Shuttle Designer Q&A
Seymour Rubenstein recalls in an interview on June 24, 2003 with the History Channel (Modern Marvels) about the significance of the first shuttle flight on April 12, 1981 and some of the early considerations in its design. Rubenstein, who was known as Sy, passed away in February 2006. Rockwell was the prime contractor for the Space Shuttle fleet of Orbiters. He served as President of the Rockwell International Space Systems Division and was a major contributor to the design, development and operation of the Space Shuttle. At Rockwell, the prime contractor for the Space Shuttle, he was the Director of Avionics System Engineering during the early development of the spacecraft. Subsequently he was promoted to Vice President of Engineering and Chief Engineer for Space Shuttle Development, followed in 1979 by Vice President and Program Manager. He then advanced to the position of President of the Space Station Systems Division (SSSD). Rockwell manufactured all five orbiters that NASA put into operational service: Columbia, OV-102; Challenger, OV-099; Discovery, OV-103; Atlantis, OV-104; and Endeavour, OV-105. The first orbiter built, Enterprise, was never flown in space, but was instrumental in achieving the early atmospheric flight test program objectives.
Q: Besides reusability in the Shuttle, what were some of the goals that were to be achieved with this new Spacecraft?
The driving reason for reusability was to lower the cost. The additional goals were the very large payload bay of 60 feet long was our first with space, and that was to carry physically large payloads into space. That was to support potential military applications and some extra large space applications like the Space Station. A second objective was to provide the large weight of lift which was not done before. So the reusability, the large payload, and then the third characteristic of the early flight that sized the vehicle was what was called "cross range." The ability as you enter from orbit to land at a fair distance cross range to your track and that was something like 1,500 miles and that drove the design of the vehicle as well.
Q: Can you talk a little bit more about the cross range? What does that mean in laymen's everyday terms?
Well, the thought if you were going to land let's say in Florida if that was your real target. The cross range would give you the ability to say land in either New York or South America. So you could pick targets alternate to your prime site. That also then determined what kind of thermal protection system you would need.
Q: Now during the time that the Shuttle was first on its way, the current state of technology was people barely had remote controls. There was no answering machines, no personal computers, so can you talk a little bit about the daunting challenge that it was to achieve the goals to achieve a working Space Shuttle?
Well, there were really a few things that didn't exist in the material sense. The electronics were there, but electronics move so quickly every five or six years. In fact, right now it's almost like three years you get a major increase in performance. So we started and picked hardware that was capable of 1973-1974 hardware. By the time we were done, it was already old. Now some of that same hardware is flying. It's very old. But the metals were aluminum, same old aluminum. The tile didn't exist. It was a new material. We had to invent it, and create it. So it was a mixture of things. Some things were materials that didn't exist that we had to create. Other things were materials that were changing so fast that we just had to pick something along the way. We had an idea of how to build it, we had a plan to build it, but we didn't really know exactly how to do it. So we had to lay it out in a plan. Each year we found some new things.
Q: Now in the early design phases before the final design was approved and came about, can you talk about what you know about any of the early designs?
The earliest design was a fully reusable spaceship. It was really a dual configuration. It was a like a giant 747 carrying an orbiter on top of it and the underneath spaceship would come back and land, and so no parts would be consumed. The problem with that configuration was that it was exceptionally expensive, and the budget constraint said that's not going to really be possible because you would have to develop two full reusable spacecraft. So the technical compromise was made to make what's called multi-stage where you have the external tank that is consumed, the solid rockets that get refurbished, and the orbiter that's fully recovered. That was a big transition, and then again to save money.
Q: What led to the final configuration of the Shuttle?
You have to look at the first driving mission for it. When we were going to the moon, what was under study was the Space Station, and the Space Station had gotten a couple years of study and then people realized that there was no way to get up and down. So the transition from the Space Station being the prime target switched over to a Space Shuttle and it started out as a fully reusable vehicle in the two stage configuration. We got a fully reusable carrier craft and a fully reusable spacecraft, and then it transitioned to the stage and a half which was the major transition. Then there were lots of design details changed during the real detailed design. We had a concept. We had a proposal. But we now have to develop the technology which was really the giant challenge. Develop the details to make it happen.
Q: The Space Shuttle had a sophisticated avionics system. What made it so sophisticated? What new technologies were needed to develop the avionics?
The real secret in the avionics was we had complete control of the total vehicle. Prior systems you would put navigation systems on or weapon systems on or subsystems, but no one had 100 percent control of the vehicle. Everything that was on that vehicle went through the computer system except for dropping the landing gear. So that was really a challenge to be able to do all that while managing the systems in the event of failures. The whole thing was if you really looked at it on paper, you would wonder how it could stay working without any failures in the few days of a mission. The real design secrets were how to design it so they could do the function and then come through and be able to handle failures in flight. So far in 20 some odd years, we've had no problems with that system. It's done beautifully.
Q: Can you talk a little bit about how many engines the avionics are controlling?
The Shuttle system has the propulsion systems which are the two solid rocket boosters and the three main engines, and they give the major impetus so that the vehicle can get through orbit. To give you a feel for how fast this thing travels when it gets to orbit. It travels at five miles a second, and at five miles a second it means you can go from Boston to New York in less than a minute or from Boston to Washington in a minute and a half. So you have to give the vehicle enough energy to get that kind of velocity. Once you attain that velocity and you orbit the earth than the other propulsion systems are there to give it fine control, movement control, circularize the orbit. For example, when a Shuttle is on orbit you can actually move it a quarter of an inch because they are very fine jets as small as 25 pounds to another set that's there as much as 700 pounds to another set that gives you 7,000 pounds. So there are three different systems on orbit that provide jet control for a variety of maneuvering purposes. The Space Shuttle is a very flexible flying machine.
Q: How does the Space Shuttle get back to Earth?
In order to land, the vehicle turns around and slows down. People may not realize how it gets back to earth, but it's as if you took a top and you spun it. If you slow it down it's going to not go out as far. The same thing happens in space. The vehicle is flying this way, turns around, fires the engines backwards, slows it down, and then you come home and land.
Q: Two of the greatest challenges to the Shuttle had to with the thermal protection system and the main engines, were there any lesser known but still just as tricky and just as challenging things that you had to deal with and overcome that were just as important as the thermal protection system?
I think when you look at the Shuttle you'll discover that even the smaller systems have major challenges. The thing that made the tile system and the engine system and the avionics so important is they were pervasive. For example, we had a 17 inch disconnect. The flow of liquid hydrogen or liquid oxygen goes to a diameter pipe of 17 inches wide and you have to shut that flow off instantaneously. Now the fuel flows to the engines, roughly at a rate fast enough that it will fill your swimming pool in one minute. So now you have a flapper, a valve that sits in there. It's going to slam shut inside that flow rate and make sure nothing goes off. That was a challenge. The other thing was these cargo bay doors. The doors in the payload bay were 60 feet long and they had a diameter of about 15 feet, and for a variety of reasons they were made of composite and they weren't strong enough to hold their own weight on the ground. So in order to use them and test them we had to put what's called a "strong back" which was effectively a bridge to support it, and we opened it and tested it. That was a unique development. I think the "Canadian arm" was another unique development to be able to have a remote manipulator and then a many small valves and high performance valves and the hydraulic system props. One of the other big items was called the "auxiliary power unit." That unit contains a turbine wheel. The turbine rotated at nearly somewhere around 60,000-70,000 revolutions per minute. High speed performance with tremendous power output and it's also another noted device that has worked beautifully. None had existed at that kind of speed before that time.
Q: Now with all these new technologies and new ways of seeing and making things possible, did it ever seem too intense or hopeless at any point?
I remember when I started on the program I asked myself is it possible to do this thing? Was it really possible because when you looked at all the things that had to happen in the time available, it just seemed impossible? But what we did is instead, we just focused on one year at a time. We had a bunch of things to get done every year. In the first five or so years, things were going along pretty well and we made all those schedules. It looked like we were all going to stay in that kind of timeframe. We had a little bit of a hiatus in 1978 and 1979 with some problems with the tile system. There were some problems with the engine system, but nothing insurmountable. It was all over and done and we stood back and looked at it. If somebody would of said it took us from 1973 roughly to 1981...so what eight years to be flying in space? I don't think anybody would have thought we could have made it even though the target date was 1979 I think originally. Six years was very ambitious. Eight years was quite a challenge. I don't think you could do it today. Today's world is quite different.
Q: And why is today's world different?
Well, today you can't make any mistakes without having instant visibility in the world. Mistakes are what create the challenge to make the improvements happen and it takes time to work out problems. But I don't think the world has patience anymore especially those people who are responsible for giving out the money. They would like everything to happen beautifully. Well, it wouldn't be a development if everything was so perfect. So there's a tremendous pressure that goes on the people who have to do the work. Also, there's a tremendous uncertainty. You don't have the same multi-year commitment. Like a trip to go to the Moon was a commitment that would occur over a number of Presidents and a number of administrations, it's very hard to get that to happen today.
Q: In 1978, the Columbia was transported from Palmdale to Kennedy Space Center in Florida. Why was it transferred? Can you talk about the loss of tiles on that flight on top of Shuttle Carrier Aircraft?
We were starting to run a little behind schedule and the pacing item to finish was the installation of the tile. We thought we could do the additional work to finish the orbiter just as easy in Florida and finish up the tile work in Florida so we could save some months, but we were quite surprised when we took it to Florida. In order to make the transport, we installed a number of foam tile, not real tile on the vehicle to fill up all the spaces and install them with fairly conventional sticky back tape. When we got to Florida a lot of them had left the vehicle and all of a sudden the world thought we had a giant tile problem. What we had was a transportation problem. So the real reason was to try to make up some schedule and get some work done ahead of time. Underneath that unfortunately, we also had discovered some other real tile problems. Once we transported to Florida we understood the problem with the tile system of how to bond it...had nothing to do with the transportation...totally different problem. It was in the certification of the tile, and we created the solution, solved it, and got ourselves back on track. If you stand and look at the tile today, when we built the system, we felt that we would be doing pretty good if we would replace 300-400 tiles a flight, and now the number that you really replace is somewhere between 30-50. So one-tenth of what we really thought and its performance has been absolutely beautiful.
Q: Now can you take me through the first launch of STS-1? Where were you? Who were you with? Was it nerve wracking? Terrifying? Joyous?
Well, I left my wife home, and she was always angry at me for doing that. We launched...the planned launch was April 10, 1981 and it was actually the anniversary of the date that I joined Rockwell. I joined April 10, 1961, so I'll always remember that date. But we had a problem on launch day. It was a software problem. It took us two days of working around the clock to discover that it was a software problem. It was really a startup problem, just initialization. Once we understood that, we went on August 12, 1981. So I was in Florida in the Launch Control Center when it took off. Then my job was to get into a Sabreliner and fly to Houston to be there for the next two days while it orbited the earth, and then come to Edwards Air Force Base to wait for it to land. In Houston, we discovered we had lost a tile on the OMS (orbiter maneuvering system) pod. It was a white tile. It was really never a critical safety of flight issue. It was really more of a question of what would happen to the OMS pod? The OMS pod is the beehive looking thing on the back of the vehicle and one tile came off and we concluded that it would be safe to enter it. At worst we might take a little damage, and it turned out that to be the case. When the vehicle was coming home I was standing here in the desert at Edwards walking in circles like I walked in circles waiting for my son to be born. Until we heard the first sounds of the crew coming out of blackout, it was a little delay, and until you hear them say...answer the calls to Houston no matter whom you are, you're nervous. We walked and we walked in circles and then we heard their voices and we knew everything was okay. I don't think I slept...probably maybe averaged three hours a night for five or six nights. Probably 18 hours in six days and it was quite an event. It's really not just me. It took a tremendous team of people to do it, and that's what I think the beauty of the Space Program is the power of the people...tremendous capability from the manufacturing technician to the senior engineers to the astronauts to the mission controllers. It took tremendous teamwork to make that happen. The same is true for almost every flight.
Q: Can you explain what happens when the engines first fire and some of the technical challenges that had to be overcome?
The real issue was when you ignite the engines the vehicle rocks back and forth. You have to calculate exactly when it's pointing straight up to ignite the solid rockets because if it's pointing another way that's the way its going. The vehicle goes exactly where the solid rockets are pointing. That was really the tremendous test and analytical accomplishment of calculating the exact what's called the "liftoff twang." You start the main engines, the whole system vibrates, it moves left to right like a wave and then you calculate exactly when its going to be here, you ignite it, straight it goes. That was one issue. And then also you put on a giant acoustics spray, a water spray. There are a lot of other things that are unique to the launch pad. You have a lot of unburned hydrogen that you have to ignite the igniters to make sure it doesn't explode. So the launch is a tremendous amount of energy. It takes a tremendous amount of energy to get that vehicle moving. It doesn't realize it's moving. You start out at rest and virtually 10 minutes later it's traveling at 18,000 miles an hour. That's what it takes to get that thing going. It kind of roars like a lion, when it takes off and when it comes home, it sounds like an Eagle.
Q: How concerned was the crew about the first shuttle mission? Were they concerned? Did you get anything from them?
They were busy. Mr. John Young and Mr. Bob Crippen were quite busy. They had a lot of things to do, and also they were our observers. This was our first vehicle with Space. In Apollo, each vehicle was different. It had different hardware. This one we wanted each flight to be the same. That was the way it was being built and we needed a good accurate description of sounds, creaks, what did the assets sound like, what did the crew feel like? How was it to sleep in? How were the controls? How were its flying characteristics? So they had a tremendous engineering workload to record, measure and monitor. Each of the crews in the first four flights and also some of the later operational flights had specific assignments to help us understand the vehicle's flying characteristics.
Q: Were there any changes through those flights that happened for up to STS-5?
No great changes. To give you the feeling of what's going on when you, typically when one builds an airplane, you have the luxury of being able to do a taxi test which means you run it on the runway. Make sure it goes fast enough. You don't let it take off. Then you let it take off and make a short run around, but on a space vehicle, the choice was either make a fully unmanned vehicle automatic which we did not do or put people in the loop then make it run that way. So STS1 had a lot of unknowns. There was a lot of risk taken. The people who flew that really were quite courageous because there was no guarantee. We had done everything we knew how prior to flight, but STS1 opened the door. Then STS2 widened the operating range. All we did on STS1 is go up, open the payload doors, close them up, and come home. Then on STS2 we stayed up a little longer. Then STS3 we flew a little tougher entry trajectory. So each time giving us more and more capability. So there were sequences of tests. I can't think of any major change we made to the vehicle that was revolutionary in every nature. I think almost all the changes were evolutionary. We saw some small problems with the structure. We had a small part that required a change. Nothing that I could think of that was truly revolutionary. It's an amazing engineering feat and it was amazing manufacturing accomplishment because there were no significant workmanship problems. Plenty of opportunity to mess up, but it was done beautifully. Manufacturing people deserve all the credit they can ever get.
Q: What can you say about the people?
It's an amazing thing to watch when people make their mind up to do something what they can really do and when you're in a leadership position a large part of your job is to create that environment that lets them go and lets them use their creativity. You want discipline on one side, but you want the inventiveness of the human spirit on the other side. So it's that mix, but they have to have freedom to do what's right.
Q: Can you talk a little bit about the ups and downs of developing that Thermal Protection System?
When I was involved with tile, I became Chief Engineer in 1977. So I had spent a lot of my attention on the avionics systems and other parts, and the tile was well underway, and all of a sudden I was in the middle of a giant brew ha-ha. It looked like we had some problems. We had shipped the vehicle, the foam tile came off, but what was happening was in the test laboratories during certification. We formed a team with experts from all over the country and gathered them up and said, "Look! Here's what we're dealing with. Tile is a ceramic and if you really looked under a microscope it's probably 97 percent air." There is nothing there. It's sand and strands that had been heat treated and then a coating put on. When the tile was attached to the vehicle, it was breaking at a point where we didn't understand why it was breaking. Then somebody finally figured out by looking at an electron microscope and understanding what was going on that what was happening is the strands were breaking. It was like all the load was being carried in these pillars. What we then did is put a thin plate of cement, very fine cement on the bottom so the pillars went into the plate of cement and then the plate of cement was glued. So the stress wasn't in each of the individual strands. It was now spread out. Once that answer was there, then it was just from there on out it was just getting everything done. But that beautiful understanding of the phenomena of the problem then, it took us about a year to get everything changed out. We had...a vehicle had about I would say at that time two-thirds of a tiles already installed. We had to take them off and put them back on with a new process, and we got it all done. And it worked. I'm still amazed today to see how well it works. It's an outstanding system.
One other thought that people may not know. The orbiter when it's built as a piece of metal it's square on the bottom. The sides come down straight and it's square across the bottom. It gets its flying shape from the shape of the tile. So it's a square vehicle and it looks round because you put tile on it that has an outer surface that's round. The tile not only gives you thermal protection, but it gives the properties to fly like an airplane. So it serves both purposes.
Q: What were some of the challenges in developing the main engines? Were there any ups and downs?
Oh, it was a tremendous challenge! A tremendous challenge! I had no direct responsibility for it, but my counterpart at another part of Rockwell who was a good friend of mine. I think sometimes we would race in to tell our bosses who had the bigger problem. The engines were really state-of-the-art. This was an engine that had to work at pressures and temperatures not really heard of before. We were really pressing the state-of-the-art of metals. This engine fits in the back of a pickup truck. That's how small it is. And for eight minutes, it has the power output is equivalent to what you get out of the Hoover Dam. So it was a tremendous output and it only goes for eight minutes. It doesn't go for a lifetime, but it's a tremendous output of power. In order to get that, you have to get the tremendous temperatures and pressures, and so any little crack or any little deformation propagates into a failure. So it took quite a bit of time to get the whole process of turbine blades and moving parts, pressures, and temperatures and valves straight on the engine. But again now, once its problems got licked, it got the process technology, it's done very, very well.
Q: Were you there when Columbia was first assembled in the vehicle assembly building getting ready for rollout and at the launch pad?
In 1979, we shipped it to Florida. It was supposed to be ready in four months or five months, and here we are in 1981 and we're still not ready to go. We had finished all the tile work, and it was clear now that we were ready to turn it in the vertical direction. It was a tremendous amount of work we got done to make sure that mate could happen. We brought the tank and the orbiter together in the vertical assembly building, and the rockets were assembled on the launcher. I think the timeframe was somewhere around November of 1980. The flight was April of 1981. So around November 1980 is when we actually turned it into the vertical direction and moved it out to launch pad. It stayed on the launch pad roughly 4-1/2 months going through all the countdown checks and finishing some work. Now it's a lot faster, but it was a big day. It was a big day.
Q: When Columbia was given the go ahead to fly, what was your predominant reaction?
Well, I remember the Chairman of my company at that time was a man named Robert Anderson and we used to review the program status with him every month. By that time we're almost down to two every two weeks. He asked, "What do you think? Are we ready to go?" I said, "Well, we don't know what to do anymore. We've done every test that we know how to test. If we keep it on the ground we're probably going to break it. It's time to go, and time to find out." And we had made an engine firing well ahead of that, so we knew the engines worked and the static properties of the vehicle were fine. It was time.
Q: Why was the external fuel tank painted white?
Well, at that time it was thought that the heat load. You need to cover them white to reflect the heat. Later on in flight we had something like I think 700 or 800 pounds of white paint that wasn't really needed then. By not painting them, you can save the weight. It was just a heating problem.
Q: We already talked about re-entry. Do any of the Columbia missions stand out as more special than any others?
The thing that always impressed me is the repeatability of the systems on each entry. If you stand back and look and ask yourself, "What are you doing?" You start to deorbit when you're over Hawaii, and you're going to hit a landing strip that's three miles long maybe 150 feet wide around the other side of the world. Every flight unfortunately other than the accident flight hit that right on the mark. It was a beautiful system and so the thing that stood out is not any given flight, but the composite of all the flights. The repeatable behavior and then the repeatable behavior of one vehicle to the next. Oh, they were slightly different because Columbia being the first and Challenger being the second had a slightly different structure than the other three vehicles. The other vehicles had some weight trimmed out of them and they were slightly different, but all of them performed in space. All of them entered the same way. All of them went to space the same way and that to me was a tremendous engineering achievement, a tremendous operational achievement.
Q: What do you think the legacy will be of the Space Shuttle?
Well, what I think happened is it changed the way people think about doing space and space systems. It was a program that was done on a pretty rapid schedule. For the parts that we worked on, the orbiter, were done pretty much within the cost constraints and I think it's a legacy to the people who operate it. Each trip to space has brought some unique demand. Whether it's a repair and upgrade through a Hubble Space Telescope which was never done before. We put up a big telescope...which will give us beautiful pictures of space for years to come or some scientific experiment. Each of those things...it's not a single event, but it's a composite of all of them. I think the other part of it is the legacy of the people who worked on it. They did a tremendous job. It couldn't have been done without the dedication of a giant workforce and the leadership of some strong people in government, in NASA, and in industry.
Q: Do you have any concluding thoughts?
I think it's important to let people know that it was a system built by people and when we started we had no assurance that we would get there. We had an idea, we had a plan, and it took work to discover what we had to do. Each time we ran into a problem. Then we found the solution, and we were lucky enough to have the freedom to find the solutions. We did it within a reasonable portion of the timeframe, not precisely, and within a reasonable set of the dollar environment. But when people are left to do what people can do which is create, then great things happen. I think that's the thing I want to make sure people know. It just takes this giant team.