Read Online Bold They Rise: The Space Shuttle Early Years, 1972-1986 (Outward Odyssey: A People's History of S) by David Hitt, Heather R. Smith - Free Book Online Page B
Authors: David Hitt, Heather R. Smith
Tags: History
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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 can’t 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 andtested 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
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 can’t 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 andtested 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
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