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LOLA: Lunar Orbit and Landing Approach - Encyclopedia of Space p.636

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Computers in Spaceflight: The NASA Experience http://www.hq.nasa.gov/office/pao/History/computers/Ch7-2.html

By mid-1963 the final configuration of the Saturn checkout computers was set by Richard's group. ... For Saturn Vs at Complex 39, one RCA 110A was located in each of the four firing rooms in the Saturn Launch Control Center, which was attached to the Vehicle Assembly Building in which the Saturns would be stacked. Each of four mobile launchers also contained a computer. In addition to the 110As, the firing rooms also had a DDP-224 minicomputer as a display driver for the CRTs showing output data to the engineers, as well as a controller for slides and other visuals. Computers in the mobile launchers could be used for checkout in the Assembly Building as well as at the pads, a foreshadowing of the later Launch Processing System. Due to reliability problems with the 110As, the launcher computers used a dual memory configuration. Checkout programs filled just half the memory, so the other half acted as a duplicate for redundancy, the same principle as applied to the LVDC memory.


Each ACE station used two digital computers with a common memory. One was the Digital Command Computer, which processed commands from the control or firing rooms to the spacecraft and was interconnected with the ground support equipment. A second machine was the Data Processing Computer, which drove the displays and controlled peripherals. Memory could be directly accessed by discrete circuits in the ground station, so data for both computers could be placed there23. ACE stations could function in manual command mode, semiautomatic, or fully automatic with manual override. Stations in the Kennedy Industrial Area serviced the spacecraft both before and after mating with the Saturn V boosters. When Launch Complex 39 went into use, checkout wires carrying digital formatted data ran over 15 kilometers from the ACE stations to and from the pad and firing rooms in the Saturn Launch Control Center using a video wideband transmission system24. Of course ACE had to cooperate with the RCA 110As at various points, so interfaces between the different computers consisted of dedicated I/O registers, sense lines, and priority interrupts25. ACE also had to talk to the Apollo guidance computers in the command module (CM) and the lunar excursion module (LEM). On the average, the CM computer operated for 50 hours in support of the countdown. A CRT display controlled by ACE duplicated the data shown on the display and keyboard while the Apollo computer was in operation.26



MIX photos

[edit] Apollo 17 Launch Operations[1]

The Kennedy Space Center team saved its most spectacular liftoff for the last Apollo mission. Apollo 17, launched on a dark December night, lit up the Florida sky for miles. Despite its early hour (12:33 a.m.), the launch attracted nearly 500,000 watchers in the immediate vicinity. Where clouds did not obstruct the view, thousands more saw the ascending Apollo-Saturn from as far away as 800 kilometers. Of course there was television coverage: the Florida launch site had become familiar to millions of viewers.

Other aspects of the Apollo 17 mission reawakened the interest of the American public. It represented man's last journey to the moon for an indefinite period. Apollo 17 would carry more scientific equipment than any previous mission and would number among its crew the first scientist-astronaut, Harrison Schmitt. The mission also marked the end of a dramatic and controversial program. Appropriately for Apollo, the last mission met acclaim and success.31

The first launch vehicle stages for Apollo 17 arrived at KSC in late 1970 during preparations for the Apollo 14 flight. Spacecraft operations got under way in March 1972. During the next four months John Williams's directorate conducted the normal sequence of tests. Spacecraft engineers ran into some typical problems. In May Grumman engineers determined that the rendezvous radar assembly had received too much voltage during the tracking and pointing test at the boresight range. A new radar was installed on the 24th. A month later the landing radar began locking up intermittently and it was replaced. The lunar rover required several changes including replacement of forward and aft steering motors.

The biggest change in command-service module operations concerned the scientific instrument module, which gained three new experiments: a lunar sounder, an infrared scanning radiometer, and a far ultraviolet spectrometer. The sounder was essentially a radar that could determine the physical properties of the lunar crust to a depth of 1.5 kilometers. This data, coupled with information gathered from cameras, the laser altimeter, and surface measurements, would allow the construction of a detailed topographical profile of the moon. The radiometer provided data from which scientists could prepare an accurate thermal map of the lunar surface. The new spectrometer measured compositional and density variations of the lunar atmosphere.

The new experiments, particularly the lunar sounder, caused considerable headaches. For testing the sounder, the lunar surface had to be simulated. The sounder recorded the returning signals with an advanced optical recorder that required a special data reduction machine. After the launch team completed a lunar sounder test, the results were sent to the University of Kansas for interpretation. As the head of the Experiments Section recalled, "It would take weeks sometimes to get the results back and they might come back and say, 'You have nothing on the tapes."' North American had trouble integrating the new experiments with the service module hardware.

The stacked vehicle emerged from the assembly building on 28 August. Although another Saturn V would make the slow journey for Skylab, area residents reacted as if this were the last one. Five thousand spectators watched Apollo 17 creep toward pad A. The astronauts (Eugene Cernan, Ronald Evans, and Harrison Schmitt) joined the Bendix crew aboard the crawler for part of the trip.

Launch operations during the next three months followed the routine established in earlier missions. The few changes in hardware went smoothly. There was one scare in late-September, again involving the command module's reaction control system. While conducting a leak check, a technician overpressurized one of the oxidizer tanks. KSC officials feared the worst - the rupture of the bladder and the spacecraft's return to the operations and checkout building. At a press conference a few hours after the accident, NASA Administrator James Fletcher announced the possibility of a month's delay in the launch. Further tests, however, indicated that the teflon bladder was all right, and Apollo 17 stayed on schedule.

In the outside world, there was an ill omen. A NASA request for 21 hours of Public Broadcasting Service network time to cover Apollo 17 stirred little excitement among the stations. Of some 70 replies, ten were favorable, ten opposed, and 50 expressed serious reservations. While this was blamed on a fear of governmental interference in programming, the commercial networks were no more enthusiastic. The prelaunch word was that they planned to cover only highlights of the flight.

The morale at the spaceport remained generally high. For most companies, KSC contracts continued through Skylab and the Apollo-Soyuz flight. Apollo 17, however, marked the end of the road for the 600 members of the Grumman team. During its years at Merritt Island, Charles Kroupa's group had earned an excellent reputation with NASA counterparts and fellow contractors. The men working for test supervisor Ray Erickson wanted to assure the astronaut crew of their continued support. The result was a large poster at the lunar module working level of the mobile service structure. Signed by Grumman's employees, it read: THIS MAY BE OUR LAST BUT IT WILL BE OUR BEST. Fletcher said the slogan "should be the watchword for the entire Apollo team."

The last Apollo mission was the first Saturn V launched after dark. As dusk approached, thousands of cars poured across the causeways leading onto Merritt Island. In front of the headquarters building, children threw footballs while the parents talked and listened for the progress of the countdown. The December weather did justice to Chamber of Commerce claims; in the mid-80s during the day, the temperature was 72 degrees at launch.

-- -- --

At T-3 minutes and 7 seconds, the automatic sequencer took over. This sequencer, the oldest and most reliable piece of automation on LC-39, chose this moment in the launching of the last Apollo to cause trouble. At T-30 seconds it went into an automatic cutoff indicating that one of the essential operations leading to the launch of the space vehicle had not been properly completed. Besides halting the countdown, the cutoff started a series of "safing" procedures which included the return of swing arm 9 to a standby position.

[edit] Tin foil and scotch tape

The "tape" you see on the outside of the CM is a Kapton polyamide tape, part of the CM's Thermal Protection Subsystem. The spacecraft needed a low emissivity, that is the ratio of radiation received to that radiated back out (not the exact technical definition, but it will do for these purposes). With the sun on one side of the spacecraft, it would heat up quite quickly, so they needed something to reflect the sun to help control the heat buildup.

As mentioned, this material was a pressure-sensitive Kapton polyamide tape which was coated with aluminium and silicon monoxide. It was applied to most of the outer surface of the CM. It also helped protect the alblator material around the CM, which would "burn away" (ablate) during re-entry.

A tape was used because it could be applied easily on surfaces with irregular shapes. Originally a paint was also used underneath the tape to act as a 'moisture barrier', but during weight-saving investigations they found that the Kapton tape also effective in that role and so they were able to eliminate the paint layers.

The thermal control requirements for the spacecraft in outer space necessitates a relatively low thermal absorptance-to-emittance ratio of 0.4 for the surface of the CM. This low ratio is achieved with a pressure-sensitive Kapton polyimide tape that is coated with aluminum and oxidized silicon monoxide and that is applied over the entire external surface of the ablator. The installation of a boost protective cover over the conical portion of the CM prevents contamination of the thermal-control coating and the CM windows by aerodynamic heating during boost and by the tower jettison engine plume. The boost protective cover, which is attached to the launch escape tower and is jettisoned with the tower before orbital insertion, consists of a layer of cork bonded to a fiber-glass cloth backing. -- Source: Apollo Experience Report - Thermal Protection Subsystem, NASA Technical Note D-7564, dated January 1974.
This page is still under development. These quotes should be merged into the transcript.
Schmitt: Quotes from oral history

Contents

[edit] Apollo Flight Journal

Schmitt: (Oral History 2000) Interestingly enough, somebody just recently has contacted me and they want to put together a journal of that particular phase of the mission, which is not in the Apollo Lunar Surface Journal that Eric Jones put together. So I think we're going to see a Web-based version of that transcript. I can't believe it's going to be of any great interest to anybody, but we'll see. [Laughter]

[edit] Apollo Lunar Surface Journal

Schmitt: (Oral History 1999) A more direct resource is now the Apollo Lunar Surface Journal that’s on the web, that Eric Jones put together. Most of the astronauts participated in editing and annotating the air-to-ground transcripts as well as the videotape transcripts. So, those are two really important historical resources. And I hope that somehow or another that Lunar Surface Journal will be maintained on the web indefinitely. NASA has put a little money into it, but probably not as much as they should in order to ensure its availability over the long haul. We don’t live forever. And right now, it’s purely the love of Eric Jones and his crew of people from all over the world that are adding checklists and all sorts of resources to that web page.

[edit] Backup crew

Schmitt: (Oral History 1999) We didn’t see an awful lot of our backup crew on Apollo 17, because they knew that they were just sort of filling a square unless something really serious happened. But still, when they were around, we did a lot of socializing with the support team and contractor teams and stuff like that. The astronauts were generally pretty good at socializing with people who were important to the success of the various missions. It was very important to do. Both formally, we had formal competitive baseball games and barbecue activities and things like that; and informally, we would golf and do things. I did a lot, particularly with the Flight Control Division people.

[edit] Checklists

Schmitt: (Oral History 2000) With only one or two exceptions, I think our crew was more wedded to following checklists than other crews. Maybe it was because I'd spent so much time mission after mission helping to develop them. We trained to them, and most of the problems that other crews had, not most, but some of the problems other crews had was when they sort of deviated from checklists. Gene, of course, had had a bad experience related to that on Apollo 10. It's not quite clear what actually happened, but it does appear like it might have been a checklist problem. After us, the Apollo-Soyuz mission had a problem with checklists on reentry.

Schmitt: (Oral History 2000) On that next to last day Gene just started playing with the computer, I think absentmindedly, and started firing thrusters, which got everybody all excited. He just accidentally hit, I guess, got a command in that started the thrusters firing. That's the only one I remember where somebody didn't really follow the checklist. He seemed as startled as anybody else. [Laughter]

[edit] Dedication

Schmitt: (Oral History 2000) When our mission actually flew, there were by far fewer component failures, system failures, probably an order of magnitude or two. Everything just worked beautifully from a hardware and a software point of view, which wouldn't have happened had people been letting down anywhere along the line in the tests and checkout and working of the hardware. We replaced a lot of stuff during tests. For example, our lunar module, we used to jokingly refer to it as the LM 9 module, because LM 9 was a lunar module that had been configured for the Block I or H missions, such as Neil Armstrong flew. It was superseded by a J mission, or Block II lunar module, the first one of which flew on Apollo 15. But we took the landing radar off of it and replaced it. It was being cannibalized to make sure that our spacecraft had everything working at the time of launch. But still there was general atmosphere on the one hand of continued clear Apollo dedication. There just was no diminution of that at all that I could ever detect.

[edit] Earth orbit

Schmitt: (Oral History 2000) We didn't have an awful lot of time in Earth orbit to look out the window, but we got a few nice photographs at 90 nautical miles. That's pretty close compared to the space shuttle. But still I can remember not only taking pictures, but really being fascinated, as everybody is, by the rapidly changing views of the Earth.

[edit] Flight Control

Schmitt: (Oral History 2000) From the very beginning, my first contact with Gene Kranz and the flight control people, as well as our own flight crew support groups, I believed that the more contact that these groups could have with each other and with the astronauts, the crew and the backup crew, the better the whole atmosphere was for success. Gene agreed with that, and so we did a lot of socializing with our various types of support people. We had softball games with them. We went out for barbecue and beer when we were at the Cape. When we were back here, we had evenings with the flight controllers. Sometimes when the flight controllers were having a gathering, I would always try to show up. I think I was probably the only astronaut that showed up regularly at these social events down at the old Hoffbrau House in Dickinson [Texas] and places like that, and the Singing Wheel when it was still around.

[edit] Meterorology

Schmitt: (Oral History 2000) My father was an amateur meteorologist and he excited my interest when I was a boy in Silver City, New Mexico. We would try to develop various predicative techniques for whether we were going to have storms or not down in that area. In those days, there was not much meteorological information coming out of Mexico, and so the weather forecasters were not too good at figuring out when we were going to have storms. But we gradually figured out what wind directions and barometer changes and what part of the solar cycle you might be in that would enable us to predict. So I had this significant interest in weather, which I still have today.

Schmitt: (Oral History 2000) As I approached the launch, I started talking with the Air Force meteorologist at [Patrick Air Force Base] down in Florida. They got interested in this, and so just as I suited up, one of my friends with that group brought in the latest satellite pictures that covered the Earth, that gave me the whole southern hemisphere of the Earth. So I had those in my pocket as we went out to the launch pad.

Schmitt: (Oral History 2000) I had planned, and we had talked about it, that in my spare time on the three and a half days to the Moon I would try to build on what those satellite pictures showed, primitive as they were, and try to experiment with how well could I forecast the weather. In what we called a lunar reference trajectory, we would see the Earth turn every twenty-four hours beneath us. So you could see what the weather pattern was, try to predict the trend for the next day, and then see how well you did the next day. Of course, we were getting farther and farther away and the Earth was changing from full to about two-thirds. But we had a 10-power binocular [ed: monocular] on board, so you could look out the window and see it. So all of that several inches of transcript was me exercising that little experiment.

Schmitt: (Oral History 2000) There really wasn't much else to do, except try to get a little exercise and eat and check out systems. But it certainly was not a full day's work any one day.

[edit] Mission Control

Schmitt: (Oral History 1999) One of the places I found you could learn an awful lot about spacecraft systems, was to go over to Mission Control and work with the various console teams because they were the ones that developed the so-called schematics of each of the spacecraft systems. And I learned an awful lot from studying those and working with those people. So, I had a real good relationship with the Mission Control folks. We went out to the Singing Wheel (the late Singing Wheel, I guess we have to refer to, it since it’s burned down), together often for barbecue and shuffleboard. And it was a good crew. I really enjoyed my time with them. Sy [Seymour A.] Liebergot and Steve [Stephen G.] Bales and the booster guy — I feel bad but I can’t remember all their names now.

[edit] NASA's focus

Schmitt: (Oral History 2000) On the other hand, it was clear NASA, as an agency, was looking to something else, that although we had the attention of the Flight Control Division, Gene Kranz's group, and we had the attention of the Flight Crew Support Division and the Apollo Spacecraft Program Office, Jim McDivitt now running it, having replaced George Low, all of that, as far as I could see, everybody was doing exactly what we needed to have done and everybody needed to have done to make Apollo 17 a success. On the other hand, NASA engineers and administration were focused on the space shuttle. They were already looking at that as the next major challenge, and so I suspect that at that level we certainly did not have the level of attention. It didn't seem to make any difference, other than the fact that Apollo 18, 19 and 20 had already been cancelled, in part, I think, due to a lack of interest by NASA, more so, though, due to a lack of media interest, which was translated into a lack of political interest in the country.

[edit] Return to Earth

Schmitt: (Oral History 2000) Probably the least interesting part of the mission were the first two days headed back to Earth, although Ron Evans did an EVA, which certainly was a highlight of the first day. The second day was a drag. All you could see was a crescent Earth; there really wasn't much to look at. There was a bit of a letdown after having had such exciting days preceding it on the Moon. We had one or two experiments to do, there just wasn't much to write home about. But then the last day, of course, you're preparing for entry and the adrenalin is starting to come back, and that's sort of the pièce de résistance, actually getting back into the atmosphere and coming home. By then you knew there was no choice, you were coming home one way or the other, so let's do it right.

[edit] Training

Schmitt: (Oral History 1999) The training is something that has a life of its own, and you live within that life, and make sure that it gets done.

Schmitt: (Oral History 2000) So the training cycle was intense. It seemed long. [At the end of it] you're ready. It was geared through experience and maybe through attitude to reach your peak performance level, just about the time you were ready to launch.

Schmitt: (Oral History 2000) Training for an Apollo mission, once you're in the queue and you're actually training, is a highly focused task. In fact, one of the things that is symptomatic of that is that my memory of day-to-day events and hour-to-hour events is very poor. I have a general recollection of the major flow and things that we did, but you ask me what did we do on a particular day or week or month, I can't recall it unless I see documents that, at least in outline form, give me that information and then I start to be able to retrieve it. It takes something else, our training schedules and things like that, to bring back some of the events of that time.

Schmitt: (Oral History 2000) In a general sense, we spent about three weeks out of every month in intense spacecraft-related training. In the first six months or so, we were here at JSC training in the simulators here, but we very quickly moved down to the Kennedy [Space] Center for simulations. We flew back and forth every week for that, because their computers were kept at a higher state of accuracy in terms of configuration. They were the first ones to be upgraded or to be fixed if something needed to be changed.

[edit] Translunar injection

Schmitt: (Oral History 2000) Our actual acceleration out of Earth orbit started in the dark and actually went through a sunrise, which we had a good chance to see as we went through that sunrise. That was spectacular, to be accelerating at those rates, about a G and a half, and then see this sunrise out the windows. It was really something to see.

References

  1. ↑ Charles D. Benson and William Barnaby Faherty, Apollo 17 Launch Operations chapter 23-7, Moonport: A History of Apollo Launch Facilities and Operations, NASA Special Publication-4204 in the NASA History Series SP-4204, 1978
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