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Apollo 12 Summary

From the Apollo Lunar Surface Journal. Reproduced with the permission of Journal editor Eric M. Jones


Table of Contents


Mission Profile

Apollo 12 Animations


A Visit with the Snowman

For NASA, 1969 was a roller coaster year. The first half was full of feverish activity as thousands upon thousands of people did whatever was necessary to make sure that the first landing was achieved. But then, with the triumph still fresh in everyone's mind, it was time to look at what the future might hold in store. Unfortunately, it soon became evident that not only would the feverish pace of Apollo have to slow but also that the program might have to end.

For four years, the NASA budget had been shrinking from the peak it had reached in 1965. A decrease was, of course, inevitable because, during the peak years, NASA had to undertake a number of expensive projects simultaneously. There was the development of the Saturn V, the CSM, and the LM, and the construction of the launch pads and the Vehicle Assembly Building at the Cape and all of the new facilities at Manned Spacecraft Center in Houston. So it wasn't surprising that spending at the 1965 level couldn't be sustained. But there was an expectation that, once the landing was a reality, the budget would stabilize at a level that would let the lunar program continue. And there were even some who thought that a Mars program was in the cards. However, soon after the 1968 election, the incoming Nixon Administration had ordered a review of NASA's list of future programs; and the major implication of that review was that, while the nation had been committed to the Kennedy goal, it was the politics of space that had opened the public purse and not an overwhelming interest in the space program itself. Certainly, President Nixon was no great fan of the program and, now that the race with the Russians had been won, NASA's budget was headed for levels that would not only force long postponements of such cherished dreams as a space station, a lunar base, and missions to Mars, but also threatened the continuation of Apollo itself. In September 1969, the White House announced that lunar exploration would not continue beyond Apollo 20.

Although the Nixon decision was a blow to NASA, the consequences were not all bad. In light of shrinking budgets, NASA immediately announced that the remaining Apollo schedule would be stretched. Money could be saved by conducting launches only twice a year. Salaries and other personnel costs dominated the NASA budget and, by stretching the schedule, the agency would have to employ only enough people, particularly at the Cape, to prepare and perform one mission at a time. Stretchout also meant that planners, engineers, scientists, and astronauts had more time to assimilate experience and data between missions and, as well, it gave NASA a chance to complete hardware and procedures modification that would make the last few missions spectacularly productive. Of great importance were LM design changes which would allow an increase in landing weight from eight tons to nine and that, in turn, meant that the LM's flown late in the series would be able to carry an electric-powered, wire-wheeled dune buggy called the Lunar Rover, and also greater stores of oxygen, cooling water, and electric power for longer visits. The combination of the Rover and an expanded-capacity backpack would let the crews stay on the Moon long enough to conduct three 7-hour EVA's and, during each of them, venture as far as ten kilometers from the LM.

Early in Apollo, NASA sketched out a sequence of missions which would lead to the first landing. "A" missions were unmanned tests of the launch vehicles and the Command Module; "B" missions were unmanned tests of the LM; "C" missions (Apollo 7) were manned, earth orbital tests of the Command Module; "D" missions (Apollo 9) were LM/CSM tests in earth orbit; "E" missions (none were flown) were tests in high earth orbit; "F" missions (Apollo 10) were lunar orbit tests; and the "G" mission was the landing. In 1968, NASA added three other mission types to the list: "H" missions (Apollo 12, 13, and 14) would be subsequent flights to other landing sites using the basic equipment; "I" missions (none flown) would be lunar orbit-only science flights; and "J" missions would be the longer visits that LM design changes would make possible. With Rovers at their disposal, each of the J-mission crews would be able to visit a variety of geologic features scattered around the local countryside, collect far greater quantities of rock and soil than walking astronauts could hope to carry, make use of an impressive number of tools carried on the Rover, and also give the research teams back on Earth a mobile experiment platform. In general, the J-missions promised a significant increase in productivity. However, before such impressive missions could be attempted, NASA had to demonstrate that crews could achieve pinpoint landings, work a full-day in the stiff suits and, if necessary, walk several kilometers back to the LM from a disabled Rover.

Site Selection

Pinpoint landings were essential for a number of reasons. First, geologically-interesting places were usually rugged and, quite naturally, tended to have few good landing spots close at hand. The chance of a successful mission into rough terrain would increase dramatically if targeting errors could be reduced down to the LM's maneuvering range of several hundred meters. Second, the site selection committees were eager to pick places rich in geologic variety. An accurate landing at a carefully pre-selected spot would allow the crews to visit a maximum number of features without spending excessive amounts of time driving from place to place. Third, pinpoint landings would allow the crews to train for specific EVA activities and, among other things, thoroughly familiarize themselves with landmarks and planned traverse routes. With crew time on the surface at a premium, there was much to be gained by minimizing the amount of improvisation caused by targeting errors. And finally, professional pride on the part of the flight crews and spacecraft designers demanded accuracy. The Mercury and Gemini astronauts relished splashdowns within sight of the recovery ship and now, much to their delight, they were going fly a truly maneuverable spacecraft to specific spots on the Moon. The Moon might not have runways or landing pads, at least not during Apollo, but that didn't matter. The targets were well-defined. Relative accuracy and, therefore, bragging rights could be claimed.

For Apollo 12, the site selection committee picked an interesting spot on the Ocean of Storms (Oceanus Procellarum), about 1500 kilometers west of Tranquillity Base. Although, as Don Wilhelm's details in To a Rocky Moon, the Apollo 12 site wasn't the first choice of the geologic community, it did have several things going for it. First, it was a reasonably level site. There were a number of large craters surrounding the target point, but otherwise the area presented no more in the way of hazards than those that Armstrong and Aldrin had faced. Second, the astronauts would be able to collect rocks and soil samples from another of the great lunar plains and, most interestingly to the geologists, from a place covered with ejecta from the young, prominent crater Copernicus which lies some three hundred kilometers to the north. And third, with an eye toward a dramatic demonstration of pinpoint targeting, if Apollo 12 Commander Pete Conrad and his shipmate Alan Bean landed close enough, they would be able to walk over to the Surveyor III spacecraft and even bring pieces of it back to Earth.

On April 19, 1967, the Surveyor landed on the inner slope of a fairly large crater, a fact which greatly reduced the immediate photographic return but which, ironically, made identification of the precise landing spot a relatively easy matter. From trajectory data, NASA knew where each of the Surveyors had landed to within a mile or two but, because each of the spacecraft was no bigger than a modest-sized lunar boulder, unambiguous identification in orbital photographs was all but impossible. However, details in the Surveyor photographs could be compared with details in the Lunar Orbiter pictures so that, in principle, the landing sites could be pinpointed. Ewen Whitaker, now retired from the University of Arizona's Lunar and Planetary laboratory, was a member of the Surveyor team and had the responsibility of identifying the landing sites. As the first pictures came in from Surveyor III, it was immediately apparent that the spacecraft had landed in a crater. It was a relatively featureless crater but there were a number of good-sized rocks scattered around, particularly to the north of the spacecraft. One pair of large rocks looked as though they were almost touching each other and it seemed to Whitaker that he might be able to find them when he started to examine the appropriate Orbiter pictures through the microscope. Within a couple of days, he was sure he had them; the rocks looked like mere pinpricks through the microscope, but there were other rocks visible as well and they made a pattern which matched up nicely with the Surveyor III pictures. Whitaker had found the crater.

A couple of years later, when the Apollo site selection committee was looking for a good place for the first precision landing, the Surveyor III site came easily to mind. Along with the other factors, the site offered NASA engineers a golden opportunity to examine spacecraft parts which had been exposed to lunar conditions for a relatively long period of time - thirty one months in this case - information which would someday be of use in designing space stations and lunar bases. If all went well, Conrad and Bean would be able to visit the Surveyor, photograph it, and then strip off a few components to bring back to Earth.

Surveyor Crater is a member of a distinctive cluster of craters. When viewed from the approach trajectory, the cluster looks not unlike a Snowman, with Surveyor Crater forming the fat torso. By using Lunar Orbiter photos and, as well, photos returned by the prior Apollo crews, NASA was able to construct a fairly realistic model of the landing site so that, during training in the LM simulators, the view out Conrad's window - actually a TV picture of the model - looked enough like the real thing that, at pitchover, Conrad would have a comfortable sense of deja vu.

Achieving the Pinpoint Landing

On landing day, November 19, 1969, Pete Conrad and Al Bean were in fine spirits. At launch from Earth, they'd had a scare when lightning struck the ascending Saturn V and tripped virtually all the circuit breakers in the Command Module. It was a heart-stopping experience for people on the ground; but the crew stayed calm, the Saturn V kept them going toward orbit, and, in a matter of minutes, they had everything back on line. There was no permanent damage; and the flight to the Moon and the preparations for the descent were otherwise unremarkable. As pitchover approached, Conrad strained forward against his harness, trying to get a view of the horizon. He'd caught glimpses of the Moon's central highlands as he and Bean swooped down, feet first, toward the Ocean of Storms, and as they got closer, he couldn't wait to find his target.

"I'm trying to cheat and look out there," he said. "I think I see my crater."

He wasn't absolutely sure but, seconds later, at pitchover, there was no doubt. "Hey, there it is! There it is! Son-of-a-gun! Right down the middle of the road!"

Bean glanced up and saw the Snowman, too. "Outstanding!", he said. The scene looked just like it had in the simulator. There was the Snowman,. Indeed, it seemed for a moment that Intrepid was going to land right in the center of Surveyor crater.

Conrad was delighted. "I can't believe it! Amazing! Fantastic!"

Bean fed him the numbers and, at four hundred feet altitude, Conrad took over manual control. He'd picked out a good spot west of the crater and short of the Snowman's Head beyond. He angled north to fly around Surveyor Crater and then south to avoid another, far shallower feature. There were very few boulders in the area and, as they got lower, the LM exhaust began kicking up a lot of dust. During the last few moments, Conrad lost sight of the ground and had to rely on his simulator training to make a blind touchdown.

Although Conrad was sure of where he was going to land during the approach, once he was down he wasn't sure exactly where he was. He'd lost track of the landmarks while he concentrated on rocks that he could see through the dust so that he could see if he was moving left or right, forward or back. But he knew he was close, certainly within a couple hundred meters of the target.

"I See the Surveyor!"

During the first few hours after landing, while he and Bean had a quick meal and began preparations for the first of two 4-hour EVA's, Conrad spent more than a little time trying to figure out just where he'd landed. It was a bit of a puzzle. The landmarks which had been so obvious during the approach weren't at all obvious from the ground. Looking west out the window, he and Bean saw an undulating and otherwise featureless plain. Among other things, there was no obvious sign of the Snowman's Head. Head Crater is about two hundred meters in diameter and should have been right in front of them. However, as they became accustomed to the subtleties of the view, they began to realize that there was, in fact, a big crater practically staring them in the face. They hadn't recognized it because they were back a bit from the east rim and were looking directly away from the early morning sun. There was a shadow in the bottom of Head Crater, but it was hidden by the near rim. There was also a lack of color variation in the scene and that, too, made the crater hard to see. However, once they realized that there was a big crater in front of them, they quickly decided that it had to be the Snowman's Head. If so, then Surveyor Crater had to be right behind them. Conrad jammed himself forward against his window as tightly as he could, probably wishing he had a rear window or at least a rear-facing mirror, and tried to peer as far around the back as possible. He was rewarded with a glimpse of the telltale slope of another large crater.

Fittingly, it was Dick Gordon, traveling overhead in the Command Module Yankee Clipper, who nailed down the landing coordinates. As he made his second post-landing pass, he put his eye to the sextant in hopes of getting a glimpse of the LM, a feat that Collins had never managed. Of course, Gordon had a real advantage in that he knew where Intrepid was supposed to be. As he picked up the Snowman, it wasn't long until he spotted the LM's fifty-meter shadow.

"I have him," he said. "He's on the Surveyor Crater; he's about a fourth of a Surveyor Crater diameter to the northwest...I'll tell you, he's the only thing that casts a shadow down there."

In seconds, he was directly overhead. "The Intrepid is just on the left shoulder of the Snowman. He is looking at me. He is about a third of the way from the Surveyor Crater to the [Snowman's] Head."

Then he really got excited. "I see the Surveyor! I see the Surveyor! Hey! That's almost as good as being there."

Now there was no doubt. Not only had Gordon seen the LM but he'd seen the Surveyor itself. Conrad and Bean had landed right on target and, thanks to Ewen Whitaker, they'd even been sent to the right crater! This was going to be fun.

"That May have been a Small One for Neil..."

With the pinpoint landing accomplished and confirmed, the next task was to get the backpacks on, get outside to set up the science gear, and, if there was any time left before they had to get back in the LM for a rest period, take a short stroll around the area. Conrad and Bean were a pair of relaxed, happy astronauts. They wouldn't be mentioned in most history books but that didn't seem to matter. If anything, it took some of the pressure off. They laughed and joked, pleased with the situation and eager to get started. As Conrad told Houston, "Man, I can't wait to get outside."

Although they'd gotten a bit behind the planned timeline while trying to figure out where they'd landed, Conrad and Bean were models of efficiency once they got started donning the backpacks. With luck, the process could be completed in under two hours and that's just about how long it took. They made a few minor mistakes when, out of eagerness, they occasionally relied more on memory than on the detailed checklists. However, thanks to the checklists, they were able to get back on track after only a few minutes of wasted effort. Finally, about four-and-a-half hours after touchdown, they made one final check to be sure that they had good, airtight suits and then radioed Houston for permission to depressurize the cabin.

"Houston, are we Go for EVA?"

"Stand by, Intrepid. We'll be right with you," said CapCom Edward Gibson.

Conrad couldn't quite believe what he'd just heard. "Stand by?! You guys ought to be spring-loaded!"

But, of course, Houston wasn't going to keep the explorers waiting long. Once all the status boards had been checked a final time, the Gibson radioed permission. "Intrepid, You're Go for EVA."

Pete Conrad is not a tremendously tall person. The one-meter jump down from the bottom rung of the ladder had always seemed a bit intimidating, but now it gave him a chance to set the tone for the mission. The time for historic phrases had past; now it was time to have fun. "Whoopie!" he said as he made the plunge. "Man, that may have been a small one for Neil, but that's a long one for me." (Readers interested in the story behind this episode should consult either the Apollo 12 Lunar Surface Journal or Andy Chaikin's A Man on the Moon.)

Bean soon joined Conrad on the surface and, once they'd both had a chance to get used to walking and a chance to savor the sight of the Surveyor sitting so close by, they got busy deploying the scientific gear. As on Apollo 11, there was a TV camera, a seismometer, and a laser reflector. And they also had a more-sophisticated solar-wind analyzer and a number of other physics packages that made up the ALSEP (Apollo Lunar Surface Experiments Package) that had gotten bumped off Apollo 11. Most of the equipment, together with a central power station and transmitter, was stowed in two compact packages tucked away in the Descent Stage. Bean lifted them down with a pulley and attached them to the ends of a carrying bar - which would double as a radio antenna mast - in dumbbell fashion. The complete ALSEP weighed 250 pounds on Earth, but only about 40 pounds on the Moon, and Bean had no particular trouble hauling the load to the deployment site about one hundred fifty meters west of the LM. The two experiment packages tended to bounce up and down as he walked and that made gripping the bar a little difficult; but, generally, he and Conrad had very few problems with this first major set of tasks.

Equipment Troubles

Apollo 12 marked the first lunar deployment of an electric generator powered by the decay of a tiny plutonium source. This thermal generator provided 75 watts of continuous power to the scientific equipment and, therefore, a continuous stream of data to the experimenters back on Earth. During the flight to the Moon, the source had been stored snugly inside a well-shielded cask designed to keep the radioactive fuel element intact in the event of an unplanned entry into Earth's atmosphere. Once they got to the Moon, Bean had the job of removing the plutonium source from the cask and inserting it into the generator but, much to his dismay, after he pulled it partway out, it stuck and refused to budge any farther. After a few minutes of fiddling with the long-handled removal tool, Bean got frustrated and suggested that they give the cask a couple of good whacks with the hammer. Conrad wasn't quite ready to be so unsubtle and wanted to try using the hammer as a prying tool. But, when that didn't work either, he, too, gave in to the inevitable and gave the cask a good, sharp rap. The fuel element slid out a fraction of an inch. He hit it again and harder. And again. And that did it.

The lesson? "Never come to the Moon without a hammer."

A second equipment problem involved the electric cables which connected the various units to the Central Station. Although the cables were fairly stiff, on Earth they tended to lie flat to the ground, held down by their own weight. However, on the Moon, the cables hardly seemed to notice the weak gravity and retained loops and bends they had acquired during storage inside the LM - loops that stood up from the ground rather like sections of a frozen garden hose. There were no disastrous tripping episodes during Apollo 12, but the need to dodge cables slowed the work.

Avoiding cables was a matter of watching one's feet or, from a more practical point of view, of watching the other guy's feet. The suits were bulky enough that, although the astronauts had to lean far forward to balance, they rarely saw their own feet and had a tough time keeping clear of obstacles. The suits also slowed the work in other ways. Because the inflated suit was stiff, it was difficult to flex the knees enough to kneel. The most practical way to grab or manipulate objects close to the ground was to use long-handled tools. However, the tools themselves were sometimes awkward to use and, as Conrad commented, it all would have gone a lot quicker had they been able to reach down easily. It was only later, during the second EVA, that he and Bean discovered a couple of handy tricks.

Within three hours of leaving the LM, the astronauts had finished deploying the scientific equipment. They had gotten about a half an hour behind the nominal time line but were otherwise well pleased. They were both relaxed - with heart rates dipping down into the 80s - and Conrad would have whistled while he worked, had whistling been possible at 3.7 psi suit pressure. The only thing that had gone really wrong during the EVA was the loss of the TV camera. This was the first color TV camera to be landed on the Moon and, unfortunately, it quit working while Bean was moving it away from the LM. As was suspected at the time, he accidentally pointed it at a bright reflection off the LM and burned out the target in the vidicon imaging tube. As Bean said in technical debriefings with the engineers once he got home, the root cause was the fact that he hadn't been able to train with an actual flight camera. Development of the camera had lagged and NASA took delivery just a short while before the launch. In the interim, Bean had trained with a mockup and never paid attention to the camera's limitations. Fortunately, the loss of the TV wasn't critical from a technical point of view. Conrad and Bean both took plenty of photographs. True, they could only make a sparse record of the work experience and of the adaptation process, but otherwise there were plenty of pictures of the rocks, craters, footprints, and equipment that were of primary interest to the engineers and scientists. Nonetheless, things were going so well and the crew was obviously having such a good time - joking, laughing, humming, and singing - that the lack of a picture was a real frustration to those of us who had taken the Wednesday morning off from school or work to watch the coverage.

Investigating the Mounds

With the ALSEP deployment finished and with plenty of oxygen and cooling water in reserve, Houston gave Conrad and Bean a half-hour extension so that they could make their way to the boulder-strewn rim of nearby Middle Crescent Crater, a short, seventy-meter jaunt north and a little west from the ALSEP site. It had to be a quick trip because the flight controllers wanted them back at the LM in about twenty minutes, ready to start close-out. Still, this was the crew's first chance to put their geology training to use.

When Conrad first went out to the ALSEP site to scout out a deployment area while he waited for Bean, he had noticed a couple of meter-sized, conical mounds and was eager to take a look. Were these volcanic features? Or something else? On their way out to Middle Crescent, Conrad and Bean finally had a chance to take a close look and they quickly decided that the mounds were probably big clods of compacted soil which had been thrown out by the Head Crater impact. They took pictures and collected a few samples and then moved on. Along the way, they found beads of glass lying out on the surface, and, at Middle Crescent Crater, hints of bedrock exposed in the inner walls. Twenty minutes didn't give them much time for careful consideration or comment; it was very much a matter of jog, stop, take a minute to marvel, take a few pictures, grab a sample, and jog again. But the hurried pace didn't really matter. If nothing else, the jaunt gave them some practice for the serious geologizing they would do during the second EVA. And, besides, it was all fun. Indeed, it took several reminders from Houston before they started back to the LM.

On the way back to the spacecraft, Conrad and Bean made good time, covering the two hundred meters in about five minutes. Despite a couple of stops to pick up irresistible rocks, they managed a net speed of about 2.5 kilometers per hour. On the second EVA, they planned to extend their range to about 400 meters and the short run proved that, should something need tending in the spacecraft, they'd have no trouble getting back in a hurry. Their heart rates had risen to only about 120 beats a minute and, although they were both a bit tired, they clearly had plenty of physical and mental reserves. They were happy and pleased with their performance.

Trying Out the Hammocks

After a four-hour, one-minute EVA, the crew of Intrepid repressurized the cabin and removed their helmets and gloves. They would have preferred to get out of the pressure suits for the night, especially since Conrad had inadvertently gotten some cooling water in one of his boots. However, as was demonstrated by later crews, doffing the suits would have taken nearly an hour and getting them on again the next morning another forty minutes or so. Their time on the Moon was limited and an hour and a half represented a sizable fraction of the total. More importantly, NASA and the crews were not yet ready to risk the chance of damaging zippers and other seals during doffing and donning. So they left the suits on, had a meal and a chat with Houston about second EVA, and then, about three and a half hours after closing the hatch, put covers on the windows and wished Houston "nighty-night." Purists might complain that the Sun wasn't about to go down. After all, local sunset was still a good ten days away. But the astronauts weren't purists. Their biological clocks said it was time for sleep; so it was "nighty-night" until the next day's wake-up call.

Conrad and Bean didn't sleep well. The hammocks and the heater made for an easier night than the Apollo 11 crew had, but nobody had been able to do anything about the excitement. Bean took a sleeping tablet but it didn't help much. In the morning, Conrad reported that they'd gotten about five hours of sleep but, in reality, they'd hardly slept at all. An hour ahead of the scheduled wake-up call, it was they who called Houston. They were eager to get outside again. After a quick meal, they got busy preparing themselves, their suits, and the LM for the day's activities. Two and a half hours after calling Houston, they were out on the surface.

A Circular Geology Traverse

EVA 2 was to be a long, circular geology walk that would take them around the west side of Head Crater, and then southwest to a small, fresh impact feature called Sharp Crater. From there, they would walk east to a point on the southern rim of Surveyor Crater opposite the LM, and then make their way down to the Surveyor itself before climbing back up to the LM. In all, they planned to cover about 1300 meters, the equivalent of walking the first four or five holes of a public golf course.

During the entire second EVA, Pete Conrad was like a man possessed, constantly aware of the timeline and the list of tasks yet to be done, single-minded in his determination to complete everything on the checklists that they wore on their sleeves. He knew that they would have to keep moving. Not counting the time they took to load the backpacks with tools and sample bags before heading out, nor the time they spent packing up and dusting each other off before they climbed back in the LM, the traverse itself lasted about 2 hours and 45 minutes. Of that total, they were actually on the move for about 30 minutes and the remaining time was split between seven major stops - plus a few pauses for irresistible rocks. On average, they had about twenty minutes at each location. There were pictures to take, samples to collect, cores to drive into the ground, and even the occasional shallow trench to dig and, unfortunately, there never seemed to be enough time to suit Al Bean's sense of wonder. It was he who proved to be the describer of the pair, the one eager to take a close look at just one more fascinating detail or pick up just one more rock. As he said at the time, he could easily have spent the whole EVA at just one of the stations. But there wasn't time, especially not with Conrad - with occasional help from Houston - urging him on.

Conscious of the time line, they moved quickly from one site to the next and, once they arrived, were in constant motion as they turned to take photographic panoramas, manipulated tools and the sample bags, and did their best to grab rocks without having to bother with the tongs. With practice, they found that they could kneel, after a fashion, if they used the tool carrier or a shovel as a crutch, but getting up again took a fair amount of effort. Bean discovered a clever, unintended use for a sturdy sample bag tied to Conrad's backpack. Midway through the EVA, he realized that he could use it as a kind of toddler's harness or belaying rope to steady Conrad as he reached down for a rock. These and other little tricks that they learned along the way let them get the work done more efficiently. As a measure of that efficiency, during the first EVA they used about as much cooling water as had been predicted prior to the mission. During the second EVA, they used about 30 percent less than the predicted amount.

Although Conrad and Bean became more efficient as they went about their work, the one thing that they couldn't do anything about was the soreness that they began to feel in their forearms. Because the suits were pressurized, the glove fingers were necessarily stiff and hard to move. The engineers had made a good-faith attempt to minimize the problem by designing the gloves with the same shape as the relaxed human hand - that is, with the fingers curved slightly inward. At the very least, it was thought, the design would give the astronauts a chance to relax their fingers from time to time. However, with the fingers in the "relaxed" position, there was an opening of three to four inches between the tip of the thumb and the tip of the index finger. Consequently, if they wanted to grip anything smaller than the opening, they had to close their hands against the internal pressure in the suit. On this second EVA, with tools and other gear to carry, Conrad and Bean had their hands closed almost constantly. In relatively short order, the muscles in their forearms began to ache. They could and did rest their hands from time to time and eventually learned to pace themselves so as to minimize the ache. Still, it was a significant problem and, had their arms not begun to ache so badly, they would have had even greater gains in efficiency.

Both Conrad and Bean were fit and certainly were in no danger of wearing themselves out. They could stop, take a rest, and, if necessary, drop an item or two from the activity list. Throughout most of the traverse they both had heart rates in the range of about 110 to 130 beats a minute. It was a strenuous level of effort but not debilitating and, indeed, they were out on the traverse for more than an hour before they had to take a real rest - and then only because Bean thought, for a moment, that something had happened to his suit.

About midway through the EVA, after a two-hundred-meter, three minutes run eastward from Sharp Crater, Conrad had to call for a stop. Bean was ready for a rest, too, commenting that it was the first time during the mission that he'd really "worked up a heart rate". They had been moving quickly, at an average pace of about 4 kilometers per hour, enjoying the long, floating strides that lunar gravity made possible. At one point, Conrad said that he felt like a running giraffe filmed in slow-motion. But, with their heart rates reaching 160 beats per minute, they were getting winded and needed a moment's rest. During Apollo 17, on several occasions Jack Schmitt ran similar distances at 5 to 6 kph; but there was an important difference in that Schmitt didn't get nearly as winded. Indeed, on one memorable occasion, with his heart rate in the 120-130 beat range, Schmitt ran so comfortably that he sang in full voice. As it turns out, the big difference in performance was due to the fact that the Apollo 15, 16, and 17 crews wore suits with a redesigned waist joint that let them bend more easily. The design was changed so that they could sit on the Rover; but, as an added benefit, it let them run with relative ease. With the stiffer suits, Conrad and Bean needed a brief stop for rest and some sampling. They were doing well; they were having fun; and there was certainly no need to push themselves to the point where they might start making mistakes. That was a sin that neither of them wanted to commit. They stopped, caught their breath, and then moved off again at a slower pace. They had learned an important lesson.

Mare Geology

During the first part of the traverse, Conrad and Bean had gotten glimpses into the structure of the soil beneath their feet and the way that it had evolved. They had landed in the middle of the Ocean of Storms, an ancient mare or "sea" which had formed about four billion years ago when a basin - carved into the lunar surface at an earlier time by a very large impact - began to fill with basaltic lavas rising from the lunar interior. The lava flowed on and off for perhaps a few hundred million years, gradually creating a smooth, level plain. And then, slowly over the years, a steady rain of impacting objects had created a layer of soil - more properly, a layer of finely pulverized rock called the "regolith" - that was a few meters thick.

Throughout its history, the Moon has been bombarded by debris left over from the formation of the Solar System, a bombardment that continues even today, albeit at a much reduced rate from what it once was. There have been impactors of all sizes - dust motes, sand grains, pebbles, fist-sized rocks, boulders, and even the occasional projectile the size of a mountain. The large objects hit only rarely and made correspondingly large craters which, on average are well separated from one another. Small impactors hit more frequently because there are many more of them, and there isn't a square centimeter of the Moon that hasn't been blasted repeatedly by sand-grain-sized objects.

All of the impactors, large and small, hit with speeds of 20 kilometers per second or more and, in the beginning, they chipped and shattered the surface of the hardened lava sea. Collectively and gradually, they built a layer of rubble. Successive impacts churned the rubble layer down to a depth of about five meters, breaking up the rock and making smaller and smaller fragments. And, all the while, the smallest impactors - the dust motes and sand-grains - collectively sandblasted rocks exposed on the surface and ground them down to a powder that gives the lunar soil its characteristic, ash-grey color. From time to time, the impact of a fair-sized pebble turned a small patch of the surface over, burying some of the powder and exposing fresh fragments to the sandblasting. Gradually, over four billion years, most of the upper five meters was converted into a fine grained soil.

In recent times - say back over the last few hundred million years or so - most of the tiny impactors have struck the powdery soil itself. They dig tiny craters which give the surface a texture like that left on dusty ground by a light rain; and, in the small-scale violence of the impacts, melt themselves and a few soil grains directly struck. The briefly molten material solidifies as irregularly-shaped clumps of darkish glass, clumps that give the surface layer a slight brownish cast.

For the most part, the appearance of lunar soil varies surprisingly little from place to place. There are few surfaces that aren't covered with fine soil; and, everywhere, the soil bears the imprints of craters of all sizes, most of them old and worn, with their circular outlines barely discernible beneath the overlapping effects of subsequent impacts. Here and there, there are fresher impacts and, at Apollo 12, there are none so fresh as Sharp Crater, a hole about 3 meters deep and 12 meters across which was dug out just a few million years ago by the impact of something about the size of a basketball. During the planning stages for Apollo 12, the crater's relative youth made it intrinsically interesting because, among other things, the crater and its ejecta would not have been disturbed very much by later events. The geologists wanted to know if there were indications that the Sharp impact had reached to the base of the soil layer. Seismological signals of such local phenomenon as astronaut footfalls, the impact of jettisoned backpacks, and the bounces of rocks thrown into craters would give indications of the depth of the soil at the ALSEP site; and the presence of rock fragments around young craters big enough to have reached bedrock could provide direct visual evidence. Significantly, the photographs taken by Conrad and Bean show relatively few rocks in the Sharp ejecta blanket, and there were certainly not enough rocks in the ejecta to elicit comment from either Bean or Conrad. At the place where Sharp formed, the regolith was probably deep enough - perhaps 6 to 8 meters - that only a few rocks were brought to the surface. Later in the EVA, they visited Block Crater and saw a lot of bedrock fragments there.

While Conrad and Bean were at Sharp, what did catch their attention was the bright, nearly white color of the fine ejecta and, as they approached the rim, the increasingly soft footing. Both the color and the footing were direct results of the violence of the impact. The impact broke the little clumps of dark glass, giving them the color and appearance of a shattered windshield; and it also tossed and churned the soil so that, when it fell, it took on the consistency of a freshly-poured pile of sand with grains balancing precariously on one another. Given enough time and exposure to the rain of small impactors, the Sharp ejecta will become darker and firmer, with each tiny impact creating a bit of dark glass and disturbing the balance of a few grains enough that they tumble into closer contact with their neighbors. That is, unless we decide to protect the area from further erosion by putting a large dome over the entire area as part of an Apollo 12 Landing Site Museum.

Surveyor Crater, itself, is old and very worn. As Conrad and Bean approached the subtle rim, they found that, like the ground near the LM, the soil was well compacted. There were only a few rocks in evidence - all of them rather small and either tossed into the immediate area from some distance away or from Block Crater on the north wall of Surveyor. Although the impact that made Surveyor Crater was certainly big enough to have reached bedrock, eons of erosion and filling had long since buried the evidence. On the inner slopes, the soil was just as dark as on the surrounding plain; and, based on their observations from the first EVA, the astronauts expected that the footing would remain good as they descended into the crater.

Examining Surveyor III

The Surveyor spacecraft sits about halfway down the eastern slope of the crater, having bounced and slid a short way as it landed. Just on the off-chance that the spacecraft was ready to slide a bit further, Conrad and Bean decided to walk down the southern slope to the Surveyor's level and then approach it by following a contour line. They had no intention of approaching it from below. As they made their way down the ten-degree slope, they found that the soil was only a little bit softer than on the rim; and, as they turned east, the only difficulty they had to report was that the slope made it harder for them to bounce from foot to foot. They simply couldn't move as fast as they could on level ground. Conrad even decided that the surface was firm enough that, had he known about it ahead of time, he might have been able to land Intrepid on the broad, flat bottom of the crater.

"It would have scared me to death," he said; but he thought he could have done it.

As the astronauts approached the Surveyor, they were surprised to find that the once white spacecraft had, apparently, turned light brown during its three years on the Moon. This was a real puzzle. The Sun was bright to be sure, but could the paint have changed color so quickly? Was Houston sure, they asked, that the spacecraft had, like the mock-up they'd used in training, been bright white when it left Earth? It took Houston a few minutes to find somebody willing to swear that the Surveyor had originally been lily-white, and by then Bean had noticed that even the camera mirrors appeared light brown. Could it really be a coating of dust? And why brown? All of the dirt in the area was distinctly grey. The only way to find out was to wipe the mirror - which came clean - and then wipe a patch of paint. Although some of the paint flaked off when Bean wiped it, it was soon obvious that, although Conrad had landed about 200 meters away, a little bit of the dust he'd kicked up with the LM engine had made it all the way over to the Surveyor. The astronauts walked around the spacecraft, trying to see if Sun angle made any difference in the apparent color. It didn't. In thin enough layers and with the right background, lunar soil looks brown.

For about forty minutes Conrad and Bean examined the robot spacecraft and the marks it had made when it landed. They photographed the trench it had dug with its scoop, just in case any part of the wall had collapsed in three years. None had. Then they used a big bolt cutter to remove the TV camera, the scoop, and a couple of other parts to take back to Earth.

By the end of the stop, they had been out of the LM a bit over three hours and, in large measure because of Conrad's determination to "cover ground", they were only about ten minutes behind schedule. With only one station left, they were in great shape.

The last stop, at Block Crater, was rather brief. It was an important stop because the impacting object - again about basketball size - had hit on the inner slope of Surveyor Crater. As firm as the soil is on the inside of Surveyor Crater, it isn't as thick as it is out on the level plain, and the Block Crater impactor easily punched through to bedrock. There were rocks and boulders lying all over the place, some of them up to a meter across, and the astronauts had no trouble filling a bag with representative samples. Then it was back to Intrepid for close-out.

In two EVA's, Conrad and Al Bean spent 7 hours and 45 minutes outside the LM. Except for the loss of the TV right at the beginning, theirs was about as flawless a performance as anyone could have wanted. They accomplished virtually all of the mission objectives. They brought back to Earth a treasure of photographs, rocks, soil, and Surveyor parts; and they demonstrated both that the LM could be landed with precision and that a four-hour EVA was nowhere near the limiting workday for a well-trained astronaut. Once, during the second EVA, they pushed themselves a bit harder than the flight surgeon liked and were in need of a short rest. But they recovered quickly and proved that, at least in this terrain, with occasional rests they could walk a long way. It would have been nice to have a sip of water from time to time and bite to eat; and, certainly, they could have gotten a bit more done if they'd had a hand cart - or better yet - a Rover on which to load tools, containers, and other gear. But this was only the second landing mission and, just as Apollo 12 represented a decided leap in operational complexity over Apollo 11, further leaps were in store. Once the LM had been modified to carry the Rover and supplies for longer stays, productivity could increase even more. The limits were nowhere in sight.

And, finally, Apollo 12 was particularly noteworthy in that Pete Conrad and Al Bean simply had a lot of fun. In large measure, the contrast with Apollo 11 was a matter of personalities. Neil Armstrong's quiet reserve versus Pete Conrad's joyful mirth. But, then too, Armstrong and Aldrin had to work in an atmosphere of intense public scrutiny, constantly aware of the attentions of a global audience and of history. Unfortunately, the relative formality of Apollo 11 created a lasting impression of lunar exploration for a great many people. Pete Conrad and Al Bean had no such weighty matters to restrain them and they hummed and sang and laughed their way from station to station. It is regrettable that the TV camera was damaged. The accident was understandable; but, no matter what the root cause, soon after the loss, the TV audience and the broadcast networks abandoned the mission. Shrinking audiences were probably inevitable after the drama of the first landing. The press of time forced the use of jargon and there were certainly long periods when the astronauts were doing little more than bagging yet another piece of rock. As entertainment, it could be pretty deadly at times. But, all in all, Apollo 12 was a lot of fun and a lot of it would have been well worth watching.


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Copyright © 1995 by Eric M. Jones. All rights reserved