Stafford, John Young and Gene Cernan to backup McDivitt’s crew. Also, if two unmanned tests proved sufficient to ‘man rate’ the Saturn V, the intention was to launch AS-503 with a CSM and LM. The crew for this mission would be Frank Borman, Michael Collins and Bill Anders, backed up by Pete Conrad, Dick Gordon and Clifton Williams. These assignments had been made after Young flew Gemini 10 in July, Conrad and Gordon flew Gemini 11 in September, and Cernan backed up Gemini 12 in November.

The Gemini missions had demonstrated that for an astronaut on a spacewalk to be able to work effectively he must be provided with mobility and stability aids. On 6 December 1966 Slayton warned Joseph Shea that without handholds and tethering points, a transfer from the forward hatch of the LM to the CSM’s hatch would not be feasible. On 26 December Slayton recommended that a spacewalk be scheduled 100 hours into AS-503, after the two firings of the LM’s descent propulsion system but prior to the descent stage being jettisoned. One of the two astronauts would egress from the forward hatch and stand on the ‘front porch’ to assess the environmental control system in the LM during depressurisation, using the hatch, the performance of the life-support backpack, and the egress procedure for the emergency transfer. In addition, whilst outside, the spacewalker was to photograph the exterior of the LM to verify that it had not been damaged during its retrieval from the S-IVB. He would then re-enter the LM and the cabin repressurisation system would be tested, simulating the end of a moonwalk.

On 26 January 1967 Schirra’s crew made a ‘full up’ systems test of CSM-012 on its AS-204 launch vehicle. But the spacecraft drew its power from the pad, and the capsule was not pressurised with pure oxygen. It had not been a very productive day. ‘‘Frankly, Gus,’’ Schirra said in the debriefing with Grissom and Shea, ‘‘I don’t like it. You’re going to be in there with full oxygen tomorrow, and if you have the same feeling I do, I suggest you get out.’’ But there was a determination to catch up on the several-times-delayed schedule.

The next day, Friday, 27 January, Grissom’s crew attempted the ‘plugs out’ test in which the spacecraft would be on internal power and pressurised with pure oxygen at 16 psi (i. e. slightly above ambient) for an integrity check. If successful, this would clear the spacecraft for flight. After a simulated countdown, they were to end the day with an emergency egress drill.

In Houston, Flight Director John Hodge was monitoring progress, but the action was at the Cape. Slayton was in the Pad 34 blockhouse talking to Director of Launch Operations, Rocco Petrone. Also present was Stu Roosa, a rookie astronaut serving as the primary communications link with the crew. The Spacecraft Test Conductor, Clarence ‘Skip’ Chauvin, was in the Automated Checkout Equipment facility of the Manned Spacecraft Operations Building.

‘‘Fire!!’’ yelled Grissom at 18:31 local time, in a hold at T-10 minutes. ‘‘We’ve got a fire in the cockpit.’’

In all, there were 25 technicians on Level A8 of Pad 34’s service structure, and five more either on the access arm or in the White Room. Henry Rogers, NASA’s Inspector of Quality Control, was in the elevator, ascending the service structure. Systems technician L. D. Reece was waiting for the ‘Go’ to disconnect the spacecraft for the ‘plugs out’ test, which had been delayed by problems with communications, most notably the whistle from an ‘open’ microphone that could not be located.

‘‘Get them out of there!’’ commanded Donald Babbitt, North American Aviation’s Pad Leader, on hearing Grissom’s call. Mechanical technician James Gleaves was closest, but a spout of flame burst from the capsule before he could react, and he was beaten back by the flame and smoke.

Gary Propst, a technician of the Radio Corporation of America, was on the first level of the pad monitoring a TV camera located in the White Room pointing at the window in the spacecraft’s hatch. On hearing Grissom’s call, he looked up and saw a brilliant light in the window and gloved hands moving about within.

As soon as Slayton realised what had happened, he sent medics Fred Kelly and Alan Harter to the pad. ‘‘You know what I’ll find,’’ Kelly observed pointedly. The best that they would be able to do would be to supervise the retrieval of the bodies. On reflection, Slayton decided to accompany them. ‘‘We were the first guys from the blockhouse to reach the pad,’’ he later pointed out. Despite the intensity of the fire, Grissom, White and Chaffee had died by asphyxiation as a result of the toxic fumes created by the incomplete combustion of the synthetic materials in the cabin. They had received second and third degree burns, but these in themselves would not have been fatal. After several minutes Slayton left the White Room to call Houston, to report the situation. Shea had just arrived back in Houston and was briefing George Low when the news came through.

The Astronaut Office in Houston was very quiet. All the ‘old hands’ were absent. With Slayton away, Don Gregory, his assistant, ran the routine Friday staffmeeting. The meeting had only just convened when the red phone on Slayton’s desk rang. Gregory answered, then reported, ‘‘There has been a fire in the spacecraft.’’ Michael Collins was the senior astronaut present. He arranged for Al Bean to track down the wives. In each case, the news had to be broken by an astronaut who was also a close friend of the family. Charles Berry and Marge Slayton went to see Betty Grissom. Pete Conrad was sent to track down Pat White. Gene Cernan would have been ideal for Martha Chaffee because they lived next door, but he was in Downey with Tom Stafford and John Young, so Collins went to give her the bad news himself.

Al Shepard was in Dallas, Texas, about to deliver a speech at a dinner. He was taken aside and told of the fire. Wally Schirra, Donn Eisele and Walt Cunningham
were flying home from the Cape, and were told upon touching down at Ellington Air Force Base. Schirra immediately called Slayton at the Cape, who filled him in on the details. James Webb, Robert Seamans, Robert Gilruth, George Mueller, Kurt Debus, Sam Phillips and Wernher von Braun were at the International Club in Washington with corporate officials, including Leland Atwood of North American Aviation, to mark the transition from Gemini to Apollo. Webb immediately ordered Seamans and Phillips to the Cape to investigate. As Webb observed to newsmen shortly thereafter, “Although everyone realised that some day space pilots would die, who would have thought the first tragedy would be on the ground?”

The Board of Inquiry was chaired by Floyd L. Thompson, Director of the Langley Research Center, with Frank Borman as the Astronaut Office’s representative. The origin of the fire was near the foot of Grissom’s couch, where components of the environmental control system had repeatedly been removed and replaced in testing. Although the investigation did not identify the specific ignition source, it did find physical indications of electrical arcing in a wiring harness. ft was concluded that at some time during either manufacturing or testing an unnoticed incidental contact had scraped the insulation from a wire and thereby created the opportunity for a spark. This had ignited nearby flammable material, and in the super-pressurised pure-oxygen situation the result had been a brief but intense ‘flash’ fire. fn fact, there had been some 32 kg of nylon netting, polyurethane foam and velcro – all of it flammable in such conditions. fn retrospect, the worst flaw was the inward-opening hatch, which even under ideal conditions took several minutes to open, and would have been impossible to open with the internal pressure above ambient. Because neither the launch vehicle nor the spacecraft had been loaded with propellants, the ‘plugs out’ test had not been judged hazardous. Nevertheless, the launch escape system was directly above the spacecraft, and if the heat from the fire had ignited the solid propellant of this rocket the White Room crew would almost certainly have been killed as well.

fn an Associated Press interview in December 1966 Grissom had told Howard Benedict: ‘‘ff we die, we want people to accept it. We are in a risky business and we hope that if anything happens to us it won’t delay the program. The conquest of space is worth the risk of life.’’

fn an effort to reduce the risk of a fire during ground testing, it was decided to use an atmosphere comprising 65 per cent oxygen and 35 per cent nitrogen. After liftoff, the nitrogen would be purged and the pressure reduced to the originally planned 100 per cent oxygen at about 5 psi.

Although the investigation into the fire would take months, on 31 January NASA headquarters directed the Manned Spacecraft Center, Marshall Space Flight Center and Kennedy Space Center to proceed as planned with preparations for AS-501 with CSM-017 and LTA-10R, except that the command module was not to be pressurised with oxygen without specific authorisation.9 On 2 February CSM-014 was delivered

LTA-10R was a refurbished LM test article serving as a mass-model.

The exterior of the fire-damaged Apollo 1 command module in which Grissom, White and Chaffee died (top left); a view through the hatch; the crew positions, with the hatch above the center couch; the vicinity of the environmental control unit, where the ignition source is believed to have been; and its disassembled outer structures. Glenn, Cooper and Young escort Grissom’s coffin.

to the Cape to assist in training the technicians who were to disassemble CM-012 for the investigation. On 3 February George Mueller announced that although manned flights were grounded indefinitely, the unmanned AS-206, AS-501 and AS-502 were to proceed as soon as delivery of the hardware allowed. While the investigation into the fire was underway, Mueller suggested that when the Block II spacecraft became available the CSM-only flight should be deleted and the effort switched to combined testing with the LM, but Robert Gilruth warned that it would not be wise to test two new vehicles at once. In March it was decided to fly an 11-day CSM-only mission, in effect to perform Grissom’s mission with the upgraded model, and Slayton tipped off Schirra that his crew would fly it, backed up by Stafford’s crew. On 21 February, the day that Apollo 1 had been scheduled to launch, Floyd Thompson gave Mueller a preliminary briefing on the investigation’s findings, and several days later Robert Seamans sent a memo to James Webb listing Thompson’s early recommendations.10

On 15 March Deke Slayton proposed that a rendezvous with the S-IVB stage be a primary objective of Schirra’s flight, and said that this should occur “after the third period of orbital darkness’’. On 5 April Sam Phillips told the Manned Spacecraft Center, Marshall Space Flight Center and Kennedy Space Center that the profile for the first manned flight would be based on that developed for Grissom’s flight, dated November 1966. As the complexity of the mission was not to exceed that previously planned, and as no rendezvous had been planned, the rendezvous exercise should be assessed in terms of how it would complicate the mission rather than how it would advance the program. As the flight was to focus on evaluating the spacecraft’s systems, Chris Kraft pointed out on 18 April that if a problem were to develop that would require the cancellation of the rendezvous, then any manoeuvres which had already been made would complicate the nominal contingency de-orbit procedures. The rendezvous should not be initiated until “after a minimum of one day of orbital flight’’ and should be “limited to a simple equi-period exercise with a target carried into orbit by the spacecraft’’. On 2 June Phillips agreed with George Low that there should be a rendezvous but insisted that this should not be listed as a primary objective. The double-hatch of the Block I had been replaced on the Block II by a single ‘unified hatch’ on a hinge that swung outward. It had a manual release for either internal or external use, could be opened in 60 seconds irrespective of the differential in pressure, and was capable of being opened in order to conduct a spacewalk. But Phillips directed that there ‘‘be no additions that require major new commitments such as opening the command module hatch in space or exercising the docking subsystem’’.

NASA announced on 20 March 1967 that the unmanned LM-1 flight would be transferred from AS-206 to AS-204, which had become available. The rationale for the AS-205/208 dual mission with CSM-101 and LM-2 had been to ensure that testing of the LM would not be held up by the Saturn V development problems. The AS-501 and AS-502 development flights were to carry refurbished LM test articles, but unless

The final report of the Apollo 204 Review Board was submitted on 5 April 1967.

the pace of LM development dramatically picked up, the heavy launcher would become available ahead of the LM, thus rendering the ad hoc dual mission redundant. It was therefore decided that if the LM-1 test flight proved unsatisfactory, AS-206 would launch LM-2 unmanned to address the remaining test objectives. On 25 March George Mueller directed that missions be numbered in the order of their launch, regardless of whether they employed the Saturn IB or Saturn V and whether they were manned or unmanned – previously only the manned missions were to be counted. On the 1966 plan, Apollo 2 was to be CSM-014 (Schirra) and Apollo 3 was to be CSM-101 (McDivitt) flying the dual mission. The cancellation of the Block I reflight advanced CSM-101 to Apollo 2. After the fire, the desire not to reassign the name Apollo 1 had resulted in CSM-101 (Schirra) being seen as Apollo 2. But with paperwork in circulation for a variety of mission plans numbered up to Apollo 3, Mueller precluded the possibility of administrative confusion by directing that the first scheduled mission, AS-501, be named Apollo 4.[47]

On 7 April 1967 Joseph Shea was transferred to Washington as Deputy Associate Administrator for Manned Space Flight, and Low succeeded him as ASPO Manager at the Manned Spacecraft Center. Several days later, Everett Christensen resigned as Director of Mission Operations at headquarters.

A joint meeting of the Manned Spacecraft Center’s Flight Operations Directorate and Mission Operations Division announced on 17 April that: (1) successful firings by the descent and ascent stages of an unmanned LM, including a ‘fire in the hole’ separation of the two stages, should be prerequisites to a manned LM being allotted these functions; (2) a demonstration of EVA transfer should not be a prerequisite to manned independent flight of the LM; (3) the Saturn V should be ‘man rated’ as rapidly as possible; (4) three manned Earth orbit flights involving both the CSM and the LM should be the minimum requirement prior to attempting a lunar landing; and (5) although a lunar orbit mission should not be a formal step in the program, this should be planned as a contingency in the event of the CSM achieving lunar-mission capability ahead of the LM.

ASPO sent the Block II Redefinition Task Team, led by Frank Borman, to North American Aviation on 27 April. Having the authority to make on-the-spot decisions which previously would have required referral to the Configuration Control Board, it was to oversee the ‘redefinition’ of the Block II spacecraft, responding promptly to questions regarding detail design, quality and reliability, test and checkout, baseline specifications, configuration control, and scheduling. Meanwhile, the company had hired William D. Bergen from the Martin Company to supersede Harrison A. Storms as Apollo Project Manager. Bergen brought with him John P. Healy to manage the production of the first Block II at Downey, and Bastian Hello to run the company’s operations at the Cape.

On 8 May 1967 George Low reaffirmed that AS-205 would launch CSM-101 on an open-ended mission of up to 11 days to evaluate its systems. The next day, James Webb told a Senate committee that this mission would be flown by Wally Schirra, Donn Eisele and Walt Cunningham. When Webb canvassed suggestions for how to impress upon Congress that the Apollo program was recovering from the setback of the fire, George Mueller urged that the Saturn V be flown as soon as possible.

Grove Karl Gilbert was born in Rochester, New York, in 1843. After conducting a number of surveys as a field geologist, he was made Senior Geologist when the US Geological Survey was founded in 1879. Over 18 nights during August, September and October 1892, Gilbert used the 26-inch refractor of the US Naval Observatory in Washington DC to study the Moon. Pointing out that lunar craters have floors lying generally below rather than above the level of the adjacent terrain, he rejected the

volcanic interpretation and argued that craters must be the result of impacts. He further proposed that the arcuate chains of mountains at the periphery of the ‘circular maria’ are the walls of craters produced by vast impacts. As evidence, Gilbert cited what he called ‘sculpture’ as the fall of ejecta thrown out during the formation of Imbrium. He announced his results in The Moon’s Face: A Study of its Origin and its Surface Features, a paper presented orally to the Philosophical Society of Washington on 10 December to mark his retirement as its president. The paper was published in the Bulletin in 1893, but as this was not a publication on the reading list of astronomers his remarkable intrusion into their bailiwick passed unnoticed.

In 1946 Harvard geologist R. A. Daly rejected the endogenic origin of craters and, argued in favour of impact, citing Gilbert’s paper. Also in 1946, geologist R. S. Dietz expanded on the subject, listing several criteria that showed how lunar craters differ from terrestrial volcanic craters.

The American geologist J. E. Spurr began to study the Moon in 1937, having been inspired by the photographs taken by Francis Pease using the 100-inch telescope on Mount Wilson. He presumed that the Moon could be described in terrestrial terms, and between 1944 and 1949 wrote up his systematic analysis in four volumes under the general title Geology Applied to Selenology, offering volcanic explanations for a wide variety of lunar features. In particular, he said that early in lunar history large calderas left cavities which were later flooded by lava to make the ‘irregular maria’, and subsequently the better preserved ‘circular maria’. Critics of the impact origin of craters pointed out that whilst there were many examples of small craters on the rims of larger ones, there were no cases of large craters overlapping smaller ones. Spurr said craters were volcanic, and were produced with progressively smaller diameters. He interpreted faults and ridges as evidence of lines of weakness in the crust. Since he mapped these up the meridian and around the limb regions, he said they were due to stresses imparted as the Moon’s rotation synchronised with its orbital period. He

claimed this ‘lunar grid system’ had significantly controlled the formation of craters. This thesis was eagerly accepted by those who believed volcanism played the main role in shaping the lunar surface. In particular, it was claimed that lines of weakness had prompted eruptions that produced ‘chains’ of large craters whose members were isolated from one other by significant distances. But critics argued that the lines of weakness were illusory, since relief highlighted by the sunrise or sunset terminator will favour north-south trends and not east-west trends. And, of course, any pair of craters can be said to be related if an observer is so inclined.

It was not until Ralph B. Baldwin made an analysis of bomb craters in the Second World War that the impact origin of lunar craters began to make real headway. As a businessman trained in physics, he developed an interest in the Moon in 1941 during a visit to a planetarium when, in viewing the pictures on display, he independently noticed Imbrium sculpture. On later reading up and finding no explanation (since he did not happen across Gilbert’s paper) Baldwin decided to conduct his own study. In an article published in the magazine Popular Astronomy in 1942 he argued that the ridges and grooves were “caused by material ejected radially from the point of explosion’’ by the impact which formed Imbrium – although, like everyone else, he presumed that the impact formed the mare itself. In a follow-up in 1943 he reasoned that the projectile had been “flattened” by the shock and had excavated the cavity in a lateral manner, which was why the nearest sculpture consisted of grooves rather than chains of craters made by plunging debris – the latter occurred further out. He published in a popular outlet because his work was rejected by professional journals – evidently the Moon was not an object for worthwhile study. In his book The Face of the Moon, published in 1949 by the University of Chicago, Baldwin reported his observations, experiments and analyses, and included a review of the literature (by now he knew of Gilbert). His own contribution as a physicist drew upon an analysis of bomb craters in which he showed that the greater the deceleration on impact, the greater the energy released. He reasoned that although the weak lunar gravity would enable an explosion to throw ejecta to a greater distance, it would not actually make the crater larger. He logarithmically plotted the relationship between the diameters and depths of explosive craters on Earth, the craters on Earth accepted to have been made by cosmic impacts, and ‘fresh-looking’ lunar craters (those which had not yet slumped and distorted the ratio that he utilised). He compiled 300 measurements of lunar craters from the literature, and measured several dozen others himself. There was a clear trend.

Significantly, Baldwin realised that although most sculpture could be attributed to Imbrium, there was some which seemed to be associated with other ‘circular maria’, from which he concluded that they resulted from individual impacts. Furthermore, the mountains peripheral to Serenitatis must have formed prior to the impact that etched the Haemus with Imbrium sculpture, yet before lava flooded the Serenitatis cavity. This established that Mare Serenitatis formed a significant interval after the impact had excavated the cavity in which it resides. Baldwin (as had Gilbert) believed all the maria to have been formed at the same time and to be associated with Imbrium, which at that time was presumed to have been the greatest impact in lunar history. However, whereas Gilbert envisaged the Imbrium impact splashing out liquid ejecta which pooled in low-lying areas to form the various maria, Baldwin saw there had been a significant interval between the formation of the Imbrium cavity and its being filled in. He proposed that the impact raised a vast dome which remained inflated for long enough to be cratered (for example by Archimedes), then collapsed (forming a system of peripheral arcuate faults) and released a pulse of extremely low viscosity lava that not only filled in the cavity but also burst through the containing walls to spread across the surface and fill in other cavities to create the maria. Irrespective of whether the maria were liquid ejecta or erupted lava, it was evident that the large circular cavities were made by individual impacts over a period of time and that there was a significant interval before the formation of the maria.

Astronomers were not impressed by Baldwin’s arguments, however, and for many years continued to associate the maria with the cavities they occupied.

After reading Baldwin’s book, Harold C. Urey developed an interest in the Moon. But Urey was not particularly interested in the surface features – as a chemist at the University of Chicago who gained the 1934 Nobel Prize for chemistry, he was more interested in the Moon’s composition. He accepted that the craters were impacts and the maria were the by-product of a giant impact, but rejected Baldwin’s inference of a significant interval between the Imbrium impact and the formation of the maria. Urey agreed with Gilbert that the maria were splashes of impact melt, and said that because they were molten they could not have preserved sculpture. He also made the remarkable suggestion that the semicircular Sinus Iridum on the northern margin of Mare Imbrium marked the ‘entry hole’ of the asteroidal body whose impact created the Imbrium cavity.

In 1943 Gerard P. Kuiper began to exploit recent technical developments to make observations of bodies in the solar system. He essentially had the field to himself, at least in professional circles, and was able to make a series of discoveries. In 1953 he turned his attention to the Moon. Although photography was the norm, he mounted a binocular eye-piece on the 82-inch reflector of the McDonald Observatory in Texas to exploit moments of exceptional ‘seeing’ to discern details of the lunar surface that

would have been blurred in photographs. In his first paper on the subject, in 1954, he argued that in the case of a body of the Moon’s size, radiogenic heating would have caused sufficient melting for dense minerals to sink to create a core and lightweight minerals to rise to form a crust. This thermal differentiation would become known as the ‘hot Moon’ hypothesis. As volcanism is a means of enabling heat to escape from the interior, Kuiper argued that the maria were formed by lava upwelling at various times from deep fractures in the floors of the cavities excavated by major impacts.

In 1891, while studying the desert between Flagstaff and Winslow in Arizona in which the Canyon Diablo meteorites had been recovered, G. K. Gilbert inspected the circular hole known as Coon Butte. It was 1.2 km in diameter, had a rim which rose 45 metres above its surroundings, and a floor lying 200 metres below the rim. If it marked the site of an impact, then, he reasoned, there might be a large iron meteorite beneath its floor. A buried iron mass should be detectable by its magnetic signature, but there was no such indication. He concluded that the hole was a marr, made some 50,000 years ago when magma caused underground ice to flash to steam and blast a hole in the overlying rock. Nevertheless, in 1903 mining engineer D. M. Barringer began to drill in search of the meteorite, to no effect. In 1916 E. J. Opik realised that a cosmic impact was such a violent event that the projectile would be vaporised, but he published in an Estonian journal and his insight passed unnoticed. In 1924 A. C.

Gifford independently came to the same conclusion and published in a New Zealand journal that had a broader readership. Opik and Gifford both realised that high­speed impacts always create circular craters because whilst momentum is a vector, energy is not, and as the projectile hits the surface it essentially explodes, liberating energy in a symmetric manner and forming a circular crater. Furthermore, they realised, the crater is always much larger than the projectile. If Coon Butte was an impact crater, then the only relic of the projectile was the field of Canyon Diablo meteorites which littered the surrounding desert.

When Eugene M. Shoemaker joined the US Geological Survey in 1948 he already had an interest in the Moon. In 1949 he made a review of the literature and turned up both Gilbert’s paper and Baldwin’s recently released book, both of which advocated the impact hypothesis. In 1955 he studied two craters about 100 metres in diameter created by underground nuclear tests at the Nevada Test Site to investigate how such explosions shocked and dispersed rock. He was impressed by their resemblance to lunar craters. In 1957, with Gilbert’s analysis in mind, he began a study of Coon Butte. He had already done the field work for his PhD thesis on salt structures, but had never gotten around to writing it up. After hearing Shoemaker give a seminar on his study of Coon Butte, his advisor at Princeton, Harry Hess, suggested that he use that as the basis of his thesis. Shoemaker put in some more field work, wrote it up, and, despite it being rather on the short side for the purpose, submitted it in 1959. The fact that the crater was recent and in a desert environment made the manner in which it was excavated readily evident. In particular, the strike had not just penetrated the surface and pushed the rock aside, as Gilbert imagined; the process, as Opik and Gifford had inferred, was explosive. Significantly, Shoemaker found that two shock waves were involved: one vaporised the projectile, and the other propagated into the ‘target rock’, compressing it so thoroughly that the rock reacted just as if an explosion had occurred beneath it. In his field work Shoemaker methodically traced how the rim and the ejecta blanket formed by the stratigraphy being flipped into an inverted sequence around a circular ‘hinge’, in the process making a hole much wider than the projectile.[5]

Early in 1960 L. R. Stieff of the US Geological Survey in Washington DC set out to obtain NASA funding for an investigation of lunar geology. NASA deliberated. In 1953 Loring Coes had produced a new very dense mineral using a hydraulic press to squeeze quartz. This ‘shocked quartz’ was named coesite. In 1956 H. H. Nininger had suggested searching for coesite at Coon Butte, but this was not done. In 1960 Stieff obtained samples of rock taken from Coon Butte which were in the archive of the Smithsonian Institution in Washington DC to enable him to say to NASA that the Survey was already at work on craters. Ed Chao identified coesite using X-ray diffraction, which proved Coon Butte to be an impact crater. A press statement was released to this effect on 20 June. When Chao wrote the scientific paper, the Survey

added Shoemaker and his assistant Beth Madsen as co-authors to imply that it had a team of specialists at work. When the paper was published in Science in July I960, Shoemaker was on his way to present a paper about Coon Butte to the Geological Congress in Copenhagen. The Rieskessel in Bavaria is a 24-km-diameter structure with the town of Nordlingen at its centre. Although widely believed to be volcanic, a study in 1904 had suggested that the circular structure might mark an impact, and its characteristics had led Baldwin to classify it as such. Shoemaker examined samples of quartz from a quarry. To his trained eye, using no more than a hand-lens, the rock showed evidence of shock. The next day he airmailed samples to Chao, who called straight back to confirm that coesite was present. In giving his paper in Copenhagen about Coon Butte, Shoemaker announced the Rieskessel finding.

With the two structures having been shown to be impacts, NASA finally released the funding to enable the Survey to undertake its lunar studies, and on 25 August the Astrogeologic Studies Group was established at the Menlo Park office, south of San Francisco, with Shoemaker in charge. A year later, in 1961, it became the Branch of Astrogeology. In March 1962 Shoemaker decided to move his team to Flagstaff. The move began in December, but some people refused to relocate and were allowed to remain at Menlo Park.