Category How Apollo Flew to the Moon

After their third and final traverse, each J-mission commander drove his rover to a spot roughly 100 metres east of the LM so that the TV camera could look at the sunlit rear of the LM and carry out the one remaining major task left to it – to treat

TV viewers on Earth to the spectacle of the launch of the LM ascent stage and hopefully to follow it as it powered towards the western horizon. As a nod towards the area at the Kennedy Space Center from which invitees and dignitaries would watch Saturn V launches, on his flight Young dubbed the rover’s final position the VIP site.

In the event, the spacecraft’s rapid rise proved difficult to track. When the INCO flight controller commanded a camera move, it took two seconds for the command to reach the pan/tilt head on the rover. It then took a further 1.5 seconds for the move to be seen on Earth if the viewer was watching an unprocessed, uncoloured feed from the Moon. Colour processing added more time. Taking these factors into account as well as the planned time of lift-off and details of the planned trajectory, a command was sent to the camera early enough that it moved in the right way at the right time.

On Apollo 15, Granvil Pennington could make no such attempt. The camera’s tilt mechanism had begun to slip as the temperature rose, and he didn’t dare command any kind of tilt for fear of never being able to return the camera to horizontal. Instead, viewers watched Falcon smartly disappear beyond the top of the picture. The timing wasn’t quite right for Apollo 16, but on Apollo 17 viewers could follow Challenger as Ed Fendell tracked it from lift-off to pitchover and beyond.

For as long as the rovers’ batteries held out, or until a circuit breaker on the Apollo 15 rover popped in the rising temperatures of a high lunar Sun, geologists continued to use the TV camera to view the landing site under the slowly varying illumination of the long lunar day. There was even an unsuccessful attempt to gain coverage of Challengers discarded ascent stage as it was targeted to impact the South Massif.

Around the time that the rovers were being driven across the lunar surface, the press divided the S38 million price tag by the number of rovers delivered and poked fun at how expensive these cars were. A different analysis would point out that these vehicles dramatically raised the efficiency of the surface crews and that, despite the extreme engineering demands place on them, the rovers performed extremely well. Given that the American taxpayer had already invested huge sums in getting to the Moon, the extra expenditure on the LRV more than paid for itself by allowing the system as a whole to give a much greater return on investment.

It will help the reader to understand the concepts behind rendezvous if a short diversion is taken into the field of orbital mechanics. At first glance, this topic seems arcane and, if studied rigorously, it is. Additionally, it can appear counter-intuitive but the basic concepts behind the subject are easy enough to grasp, and are really an extension of the orbital lessons discussed in Chapter 4.

To lay down the groundwork for this we need to establish some basic ideas. Unless some kind of propulsion is being used, all movement in space is governed by the gravitational attraction of the bodies (stars, planets, moons, asteroids, etc.) among which things move. In general, the gravity of the nearest large body dominates, so for the purposes of this explanation we shall ignore the pull from other bodies. Any spacecraft in orbit moves around the central body in an ellipse. Even a perfectly circular orbit is treated as a special form of ellipse whose eccentricity value is zero.

There are three principles to bear in mind with orbital motion. First, a spacecraft in a higher orbit takes longer to go around than one in a lower orbit. At first glance, this appears obvious because there is a longer circumference to travel, but that is only part of the story. The more important point to grasp is that it really is a slower orbit. The spacecraft is moving at a slower linear speed because the pull of gravity from the central body becomes weaker with distance, and hence a lower speed can maintain the perpetual fall that is orbital motion. As an illustration, the Saturn V inserted the Apollo spacecraft into an orbit only 170 kilometres above

Earth, taking only an hour and a half to go around at a linear speed of 7.8 kilometres per second. Geostationary satellites, which are the mainstay of global communications and televi­sion satellite broadcasting, orbit 35,800 kilometres above Earth’s equator, take 24 hours to get around once and travel at only 3.1 kilometres per second.

With this in mind, we can see a method by which one spacecraft can manoeuvre with respect to another, assuming that both are travelling in the same orbital plane. If the target ship is ahead, a pursuer can catch up with it by manoeuvring into a lower orbit, which is achieved by firing

Orbital mechanics 397

against the direction of travel, as if trying to get away from the target. We said it was counter-intuitive. The burn will cause the pursuer to fall into a lower orbit, which will have a shorter period and a higher linear speed. This will allow it to catch up with the target. The difficulty lies in choosing the exact moment to start climbing back into the original orbit, which we shall deal with later.

The reverse is also true. If the pursuer is ahead in the orbit, it can ‘slow down’ by accelerating forward, which causes it to rise to a higher and therefore slower orbit. It can then drop down again when the target has caught up.

The concept of changing from one orbit to another is a common requirement in space­flight and is embodied by our second principle which we have already met in Chapter 4 as the Hohmann transfer orbit. It is the most efficient and simplest way to change an orbit whereby firing a spacecraft’s engine along the direction of motion at one point in the orbit will increase its speed and thereby raise the altitude that will be reached on the opposite side of the orbit. Firing against orbital motion will slow the space­craft and lower the altitude of the opposite side of the orbit. Control of the total impulse from the burn allows control of the altitude that will be reached at the opposite side. We have met this already in the way the CSM and LM made burns around the Moon’s far side to raise and lower their near-side altitude.

To move from a lower circular orbit to a higher one, a burn must be made in the direction of motion until it is calculated that Diagram of basic rendezvous the point in the orbit opposite the spacecraft, techniques, now the apogee, is at the height of the

intended circular orbit. Once the spacecraft has coasted around in its orbit to its apogee, another burn must be made along the direction of motion to raise the perigee until it equals the apogee’s altitude.

So far we have dealt with two spacecraft within the same orbital plane. The third principle behind orbital mechanics deals with the situation when the two objects are

in different orbital planes. This is a common requirement, since few launch sites are located cqualorially yet many satellites need to reach a geostationary orbit above the equator. For example, a spacecraft launched from Cape Canaveral will necessarily have an orbital inclination of at least 28 degrees: this being the latitude of that site. The most efficient way for a spacecraft to move from one orbital plane to another is for it to make a burn at the point in the orbit where the two planes intersect, known as a node. Unfortunately, the physics of the situation dictate that all but the smallest of plane changes will be expensive in propellant – indeed to move a communications satellite from a 28-degree low Earth orbit to its geostationary outpost requires almost as much energy as would be required to send it to the Moon! For Apollo, it was vital to minimise plane change manoeuvres, especially for the LM’s ascent stage where propellant margins were very Light.

The right time to return from the Moon was dependent on the mission, the consumables available to the crew, the propellant available to the engine, and the status of the flight; that is, whether an emergency forced an early departure. As soon as they arrived in lunar orbit, and throughout their stay, the crews of all the missions were given abort PADs at regular intervals, lists of numbers giving instructions for a TEI manoeuvre that would allow them to make an early independent return to Earth. None of the missions ever needed to use these PADs.

The first flight to enter lunar orbit, Apollo 8. did not stay for long because, as a pioneering flight, it was noi one of intense exploration. Rather, it was more of a ‘grab and run’ affair, orbiting for only 10 revolutions and 20 hours in the second Apollo CSM to fly, and proving that it and its crew – could achieve lunar orbit and still return home safely, with a little reconnaissance thrown in for good measure. Prior to loss of signal on each orbit, Frank Borman insisted that mission control give him an explicit Go to continue orbiting, otherwise he intended to use the contingency TEI data to fire up the SPS engine and send the spacecraft back to Earth. In the event, Apollo 8’s CSM worked like a charm and there was no reason to come home early. Borman and his crew made a successful burn at the end of the tenth orbit around the far side to begin their long fall to Earth as planned.

Similarly, the lunar missions immediately following Apollo 8 did not stay around the Moon for long. Once the LM crew had returned from their exploration of the surface, the crews either headed for home soon after the lander’s ascent stage had been jettisoned, or took a single night’s rest in lunar orbit. This changed with the introduction of the J-missions. Having spent significant sums to extend the capability of the CSM and to pack a suite of scientific instruments into the side of the service module. NASA decided that the spacecraft should remain in orbit around the Moon for a full day after the LM had been jettisoned. This additional time was of particular benefit to Apollos 15 and 17. ‘fheir northerly landing sites required the CSM’s orbit to be significantly tilted with respect to the lunar equator. This meant that the Moon’s rotation brought new terrain into the realms of the sensors and cameras and allowed the sunrise terminator to crawl across the surface for another day, another 12 degrees of longitude, thereby bringing more landscape into view?. The near-equatorial orbit of Apollo 16 offered little benefit from an extended stay and, in the event, the problem with Casper’s SPS engine gimbals led mission control to forego the extra day. The crews of the other two J-missions reported that extra time in lunar orbit gave them a chance to wind down and rest after w hat had been an arduous expedition to the surface.

The first generation of manned spacecraft for example, the American Mercury and the Soviet Vostok ships – were designed to re-enter the atmosphere in a purely ballistic fashion. Once they were set on their Earthward trajectory, they had no ability to change their flight path and steer towards a landing site. Later generations of spacecraft like Gemini and Apollo, and the Soyuz, could fly in a controlled manner even without wings.

Although the Apollo command module had a symmetrical shape, its internal weight distribution was deliberately offset to place its centre of mass towards the crew;’s feet. This made it adopt an aerodynamically stable attitude that leaned to one side as it ploughed through the atmosphere because the lighter side of the spacecraft tended to succumb to the atmospheric drag to a greater extent. Such a lopsided presentation to the hypersonic airflow turned the stubby spacecraft into a crude
wing, giving it the ability to generate lift in a direction towards the crew’s feet. Therefore, simply by performing a roll manoeuvre, the spacecraft could aim this lift vector in any direction perpendicular to the flight path which allowed the re-entry to be flown in a controlled manner, usually by the computer.

This term, ‘lift vector’ can be confusing as it is borrowed from the aeronautical world where it is applied to a wing’s ability to provide a lifting force. But just like an aerobatic aircraft that rolls and loops, that force can be in any direction perpendicular to the airflow. It is perfectly possible for the direction of the so – called ‘lift’ to be downwards, towards Earth. If the spacecraft was a little high in the re-entry corridor and was going to overshoot the landing site, the roll thrusters could fire to turn the spacecraft around to a heads-up attitude and aim the lift vector towards Earth. This would force it into a lower flight path where the thicker atmosphere would reduce its speed further. The meagre lift that such a poor wing could generate was amplified by the huge speed of re-entry to the extent that, for a few minutes, the spacecraft would typically fly at about a constant 60-kilometres altitude and, in some cases, even manage to rise away from Earth.

If the entry plan required the spacecraft to make a skip, perhaps to extend the flight path as happened on Apollo 11, the computer advanced to P65 which controlled the ascending part of the skip-out trajectory. Whether the skip caused the spacecraft to briefly leave the atmosphere depended on how far the flight path was being extended from entry interface. Nevertheless, there was a program, P66, ready to revert attitude control to the RCS thrusters should P65 sense that deceleration had dropped sufficiently low. If the spacecraft did not rise out of the atmosphere, as was the case with Apollo 1 l’s skip, then P66 was not used and P65 handed over to P67. If there was a second re-entry, it would be P66 that passed control to P67. In most cases however, re-entry did not include a skip-out phase so P64 handed directly to P67.

In the case of Apollo 11. as they approached Earth on their three-day coast, the weather in the prime recovery area looked increasingly poor so the decision was taken to maintain their trajectory and revise the re-entry flight path to include a skip – out. thereby extending their flight through the atmosphere from 2,200 kilometres to nearly 2,800 kilometres. “1 wasn’t very happy with that,” said Collins at his debrief, "because the great majority of our practice and simulator work had been done on a 1.187 [2.200-km] target point. The few Limes we fooled around with long-range targets, the computer’s performance and the ground’s parameters seemed to be in disagreement. So. when they said 1,500 miles [2.800 kilometres], both Neil and I thought. ‘Oh God. we’re going to end up having a big argument about whether the computer is Go or No-Go for a 1,500-mile entry.’ Plus 1,500 miles is not nearly as compatible. It doesn’t look quite the same on the EMS trace. If you had to take over, you’d be hard-pressed to come anywhere near the ship. For these reasons. I wasn’t too happy about going 1.500 miles, but I cannot quarrel with the decision. The system is built that way and. if the weather is bad in the recovery area. 1 think it’s probably advantageous to go 1.500 miles than to come down through a thunder­storm.”

Apollo missions were always timed to arrive at their planned landing sites soon after sunrise and therefore close to the terminator the line that divides night from day. If the mission had been planned to set down on the eastern side of the Moon’s disk then, from Earth, the Moon would appear as a crescent at the time of landing because the sunrise tenninator would also be to the east. Л western landing site called for a western terminator, at which time the Moon would appear gibbous, or approaching full. In all cases, the spacecraft flew’ over a night-time Moon soon after it lost contact with Earth in the run up to LOI.

Apollo 8 pioneered human travel to the Moon. Its crew’ did not intend to land, but were to reconnoitre an easterly landing site in Mare Tranquillitatis under planned lighting conditions. The flight was limed to have the sunrise terminator near their target which meant that most of the illuminated surface was on the far side. Having approached through ihc lunar night, they could hope to cross the sunset terminator and fly back into daylight around the far side barely five minutes before they were to fire the LOI burn. Frank Borman peered out of a rear-lacing spacecraft, hoping to see some sign of a lunar horizon in order to crosscheck his attitude, even if only by seeing a part of the sky that lacked stars.

“On that horizon, boy. I can’t see squat out there."

Bill Anders suggested that they turn some lights off to help him to see some trace of the lunar surface. As they w’ere flying heads-dowm. their large windows were looking off to the side and below and even though they were fogged, a sunlit lunar surface ought to have been visible. Then Lovell, looking through the hatch window’, piped up: “Hey. I got ihc Moon."

For the first time in the mission, the crew could see shafts of sunlight obliquely illuminating the lunar surface.

"Do you?" asked Anders.

"Right below’ us."

When Anders managed to catch his first view of the forbidding, harsh landscape, he expressed his astonishment. "Oh, my God!"

His commander, wlio was focused on the preparations for the burn, was brought up short by this most uncharacteristic of utterances for a test pilot.

"What’s wrong?" he demanded.

"Look at that!" Anders exclaimed again. But his commander w as more concerned that, at this critical phase of the mission, his crew mates had become distracted by the unreal scenery passing below’.

"Well, come on," said Borman, working to bring the crew back onto the task in hand. "Let’s – What’s, what’s the…" Lovell immediately got into line, calling out the mission time.

"69:06"

"Stand by." commanded Borman. "We’re all set."

For the next minute, the crew’s concentration returned to the cheeks and calls defined in their checklists. Yet with three minutes remaining, Anders’s attention returned to the scenery below’. "Look at that fantastic!"

"Yes," confirmed Lovell.

"See it?" continued Anders. The curious scientist in him was dominating.

"Fantastic, but you know. I still have trouble telling the holes from the bumps."

Borman, whose main responsibility was to ‘keep the troops focused’, had to gently chide his crcwmatcs to keep their eyes inside the cabin.

‘‘All right, all right, come on. You’re going to look at that for a long time."

And they did, while circling the Moon ten times over a period of 20 full and tiring hours prior to the crucial burn that would get them home.

The Apollo 10 crew experienced the same dynamic when LMP Eugene Cernan had opportunities to see out w hile his commander Tom Stafford and the CMP John Young exchanged checklist calls.

"Look at the size of..he exclaimed in the middle of his colleagues’ dry technical checks. "God, that Moon is beautiful; we’re right on top of it…”

"Oh shit!" wfas Stafford’s reaction. Cernan continued. "God dang. We’re right on top of it. I can see it.’’

Stafford began telling Young what was out of his window on the left. "Oh. shit; John! It looks like a big plaster-of-paris cast.”

With less than two minutes to their LOI burn. Stafford’s sense of responsibility reasserted itself. "Ok. let’s get busy," he called to his crew.

For some time, their procedures took precedence until Cernan’s curiosity bubbled up again. "My God. that’s incredible." he said in w’onderment as the very rough, obliquely-lit landscape of the far side slid below.

"It looks like we’re close.” said Stafford.

"That’s incredible,’’ interrupted Cernan.

"It does look like we’re – well, we’re about 60 [nautical] miles, I guess.”

And they w’ere. With only a minute to go. the spacecraft was at its perilune of 110 kilometres and Stafford and Cernan were again getting caught up in the view’.

"Shit, baby; we have arrived – It’s a big grey plaster-of-paris thing…”

"Oh, my God, that’s incredible," Cernan interjected.

"Okay, let’s keep going; we’ve got to watch this bear here,” said Stafford, referring to the strength of the engine about to keep them in the Moon’s arms. Eventually, it w’as the ever-cool Young w’ho reeled the moonstruck Cernan back in.

"Put your head back in the cockpit. Genc-o.”

"Look at that!” was the final spurt of wonder that came from Cernan before he settled dow’n to monitor the health of the engine on which their lives depended.

Each crew’ reacted differently to their initial view’ of the Moon. Apollo ll’s crew’ were very focused during their preparations for LOI, making little comment on anything but the health of their ship until the last few seconds before the burn. Then Mike Collins, the most gregarious of the three, threw in an observation: "Yes, the Moon is there, boy, in all its splendour.’’

Neil Armstrong started into conversation. "Man, it’s a…,” before Collins interrupted, "Plaster-of-paris grey to me.’’

Buzz Aldrin felt moved to speak. "Man, look at it,” he said before Armstrong, maintaining the mantle of his command, advised, "Don’t look at it; here we come up to Tig [time of ignition].”

Apollo 11 began its entry into lunar orbit and the crew’ chatted about tank pressures, propellant utilisation and how much their engine w’as moving from side to side as it controlled its aim which prompted them to wonder whether there might be a problem with it. After the burn’s successful conclusion, they concentrated on the follow-up activities; power-down, backing out of the armed status of the SPS engine and setting up the spacecraft for coasting flight again. Only then did any of them relax enough to take in the scene. Armstrong was first to comment; "That was a beautiful burn.’’

Collins agreed, "God damn. I guess."

"Whoo!" exhaled Aldrin. before making an initial window observation. "Well, I have to vote with the [Apollo] 10 crew. That thing is brown."

There had been some debate and contradiction between the first two flights about what colour the Moon appeared to be close up. The Apollo 8 crew had reported nothing but grey, whereas the Apollo 10 crew thought that tans and browns were common. Armstrong and Collins agreed with them but took their observations further.

"Looks tan to me," observed the commander before Aldrin qualified himself.

"But when I first saw it, at the other sun angle.. .”

"It looked grey." interjected Collins.

".. .it really looked grey," Aldrin concurred.

The last word goes to John Young when he arrived at the Moon for the second time on Apollo 16. Soon after their first AOS, Young described his crewmates’ reaction to the scenery: "It’s like three guys, they’ve each got a window, and we’re staring at the ground. Boy. this has got to be the neatest way to make a living anybody’s ever invented.”

Immediately after undocking, the CMP executed a short burn to put some distance between the two spacecraft to avoid a collision. This was a translation manoeuvre in the CSM’s minus-.v direction to back it away from the LM at 0.3 metre (1 foot) per second. Both crews filmed each other and, especially on the early flights, the CSM would station-keep to allow the LM to be visually inspected and its landing gear verified.

Now flying as separate spacecraft, two important checks had to be made before the LM would be allowed to fly away from the safety afforded by its mothership. The first check looked at the main engine that would control the descent to the Moon, including the control system that throttled its thrust. The second check exercised the rendezvous radar that would be crucial to navigate a return to the CSM. ~

Six minutes into Apollo ll’s descent. Duke came up with a time for the crew. "Six plus 25. throttle dowm.”

“Roger. Copy,” said Aldrin.

‘’Six plus 25.’’ reiterated Armstrong.

Houston had calculated that they could expect the engine to start to throttle 6 minutes 25 seconds into the descent. It was part of a clever strategy that engineers had come up with to w’ork around the engine’s forbidden throttle settings in its high thrust range. They arranged that P63 should compute a course to a spot 4.5 kilometres short of the landing site. In some cases, strangely enough, this point could be below’ the surface but this didn’t matter since P63 never took the LM anywhere near it. This profile had been chosen to achieve two goals. First, it protected the engine from the erosion that would result from the forbidden throttle settings. Second, it yielded nearly optimal efficiency. The profile called for an initial thrust level that w as higher than the engine could achieve, to which the engine responded with its constant high thrust setting that is, 92.5 per cent of maximum, referred to as the fixed throttle position. For about 6.5 minutes of the burn, the spacecraft continued to lose speed and gently arc towards the surface while the engine continued in its high thrust setting. Hvenlually, the thrust required to achieve the profile fell below 57 per cent of maximum whereupon the program’s logic permitted the engine to move into its allowable throttle range which lay between 65 and 10 per cent of maximum. For the remaining 2.5 minutes of P63’s work, the computer could control the throttle and adjust it as necessary to compensate for any errors and drive the spacecraft’s trajectory towards an optimal flight path.

"Wow! Throttle down," called Aldrin. joyfully.

“Throttle down on time,” said Armstrong.

“Roger." said Duke. “We copy throttle down."

“You can feel it in here when it throttles down," noted Aldrin. "Better than the simulator." The crews had intensively simulated the descent, but the one thing the simulators could not provide was the g-force provided by the engine.

Navigation on the lunar surface was of no concern to Armstrong and Aldrin. They never ventured more than 60 metres from the LM. But as the crews of Apollos 12 and 14 made their H-mission traverses it became increasingly difficult to tell where they were as they roamed further on foot to locate features of scientific interest that geologists had identified from aerial photographs. At close quarters, the lunar surface is remarkably homogenous, especially on the plains. Huge areas consist of little more than large, time-worn craters pockmarked with smaller craters, all covered with a ubiquitous layer of grey dust and shattered rock.

The issue came to a head as A1 Shepard and Ed Mitchell set off to reach the rim of Cone Crater, their primary scientific target. Seen from above, Cone was a majestic 1,000-metre-wide hole in the ground but it was surrounded by a landscape that, at a human scale, w7as unrelentingly undulating. Worse, they had to climb a rough slope to reach it and since from their perspective atop the ridge the far rim of the crater was lower than its near rim, it would remain invisible until they were almost at its edge. It had been thought that the crater would have a raised rim that would make it easy to locate.

“Okay. We’re really going up a pretty steep slope here,” puffed Mitchell as his heart rate peaked at 128 beats per minute.

“Yeah. We kind of figured that from listening to you,” said Fred Haise in Houston. The heart rate of Shepard, a much older man at 47, had just risen to 150 as the effort of their climb and the frustration of their inability to locate the rim of Cone began to tell.

As the two laboured up the ridge, they pulled a little hand cart, the modular equipment transporter (MET) which was the engineers’ answer to the shortcomings of the hand tool carrier. It not only provided a place for the tool carrier, it allowed a much larger range of tools to be taken on a walking traverse as well as cameras, film magazines and sample bags; and it permitted a greater weight of rock to be returned to the LM. The MET rolled along on two rubber tyres pressurised with nitrogen. It was of some surprise to the crew that the wheels did not throw up rooster-tails of dust, but rather formed smooth ruts in the soil that reflected the Sun when viewed into the light. Included with the MET was a magnetometer to measure the local magnetic field at points along the way to Cone. Its sensors were mounted on a tripod which was deployed on the end of a 15-metre cable. After allowing time for the unit to settle, readings were gathered from a unit on the MET itself.

"I thought the MET worked very well." said Shepard alter the flight. "It enabled us to operate more efficiently than we would have otherwise.”

Mitchell agreed. "’We would have been in real trouble trying to move all that stuff out with just a hand tool carrier, and still get the same amount of work done.”

Thick soil and an increasing incline were adding to their difficulties. "The grade is getting pretty steep,” warned Mitchell, clearly breathing heavily. "And the soil here is a bit firmer, 1 think, than we’ve been on before. We’re not sinking in as deep."

"‘That should help you with the climb there.” said Haise encouragingly.

"’Yeah. It helps a little bit.”

Shepard had another way of making the climb easier.

"’Al’s got the back of the MET now, and we’re carrying it up. I think it seems easier.”

"Left, right, left, right,” prompted Shepard as he tried to quicken their progress up to Cone.

The backup crew of Gene Cernan and Joe Engle were listening in next to Haise. "There’s two guys sitting next to me here that kind of figured you’d end up carrying it up."

“Well, it’ll roll along here,’’ explained Mitchell, "except we just move faster carrying it.”

Always mindful of the need to return before their consumables ran out, and having already awarded a 30-minute extension, mission control enquired of their progress.

"Л1 and Ed. do you have the rim in sight at this Lime?”

"’Oh, yeah,” confirmed Mitchell.

"’It’s affirmative.” said Shepard. "It’s down in the valley.”

But they had misheard ’rim’ as ‘LM‘.

"’Em sorry,” said liaise. ""You misunderstood the question. I meant the rim of Cone Crater.”

"’Oh, the rim. That is negative,” said Shepard. “Wc haven’t found that yet.”

The problem they faced was that they were being fooled by the terrain that surrounded the crater and. by heading for the highest ground, they were being taken south, to one side of their goal. They were not lost in the strict sense of the word. The LM was easily visible from their elevated route and there would be no difficulty in finding their way back. On behalf of mission control, Haise called a halt to the quest. "Ed and Al. we’ve already eaten in our 30-minute extension and we’re past that now. I think we’d better proceed with the sampling and continue with the EVA.”

It was a bitter moment for the two explorers. They had come 400.000 kilometres to the Moon and had laboured uphill for over a kilometre to sample the deepest ejecta from the rim of Cone Crater. The superficial metric of their success would have been to take possibly spectacular pictures that looked across the crater to its far rim.

"It was terribly, terribly frustrating,” remembered Mitchell twenty years later, on how it felt to have seemed to have failed. "Coming up over that ridge that wc were

going up, and thinking, finally, that was it; and it wasn’t – suddenly recognizing that, really, you just don’t know where the hell you are. You know you’re close. You can’t be very far away. You know you got to quit and go back. It was probably one of the most frustrating periods I’ve ever experienced. There’s no feeling of being lost. I mean, the LM is there; we can get back to the LM. It’s not reaching and looking down into that bloody crater. It’s terribly frustrating.”

Like most of the Apollo astronauts, Mitchell came from a high-achieving military background and was used to reaching goals that had been set. This particular goal was also the pinnacle of a crewman’s career and the apparent failure was a blow to a pilot’s pride. But in truth, Apollo 14 admirably fulfilled the scientific task it had been set. Their objective was to gain deep samples from the rim of Cone and since their closest sampling point was later established to be only about 30 metres from the true edge of the 1,000-metre crater, they had, without realising it, been successful.

Scientists had always been vocal that Apollo crews must place high-quality scientific instruments on the lunar surface. After all, many in the scientific community saw manned spaceflight as a sink for funds that ought to go to unmanned craft. If man on the Moon was being shoved down their throats, then at least something useful ought to come from it. Arrangements were made to develop a system of instruments that would work off a common pow’er source and radio system. It was known as the Apollo lunar surface experiments package (ALSHP) and would be deployed on the surface with sufficient radioactively-sourced pow’er to last years. Across 1965 and 1966. principal investigators were recruited by NASA to design the instruments which Bendix would develop and supply. Early plans assumed that the first landing would to have tw’o moomvalks; one to deploy the ALSEP and the other for a geological traverse. However, as the planning for the initial landings continued, it became clear that an ALSEP would not be ready in time for the first crew. There would be a single short moonwalk which w’ould combine the history and ceremony of the moment with a small amount of sample gathering and photography. ALSEP would have to wait for subsequent missions.