"PRESIDENT KENNEDY:" "I believe that this nation should commit itself to achieving the goal before this decade is out of landing a man on the moon and retuming him safely to the earth." "ALDRIN:" "Picking up some dust." "NARRATOR:" "In the 1960s, an impossible dream came true when human beings walked on another world." "ARMSTRONG:" "The Eagle has landed." "NARRATOR:" "In all, 24 Americans went to the moon." "But it took an unseen army of over 400,000 engineers and technicians to make it possible." "This is the story of the men and women who built the machines that took us to the moon." "Washington, D.C., 1961." "And as the implications of Kennedys speech sank in, many of the countrys top aerospace engineers wondered whether it was really possible to get to the moon." "Kennedys speech shocked me, personally." "And I was relatively close to what was going on." "I mean, it was, 'Wow." "Can we conceive of doing this?" "'" "Because we literally hadnt gotten off the ground yet." "SEAMANS:" "The planning in NASA, at that time, said that we should not have, as part of our program, a manned lunarprogram." "We're not ready enough with our rockets and so on to spend any time on it." "NARRATOR:" "But NASA was in a hurry." "And two months after Kennedys announcement, the first Apollo contract was awarded." "It was not for a rocket, butfora system that would guide the rocket to the moon." "MINDELL:" "If you look at all of the prime contracts to build the rockets, to build the spacecraft, to build the capsules, to build the lunarlander, none of those contracts would even be let for months." "In some cases, years." "Thats a measure of the importance that the upper NASA administration saw in guidance." "How are we going to get to the moon?" "...and ran into immediate controversy." "MINDELL:" "There was, actually, a budding industry out there that had developed guidance systems, and people from industry were quite upset." "They felt that they should have been given a chance to bid on the contract, and a university is not ordinarily what the govemment contracts out to build hardware for operational systems." "Here wasa university essentially committing to build a system that was gonna fly to the moon." "NARRATOR:" "But M.I.T. was no ordinary university." "And M.I.T.'s lab no ordinary research lab." "M.I.T.'s instrumentation lab was run by a colorful and charismatic engineer called Charles Draper." "DRAPER:" "An overriding policy in the laboratory is its emphasis on technology of the real world." "MINDELL:" "Draper was this sort of larger-than-life personality." "He had this unique background in psychology and physics, and a lot of people felt that gave him a Kind of special insight into human characters that surrounded these types of technologies." "NARRATOR:" "Bob Seamans was one of Drapers early students." "He said, "You're not gonna have money for the babes", you're not gonna have money for the horses," ""but you'll have an awful lot of fun."" "There wasa big clock on the wall, and he could control the speed of the clock" "And all of a sudden, it would be 5:30, even though your own watch might not say 5:00 yet." "And he'd yell to his secretary, "Marie, come on in." "Its time for drinks."" "[ Engines roar]" "NARRATOR:" "But eccentricities aside," "Draper was a single-minded engineer who had caught NASA's attention with a revolutionary navigational aid." " Hi, Harry." " Hello, Dr. Draper." "NARRATOR:" "He called it an inertial-guidance system, an extraordinarily clever device that, in 1953, had enabled him to navigatean airplane from Boston to Los Angeles without any reference to extemal landmarks." "MINDELL:" "They put this inertial system." "At the time, it was quite large." "It looked like, you know, the size of an atomic bomb or something." "Put it aboard an airforce bomber and flew it all the way across the country." "NARRATOR:" "Chip Collins was Drapers pilot on what turned out to be an eventful 3,000-mile flight." "My job was to get out of the seat and let the system work through the autopilot." "As far as navigation is concemed, we could be flying in a sealed box deaf and blind." "NARRATOR:" "All went well for the first few hours." "Then, towards the end of the flight," "Drapers guidance system suddenly appeared to lose its way." "COLLINS:" "I saw it, and I heard Doc say," ""Hey, Chipper, what the hell's going on up front?" ".'"" "[ Laughs]" "I said, "Doc, I don't know", but the system is commanding a turn to the right."" "Well, there wasa big bustle in the back of people trying to decide what to do next, what was happening." "Here, we were in the 11th hour, and the thing looked like it was gonna go crazy." "NARRATOR:" "Yet, as the plane emerged from clouds over Los Angeles, it was precisely on course." "The guidance system had simply been correcting for side winds." "The system recognized that it was being pushed off course, and it was merely resisting that and doing just what it was supposed to do." "MINDELL:" "By the time they reached their destination, they were within sight of the airport based entirely on this inertial-guidance technology." "Long ways from M.I.T., sir." "Thanks so much for letting us come along." "Maybe one could say this is one small step toward the age of spacecraft." "NARRATOR:" "it was this technology" "NASA now hoped could be developed to take humans not a few thousand miles across America but the half-million miles to the moon and back" "It would be a huge challenge." "Spring 1962." "And as engineer sat M.I.T." "got down to work on the Apollo navigation system, their starting point was the universitys revolutionary guidance technology." "It consisted of a bundle of gyroscopes and instruments for measuring changes in direction." "It looked like a basketball." "Its about that size." "And inside of it are these very, very precise gyroscopes." "And all the gyroscopes do is actually keep the platform perfectly flat and aligned in whats called inertial space." "That means not space relative to the Earth or to the Earth horizon, but out there in some abstract idea of place." "NARRATOR:" "The system was based on the principle that when agyro is set spinning, it remains on a fixed axis, what ever happens around it." "So it provides a known baseline, or platform, against which to calculate movement." "In this demonstration, the gyros are the rock-solid blue cylinders in the center of the spinning chamber." "MINDELL:" "Then, on that platform, are accelerometers." "Theyrea separate instrument that measures the accelerations." "NARRATOR:" "These detect whethera craft is moving forwards or backwards, left or right, up or down, relative to the fixed platform." "If you then keep a record of these movements, you'll always know exactly where you are." "MINDELL: it was really high mechanical technology." "Draper worked, actually, closely with the Waltham Watch Company out in the suburbs of Boston, where he taught his people precision machining." "Mechanical gyroscopes, spinning with ever-higher precision, very low friction, very low wear." "Really, these things were put together like watches." "Like, the most precise watch you can imagine." "NARRATOR:" "Nobody had ever tried to manufacture instruments that would work with such accuracy." "Draper imposed new standards of hygiene and cleanliness." "MINDELL:" "He forbade workers from coming to work and assembling the gyroscopes if they had just come back from vacation in a sunny area and they might have skin flaking off from their suntans." "And he wouldnt allow women to wear makeup when they were assembling the gyroscopes." "NARRATOR:" "The most troublesome component was the gyro's ball bearings." "Even a minute flaw could, over the huge distances in space, lead to major inaccuracies." "Gyro after gyro failed to meet the required standard." "GILMORE:" "People were clamoring on us, our group, saying, 'Well, why are you rejecting these gyros, you know?" "How can you keep rejecting them?" "'" "[Chuckles] And meanwhile, we're saying," ""'Well, we don't trust their reliability."" "It didn't take long to feel like," ""Holy mackerel, where am I?" "' you know?"" "After a couple months, I knew that this was a very big job." "NARRATOR:" "Nobody was sure the new system would ever be reliable enough on its own, and so M.I.T. added a very ancient instrument something sailors had used for hundreds of years to navigate out of sight of land." "Its called a sextant." "Draper built a simulator on the roof at M.I.T." "that enabled astronauts to practice manually checking the inertial-guidance system against the stars." "But the lab would also need to provide one other vital piece of equipment." "Drapers aircraft experiments had used a simple electromechanical device to read the data from the gyros and turn it into flight instructions." "The joumey to the moon would require something much more sophisticated." "They would need a modem digital computer." "Yet to put one of these in a spacecraft was an entirely new challenge." "Computers in the early 1960s were huge." "The idea of squeezing such a monster into a spacecraft seemed preposterous." "Dick Battin was the man who had to do it." "When North American got the job to build the command module, they get on the phone and call M.I.T. and say," ""I understand that there's gonna be a computer"" "in the command module." "How big is it?" ".'" "And we had no idea how big it was gonna be." "Right now, it was just this bunch of equipmenton a rack" "And so we asked around, 'What do you thinK?" "What should we tell them?" "'" "And they said, "Oh, well, maybe a cubic foot." "Lets say its a cubic foot."" "NARRATOR:" "Battin's new computer would draw heavily on a newly emerging technology that used silicon chips." "But the chips were still very new." "Manufacturers were still Ieaming to make them, and nobody was sure of their reliability." "MINDELL:" "One of their tests involved taking all of these integrated circuit chips and immersing them in a bath of freon." "Then they would take them out, and they would dry them off." "And they would weigh them." "And if the weight of the chip came out after the bath of freon just a few micrograms greater than it was supposed to be when it went in, that meant that some of the freon must have gotten into a little hole in the chip." "And somewhere, there was a fault in the chip." "And just those few micrograms would indicate that this chip should be rejected, and the whole batch would be rejected, too." "So that put a lot of tension on making sure every part was built properly and had quality components." "MINDELL:" "What was special about this computer was people had to stake their lives on it." "If this computer failed, if one of the circuits went bad or crashed or had a bug atthe wrong moment, people were gonna die." "And that was really a first, to put people's lives on the line with integrated circuits and hardware." "No one had done that before." "NARRATOR:" "At its height, the Apollo program was consuming 60% of the chips manufactured in the United States." "But even when they were reliable, their processing speeds were so slow there were severe limits to the number of tasks they could handle simultaneously before the computer ground to a standstill." "For a while, it looked as though the technology would never match the needs of landing on the moon." "The man who came up with a solution to the problem was Hal Laning." "LUCKLY:" "Hal was one of the most brilliant people" "I eve rworked with." "He was very quiet, hard to get a word out of him." "He'sa very shy person, it struck me." "Keptout of the limelight." "And it was others who spoke for him and recognized his brilliance." "He was someone who everybody at the laboratory knew about and looked up to as sort of agenius at the laboratory." "NARRATOR:" "Laning remembers wrestling with the difficulty of computer overload." "LANING:" "I think it was a pretty tough job." "I know a lot of meetings were held on the subject of what was expendable, fitting of things together, how things could overlap each other, what liberties you could take." "NARRATOR:" "Laning's answer was a radical but beautifully simple solution that ensured important jobs got priority." "MINDELL:" "The high-technology way to run computer systems in the 1960s was called time-sharing." "And in time-sharing, there were a bunch of different users, or demands on the computers time, and each one got an equal slice of the computers time." "Hal Laning really took an entirely different approach, and that is assigning a different priority to each task" "So, a low-priority job might be updating the display to show the astronauts something that was just sort of an indicator of how it was doing." "A high-priority job is keeping the lunarmodule upright as its moving toward a landing." "And then, if you got into trouble, you could drop the low-priority jobs, keep the high-priority jobs running." "NARRATOR:" "Yet as the computer evolved, there was confusion at NASA." "The technology was so new nobody was sure exactly what it could do." "Should it provide the navigation for the entire mission, or was it primarily an aid to the astronauts?" "Over the course of the 1960s, you see groups of astronauts and groups of engineers at the instrumentation lab really workng together, almost negotiating outa role for the human operator." "NARRATOR:" "it was a fundamental confusion that would, in the years to come, cause serious problems for the newly emerging breed of software engineers." "What Kind of computer programs would they need to write?" "What would they need to do?" "And how many would there need to be?" "In the early 1960s, as work on the Apollo computer and navigation system got underway, software was an almost unknown concept." "I went homeand told my wife that I was in charge of software, and she said, "Please don't tell any of ourfriends."" "[ Laughs]" "It sounded like a real nothing piece of work" "The word was barely invented at the time, and the original contract for the Apollo system says," ""Of course, the instrumentation lab will write the programs that will run the thing."" "It turns out that software became one of the major defining problems of the system." "NARRATOR:" "With nobody clear on exactly what the computer should do, the software engineers were free to write almost anything they liked." "At least at first." "There were no specs." "We made it up." "And its always amazing to me." "Why was I allowed to program something that hadnt even been specified that would be critical in assuring the success of the whole Apollo program?" "I couldnt believe it, but thats the way it was." "We made it up as we went along." "NARRATOR:" "The lack of specifications led to a proliferation of software routines at a time when programs were agonizingly laborious." "Each program was written by hand and turned into punched cards a computer could read." "EYLES:" "If you submitted a job during the daytime, it was likely to be hours before your output would appear on the table outside the computer room." "KOSMALA:" "We could stand there and watch it and wait for it to come out as a line-printer output." "It was maybe 1/8 of an inch thick" "If you screwed up, you got an output that was maybe two feet thick" "NARRATOR:" "But the real problem was not the glut of paper." "It was memory." "The computer simply didn't have much." "EYLES:" "The overall memory for the Apollo guidance computer program was equivalent to 72k" "72 Kilobytes of memory, in modem terms." "NARRATOR:" "Today, a $100 mp3 player has 50,000 times more storage space." "Further more, the computer disks that stored the programs were fragile and unreliable." "The solution today seems extraordinary." "It was called rope memory." "MINDELL:" "You actually had to send the program to a factory, and women in the factory would literally weave the software into this core rope memory." "BATTIN:" "We called it the L.O.L. method - the"Little Old Lady' method - of wiring these cores." "Not a very nice..." "[ Laughing ] Today, you couldnt say that." "NARRATOR:" "Computercode consists of ones and zerces." "In this case, it was a physical distinction." "Margaret Hamilton was one of the very few female engineers on the project." "The rope is made up of ring sandwires." "And if the wire goes through the core, it represents a one." "And around the core, it represents a zero." "NARRATOR:" "it was extremely slow." "One program could take several months to weave." "And if there was an error, it was a nightmare to correct." "The software program was falling dangerously behind schedule." "Everybody was running behind." "We werent the only ones." "But it became more and more nerve-racKing to Houston to see, 'What are those M.I.T. guys up to?" "Are they gonna pull this off?" ".'" "NARRATOR:" "it was becoming painfully clear that everybody had dramatically underestimated the scale of the job facing Drapers lab." "In 1966, NASA sent in a troubleshooter." "MINDELL:" "Bill Tindall starts looking at the Apollo software and ringing alarm bells." "In fact, he writes back to headquarters and says," ""I worry that we might not make the end-of-the-decade deadline for the moon landing because the programs wont be finished."" "Very strong statement when you're building these enormous rockets and you're building launchpads and you're training astronauts, and then a bunch of programs might keep you from getting to the moon on the presidents deadline?" "Very, very unusual situation." "NARRATOR:" "Bill Tindall started going through the lab's work with a fine-tooth comb." "He found widespread duplication in the software that made it grossly inefficient." "It was slow, full of bugs, and was outgrowing the available memory." "He began writing this series of memos from Cambridge, where he would come visit, back to the NASA headquarters which are known to this day as "Tindallgrams."" "They basically said, "M.I.T. is screwing this up."" "Theyre not paying enough attention." "They don't have the discipline of a large organization." "This is not a research project anymore." ""They really have to get serious."" "NARRATOR:" "Tindall started knocking heads together." "Bill Tindall came to the laboratory on Friday the 13th." "Already, it was bad news." "[ Laughs]" "Weall resented these guys coming in here and ripping ourbaby apart." "MARTIN:" "He really put our nose to the grindstone and really kept bird-dogging us." "That is, "This is what you said last week"" "What are you gonna tell me next week?" "You told me it was gonna be ready now." "When is it gonna be ready?" ".' And so on." "And he kept pushing this in our face to the point of being, we thought, extremely arrogant." "NARRATOR:" "As programs were discarded, there wasa whiff of rebellion." "MARTIN:" "People at the instrumentation laboratory, in one case, actually rebelled." "We actually had, I can recall, a meeting where we all got together and actually complained about how difficult it was to work under this environment." "By mid 1966, Drapers dream of an on board navigation system that ran the entire mission had vanished." "MINDELL:" "They now said," "'We will make the navigation from the ground, " primarily."" "'We will use the radio waves as the primary source of navigation." ""And the on board computer will be, essentially, the backup."" "NARRATOR:" "The astronauts would now get their principal navigational data from radio signals from the Earth." "Yet Drapers guidance system would still be their only backup on the farside of the moon, or if the radio signal failed altogether." "But would even the demoted system be reliable enough, and would it everbe ready on time?" "1967." "And with the deadline for landing on the moon getting closer, the instrumentation lab at M.I.T." "was struggling to meet its schedule." "Engineers began to put in long hours." "Too long for some of them." "KOSMALA:" "In my personal case," "I think that contributed to the end of my first marriage." "LICKLY:" "Almost all of us are divorced, ended up doing that." "I don't know that thats directly responsible, but its probably more than a coincidence." "My wife said to the Kids- they were youngish then " ""Guess who's coming to dinner tonight?" ".'"" ""Daddy?" ".'"" "That was their response because it was a fairly rare event that I was home for dinner." "NARRATOR:" "Finally, after one of the hardest years many at M.I.T. could remember, the computer had been squeezed into what looked like a small refrigerator." "And the software had been tested to exhaustion." "In October 1968, Apollo 7 became the first successful manned Apollo mission." "For 11 days, three astronauts orbited the Earth using the sextant to check the automatic guidance system." "It worked perfectly." "It was time to take the next step." "MAN:" "We have ignition-sequence start." "The engines are on." "4, 3, 2..." "NARRATOR:" "On December21, 1968," "Apollo 8 took off from Cape Kennedy and headed into space." "It was going to be the first attempt ever to send men around the moon." "At the Draper Lab in Cambridge, tension was high." "Well, it was more or less unbelievable." "You were trying to think" ""You mean this stuff is all finally going to work?" ".'"" "They kept announcing what the velocity of the spacecraft was." "It was getting bigger and bigger, and I turned to the guy next to meand I said," ""By God, they're really gonna do this."" "Its very hard for me to convey to you at this time the level of excitement in that room." "It was like listening to every syllable of every word that the astronauts might say." "BORMAN:" "Transmission is coming to you approximately halfway between the moon and the Earth." "We have about less than 40 hours left to go to the moon." "NARRATOR:" "As the astronauts headed towards the moon, they checked their position over and over again." "GILMORE:" "Jim Lovell decided that he would show that you could do navigation on board the spacecraft using the sextant." "And he did that many times, actually, and demonstrated it worked extremely well." "NARRATOR:" "Then, as Apollo 8 disappeared behind the moon, all communication with Earth vanished." "Now they would be entirely dependent on the M.I.T. system." "JOHNSTON:" "Everything went blank for a while." "And you had to wait, and you knew when you would pick up their voice again if they were in lunar orbit." "And you know when you'd pick it up if they never made lunar orbit or if they were halfway into lunarorbit, which wouldve been even worse." "We all knew what instance of time they- if everything went right, when we would hear from them again." "MARTIN:" "We just sat there for 45 minutes, waiting to hear whether this was a success or not." "And after 45 minutes, the communication officer at Houston started to call the Apollo spacecraft." "CARR:" "Apollo 8, Houston." "Over." "MAN:" "Apollo control, Houston." "Gerry Carr has placed a call." "We're standing by." "No one answered, and so everyone was pretty concemed." "[Static]" "Finally, just a little bit after we expected to hear from them, there was a voice." "LOVELL:" "Goahead, Houston." "This is Apollo 8." "Burn complete." "Our orbit is 160.g by 60.5." "CARR:" "Apollo 8, this is Houston." "Roger." "Good to hear your voice." "NARRATOR:" "Apollo 8 had re-emerged right on schedule and was back in radio contact." "Seconds later, M.I.T.'s computer relayed back its on board calculation of where the spacecraft was." "It corresponded exactly with NASA's Earth-based calculations." "There was a tremendous amount of relief in the room, a lot of cheering, a lot of satisfaction that what we had produced actually worked." "NARRATOR:" "For the engineers, it was the vindication of years of hard work and broken marriages." "KOSMALA:" "I remember watching it at home, Christmas Eve, 1968." "So I was like a million otherpeople that watched the same flight." "It brought tears to the eyes." "I think its doing it to me now." "Even just sitting at home, watching on a little TV, black-and-white, it wasa'We did that' staggering thought." "NARRATOR:" "But now the computer that had helped them around the moon would have to do something even more demanding." "It would have to land them on the moon." "ARMSTRONG:" "And you're maneuvering, right?" "COLLINS:" "Will be shortly." "NARRATOR:" "July 21, 1969, and Apollo 11 was three days into its mission to land on the moon." "As the lunarmodule separated from the command module Armstrong and Aldrin were 12 minutes from the lunar surface." "They were about to draw on an entirely new software routine never fully tested in space before." "The program without which it would be impossible to land on the moon." "Yet, incredibly, the program had been written almost as an after thought by a junior engineer." "MINDELL:" "If you talk to the guy who really wrote a lot of that software, Don Eyles, here's this 22-year-old guy, gets his first job." "The program is already 2/3 of the way complete, and they assign him to write the programs to do the actual lunar landing." "There was always a trade off of time versus memory." "You could always write something quicker if you could use more space to do it." "NARRATOR:" "it wasnt just brand-new." "It was one of the most complicated routines" "M.I.T. had everwritten." "MINDELL:" "Neil Armstrong said," ""In terms of a scale of 1 to 10 of difficulty,"" "walking around on the moon was about a 3." ""Landing on the moon was a 13."" "it was the most complex series of continuous operations in the entire Apollo mission." "NARRATOR:" "As the lunarmodule dropped towards the moon's surface, everything seemed to be going smoothly." "But then, out of the blue, there was an alarm." "ARMSTRONG:" "Program alarm." "Its a 1202." "ALDRIN: 1202." "When wegot this first program alarm, and that was total news to me." "MAN: 1202 alarm." "MAN#2:" "Yeah, the same thing we had." "Then more of these alarms started to show, and we got extremely nervous." "Everybody in that room, management and programmers, listening to this, not knowing exactly what was happening and not knowing what these alarms were." "Maybe some people in the room knew what a 1202 alarm was, but I don't remember anybody saying, "I know what that is."" "NARRATOR:" "With only seconds to go before landing, the astronauts asked foradvice." "Should they abort the mission or override the alarm?" "ARMSTRONG:" "Give us the reading on the 1202 program alarm." "LICKLY:" "I was panicked." "They were actually going in close to the moon, landing, and they were getting a 1202 alarm?" "No way that shouldve been happening." "NARRATOR:" "As concem spread through mission control, one man put his hand up." "Jack Garman had the only summary of the alarms in the building." "I wrote them down in pencil on a piece of paper." "Every alarm, what it would do." "I taped it to a piece of cardboard and I stuck it under the Plexiglas that was on top of our consoles." "You know, its like an umbrella." "If you carry it, it wont rain." "JOHNSTON:" "We had a nickname forJack" "He wont forgive me for saying this, but we call him "Garflash."" "GARMAN:" "You know, I havent heard that in a long time, but, yeah, Garman, Garflash." "I did tend to react rather quickly sometimes." "NARRATOR:" "Garman's note told him the alarm indicated the on board computer was overloaded." ""Executive overflow," it was called." "That is, the computer did not have enough time to do its work" "Thus, it was overflowing, and it spewed out this alarm." "NARRATOR:" "A normal computer would have ground toa stand still." "But thanks to Hal Laning's revolutionary operating system, the lunarmodule's computer was simply dumping low-priority jobs and carrying on with the important ones." "There was no immediate threat." "Garman gave the okay to land." "MAN#1:" "All flight controllers, go for landing." " RETRO." "FIDO." " MAN#2:" "Go." " GUIDANCE." "CONTROL." " Go." " PHALCON." "GNC." " Go." " EECOM." "SURGEON." " Go" "CAPCOM, we'rego for landing." "Eagle, Houston." "You'reago for landing." "Over." "NARRATOR:" "Yet as the lunarmodule touched down the big unresolved question was, why had the computer overloaded?" "And would it compromise the return journey?" "GARMAN:" "The expression "out of the frying pan, into the fire"" "comes to mind because there was no time to think really, for anybody." "It was time to get on with the check lists and procedures." "MARTIN: it wasnt, I would say, 15 seconds after they landed, we have Houston on the telephone wanting to know, what is that 1202 and 1201 alarm?" "I saw Fred Martin across the room, and our eyes locked." "It was like, "Oh, no." "What is going on?"" "Why are these 1201, 1202 alarms happening?" "'" "She looked at me, and I looked at her." "Not really seeing anybody else in the room," ""but more of registering, 'Weve got to find out what this is."" "MARTIN:" "In all the testing that I had witnessed and all the things that I had witnessed at the laboratory," "I had never seen one of these alarms come up, so I didn't know what it was about." "NARRATOR:" "Eventually, they discoveredt he problem." "Buzz Aldrin's checklist had instructed him to turn on the return radar too early, and the computer had simply been unable to handle that as well as all the immediate landing data." "It was a checklist error." "The computer had worked exactly as it had been designed to." "MAN: g, 8..." "NARRATOR:" "They were safe to return, and after nearly 22 hours on the moon," "Armstrong and Aldrin were given the go-ahead to return home." "ARMSTRONG:" "Very smooth." "NARRATOR:" "2 1/2 days later, with the support of the computer guidance system, the command module crashed through the Earth'satmosphere at precisely the rightangle." "JOHNSTON:" "I had teared up because of that, but I think a lot of people did." "It was the culmination." "That moment was the moment." "As much as Apollo 8 was the biggest step, perhaps, that moment was it." "You know, I remember more about the 1201, 1202 alarms than I do when it finally landed back on Earth." "NARRATOR:" "The relief at M.I.T. was overwhelming." "Everybody was just super happy that we were successful." "And we were super happy." "NARRATOR: it was the end of nearly a decade of some of the most fruitful and creative computer engineering in U.S. history." "For many who took part in it, its still the most remarkable thing theyve everdone." "KOSMALA:" "I spent agood chunk of my life workng hard to produce guidance software that enabled that to happen and that they left behind." "So sitting on the moon is code I wrote." "Thats always been my proud boast." "Something I did is sitting on the moon right now." "That is a neat thought."