The Apollo flights a brief history

AN ALPHABET OF MISSIONS

Owen Maynard, one of the engineers who had been designing manned spacecraft for NASA from the beginning, reduced the task of reaching the Moon to a series of missions that, one by one, would push Apollo's capability all the way to the lunar surface. These missions were assigned letters of the alphabet: A, B, C, etc. Managers believed that if the lunar goal was to be realised, each of these preliminary missions would have to be successfully flown - more than once if necessary - before the subsequent mission could be attempted.

The A-mission would be an unmanned test of the Saturn V rocket to rate it for manned flight and test the ability of the Apollo command module to re-enter safely; the B-mission would take an unmanned lunar module up for a workout on a Saturn IB launch vehicle; the C-mission would be an Earth orbital test of the CSM with a crew, again using the Saturn IB; and the D-mission would be a full manned test, in Earth orbit, of the CSM and LM Apollo system, launched by a Saturn V.

NASA would then begin to move away from the Earth. The E-mission would be another full test of both spacecraft, this time taking an orbit that would go much higher than any manned spacecraft had gone previously, testing the combination away from Earth where navigation, thermal control and communications would be different. The F-mission would be a full dress rehearsal of a flight to the Moon, carrying out every manoeuvre except the actual landing. This would give crews in the spacecraft and the people in mission control their first operational experience of lunar orbit. The first landing was designated the G-mission, whose goal would not extend much beyond the landing, as its crew would take only one short walk on the Moon's surface.

Three further mission types were later envisaged by the planners. The H-mission would maximise the capabilities of the basic lander to allow a crew to make two forays outside the lunar module on foot, and to deploy a suite of science instruments on the surface. The I-mission, which was never flown, would have used only the CSM for a month-long stay in lunar orbit. Cameras and other remote-sensing instruments built into the side of the service module, or an instrumented module docked onto the CSM, would have mapped the entire Moon. The final mission type to enter the planners' lexicon was the J-mission, which would use an uprated Saturn V and LM to extend surface operations to three days. In the event, a little electric car would be added to allow its crew to venture much further around the landing site and explore areas with multiple scientific objectives. Because the bulk of this book deals with the steps involved in flying to the Moon, the following is a resume of what each flight achieved.

Across two hectic years of 1965 and 1966, the highly successful Gemini programme taught NASA the fundamentals of spaceflight. Ten increasingly ambitious flights were launched at two-monthly intervals, each tasked with testing some technique that would be central to Apollo - controlled re-entry, rendezvous, docking, spacewalking and long-duration flights being among its achievements. It placed America ahead in the space race for the first time. As 'Go-fever' gripped the programme, NASA looked forward to getting the Apollo programme flying in the new year of 1967.

CM-012 scorched by the intense heat from its internal conflagration.

FAILURE OF IMAGINATION

In the early years of the space programme, America had lagged behind the Soviet Union in the lifting ability of their launch vehicles. Attempts to lighten payloads became habitual as the American space industry strove to maximise spacecraft capability within the constraints of the available rockets. One decision to save weight would have tragic consequences for what was to have been the first manned Apollo mission.

On Earth, the atmosphere consists of four-fifths nitrogen and one fifth oxygen, the latter being the gas necessary to sustain life. To save the substantial mass of the equipment required to supply two gases in a manned spacecraft, NASA decided that the cabins in its spacecraft would be filled with 100 per cent oxygen, but at a lower pressure to ensure that the crew received only the concentration of oxygen molecules to which

CM-012 scorched by the intense heat from its internal conflagration.

their lungs had been accustomed. This arrangement worked well throughout the Mercury and Gemini programmes. As the first Apollo crew prepared for the first test flight of the command and service module, this single-gas decision nearly ended the programme.

On 27 January 1967, the AS-204 mission, so designated because it was to use the fourth vehicle in the Saturn IB series, but informally dubbed Apollo 1, was three weeks away from its planned launch. The Apollo spacecraft, CSM number 012, was a Block I type and was sitting on top of an unfuelled launch vehicle. Its crew of three were strapped in for a 'plugs out' countdown simulation whereby the entire stack's ability to function on its own power would be tested. Its cabin had been overpressurised with pure oxygen in order to test for leaks, as had been done in ground tests for the Mercury and Gemini programmes. Five and a half hours into a simulated countdown that had made only halting progress, a fire began near the commander's feet. In the super-oxygenated environment, it quickly grew into an intense conflagration that ruptured the hull of the spacecraft and asphyxiated the three crewmen - Gus Grissom, Ed White and Roger Chaffee.

NASA sustained heavy criticism from the press and political classes for this tragedy. Some of the blame landed on the spacecraft's manufacturer, North American Aviation, with accusations of sloppy workmanship. North American rebutted, pointing out that as it tried to build the spacecraft, NASA had insisted on interfering with the process by ordering a succession of changes. During congressional hearings on the fire, Frank Borman appealed for support from the lawmakers. ''We are confident in our management, our engineering and ourselves. I think the question is: are you confident in us?''

NASA learned many lessons from this accident and applied them to the rest of the Apollo programme. Some commentators have said that there was a very real possibility that, had the fire not occurred, NASA would never have realised its lunar dream because the shock of the deaths spurred all those involved with the programme, especially at NASA and North American, to make the Block II spacecraft into the great spacefaring ship it became. Without the changes brought about by the tragedy, casualties may have occurred later in the programme, possibly in space. At the very least, the development problems of the Block I Apollo spacecraft that were brought into sharp focus by the tragedy would probably have crippled the programme at a later stage.

Although NASA wanted to keep this unflown mission's name as AS-204, it acceded to the widows' requests that the name Apollo 1 be reserved for their dead husbands' flight. Apollos 2 and 3 never existed, lost within the memos of NASA's bureaucracy relating to missions that would have flown later in 1967 if the fire had not prompted their cancellation.

Meanwhile, a few months after the Apollo fire the Soviet Union lost its first cosmonaut, testing the new Soyuz spacecraft, which set back that nation's race to the Moon.

BACK IN THE SADDLE: APOLLO 4

NASA resumed their Apollo operations on 9 November 1967 with the A-mission, the first unmanned flight of the Saturn V launch vehicle, as Apollo 4. As so often happens with new, complex systems, getting this vehicle ready for flight proved to be a slow, difficult affair. Its Block I spacecraft, CSM-017, had to be modified in the light of the investigation into the AS-204 fire, and its S-II second stage caused headaches by repeatedly exhibiting cracks during inspections.

The Saturn V launch vehicle turned the normal procedures of rocket development upside down. Traditionally, engineers would follow a careful, progressive programme of testing a rocket stage to ensure that it worked before setting another stage on top, and testing that. To test the entire configuration at once - so-called all-up testing - was deemed too risky. However, when George Mueller became head of NASA's Office of Manned Space Flight in 1963, he argued that this incremental approach to testing rocket stages not only wasted expensive flight-capable stages, it also wasted precious time. He ordered that the engineering and ground testing of the rocket's components should be of such a quality that all stages of the vehicle could be flight tested at the same time. Apollo 4 would prove to be a triumphant vindication of his methods.

When it finally launched, a noise like none that had ever been heard before across Cape Canaveral blew away much of the pessimism from the spacecraft fire. As the acoustic and thermal energy was enough to cause substantial damage to the launch tower, NASA had subsequently to make modifications to the launch pads in order to suppress the extreme conditions.

As well as testing the entire rocket system, Apollo 4 placed its CSM payload into a high ballistic arc from where the SPS engine powered the

The launch of Apollo 4, the first flight of the Saturn V.

command module into a high-speed dive into the atmosphere to test its heatshield by re-entering at the speed it would have if it were returning from the Moon. The CM was recovered for analysis in the Pacific after an 8^-hour flight that, in all important respects, was a complete success.

THE LUNAR MODULE FLIES: APOLLO 5

Launched on 22 January 1968, Apollo 5 is the flight that history treats almost as a footnote. It was neither manned nor did it have the remarkable Saturn V as its launch vehicle. It used the AS-204 launch vehicle that had been intended to lift Apollo 1, but it is important to the story as it tested the first Apollo lunar module, LM-1, and was the B-mission in the planners' minds. The test allowed engineers to verify the lunar module's structure and its response to the launch environment, and it gave them their first opportunity to test the spacecraft's two engines in the space environment.

In the case of the ascent engine, it was NASA's first opportunity to try out a fire-in-the-hole burn when they ignited the ascent engine just as the descent stage was being jettisoned. In their effort to give crews the best possible chance of escape from any reasonable failure of equipment, the LM's designers planned that if the descent engine should fail while a crew were descending to the Moon, the ascent engine should fire and lift the crew back to the safety of an orbit. For this to happen, its engine would have to ignite while the descent stage was still attached beneath it, literally a fire in the hole. Despite some problems, the legless module successfully demonstrated everything that was asked of it, and a second B-mission was cancelled. The second test lander, LM-2, therefore became an exhibit at the National Air and Space Museum in Washington DC where it rests to this day. The next spacecraft to fly, LM-3, would be entrusted with the lives of two men.

THE SATURN BALKS: APOLLO 6

By the spring of 1968, with two flights successfully completed, the Apollo programme seemed to be hitting its stride. It had demonstrated that the Saturn V

The unused, flight capable LM-2, now at the National Air and Space Museum, Washington DC.

worked, the command module had survived its high-speed re-entry, and an early version of the lunar module had been flown successfully. NASA wanted to further prove the Saturn V before declaring it fit to carry astronauts, so a second A-mission was ordered. This flight was Apollo 6 and, once again, the results threatened to stop the programme in its tracks.

After a successful launch on 4 April 1968, the first minute of flight was trouble-free, but towards the end of the S-IC's flight, the first problem appeared. Rockets have always been prone to vibrations along their length, but for about ten seconds immediately before the first stage completed its task, the backwards and forwards shaking of the entire vehicle (known as pogo) became alarming. Meanwhile, at the front end of the rocket, the conical aerodynamic shroud that would normally protect a lunar module (but not carried in this case) was losing chunks of its outer surface. Since this section had to support the mass of the CSM multiplied by the ^-forces of acceleration, its structural integrity was of some concern.

Halfway through the flight of the S-II stage, one of its five J-2 engines began to falter, which prompted the instrument unit to shut it down. As it did so, another engine also promptly shut down, causing the thrust from the other three to be applied asymmetrically to the stage. Considering that the Saturn's control system had not been programmed to deal with a two-engine failure, it did a remarkably good job of compensating for the off-axis thrust and burned the remaining engines for longer on the residual propellant. The first burn of the S-IVB third stage successfully put the vehicle in orbit, but a subsequent command to restart the engine failed. Some of the flight's objectives had been met, but if the problems could not be fixed, NASA would not dare to put men on top of the next Saturn V, as was being considered instead of flying a third test.

In the event, engineers managed to find solutions for all these problems. The first stage vibrations were suppressed by the addition of helium gas to cavities in the LOX feed lines, which damped out pressure oscillations. Elaborate tests on the J-2 engine discovered a design fault in a liquid hydrogen fuel line that not only led to the shutdown of one of the engines on the S-II, but also prevented the engine on the S-IVB from restarting. Compounding the S-II problem, a wiring error had sent the shutdown command from the Saturn's instrument unit to the wrong engine, shutting it down unnecessarily. The aerodynamic shroud had failed because trapped moisture and air within its cork insulation had expanded owing to frictional atmospheric heating as the rocket went supersonic, causing the skin to peel away in sheets. This problem was cured by making small vent holes in the shroud's skin.

The launch vehicle issues apart, the CSM-020 spacecraft it carried performed as planned, making several remote-controlled manoeuvres that ended with splashdown in the Pacific Ocean. Preparations for Apollo 7 continued because it would use a Saturn IB launch vehicle. If it was successful, managers decided that the third Saturn V could indeed carry a crew.

TESTING THE BLOCK II: APOLLO 7

The Apollo programme became a juggernaut towards the end of 1968 as flights began lifting off every two to three months in the race to achieve Kennedy's deadline. The C-mission of Apollo 7 gave the Block II spacecraft, without a lander, its first manned test starting on 11 October 1968 with a launch on top of the smaller Saturn IB vehicle. Its crew of Wally Schirra, Donn Eisele and Walt Cunningham spent 11 days in orbit around Earth - a duration that would be more than enough time for a mission to get to the Moon and back, which proved that the new spacecraft was a worthy, spacefaring ship.

As soon as the spacecraft achieved orbit, the crew separated it from the S-IVB second stage and attempted to practise the type of turnaround manoeuvre that would be required of future flights, when the lander would have to be plucked from inside its protective shroud. As soon as he saw the S-IVB, Schirra noticed that one of the four hinged petals of the shroud had not

The Florida peninsula, as seen from Apollo 7.
Apollo 7's S-IVB and its deployed shroud petals.

fully deployed. He cancelled a simulated approach manoeuvre for fear of it hitting the spacecraft, and later recommended that the panels be jettisoned instead.

Throughout the early part of the mission, the crew concentrated on achieving their most important goals: firing the main engine repeatedly to make rendezvous passes with the S-IVB (whereupon it was noted that the balky shroud petal had properly deployed) and proving the operation of the spacecraft's navigation system. With these test satisfactorily performed, the crew spent their remaining time carrying out secondary tests of the Apollo system and completing a programme of Earth photography.

Despite the operational success of the mission, history tends to remember this flight for the breakdown that occurred in relations between the crew and flight controllers in mission control. A dose of the common cold had made its normally wise-cracking commander increasingly grumpy. A cold in space is made more unpleasant by the inability of the congested head to drain itself. The other two crewmen, both rookies, were drawn into the soured atmosphere with the result that, having irritated management, neither of them flew in space again. Schirra had already announced his retirement from space flight.

GUTSY DECISIONS: APOLLO 8

Even before Apollo 7 had launched, managers were dreaming up something special for Apollo 8: an audacious six-day excursion to the Moon. This was a hastily arranged mission that took full advantage of an otherwise unfavourable set of circumstances.

Apollo 8 had originally been planned as the D-mission, a test of the entire Apollo system including a lunar module in low Earth orbit, on the assumption that Apollo 7 would successfully carry out the C-mission. However, the first man-capable LM was not ready for flight owing to a litany of problems: stress fractures had appeared in some of its structural components; the type of wiring used on the intended spacecraft was prone to breakage; and the engine for the ascent stage was prone to combustion unwilling simply to repeat Apollo 7, brought the deep-space goals of the

The Moon's far side, photographed from Apollo 8 after it departed for Earth. The distinctive dark-floored crater is Jenner, 71 kilometres in diameter.

instability. Bereft of a LM, managers were so they altered the mission sequence and E-mission forward, but without a lander.

TV image of the Moon's sunrise terminator as seen through a space craft window, broadcast as the Apollo 8 crew read from the book of Genesis.

Furthermore, they took the gutsy decision to send the CSM all the way to the Moon and place it in orbit. Although this would fulfil some of the goals of the E-mission (deep space tracking, deep space thermal control, lunar navigation), NASA labelled it as a C'-mission (C-prime-mission) on the basis that it would be a CSM-only flight. It would give NASA the operational experience it needed to manage lunar missions, but its unstated purpose was to reach the Moon before the Soviet Union. Intelligence reports were suggesting that a Soviet circumlunar mission was close, and the propaganda value of such a mission, even though it would not land, would be immense. If the Americans could get there first, they could claim to have essentially won the space race as long as the Soviets did not achieve a landing.

On the morning of 21 December 1968, Frank Borman, Bill Anders and Jim Lovell rode a Saturn V away from Earth to become the first people to swap the Earth's gravitational hold for that of another world. The three-day long coast out to the Moon gave Jim Lovell plenty of time to practise monitoring the ship's trajectory by taking sightings of Earth, the Moon and the stars. By 24 December 1968, Apollo 8 took its crew around the lunar far side where they fired its SPS engine to enter lunar orbit to begin 10 revolutions, each lasting two hours. As they coasted 110 kilometres above the cratered surface, the crew closely examined two sites that were being considered for the first landing and, along with tracking stations on Earth, practised techniques for navigating around the Moon. Much of Earth's population with access to television watched with amazement when the crew made an extraordinary Christmas-time black-and-white television broadcast on their penultimate orbit during which they read the first few verses from the Bible's book of Genesis, while the stark early morning landscape of the Moon passed in front of the camera.

If their burn to enter lunar orbit had failed, the crew would have simply slingshot around the Moon and returned to Earth with little intervention. It was Apollo 8's next manoeuvre that really scared the managers. Although the SPS engine had been designed for utmost reliability, everyone was aware that its failure would doom the crew to stay forever in the Moon's grasp. Worse, as the firing of the engine would take place around the Moon's far side, no one on Earth would be able to monitor its progress, and instead would have to wait until the spacecraft re-emerged, hopefully on a path for home. Shortly after midnight in Houston, Texas, on Christmas Day, Apollo 8 reappeared around the Moon's eastern limb exactly on time, with Jim Lovell playfully informing mission control, "Please be informed, there is a Santa Claus.''

Sending Apollo 8 to the Moon raised the morale of the many thousands who were working brutal hours towards the landing goal, and it gave NASA the operational experience it needed to make future lunar trips by allowing navigation, thermal

The first image of Earthrise taken by a human. Bill Anders's Apollo 8 photograph was taken a few seconds before more famous colour images were snapped.

control and communication procedures to be tested. On a philosophical level, the flight gave the human race its first glimpse of its home planet as seen from another world. The crew returned TV images of Earth to millions from a vantage point between the two worlds. While orbiting the Moon, they photographed Earth rising over a barren lunar horizon as they watched in awe. These photographs became a catalyst for the rise of the environmental movement and icons of the age.

A COMPLETE SYSTEM TEST: APOLLO 9

By now, NASA had confidence in the Apollo CSM, but no one had yet flown the flimsy lander that was to take crews to the Moon's surface. So NASA ticked the D-mission box by flying the entire Apollo system, consisting of the main spacecraft and a fully configured lander, LM-3, in Earth orbit as Apollo 9. This flight would rehearse all the manoeuvres that a Moon flight would require and it was the first time astronauts would entrust themselves to a craft that had no heatshield and could not bring them home, but it was a trust that would have to be gained if the LM was to take their colleagues to the Moon's surface.

After a successful launch on 3 March 1969, the crew followed a ten-day timeline roughly similar to a lunar mission without leaving low Earth orbit. This began with pulling the LM from its station on top of the S-IVB stage, one of many firsts achieved in this crammed mission. Controllers on the ground then commanded the booster stage to reignite its engine to leave Earth's vicinity, as if dispatching an

Rusty Schweickart's view from the lunar module's porch of David Scott in the CM's open hatch.

Apollo mission to the Moon, in the process escaping from Earth's gravity and entering its own independent orbit around the Sun. After a number of firings of their SPS engine to set up the correct orbit, Jim McDivitt and Rusty Schweickart entered the LM, call sign Spider, and powered it up. David Scott remained behind in Gumdrop, the CSM. The names selected by the crews simply reflected the shapes of their spacecraft.

Schweickart was due to test the type of space suit and back pack that crews were to use on the Moon by going out of the LM's front hatch. He was also due to prove that, in the event of an unsuccessful docking or a blocked tunnel, a crewman could make his way from one spacecraft to another by using handrails on the outside. The attempt was cancelled when Schweickart experienced a bout of space adaptation sickness the day prior to his task. Instead, managers limited him to moving out onto the LM 'porch' to prove the space-worthiness of the suit and back pack, while Scott stood in Gumdrop's hatch to retrieve samples from the spacecraft's surface.

Four days into the flight, McDivitt and Schweickart sealed the tunnel between the two vehicles and undocked Spider. After a visual inspection by Scott, they fired the LM's descent engine to move 185 kilometres away from Gumdrop and set up the conditions for a lunar-type rendezvous. After jettisoning the descent stage, they flew the LM's ascent stage back to Scott, as would happen on a lunar mission, eventually docking and transferring back to the command module without difficulty.

For the remainder of the flight, the crew practised navigation techniques, made multiple adjustments to their orbit with their dependable SPS engine, and carried out experiments including multispectral photography of Earth's surface in support of future Earth resources satellite programmes and Skylab. Apollo 9, though less glamorous than the missions to come, was a highly successful overture to Apollo's climax: flying to the Moon.

A DRESS REHEARSAL: APOLLO 10

Most of the major components and procedures required for a landing had been tested, though not always in the context in which they would be needed during a lunar flight. To minimise the surprises that the landing mission would uncover, NASA wanted to practise a complete lunar mission as far as they dare, short of actually touching down on the Moon. This dress rehearsal flight, the F-mission, was accomplished by the crew of Apollo 10 - Tom Stafford, Eugene Cernan and John

Waypoint to a landing. Left, crater Moltke at 6 kilometres diameter. Right, the Apollo 10 CSM Charlie Brown over a distinctive triangular feature named 'Mount Marilyn' by Jim Lovell. Both features led the way to the Apollo 11 landing site.

Young. Their spacecraft were named after well-known characters from Charles Schultz's cartoon strip Peanuts, who had also featured in NASA campaigns promoting quality control. The CSM was therefore named Charlie Brown while the LM took the name Snoopy.

Launch took place on 18 May 1969. Every element of the launch vehicle had to operate exactly as it would on a landing mission, including the firing of the S-IVB stage to send the spacecraft to the Moon. Likewise, all the functions of the CSM to take a lunar module to an orbit 110 kilometres above the Moon had to work.

Once the two docked spacecraft had entered a parking orbit, the crew settled down for their first night in lunar orbit as their ship hurtled around the Moon at 5,800 kilometres per hour. Next day, Stafford and Cernan entered the lunar module Snoopy, separated from Young in the command module Charlie Brown, and took the LM into the same low orbit from which a landing mission would make its final descent. This orbit brought Snoopy down to an altitude of less than 14,500 metres above the lunar surface from where Stafford photographed and described the approach to the landing site NASA had selected. The most important task was to prove that lunar orbit rendezvous would work as planned. After jettisoning the descent stage, the ascent engine was used to set up an orbital situation similar to that which would be presented after lift-off from the Moon. NASA's management had once been wary of bringing two speeding craft into close proximity when they were in orbit around another world, and wished to prove that the techniques worked prior to committing a lander to the surface. This successful rendezvous and docking finally cleared the way to a landing attempt.

As is usually the way with the media, Apollo 10 is more often remembered for the 'son-of-a-bitch' language Cernan used when a pilot error caused the LM to gyrate unexpectedly as the descent stage was being jettisoned. The journey home was uneventful except for the unprecedented colour television coverage of a receding Moon that was beamed to Earth soon after Charlie Brown's SPS engine was fired. Stafford had promoted the importance of TV to Apollo, not only to the public, but also to engineers and lunar scientists. The 8-day flight of Apollo 10 put NASA on the home straight, leaving the G-mission with no unknowns except the landing itself.

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