Arguably, it could only have happened when it did.
Astronaut John Young, who would go on to become the commander of the first Space Shuttle flight, was standing on the surface of the moon during the Apollo 16 mission in April 1972 when he heard the news that Congress had approved vital funding for the development of the shuttle in its budget for fiscal year 1973. He reportedly jumped three feet into the air on the lunar surface upon hearing the news.
The Space Shuttle would be the most complex piece of machinery built by humankind. It was an incredible challenge and a daunting undertaking. At another point in history, a decade earlier or even a decade later, it might have seemed too challenging, too ambitious. But the project was born when men were walking on the moon. From that perspective, anything was possible.
It would be, far and away, the most versatile spacecraft ever built. But to many of the early astronauts who were involved in its creation, it was something even more fascinating—an aircraft like no other. Talk to the astronauts brought in as pilots during the 1960s, and there’s a fair chance they’ll refer to the orbiter as “the airplane.” Many of them will talk about its development not in terms of rocket engines and life-support systems but in terms of avionics and flight control systems. They had been pilots, many of them test pilots, and they had come to NASA to help the agency fly capsules through space. But now—now they were aircraft test pilots again, helping to design an aircraft that flew far higher and far faster than any aircraft before.
Since the selection of the first astronauts, members of the corps had been involved in the development of new spacecraft and equipment, providing an operator’s perspective. These were the people who would have to use the things that the engineers were designing, so it was their job to give the engineers feedback on whether the things they were designing were actually usable. For much of the time the Space Shuttle was being developed, most
of the astronaut corps was grounded, with only a dozen flying between the last moon landing in 1972 and the first shuttle flight in 1981. As a result, there was plenty of opportunity for astronauts to be involved in the development of the shuttle, and they participated more in the development of this vehicle than any before.
Even so, there were some at nasa with the idea that the moon would be just the first step into the solar system, who were concerned about what the shuttle wouldn’t be able to do—go beyond Earth’s veritable backyard.
In January 1973 astronaut T. K. Mattingly was assigned to be head of Astronaut Office support to the shuttle program. This was around the same time that the contracts were being awarded to the companies that would be responsible for making the shuttle’s various components. Mattingly, who had orbited the moon on Apollo 16 while Young was walking on it, recalls talking to Deke Slayton, the head of flight crew operations at nasa’s Johnson Space Center (jsc) in Houston, Texas, about the assignment. “When I got back from Apollo 16, Deke asked me, he said, ‘You know, there’s only one more flight, so if you really want to fly again anytime near-term, you might want to take the backup assignment on [Apollo] 17,’ he said. ‘Chances aren’t very good, but we do know that we replace people occasionally. So if you would like to have that chance, you can do it, or you could work on the shuttle program.’ Really, I hadn’t paid much attention to it,” Mattingly said of the shuttle program at that point.
I kind of knew the work was going on, but I didn’t know what it was, because my ambition had always been—I didn’t think I would go to [walk on] the moon, but I was really hoping that I’dget to be on the Mars mission, which I was sure was going to happen the following year. To a young kid, it just seemed obvious that the next step is you go to the moon, then you sharpen your tools and you go to Mars, and I thought, “Boy, that’s where I’d like to go. ”
Even by then it was becoming obvious that that wasn’t really a likely proposition. I wasn’t enthused about the shuttle because I still thought going to Mars was the next step. I believe that we needed to build a space station first so we could have hardware, which would gather years oflifetime experience while we could get to it and fix it, and we could build the transportation system while we’re gaining the experience with a space station. All of that architecture was obviously politically driven, and they were having to fit into a tighter budget.
There really was not a great swell of emotion or enthusiasm for things following Apollo in the political arena, nor in the public arena, for that matter. So I think they had to walk some very, very tight lines in order to keep the program going, and so they chose the Space Transportation [System] as the way to go.
George Mueller, the head of manned spaceflight at NASA during the Apollo program and the man many recognize as the father of both the Sky – lab space station and the Space Shuttle program, said that, even with the development of the shuttle, human exploration of other worlds remained the ultimate goal. “It became clear that the cost of getting into orbit was the driver for all future programs. I began to think about, how do you get the cost down. In air travel, you can’t fly from here to London and then throw the plane away when you get to London. What we came up with was a completely reusable vehicle. We had every intention of going back to the moon. What we were doing was going into low Earth orbit and establishing a base there; it was a requirement for reaching our long-term goal.”
Former Johnson Space Center director Chris Kraft recalled the approval of the shuttle as “a real come-down for NASA.”
We, the powers that be at NASA, had grand visions of going back to the moon, having bases on the moon, and on to Mars. They made very significant reports on what the future of NASA could and should be. But when the Nixon administration decided that the limitations of the budget in his [thepresident’s] mind would not allow us to do those kinds of grand things in space, that’s when the powers that be in NASA decided, well, what is the one thing that we need to start the next generation of spaceflight? And that is we need a cost-effective launch system. That’s the first thing we need. If we’re going to go into orbit and do grand things, or if we’re going to put things in orbit and rendezvous and go other places, what we need is a good truck. We called it a truck, at times. And so that’s how we arrived at that being the next step in the space program being a reusable, therefore fly-back vehicle. We signed a fixed-price, seven-and-a-half – billion-dollar contract to build the Space Shuttle, and that was to be provided with annual increases in the budget for inflation. We never got the first piece of inflation at any time in the history of the budget of the shuttle. They welshed on that guarantee immediately, and furthermore, they delayed the program a year and did not give us any relief on the total cost, on the total fixed cost. They didn’t want the money in the budget that year, just that simple. So in the history of the shuttle program, up until we made the first flight, we were always pushing a bow wave of being behind budget.
Many in the astronaut corps had doubts as to what the shuttle decision would mean for the future of exploration. Mattingly considered leaving nasa completely, believing he would probably never leave Earth orbit again.
I went up to pay courtesy calls to the navy after we got back, and John Warner was then secretary of the navy, and we made a courtesy call to him. He was all enthusiastic. He says, “You navy [astronaut] guys need to come back, and we’ll give you any job you want. You pick it. Whatever you’d like. You want a squadron? You want to do this? Just tell me. It’s yours. ” Boy, my eyes lit up, and I thought, “Wow. ” One of my escort officers was a captain in the Pentagon. He went back and told his boss, who was the chief of naval aviation, what Warner had said, and very quickly I had an introduction to the chief of naval aviation, who made sure that I understood that despite what the secretary had said, in the environment we were in, I was not going to come in and take over his squadron. He’d find a place for me, he’d give me a useful job, but don’t think that with the Vietnam War going on and people earning their positions the hard way, that I was going to walk in there and do that. He says, “The secretary means well, but we run the show. ”
So armed with that piece of information that if I went back on real navy duty at that point I was probably not going to find a particularly rewarding job, I thought the opportunity to get in on the shuttle at the beginning and go use some of the experience we gained would be useful, so I told my sponsor I’d do whatever the navy preferred I do. After all, they gave me my education and everything else that mattered. “So you tell me, but if I had a vote, I would say why don’t I stay because the shuttle program’s only going to take four years. ” That’s what we were advertising. You know, four years, that’s not all that long. So after a significant amount of discussion within the navy side ofthe Pentagon, they said, “Okay. Well, we agree. You probably can contribute more if you stay there. ” So that lead me to stay with the shuttle program, and so the beginning of that was a period of a great deal ofthe turmoil of getting started.
Step one of designing a Space Shuttle was deciding exactly what a Space Shuttle should be designed to do. Its official name, the Space Transportation System, summarized a basic part of the requirement. The shuttle would transport astronauts and cargo from the surface of Earth into space and back. It also was to be, as much as possible, reusable. The idea was that creating a spacecraft that was as reusable as possible would cut down on what had to be built for each launch, and thus on the cost of each launch. Lower the cost of putting a pound of material in orbit, and you can put more pounds of material in orbit. The space frontier opens up.
“We had a general idea of what specifications the shuttle was supposed to be, but in those days it was substantially larger and more aggressive than what we know today,” Mattingly said. “So we went through this requirements refinement where everybody broke up into groups to go lay out what they had to do, and it evolved into something we called design reference missions. Rigidly, the idea was, we knew the shuttle was going to last for decades, and we knew nobody was smart enough to define what those missions that would come after we started were going to evolve into. So we took great pride in trying to define the most stressful missions that we could.” Mattingly said the program initially outlined three types of possible missions. One was for the shuttle to be used as a laboratory. “We laid out all the requirements we could think of for a laboratory—the support and what the people need to work in it, and all that kind of stuff,” Mattingly recalled. A second type of mission was defined as deploying a payload on orbit. “That was to be one that launched and had the manipulator arm and cradles and all of the things necessary to do that.”
Then there was the idea of a polar mission. Such a mission would involve putting the shuttle in a polar orbit—leaving the launch site and heading into a north-south inclination that would cause it to orbit from one pole to the other. A satellite in polar orbit would be able to fly over any point on the surface of Earth—a valuable capability for intelligence gathering. “The polar mission was really shaped after a DoD [U. S. Department of Defense] requirement,” Mattingly said.
The original mission, as I recall, was a one-rev mission. [A “rev" is essentially one orbit around Earth.] You launched, got in orbit, opened the payload bay doors, deployed a satellite, rendezvoused with an existing satellite, retrieved it, closed the doors, and landed. And this was all going to be done in one rev or maybe it was two revs, but it was going to be done so that by the time anyone knew we
were there, it was all over. Well, we worked on that mission and worked on it and worked on it, and finally it became [two different design reference missions]. We just couldn’t figure out how to do it all on one short timeline.
The military design reference missions were a response to a political exigency NASA had learned to deal with during the 1970s. Most notably, in developing the Skylab space station, nasa found itself competing for funding against the air force, which was seeking money at the same time for its Manned Orbiting Laboratory program. Although the two programs were very different in their goals, they shared enough superficial similarities that Congress questioned why both were necessary. With the shuttle, nasa hoped to avoid a repeat of this sort of competition, and have an easier sell to Congress, by gaining buy-in for the idea from the military. According to astronaut Joe Allen,
Leadership in the early 1970s decided the only way the Apollo-victorious NASA would be given permission to build a reusable space transportation system is that there be identified other users for the system other than just the scientists. This nations leadership identified the other users as the military. The Space Shuttle would be used to carry military payloads. The military has its responsibilities, and they said, “All right. If our payloads are going to go aboard, we do have one requirement; that is that your Space Shuttle be able to take the payloads to orbit, put them there, and land back at the launch site after making only one orbit of the Earth. ”
The need for quick, polar missions greatly affected the design of the shuttle, yet interestingly the Space Shuttle never flew a polar-orbit mission. “At face value, that doesn’t seem all that difficult to do,” Mattingly said of the polar-orbit missions,
but what it meant was, the shape of the orbiter went from being a very simple lifting body-type shape, with very, very small wings, to a much larger vehicle with delta-shaped wings. I don’t know the exact numbers, but the wings that go to orbit and come home again [make up a large portion of] the weight of the vehicle, and they’re never fully used; only the outermost wingtips are used. All that vast expanse—with all that tile, and all the carbon-carbon [carbon-fiber – reinforced carbon] along the leading edge—is never used. It would be used if it were to go to space in a polar orbit and then come home. It would be used to gain the fifteen hundred miles of cross-range that one needs because the Earth moves fifteen hundred miles in its rotation during the time you’ve gone once around. So you have to have some soaring ability. That’s what these large wings are for. The Space Shuttle would have cost much less money. It would cost much less to refurbish each time. Still, it would not be an economic wonder, but it would be economically okay, were it not for these huge wings. Of course, that requirement, in hindsight, was never used, was never needed, but the current Space Shuttle will forever be burdened with these wings.
Mattingly also said that the design missions established the capabilities that the Space Shuttle system would need to have. Each specification let to a variety of trickle-down requirements, and gradually the vehicle began taking shape.
These requirements we set really had some interesting things. Some of them were politically defined, like you’ll land at any ten-thousand-foot runway in the world. That’s all it takes. In selling the program, they had to appeal to just every constituency you could find to cobble together a consortium of backers that would keep the program sold in Congress. People don’t recognize how that ripples back through a design into what you really get, and, of course, by the time you know what you’ve got, the people who put those requirements in, they’re history. So it’s interesting. But that ten-thousand-foot runway requirement set a lot of limits on aerodynamics and putting wings on the airplane. The cross
range—that was the airforce requirement for this once-aroundpolar mission abort—that sized the wings and thermal conditions. That precluded us from using a design called a lifting body that the folks out at Edwards [Air Force Base, California] had been playing with and had demonstrated in flights. It was structurally a much nicer design, but you just couldn’t handle the aerodynamic characteristics that were required to meet these things. So we had a vertical fin on this thing and big wings, and it’s a significant portion of shuttle’s weight, and the maintenance that goes with it is attributed to the same thing.
Mattingly had the unique vantage point of watching the shuttle program evolve from a concept through logistical support into its mature state, he recalled. “I look back and I say, ‘Well, we know what we started to do, and we know what we have, and they’re not always the same. Why?’ Because it was an extraordinary job. Apollo was a challenge because it was just so big and it was audacious, and time frame was tight, and all of those things.” But in many ways, Mattingly said, the shuttle was even more challenging.
Essentially, it was so demanding that all of the engineering and ops [operations] people. . . generally stayed on. We didn’t have a lot of technical attrition after Apollo. At least that’s my impression. At least the middle-level guys all stayed, and they kept working it because they recognized that the shuttle was a far more challenging job than Apollo in many technical senses.
The part ofthe shuttle that was different was Apollo was a collection of boxes. If you had a computer, you could build it, you could test it, you could set it out and do it all by itself. You had a second stage. You could build and test the whole thing by itself. Well, with the concept of this reusability and integration, you didn’t have anything until you had everything. There was no partial thing. There was nothing that was standalone. I remember we were trying to buy off-the-shelf tacans [Tactical Air Control and Navigation systems], an airplane navigational system, and as part of this integration process, rather than take the tacan signal that an airplane generated in those days and used for navigation, we stripped it all out and put in all our own software so that this off-the-shelf tacan box was absolutely unique. There was nothing else. And it was part ofthe philosophy of how we built this system.
Despite the areas where the shuttle fell short of the original requirement – based specifications, Mattingly said NASA ended up with a very robust and versatile vehicle because of how ambitious the original discussions were. “At
4- Possible configurations considered for the Space Shuttle, as of 1970. Courtesy nasa.
the time we were doing this and putting all these requirements on there, we were actually, I think, quite proud of having had the foresight to look at all of these things. Today you can hardly think of a mission. . . you’d like it to do that it can’t do. It is an absolutely extraordinary engineering piece, just unbelievable. The shuttle really did fulfill almost all of the requirements that we were tasked to put into it.”
The shuttle went through a variety of widely different configurations during its early development. An inline version would have had the orbiter on top of a more traditional rocket booster, which would use parachute recovery to make it reusable. Another version would have had the orbiter launched atop essentially another space plane that would fly back to a ground landing site.
Discussions were held as to whether the primary fuel tank, which ended up being the external tank, should be inside the orbiter or not. There were trade-offs, according to Chris Kraft, the Johnson Space Center director at the time. Putting the tank inside the orbiter would have required that the orbiter be much larger but would have greatly increased the reusability of the shuttle system. However, Kraft said, the ultimate limitation was the difficulty of designing an integrated vehicle that wouldn’t suffer substantial damage to the fuel tank during landing.
Another major issue that had to be figured out early on was what sort of escape system should be provided for the crew. The Mercury and Apollo capsules both had powerful solid rocket motors in the escape towers at the top of the vehicle that would have been capable of lifting the spacecraft away from the booster in case of an emergency. “From the get-go, we tried desperately to put an abort system on the shuttle that would allow us to abort the crew and/or the orbiter off of a malfunctioning solid rocket or malfunctioning ssmes [Space Shuttle main engines],” Kraft said.
Originally we tried putting a solid rocket booster on the ass end of the orbiter, and the more we looked at that, the more we could not come up with a structural aerodynamic qualification and weight that would accomplish that job. We looked at putting a capsule in the structure of the crew cabin, making it something that would separate. We looked at the possibility of putting a capsule in the orbiter, at the structural problems of attaching a capsule, getting rid of the front end, making it strong enough, making it aerodynamically sound, building a control system that would allow it to descend under any and all Mach numbers. And we decided if we do that, we can’t build a Space Shuttle. We cant afford the mass, and we don’t think we could build it in the first place.
So the answer to that question was, we will use the solid rockets that we have as our escape system and fly the orbiter back to the launch site if we have an abort. So we said to ourselves, the solid rockets have to, once you release them from the pad, bust those bolts on the pad, it has to be 100 percent reliable. And
SPACE SHUTTLE VEHICLE
5. An early depiction of the Space Shuttle identifies major components as the orbiter, the three main
engines, the external tank, and the two solid rocket boosters. Courtesy nasa.
we always assumed it was, and any decision we made could not screw around the reliability of those solids. So our abort system was the solid rockets and a return to launch site, rtls;you could fly that orbiter back.
Kraft said critics gave nasa a hard time about the shuttle not having an escape system. “I always thought that was unfair as hell,” Kraft said. “I don’t think they understood the system. And if you ask them over there [at nasa] today, I guarantee you won’t find five people who understand that’s what we did. But we did have an escape system, we had the solid rockets and the fly-back capability. Now, it didn’t save the Challenger, and nothing would have saved Columbia. But those two accidents were created by the fallacies of man, not by the machines.”
Recalled astronaut Charlie Bolden of the rtls abort:
While a lot of us flew a lot of them in [simulation], I’m not sure any of us ever believed that that’s something you really wanted to do. This was a maneuver in which something goes wrong shortly after liftoff, and you decide you’re going to turn the vehicle around and fly it back to the Kennedy Space Center. And the computer’s got to do that, so the software really has to work. It’s crazy, because
you’re going upside down outbound, and all of a sudden you decide you’re going to go back to Kennedy. And while you’re still flying downrange, you take this vehicle and you pitch it back over so that it’s flying backwards through its own fire for several minutes. What has to happen is the computer has to calculate everything precisely, because it’s got to flip it over, have it pointing back to the Cape while it’s flying backwards, so that just before the solid rocket boosters burn out, it stops the backwards downrange travel and starts it flying back to the Cape. And then once that happens, then the solids cut off They separate; they go their way, and then you fly back for a few minutes, for another six minutes, and the main engines cut off and you separate from the external tank. And that became a very tricky maneuver, because what you’re worried about was reimpacting with the tank, and if you did that, you were dead. So it’s a maneuver that. . . nobody ever wants to fly it, because just, it’s like, boy, this is really bad if you have to do this.
Once the general requirements were outlined from the mission baselines and the general type of vehicle was decided, work began on figuring out how exactly to design a spacecraft that would meet the requirements. Making the process particularly interesting was the fact that the shuttle was a collection of very diverse elements that had to be designed to work as an integrated system. The orbiter, for example, ended up with engines that, by itself, it couldn’t use because they had fuel only when the orbiter was connected to the external tank. The diameter of the external tank is another example of the integrated approach used in designing the entire shuttle system, according to retired NASA engineer Myron “Mike” Pessin, who spent the bulk of his career working with the external tank. Taken as a single element, there is no reason for the tank to have its 27.6-foot diameter. There was a constraint to the diameter of the solid rocket booster, however—it would have to be transported by rail from Utah to Florida, and so it was designed with a train’s dimensions in mind. That diameter determined the length of the boosters, which in turn established the range of locations for the explosive bolts that connected the boosters to the external tank. Given that engineers wanted to keep the connecting bolts off of the liquid hydrogen and liquid oxygen tanks inside the external tank, they were able to establish exactly how long the structure would need to be to make that possible. Since they knew how much fuel the tank would need to hold, they could use the volume and the length to determine the needed diameter. Thus the diameter of the external tank was indirectly determined by the dimensions of the train that would be carrying the solids.
Another important part of the shuttle system design process involved computer technology that had evolved substantially since the development of nasa’s earlier manned space programs. “Now we get into the hard part of, okay, now we know the requirements, how do you make this all happen?” Mattingly said.
And that all settled down certainly after Skylab, and maybe even after astp [the Apollo-Soyuz Test Project]. Then we started working. I remember Phil Shaffer was designated as the lead for pulling together all of our software and stuff. Because the shuttle is such a highly integrated vehicle, it has the [software] architecture that makes the system run, and then it’s got all of the applications which are the heart of the vehicle. And so we were building all of this from scratch, and in Apollo we were astounded we had computers. I guess Gemini had a little computer, and then Apollo had something which, by today’s standards, your wristwatch is far more powerful than what we had those days. But we were still astounded with what you could do with these things. Now we were going to build this shuttle with these computers and they’re going to be its lifeblood. There wont be a lot of direct wire. Everything goes on a data bus, and this was all relatively new for most of us.
It meant learning a whole new design process, and we learned that the software was the pacing item. We blamed it on software. When we think ofdeveloping software, we think of it as coding, “if/or " statements and counting bits, but in fact the massive amount of energy went center-wide into collecting the requirements— what does it have to do, write it down, and then see if you can package it, before anybody could start worrying about building. That was an extraordinary operation. Phil drove that thing. I’m sure if Phil hadn’t been there, there would have been somebody that could have done it, but I have a hard time imagining anybody that could have done it the way he did. He just had the extraordinary personality and insight. He knew all the key players from the Apollo days, and they just set out and they went to work, and they really made the program go.
In spite ofall the delays that the shuttle program experienced—and we generally tended to blame that on truncated budgets, maybe some more money would have held the schedule a little better—the best I could tell, we were working as fast as that group of people [could]. It was such a massive job, and it just took so long to get everybody educated up to the same level, because it was all integrated. I don’t think when we started anybody knew that it was going to be such a challenge, and so we learned to do those things and went through it. This doesn’t sound like a CB [Astronaut Office] perspective, but. . . a little more than half[of the astronauts] were working the engineering side, working on the development ofthese things and trying to look ahead to see what was going to be required as part ofgetting started.
“We not only wanted to land on ten-thousand-foot runways, but we were going to be an airline,” Mattingly said, explaining that since the shuttle would be a reusable aircraft with, ideally, a short turnaround time, nasa decided to turn to airline officials for help with how to do that.
So people went out and got contracts with American Airlines to teach us how to do maintenance and training, and we had people come in and start giving classes on how you give instructional courses and how we do logistics [in] the airlines. For a couple of years, we studiously tried to follow all that, and finally after a good bit it became clear that, you know, if there is anybody that’s going to explain this to someone, it’s going to have to be us explaining it to ourselves. That’s where it evolved back into the way we had done things in the earlier programs.
Developing the systems was very much a group effort, Mattingly recalled.
I remember when we first started building the flight control schematics. Those are the most magnificent educational tools I’ve ever seen. I’ve never encountered them in any other organization. I don’t know why. I used to carry around a couple of samples and give them to people and say, “This is what you really need." And they’d say, “Oh, that’s all very interesting," and then nothing ever seemed to happen. But working with people to put those drawings together, and then understand what they meant and develop procedures and things from, was a massive effort. During those days the Building 4 [at Johnson Space Center] and the building behind that, where flight control teams had some other offices, the walls were just papered with these things. People would go around, and they’d walk by it and look at it, and they’d say, “That’s not right. "They’d draw a little red thing on it and say, “See me. "And it was an evolutionary process going on continuously.
The shuttle was built with redundant systems. The idea was it should be able to suffer loss of any piece of equipment and still be able to fly safely. It was called “fail op, fail safe,” meaning that one failure wouldn’t affect normal operations and that a second failure could affect the way the vehicle operated but not its safety.
That generally led to a concept offour parallel strings of everything. And that was great, but now how do you manage it, and what do you do with it? Now, a schematic has all of these four strings of things, sometimes they’re interconnected, and you could study those things, you’d pull those long sheets out, and you go absolutely bonkers—“Oh no. This line’s hooked to that. I forgot that." Trying to figure out how this all works. So you’d go get your colored pencils out, and you’d color-code them. By now the stack of these things is building up, and I’m really getting frustrated in doing this dog-work job just before—I had to spend many, many hours for each drawing to get it sorted out before you were ready to use the drawing. So I said “We’ve got to take these things and get them printed in color, right offthe bat."
And so my friends in the training department said, “Well, you’re probably going to have to talk to Kranz about that. He’s not that enthusiastic about it." I thought, “Oh God." So I got an audience with Gene and went over and sat in his office and explained to him what we were doing in trying to get the training program started and how we were trying to get ready to do that, and I really wanted to get these things printed in color so that it would make it easier for people. I knew color printing would be a little more expensive, but it would sure save a lot of time. He said, “No. We’re not going to do that." I was just overwhelmed. I said, “Gene, why?" He didn’t say a word, he just turned and looked at his desk, and there on his desk, right in the corner, was this big mug filled with colored pencils. And he says, “That’s how you learn." And so that was the end of the story. I don’t know, I’ll bet today they’re still black and white. But that was Gene’s method of learning, and he figured that by having to trace it out, he had learned a lot, so he felt that others would benefit from that exercise. Even if they didn’t appreciate it, they would benefit.
The process of how the orbiter cockpit was designed would produce rather interesting and, in some cases, counterintuitive results, Mattingly said. He was part of a working group on controls and displays with fellow astronaut Gordon Fullerton, which made decisions about the center console.
If you sit in the orbiter, the pilot and commander are sitting side by side in the center console. It was one of the few places when, if you put on a pressure suit, . . . you could see and touch. I mean, you can see the instrument panel. Stuffup here gets really above your head, gets really hard to see. It’s in close, so it’s difficult for some of us older people to focus, and you cant see a lot. You have to do it by feel, which isn’t a good thing to do with important things. So the mobility was small, and this was prime real estate. We all knew it. As we went on with the program, every time someone said, “Oh, we’ll just put this here [in the center console]," we’d say, “No." We’d have a big office meeting. We’d all agree that, no, that’s not that important. We can put that here, we can do this. Well, after working on this thing for years, there’s practically nothing that’s important on the center console. We kept relegating everything to somewhere else, and it’s now the place where you set your coffee when you’re in the [simulator]. We protected that so hard, and poor old Gordo fought and fought for different things, and we’d think something was good, and then after we’d learn about what it really did and how it worked, we’d say, “No. You don’t need that."
Then there was the question of how the Space Shuttle would fly. Each airplane flies slightly differently, or feels slightly different to a pilot flying it, and the only way to really understand exactly how a plane flies is to fly it. Further, a pilot’s understanding of how airplanes fly is, to some extent, limited by the variety of airplanes he or she has flown. Those differences are rooted in the physical differences in the airplane’s control systems, a factor that means something entirely different with the computer-aided fly-bywire controls of the shuttle. “There is a military spec that publishes about flying qualities, handling qualities of airplanes,” Mattingly said.
It started back in World War II, I guess, maybe even before. It tells you all of the characteristics that have to go into making a good airplane, like how many pounds of force do you put on a rudder pedal to push it. Well, even dumb pilots finally figured out that with an electric airplane this maybe isn’t really relevant. Then the engineers wanted to just throw out all of the experience and say, “Hey, we’ll just make it cool and you’ll like it." So we went on a crusade to rewrite this document, which turned out to be one of the most interesting projects I’ve ever been in, because it required rethinking a lot of the things that we all took for gospel. Every airplane that a pilot flies is the Bible on how airplanes fly. Fortunately, in the office we had people who had flown a lot of different kinds of airplanes. But nevertheless, that shapes your image. And now you get into something that’s totally different, and there’s a tendency to want to make
this new airplane fly like the one you like the most. The software guys contributed to this bad habit by saying, “Hey, it’s software. You tell us what you want, we’ll make it fly." I remember one time they gave us a proposal that had a little dial and you could make it a P-51 or a T-33 or a f-86 or a 747. “Just tell me what you want." We had a lot of naive ideas when we started.
While the computer for the Space Shuttle allowed many things that were groundbreaking at the time in the world of avionics, Mattingly pointed out that they were still quite primitive compared to modern standards.
I don’t remember the original size of the computer, but it had a memory that was miniscule by today’s standards, but it was huge compared to Apollo. By the time we finished this program, we had this horrendous debate about going to what we called double-density memory that would expand it. It was still nothing, and the only reason management did not want to change to it was for philosophic reasons. And IBM finally said, “Look, you guys said you wanted to buy off-the-shelf hardware. Let me tell you, you are the only people in the world with that version of a computer. So if you want to stay with the rest of the world, you’re going to have to take this one." And fortunately, we did, and still it was miniscule. Today I think they’ve upgraded it several more times so that it isn’t nearly the challenge. But that caused us to partition the functions in prelaunch and ascent and then get out of orbit and do some servicing things and then another load for reentry.
Don Peterson, who was selected as an astronaut in 1969 and flew one shuttle mission, said the orbiter computer systems were quite complicated.
My little desktop computer at home is about a hundred times faster and it has about a hundred times more capacity than the computers that were flying on the orbiter. They were afraid to change the computers very much because part of the flight control scheme is based on timing. If you change the computer, you change the timing, and you’d have to redo all the testing. There are thousands of hours of testing that have gone into there, and they know this thing works, and they’re very loathe to make those kinds of changes. They cant change the outside of the vehicle for the same reason; that affects the aerodynamics. So they can change some things in that vehicle, and they [improved] some of it. But they’re not going to make big, drastic changes to the control systems. It’s just too complicated and too costly. The flight control system on the orbiter is almost an experimental design. In other words, they built the system and then they tested it and tested it and tested it. They just kept changing little bits and pieces, primarily in the software, until it all worked. But if you went back and looked at it from a theoretical point of view, that’s not very pretty. You know what I mean? It’s like, gee, there doesn’t seem to be any consistent deep underlying theory here. It’s all patchwork and it’s all pieced together. And in a sense, that’s true. But that’s why they would be very loathe to try to make big changes to that, because putting all that stuff together took a long, long time.
Working on a project with so many systems that all had to be integrated but that were being developed simultaneously was an interesting challenge, recalled Mattingly. “Within the office, we were all trying to stay in touch with all these things going on in each of these areas to keep them somewhat in sync from the cockpit perspective. So that gave us a lot of insight into all of these tasks that people were doing,” he said.
We even found, for instance, that as part of this development program, people working with thermal protections systems, the structure guys found that they were discovering limitations that were going to be imposed on the vehicle downstream that we weren’t thinking about—if you fly in the wrong regimes, you will get yourself into thermal problems. Yet nothing in our flight control work or displays was considering that. We had never encountered anything like that before. So the guys, by working all these different shops, were picking up these little tidbits and we were trying to find ways to look ahead.
Another major change, Mattingly said, was developing and testing the flight control software for the shuttle. “We learned quickly that the man – machine interface is the most labor intensive part of building all this software,” he said, explaining that the code dedicated to computer control of the vehicle made up less of the software—and less of the time it took to develop it—than the code related to the interface that would allow the astronauts to control use of that software to control the vehicle. In addition, he said, a conflict arose because of the computer use needed to develop and test that software. To the engineers who were using those computers to design the vehicle, the time the astronauts spent testing and practicing with the flight control software seemed like “video games.”
We ended up building a team of people: Joe Gamble, who was working the aerodynamics; Jon Harpold, doing guidance; and Ernie Smith, who was the flight control guy. They all worked in E&D [Engineering and Development]. We all got to going around together in a little team, and we would all go to the simulators together, and we would all study things. We built a simulator from Apollo hardware that was called. . . its, the Interim Test Station. We had a couple of people—Roger Burke and Al Ragsdale were two sim engineers that had worked on the cms [CommandModule Simulator] and the lms [Lunar Module Simulator]. They were very innovative, and they took these things before we had the Shuttle Mission Simulator that was back in the early part of the design and went to the junkyard and found airplane parts and built an instrument panel out of spare parts and had a regular chair that you sat in and had different control devices that we had borrowed and stolen from places. These folks were so innovative; they could hook it all up.
“They took the initial aerodynamic data books and put them in a file so we could build something that would try to fly,” Mattingly said.
We even took the lunar landing scene television. In the Lunar Module Simulator they had a camera that was driven by the model of the motion and it would fly down over the lunar surface, and so you can see this thing, and that was portrayed in the lms as what you’d train to. So they adapted that to a runway. We tried to build a little visual so we could have some clues to this thing, put in a little rinky-dink CRT [cathode-ray tube] so we could play with building displays. And we got no support from anybody. I mean, this wasn’t space stuff And it is probably one of those things I was most proud of, because we were able to get this thing into someplace where we could actually tinker with how were going to fly the vehicle and what we’re going to do and what the aerodynamics mean. It was only possible because we had these two simulator guys who were wizards at playing with software and this team from e&d who joined us.
We ended up realizing that we had built an electric airplane that had essentially only one operating flight control system. So we said, “Well, what if we’re wrong? No one has ever flown a Mach 20 airplane. This whole flight envelope is something that nobody’s ever had the opportunity to experience. So what do you suppose our tolerance is to this?" Because wind tunnel models for the ascent vehicles, they fit in your hand, because the tunnels that were able to handle these things were small. The wind tunnel models for the orbiter were larger, but they’re still not all that big, and going through this tremendously wide flight regime where the air density is going from nothing to everything, and it’s just high speeds to low speeds, I said, “What’s the chance of getting all that right?" And yet as we played in these simulators, … we proved to ourselves that, boy, if you’re offon that estimate of the aerodynamics, you can often play with the software to make it right, but if the real aerodynamics and the software you have don’t match, it’s a real mess. I know I worried a lot about that.
So we came up with a concept that we would have some tolerances on the aerodynamics, and we would try to make sure that the flight control system could handle these kind of uncertainties in aerodynamics. We did something which is not typically done—we decided to optimize the flight control performance to be tolerant on uncertainties rather than the best flight control system they could build. The whole idea was, after we’ve flown and we have some experience and we know what the real world is, now we can come back and make it better, but the first job is to make ours as tolerant as possible to the things we don’t know.
While Mattingly was working with the computer models of the flight dynamics of the shuttle, astronaut Hank Hartsfield was on the other side of that research, working with the wind tunnel models and encountering the same concerns about the scalability of the data coming out of those tests.
As I recall, the shuttle program had over twenty-two thousand hours of wind tunnel time to try to figure out what it flies like. Because the decision had been made, there are no test flights. We were going to fly it manned the first flight, and an orbital flight at that, which demanded that, the best you can, [we] understand this. Well, hypersonic aerodynamics is difficult to understand, the uncertainty on the aerodynamic parameters that you get out of the tunnel are big. The things that we were looking at in the simulations were if these uncertainties in the different aerodynamic parameters stack in a certain way, the vehicle could be unstable.
What we were looking for, for those combinations, statistically were possible, but hopefully not very probable they’d happen, but if they did, that was the kind of things we had to plan for. It’s just an uncertain world. You can’t predict, because in the wind tunnel, you have to put in scaling factors. If you’re doing wind tunnel things off a small model, it doesn’t really scale to the big model perfectly, and you have to make assumptions when you do that. The scaling ratios have a big factor, a big effect on what the real numbers are. So if you could fly a full-scale orbiter in the wind tunnel and it would go Mach 15 or something, it would be great, but you cant do that. You have a little-bitty model, and it’s a
6. Space Shuttle vehicle testing in the fourteen-foot Transonic Wind Tunnel at nasas Ames Research Center. Courtesy nasa.
shock tunnel or something. You’d get a few seconds of runtime at the right Mach numbers and then try to capture the data off of that.
Astronaut Don Peterson was involved in studying the redundancy of systems on the orbiter, and particularly the flight control computers. In the report he pointed out that failure rates on some of the avionics could be high. On Apollo and earlier vehicles, nasa built “ultra-reliability components,” components that were overdesigned and tested to make failures less likely.
Failures on Apollo, for that reason, were pretty rare. But that’s very expensive. That’s a very difficult thing to do. I was told that after the lunar program ended, MIT had two of the lunar module computers left over, spares. So they just turned them on and programmed them to run cyclically through all the programs. I think they ran one of those computers for, like, fifteen years, and it never failed. It just kept running, and finally they turned it off They just said, “It’s not ever going to fail. ” That’s the way that equipment was built. But that makes it very
expensive. So when they built the Shuttle, they said, “We can’t do that. So what we’re going to do is, instead of ultrareliability components, we’re going to rely on something called redundancy. " They were going to have four computers, and they were going to have three tacans, and they were going to have four of this and two of that and so on. That way, you could tolerate failures. But as a result of that, the failure rate on some of that equipment was fairly high, compared to Apollo.
They also made the multiple units interdependent. “On a typical automobile you have five tires, but that’s not five levels of redundancy because you need four of them,” Peterson explained.
So you can really only tolerate one failure. You can have one tire go bad and you can take care of that. But we got into that same situation on the shuttle because of the way they did the software. The shuttle, when it’s flying, the computers all compare answers with one another, and then they vote among themselves to see if anybody’s gone nuts. If a computer has gone bad, the other computers can override its output so that it isn’t commanding anything. But to make that scheme work, you have to have at least three computers working. Otherwise, you cant vote. You could have [two systems voting], but if they vote against each other, you don’t know which one’s the bad one.
The decision was made to put five of the computers on the orbiter, with four of them active in the primary system, with the idea that this would create a system that could tolerate three failures. However, Peterson said, this produced much higher failure rates than expected. While the system provided a high amount of redundancy in theory, the reality was that because of the way it was designed, the system actually could tolerate only one failure safely. The four primary computers were not truly redundant for each other; only the spare provided redundancy. If one computer failed, the spare would take its place. After that, however, further failures would endanger the cooperative “voting logic” between the computers that verified the accuracy of their results.
But the complexity of the way the thing was put together kind of defeated the simplistic redundancy scheme that they had. It’d be like driving a car that had two engines or three engines, and any one of them would work. Well, that way you could fail two engines and you’d still drive right along. But if it takes two engines to power the vehicle, then you don’t have that, and if it takes three engines to power the vehicle, you don’t have any redundancy at all. It gets to be a game then as to how you trade all this off. When I looked at all that and we put the study together, we said, “You know, you’re going to have some failures that are going to really bother you because you’re going to lose components. ” For example, you’re on orbit and you’ve got four computers and one of them fails. Well, now you’ve got three computers left in the primary set. But do you stay on orbit? Because if you suffer one more failure, your voting algorithm no longer works. Now you’re down then into coming home on a single computer and trusting it. And nobody wanted to do that.
So they said, “Gee, I’ve got four computers. I can only tolerate one failure, and then I’ve got to come home. ” We had four of some of the other components, and it was kind of the same sort of thing. If one of them fails, we are no longer failure tolerant. We’ve lost the capability to compare results and vote, and so we don’t want to stay on orbit that way. So now, all of a sudden, the fact that you’ve got four of them causes more aborts because the more things you have, the more likely you are to have one fail. You’d get more failures and more aborts with four computers than if you’d gone with some other plan. That was pretty controversial for a while. We predicted—and there were some people that were really upset about that—we predicted a couple ofground aborts due to computer failures. Essentially we’d get chewed out for saying that, but in the first thirteen flights, we hit it right on the money. We had two ground aborts in thirteen flights.
When the shuttle was built, the air force was also using redundancy systems, Peterson recalled. Then the air force built what it called confederated systems, in which each component was independent. “They cooperated with each other, but they shipped data to each other, but they weren’t really closely tied together,” Peterson explained.
The shuttle was tightly integrated. It runs on a very rigid timing scheme. The computers on the shuttle actually compare results about a little more than three hundred times a second. So it’s all tightly tied together. Well, when they decided to build the [International] Space Station, NASA said, “We’re not doing this integrated stuff anymore. Boy, that was a real pain. We’re going to use a confederated system. ” The air force, on their latest fighter, said, “This confederated stuff doesn’t work worth a damn. Were going to build a tightly integrated [system]. ” So they both went along for ten years or twelve years, and then they flip-flopped. The military’s going the way NASA originally went, and NASA’s now going the way the military went originally. I think the answer is, there is no magic answer to all that. Probably one concept is maybe not that much better than the other. It’s how you implement it and how much money you spend and how much to test. What do they say? The devils in the details. I think that’s right with all this stuff.
Mattingly recalled excellent cooperation between the engineering staff working on the shuttle and the Astronaut Office. “I seldom have seen that integration of the people that were going to fly it with the designers and people who were doing the theoretical work and the operators from the ground,” Mattingly said.
All of that stuff was converged in parallel, and I think that’s one of the reasons that the shuttle is such a magnificent flying machine. It does all the magic that we set out to do. I’m ignoring the cost because the shuttle, in my recollection, by the time it was sold to Congress, it was probably different than what the people in the trenches remember, but we had to do all these technical things, and it was a matter of faith that if you build it, it will be cheap. I mean, it was just simple. If you could reuse it, it saves money, and so you’ve got to make it reusable. If you fly a lot, that will be good, and we’re going to fly this thing for $5.95, and we’re going to fly it once a week and that’s how we’re going to do this. And none of us were ever told to go build a vehicle that we could afford to own. And had we been told that, I doubt if we would have been able to do it. I think the job was so complex, you had to build one that flies in order to learn the lessons that say, "Now I know what’s important and what isn’t. ” I just think it would have been asking too much, but that’s just personal opinion, but it’s from having struggled through ten years of this development program. It was an extraordinary experience to do that.
The role of the Astronaut Office during the development of the Space Shuttle was quite different from what Mattingly experienced during the Apollo program. “Our involvement was far more extensive and pervasive, and a heck of a lot more fun,” he said.
I mean, this was really cool stuff. There was a problem every day, and you got to learn about all of these little things that were interesting. I spent a lot of time trying to understand the stress loads and the thermal characteristics on the tps [thermalprotection system], and how do you get it to stay on, and all of those things were things that came through the office as experiences that really were just extraordinary opportunities to go see that. As we moved down the stream and we got into some of these development programs and started turning out hardware, we started splitting people up to go follow different components of hardware, whether it be the engines or the SRBs or the orbiter.
The decision to have the orbiter be an unpowered glider rather than a jet during its return to Earth and the various ramifications of that decision were also among the things that had to be considered during development. “Somewhere earlier in this development stage, we went through a series of activities where the first orbiter was going to have air-breathing engines, and it had some solid rockets that were on the back that were for aborts,” Mattingly said.
Right off the pad you could fire these two big rockets, and they would take you off in a big loop so you could come back and land. We had these air-breathing engines that were going to—after you come down through the atmosphere, you open the door and these engines come out, and you light them and you come around and land. They had enough gas for one go-around. The other thing we had was the big solids were to have thrust terminations and ports that blew out at the front end so you could terminate thrust on them if you needed to in an emergency. Every one of those devices was something which had a higher probability of killing you by its presence than it would ever have in saving you. I’ll put that ejection seat in the same boat. Everybody was willing to get rid of the air-breathing engines. They were really, really not a very bright idea. And we got rid of the thrust termination and we got rid of the abort solid rockets. My guess is John Young was probably the most active stimulus in pushing those issues, and that was one of those cases where the flight crew perspective and the engineering perspectives converged. We all wanted to get rid of these things, and yet we retained the ejection seats for reasons which I will never understand. If anyone knew what the useful envelope of those ejection seats was and the price we paid to have them. . . . But it had become a cause: “You will protect these kids by giving them an ejection seat." So we had one, not that anybody wanted to ever use it, but it was there.
Astronaut Bonnie Dunbar was still an undergraduate student at the University of Washington during the early portions of shuttle’s development, and she worked with the school’s dean of ceramics engineering, who had received a grant to work on the tiles for the shuttle’s thermal protection sys-
7. A worker removes a tile as part of routine maintenance activities on the orbiter fleet.
tem. nasa’s earlier manned spacecraft had used ablative heat shields, which absorbed heat by burning up, protecting the rest of the vehicle. Such a system was simple and effective, but for the new, reusable Space Shuttle, nasa wanted a reusable heat shield, one that could protect the vehicle without itself being destroyed. The solution that was settled upon involved a vast collection of tiles and “blankets” covering the underside of the orbiter and other areas of the vehicle that would be exposed to extreme temperatures.
“First of all, tiles are a ceramic material, so by definition they’re brittle,” Dunbar said.
But the reason they have an advantage over metals is that they don’t expand ten times over their thermal exposure range. It’s called the coefficient of thermal expansion. Also, they are an insulator; they don’t conduct heat. We looked at metals, or what they call refractory metal skins, and there are two disadvantages. You still have to insulate behind them, because metals conduct heat. The other is that when you go from room temperature, let’s say seventy-five degrees Fahrenheit, to twenty-three hundred [degrees], you have a large growth. It’s like your cookie pans, I guess, in the oven. So the airframe would distort. The ceramic materials [have] very small thermal coefficients of expansion, ten to the negative sixth, so you’re not going to see a lot of deformation. Also you could, on a very
low density tile, expose the surface to twenty-three hundred degrees Fahrenheit, and the backface, three inches deep, would not see even close to that, less than a couple hundred degrees, till after you’re on the ground. It’s a very slow coefficient of thermal expansion and heat transfer. So ceramics had a definite advantage. We knew that from the work we’d done in the sixties, and in fact, ceramics were already being used as the heat shields on nose cones for missiles and so forth. So the next big challenge was to put them in a low-density, lightweight form that could be applied to the outside of a vehicle. Apollo vehicles, Gemini, Mercury, were all covered by ablators, which meant that they burned up on the reentry to the Earth’s atmosphere and could not be reused. The tiles were meant to be reusable. They didn’t deform. They didn’t change their chemistry. We had to, though, shape them so that they were the shape of an airplane, so we had all the aerodynamic features there. So we sort of did a little reverse engineering, in that we said, “Okay, here’s what the shuttle looks like; got to maintain that shape. Here’s how hot it gets from the nose to the tail. Most of the heat’s at the nose, on the nose cone, and the leading edges of the wings. We want to make sure the aluminum substructure doesn’t get over 350 degrees Fahrenheit; that’s when it starts to change shape. So how thick does the tile have to be?" So we used all those limits and constraints, then you’d use the computer. . . to calculate how thick each tile had to be. Then we started looking at, well, okay, how big should each tile have to be? Could I just put large sheets of tile on there?
Well, we started looking at what the structure does during launch, and now we’re getting to something called vibroacoustics. There’s a lot of force pressure on the vehicle, a lot of noise, if you will, generated into the structure, and it vibrates. We calculated that if we put a foot-by-foot piece of tile on there, the vibration would actually break it up into six-by-six-inch pieces. We said, “Well, we’ll design it six by six. " So you’ll see most tiles are six by six. Now how close do you put them? We thought, well, you cant get them too close, because during that vibration they’ll beat each other to death, because they’re covered with a glaze. You’ve got silicon dioxide fibers that are made into very low mass tiles, nine pounds per cubic feet, or twenty-two pounds, and to ensure they don’t erode in the airstream when you reenter, they’re covered with a ceramic glaze. So that’s also brittle, so you can’t get them too close or they’ll break the glaze. You can’t get them too far apart or, during reentry, the plasma flow will penetrate down in those gaps and could melt the aluminum. So that’s called gap or plasma intrusion. So that then constrained what we called the gap. Then from tile to tile, how high one was compared to the next one, we called step. That became important because if you had too large a step towards the leading edge of the wing, that would disturb the boundary layer, and you would go up the plasma, and instead of having smooth layers, it would start to transition to turbulent, from laminar to turbulent, and turbulent results in higher heating. So that controlled the step. So gap and step were very important to that as well.
“Those were all challenges,” Dunbar said. “We depended on advances in computerized machining capabilities, wind tunnel work with models to help us determine the requirements on step, the manufacturing, just everything. Firing a tile, a certain temperature and time was important to maintaining its geometry. . . . It’s, I think, a real tribute to the program that if you look at follow-on programs, even in NASA but also in Japan or in Europe or even the Russians, who built the Buran [Soviet shuttle], you’ll find that the system on the surface is very similar to the shuttle tile system. It was a good solution.”
Dunbar said that working on the shuttle during that early time was an exciting opportunity.
This was the next-generation vehicle. Not only was it next generation, it was…
“transformational" is the word we use now. If you think about it, everything to that point was one use only. Couldn’t bring any mass back. We sent a lot of things into orbit that we had to test and leave there, and it became a shooting star, coming back to Earth. So this transformed our ability to do research. It’s why we have a space station now. We not only learned from Skylab, but we flew [on] Spacelab countless research projects that we could bring back to Earth, get the results out, diagnose problems with equipment. I think it saved the government billions of dollars, because we didn’t throw it away each time. So it was exciting, and we knew what it could do. New technology. It was leading edge on not only the thermal protection systems, but it was the first fully fly-by-wire vehicle, in terms of the computers and the flight control system. The main engines were also a pathfinder as well, and so it was exciting, even if it delayed till ’81. If you think about it, we baselined it to the contractor, to Rockwell, in 1972, I believe. So nine years later we have a vehicle, a reusable vehicle, flying.
Astronaut Terry Hart was the Astronaut Office’s representative in the development of the Space Shuttle main engines.
Since I had a technical background, mostly mechanical engineering, John Young had asked me to follow the main engine development. This was a couple of years before sts-1. In fact, it was ironic that we showed up [as NASA astronauts] in ’78, and everyone said we’re one year away from the first shuttle launch, and two years later, we were still one year away from the first shuttle launch, and it was really because of two main areas of technical difficulty. The main engine development was somewhat problematic, with some turbo pump failures that they’d had on the test stand, and the tiles. We had difficulty with the tiles being bonded on properly and staying on. But the main engine was one that John Young wanted me to follow for him, and so I spent a lot of time going back and forth to [Marshall Space Flight Center in] Huntsville [Alabama] and to nstl, the National Space Technology Laboratories, in Bay St. Louis [Mississippi, currently called the NASA John C. Stennis Space Center], where NASA tested the engines. And Huntsville, of course, was where the program office was for the main engines. And that was very exciting. I mean, I was like a kid in a candy store, in the sense that a mechanical engineer being able to kibitz in this technology, with the tremendous power of the fuel pumps and the oxidizer pumps, and the whole engine design, I thought, was just phenomenal. The hard part of that job was when we had failures on the test stand, which were, unfortunately, too frequent. I’d get the pleasure of standing up in front of John Young and the rest of the astronauts on Monday morning to explain what happened. And, of course, everyone was always very disappointed, because we knew this was setting back the first launch and it was a jeopardy to the whole program. But we got through that, and the engines have done extremely well all through the program here, where it was always thought to be the weak link in the design.
Astronaut Don Lind was involved in the early planning and development of the remote manipulator system, the shuttle’s robot arm.
I guess the first significant assignment I had [for the shuttle] was in developing the control system for the remote manipulator system, the RMS. In the hinge line of the cargo bay doors, there is an arm that’s articulated pretty much like the human arm. It’s about as long as two telephone poles, and it’s designed for deploying and retrieving satellites. Again, somebody had to worry about the operational considerations of that arm. It was built by the Canadians with the agreement through the [U. S.] State Department, and I was assigned to work on that. So I made a lot of trips into Canada to work with those people. The people who were actually building the hardware were very, very compatible, very easy to work with, and we had a very nice working relationship.
Lind contributed to the development of the three different coordinate systems that were going to be built into the arm’s software.
One coordinate system, obviously, applied when you’re looking out of the window into the cargo bay, and so you want to work in that coordinate system. If you wanted the arm to move away from you, you pushed the hand controller away from you. Also, if you’re trying to grasp a satellite up over your head and you’re looking with the TV camera down the fingers at the end of the arm, which is called the end effector, and you want to move straight along the direction the fingers are pointing, you don’t want to have to try to figure out which way you should go, so you shift to a totally different coordinate system. So if you’re looking in the TV picture with the camera that’s mounted right above the end effector, you want to push the hand controller straightforward. You want it to move straight forward in the television picture.
Lind also helped answer the question of how the hand controllers were to be configured.
We wanted hand controllers where the translation [movement] motion would be done by one hand controller, which we decided would be the left hand, and the rotational motion controlled by a hand controller which would be handled with the right hand. We decided, as a joint decision, that the hand controller for translation should be a square knob.
Then I said, “Now, remember you’re floating. You’re floating, so you’ve got to hang on to something while you’re translating, and you don’t want your bobbing around to affect the hand controller. So you need to put a square bracket around it so you can hold on to the bracket with your little finger and can use the hand controller." “Oh yeah, we hadn’t thought of that. Well, how big do you want it to be?" We actually measured my hand and designed the controller and bracket to the physical dimensions of my hand. Obviously, when you make a decision like that, then you have five other astronauts check it out, and they say, “Yeah, that was a really good decision." I didn’t want the hand controller for the right hand to be mounted square on the bulkhead, because the relaxed position of your arm is not at a square angle; it’s drooping down to the side. And I wanted that position to be the no-rotation position. We set up a simulation, and I stood up there, and they measured the angle of my arm and then built a bracket to mount that hand controller just exactly the way my arm relaxed. And again, we had several other astronauts check it, and they said yes, that was a fine thing. So the hand controllers were literally fine-tuned to my design.
Other people were worrying about the software, how to implement these coordinate systems. Other people were doing all the very sophisticated engineering. But the human factor was my responsibility, and basically it was a very pleasant experience to work with the Canadians, with one exception. The arm has two joints: like the elbow, and like the shoulder; one degree offreedom in the elbow, two in the shoulder, and three degrees offreedom in the wrist, so there are three literal components to the wrist junction. They had mounted the camera on the middle one. As you maneuver in certain ways, the wrist has to compensate for the rotations of the other joints, and every once in a while the TV picture would simply rotate. Not that anything had actually rotated, but the wrist was compensating. I said, “That’s unacceptable. ” They said, “No, no, no, no, it has to be there. That’s the cheapest place to put it. ” The engineers were all in agreement that this was a mistake, because you could lose a satellite when suddenly the picture rotates and nothing really has happened. But the management people said, “This meets our letter of intent with the State Department. We’re not going to change it. ” So in one meeting I had to be very unpleasant. I said, “Now, gentlemen, if we ever lose a satellite because of this unnatural rotation, I will personally hold a press conference and say that you had been warned, and it’s the Canadians’ fault. ” They looked at me like, “Ooh, you’re nasty. ” At the next meeting, they said, “Well, we’ll change it, and it doesn’t cost as much as we thought in the first place.” Usually you could get good cooperation, but occasionally, particularly with people up in the bureaucratic levels, you had to be a little bit pushy. I try not to be pushy, but that’s one time I did.
Astronaut George “Pinky” Nelson was involved in the development of the Extravehicular Mobility Unit (emu), the spacesuit used for conducting activities outside of the spacecraft. “The suit was one of the long poles in getting the shuttle ready to fly,” he said.
The folks in Houston who were in charge of it, [Walter] Guy and his group, were really working hard, and it was a difficult task to get it pulled together. The suit actually blew up shortly before sts-1. I was home working in my garden. I was playing hooky one afternoon, and I got a call from George Abbey.
He said, “Where the hell are you?” “Well, I’m home working in the garden.” He said, “Okay. Get in here. We just had an accident with the spacesuit. "They were doing some testing in one of the vacuum chambers in Building 7, and they had the suit unmanned, pressurized, in the vacuum chamber. They were going to do some tests and they were going through the procedures of donning the suit and flipping all the switches in the right order and going through the checklist. There’s a point when you get in the suit that you move a valve. There’s a slider valve on the front of the suit, and you move this slider valve over, and what it does is it pushes a lever inside a regulator and opens up a line that brings the high-pressure emergency [oxygen] tanks on line. You do that just before you go outside. You don’t need them when you’re in the cabin, because you can always repressurize the airlock. When you’re going to go outside, you need these high – pressure tanks. They’re two little stainless steel tanks about six inches in diameter, maybe seven. And it turned out that when this tech did that, he threw that switch and the suit basically blew up. I mean not just pneumatically, but burst into flames [and] got severely burned. It was pure oxygen in there. The backpack is made basically out of a big block of aluminum, and aluminum is flammable in pure oxygen. So this thing just went “whooff,” went up in smoke.
So then I was put on the Investigation Board for that, and spent I don’t know how long, a couple months at least, just focusing on what had caused this and could we identify it and fix it and get it ready so that it wasn’t the long pole for flying sts-1. So I learned even more about the design and manufacturing and materials and all ofthat in the suit during that process. It was fascinating. And the NASA system for handling that kind ofan incident really is very good. We’ve seen it with the big accidents we’ve had. They really can get to the bottom of a problem very well.
After that, Nelson said, there weren’t any major problems in the development of the suit. “There were lots of little stuff. The displays and controls on the suit are a challenge because, one, you have to see them from inside the suit, looking down, so a lot of these old guys in the office who were, you know, the stage I am in my life now, where I have to wear reading glasses, couldn’t read the displays because they were close to your face. So we worked on lenses and all kinds of ways to make the displays legible to people with old eyes.”
For all the capabilities built into the vehicle, one of the notorious disappointments of the Space Shuttle program is that launch costs ended up being much higher than promised. The original appeal of the shuttle was that its reusability would bring launch costs down dramatically, but those dreams were never fully realized. Explained Don Peterson,
The shuttles, unfortunately, are pretty difficult to work on. When the military builds an airplane, it tries to make everything in the airplane designed so that you can remove and replace parts quickly and easily. The shuttle is much more difficult to get to some of the stuff. Therere not big [easily opened]panels on it. You cant release a few latches and open a big panel on the side of the orbiter. You literally have to take it apart to get into it. You can go in through the inside, through the bay, and get to some of that stuff, but even then you’re removing parts that aren’t designed [for that]. It’s not like opening doors and looking inside. The military builds a lot oftheir stuff to be easy to work on, and they really didn’t build the shuttle that way. So the shuttle is more expensive to operate. For example, the little jet engines, there’s, like, thirty-eight of them, I think, on the orbiter that control attitude when it’s on orbit. If one of those engines fails, you cant just unscrew some things and take it out. You have to cut it out with a torch, and you have to weld the new one back in, because they didn’t build it to be removed. The heat shield is [24,300] little individual tiles, and they’re all different shapes and different thicknesses, and so every tile is like a little individual item. When the shuttle comes back, they have to inspect visually, and with a pull device, every single tile. If any of them don’t pass, you’ve got to cut that one out and clean off the glue and go get the new one and put it all back. Those are very high maintenance items. So the shuttle really wasn’t built to be easy to maintain, and that’s because NASA has always had, as [former Johnson Space Center director] Gerry Griffin used to say, a standing army at the Cape that did all that, and nobody really worried about it. If you needed something done, you just called and they sent over four or five guys and they fixed it. But that’s expensive.
The shuttle was designed to fly, I think it was fifty flights a year, and they were going to have five shuttles to do that. So each shuttle would fly ten times in a year. Well, right now the whole fleet’s only flying about eight times a year. Well, you’re trying to amortize the cost of the whole program over eight flights. It’s like we’ve got all this capability to repair and replace and analyze and monitor things, and we’re not using a whole lot of it. If you were flying fifty times a year, the cost per flight would go way down because you wouldn’t add that much to the facilities and the maintenance costs. The facilities costs don’t change much if you never flew. You’ve still got to have all the facilities, and you’ve got to pay for all that. You have to keep this whole group of specialists on, technicians and people, to do the work. With eight flights a year, some of those guys may only get used twice a year, but you’ve got to pay them and you’ve still got to have them there. If you were flying a lot more, the cost per flight would go way down.
George Mueller, the NASA head of human spaceflight who launched the Space Shuttle program, explained that there were several factors that drove the operational cost of the shuttle up, including many decisions, like the use of solid rocket boosters, that reduced development costs at the outset and presented Congress a lower buy-in budget request to build the vehicle but that resulted in higher operational costs once the shuttle started flying. However, he said, the ultimate problem with the shuttle was that it ended up being designed to use far more people to process it than were absolutely necessary. “If you really want to know why the shuttle failed, it’s because they designed it to use all the people from Saturn and Apollo, to keep them employed.”
Countless technical problems had to be overcome, and ultimately the shuttle’s greatest limitation was that it was designed to be too nice.
Former jsc director Chris Kraft, however, still speaks highly of the shuttle. “It’s the safest spacecraft we ever built.” Kraft noted that while shuttle crews have been lost because of problems stemming with the solid rocket boosters and the external tank, the orbiter itself has not been responsible for any fatal accidents. “The orbiter itself is flawless, since we’ve been flying. Absolutely flawless.” Rather than retiring the shuttle, Kraft argued, NASA should have continued to make it better and continued to fly it, adding that many ideas for improving the orbiter were never implemented. “That’s what we should still be doing. We still ought to be improving. We could improve the hell out of it. We could improve the hell out of the thermal protection system, we could improve the control systems, get rid of the apus [auxiliary power units]. All of that has been designed and is ready to be built. You don’t have to stop and redesign it, it’s done.”