NASA KNEW THEY WOULD NEED MORE astronauts to accomplish all the upcoming flights with the new challenges of rendezvous and lunar landing, so in mid-September, a new batch of astronauts was announced: Neil Armstrong, Frank Borman, Pete Conrad, Jim Lovell, Jim McDivitt, Elliot See, Tom Stafford, Ed White and John Young. All had test pilot experience and four had advanced engineering degrees.
The remainder of the year unfolded like a preview of what the rest of the 1960s would hold. On October 4, Wally Schirra’s Mercury-Atlas 8 flight launched from Cape Canaveral and returned to Earth after six orbits; in December, the US spacecraft Mariner 2 passed by Venus, becoming the first spacecraft to transmit data from another planet; and that fall, the cartoon The Jetsons debuted on TV. The space age was irrevocably here.
Television became a central part of more American homes, so not only could people see NASA’s every rocket launch but viewers watched live—sometimes in horror—as political and racial tensions erupted across the country in riots and demonstrations, some turning deadly. The nightly national news reports also stoked Cold War fears, especially during the thirteen-day Cuban Missile Crisis, a political and military standoff in October that brought the United States and the Soviet Union to the brink of nuclear war. Even though President Kennedy and Soviet Premier Nikita Khrushchev negotiated a peaceful outcome, tensions and suspicions continued between the two countries.
Not as well covered by the national news were fires that broke out in two separate tests simulating the length of an Apollo mission to the Moon. These NASA experiments were conducted to help determine the effect on the astronauts of breathing pure oxygen for fourteen days. Even though the Air Force and Navy participants were injured in these fires, NASA decided they still favored the use of pure oxygen inside spacecraft.
CHAPTER 2
1963
The Apollo Lunar Module being installed in the Vibration and Acoustic Test Facility at MSC in Houston, Texas. Credit: NASA.
Just go like crazy and get the job done.
—BOB WREN, lead test engineer for the Manned Spacecraft Center’s Vibration and Acoustic Test Facility
NAVIGATING A SPACECRAFT TO THE MOON and back was going to require a computer. It was that simple. But in the early 1960s, putting a computer inside a spacecraft was not at all a simple proposition.
“Computers were huge, room-size things,” said Dick Battin, who worked at the Instrumentation Laboratory at the Massachusetts Institute of Technology (MIT) in Cambridge. “The idea of squeezing one inside a spacecraft seemed preposterous.”
Battin knew that only a computer could solve the dynamic equations of motion required for accurate navigation of space vehicles operating at high speeds. Because of the complexities and distances of spaceflight, such a computer would need to operate autonomously and in real time. But most of the computers considered real time in the early 1960s were analog—with vacuum tubes that failed frequently and required huge amounts of electricity. Those requirements weren’t feasible in a spacecraft, and digital computers of the day were just not fast enough to do real-time computations. In order to meet the national goal of landing humans on the Moon, NASA would need to find a capable navigation system and computer.
MIT’s Instrumentation Lab had been working on small computers for military and aerospace use since the mid-1950s. Dr. Charles Stark Draper, a gregarious and larger-than-life engineer and longtime professor of aeronautics at MIT, founded the lab in the 1930s. At first, the Lab allowed Draper’s students to get hands-on experience with things like wiring fuel and altitude gauges for airplanes—but over time it became a full-on laboratory, developing instrumentation for aircraft navigation. During World War II, the Lab developed gyroscopic equipment that led to the gunsights used by the Navy’s antiaircraft weaponry, which subsequently led to the guidance systems for Cold War intercontinental ballistic missiles (ICBMs).
With Sputnik 1‘s launch, Doc Draper wanted to get involved with spaceflight too. And with his blessing, a small group at the Lab started working on a secret project, a small little spacecraft they called the Mars Probe.
Composite image of a block diagram of the hardware formula for the Apollo Guidance Computer for the Command and Service Modules, drawn on a chalk board at NASA, drawn up by MIT engineers. The diagram depicts how the different systems and components communicate with each other Signatures of the different participants are on the right side (NASA, MIT and NAA [North American Aviation]). Credit: Draper.
“We were trying to design a spacecraft and the guidance system for a round-trip flight to Mars,” said Battin. “It would take a picture of the surface of Mars and bring the picture back to Earth. We suspected that if we were ever going to get into the space business, we ought to do it right away. Rather than sitting there waiting for somebody to ask us to do something, we decided to make a dramatic proposal ourselves.”
The group included Milt Trageser, who led the spacecraft design; Hal Laning, who performed preliminary calculations of trajectories to Mars; and Battin, Eldon Hall, Ralph Ragan, David Hoag and a few others, who performed studies on what would be required for guidance and navigation. The Mars Probe team realized a small onboard computer to direct the spacecraft operations would be the most critical component they could design, and to test their ideas, they turned to the power of MIT’s famous Whirlwind computer. This gigantic vacuum-tube computer was housed in an enormous building, and before turning Whirlwind on, the lab team needed to first notify the Cambridge power plant because of the tremendous strain the computer put on the city’s electrical system.
With Whirlwind’s help, the team figured out how to make it all work. The overall autonomous operation was managed on board by a small general-purpose digital computer, configured by its designer, Lab member Ramon Alonso. It didn’t need much power except occasionally for higher-speed computations. A unique feature of this computer was a prewired, read-only, non-erasable memory called a core rope, a configuration using wires threaded in and out of tiny magnetic rings. A ring, or core, with wire threaded through the center represented a one; an empty core represented a zero. The pattern of wires formed the ones and zeros of a hardwired computer program.
The Mars Probe team’s design was remarkable, their documentation comprehensive. In July 1959, they compiled a four-volume set of descriptions, details and schematics about the little spacecraft, the small computer and the guidance, navigation and control system. What the team didn’t know at the time, however, was despite their groundbreaking work, their beloved Mars Probe would—sadly—never fly. But everything they designed, tested and calculated for this far-fetched little computer would soon transform into the guidance computer for the Apollo spacecraft.
In the fall of 1960, word reached Doc Draper that his good friend and former student Robert Seamans was going to join NASA.
“Just before I went down to Washington,” Seamans recalled, “I got a call from Doc, and he said, ‘Before you go down there and get involved in everything, how about spending a half a day over at the Lab so we can tell you what we’re doing, that we think ought to be at least considered by NASA as part of the space program.’“
Seamans visited and was duly impressed. The concept for a self-contained computer and navigation system was intriguing. Seamans set up a meeting between Draper and Harry Goett to discuss how the Lab’s ideas might fit into the various long-range plans Goett’s committee had proposed for NASA, and in subsequent meetings, they determined the system should consist of a general-purpose digital computer with controls and displays for the astronauts, a space sextant, an inertial guidance unit with gyros and accelerometers and all the supporting electronics.
Charles Stark “Doc” Draper. Credit: Draper
In all these discussions, everyone agreed the astronaut should play a role in operating the spacecraft—he should not just be along for the ride. And all the NASA people especially liked the self-contained navigation capability, since there was fear the Soviet Union could interfere with communications be
tween a US spacecraft and the ground, endangering the mission and the lives of the astronauts.
From there, accounts diverge of what happened next, depending on who tells the story. Seamans says that after Kennedy’s April 1961 challenge to land on the Moon, Seamans himself recommended the MIT Instrumentation Lab to NASA administrator James Webb but was worried about appearing to play favorites.
“I said, ‘I know I’m prejudiced. I used to work in that laboratory. But if we want to have the most imaginative, innovative work done on that very key piece, I think it should be the Draper Lab,’” Seamans recalled. “And Jim Webb said, ‘One of the important things when you’re contracting is to know what you’re going to get, and the best way of knowing is to know who the people are. You shouldn’t look at yourself as being prejudiced. That’s the kind of information we need.’”
And that’s when, Seamans said, a sole-source contract for the Apollo Guidance Computer was offered to Draper and the Lab.
Hal Laning, Milt Trageser and Dick Battin with a model of the Mars Probe. Credit: Draper.
But Battin thought it was Robert Chilton, head of NASA’s Flight Dynamics Branch at Langley, who recommended giving a contract to the Lab.
“He wrote a letter, which he gave me a copy of, recommending that we be included in the Apollo project,” Battin said. “He said that the kind of work MIT was doing was really exactly what was needed for the Apollo program, because Apollo was not going to depend on communication with the ground, as the Russians might interfere with the communication link. I always thought that was the reason for our selection for Apollo.”
David Hoag remembered it differently. In a paper he wrote years later, he outlined that several meetings took place in early to mid-1961 between NASA officials and Lab engineers to work out the details of a guidance computer for Apollo. By July, the lab had put together an eleven-page proposal that included just one graphic: a hand-drawn depiction of the Earth-Moon system. And on August 10, by letter, NASA contracted the Laboratory for the first year’s development of the Apollo guidance and navigation system.
However, Doc Draper always insisted that Webb called him up on the phone to offer the contract.
Despite the differing stories, everyone agrees an approximate version of this terse discussion took place between Webb and Draper:
This diagram depicts early ideas for the self-contained inertial-celestial navigation system for the Apollo spacecraft. The diagram details the layout of many of the system’s component parts inside the Command Module, including the space sextant, guidance display and control console, star catalogue, chart book, inertial measurement unit and Apollo Guidance Computer. Credit: Draper.
Webb: “Dr. Draper, you know we have to build a spacecraft to go to the Moon. And I think the guidance system is one of our hardest problems. Do you think you could help us with that?”
Draper: “Yes, of course.”
Webb: “Well, then, when would the system be ready?”
Draper: “It would be ready when you need it.”
Webb: “So, how will I know if it will work?”
Draper: “I’ll volunteer to go along and fly it for you to the Moon.”
Dick Battin at the Instrumentation Lab. Credit: Draper.
However the details actually played out, the truth of the matter was that just weeks after Kennedy announced that NASA was to land a spacecraft on the Moon, the very first NASA prime contract for Apollo was signed with the MIT Instrumentation Laboratory to build the guidance and navigation system.
“We had a contract,” Battin said, “but we had no idea how we were going to do this job, other than to try to model it after our Mars Probe.“
Part of the lore of the Apollo Guidance Computer is that some of the specifications listed in the Lab’s eleven-page proposal were basically plucked out of thin air by Doc Draper. For lack of better numbers—and knowing it would need to fit inside a spacecraft—he said it would weigh 100 pounds (45 kg), be 1 cubic foot (0.3 cubic meter) in size and use fewer than 100 watts of power.
Battin said a new guidance computer design they’d been tinkering with had 4,000 words of 16-bit memory, which was read-only, and 250 words of volatile memory, or RAM. This was small by any standard.
But at that time, very few specs were known about any of the other Apollo components or spacecraft, as no other contracts had been let. And NASA hadn’t yet decided on its method—Direct Ascent, Earth-Orbit Rendezvous (EOR) or Lunar Orbit Rendezvous (LOR)—and the types of spacecraft to get to the Moon.
“We said, ‘We don’t know what the job is, but this is the computer we have, and we’ll work on it, we’ll try to expand it, we’ll do all that we can,’” Battin said. “But it was the only computer that anybody had in the country that could possibly do this job … whatever this job might be.”
While no other company had advanced in the computing area as much as the MIT Lab, there was a budding industry to create space-worthy navigation systems. So, the fact that no one else had the chance to bid on this potentially lucrative project created a controversy in the industry. But NASA stood by its choice. They also knew some of the other companies would have a chance for a piece of the guidance, navigation and control (GNC) pie.
From the outset, there was a clear understanding that MIT would do only the technical design and prototype development for the hardware. Following the precedent set by the Lab’s work on the gunsights and missile-guidance systems, industrial contractors would conduct the manufacturing phase. Over the course of 1962 and 1963, NASA chose companies to produce specific parts: Raytheon would build the guidance computers, AC Spark Plug—part of General Motors—would manufacture the inertial guidance system and Kollsman Instrument Company would construct the optics for the system. The Lab would be responsible for creating the software.
The early conceptual work on the GNC proceeded rapidly, with Trageser, Battin and Laning working out the overall configuration. Guidance meant directing the movement of a craft, while navigation referred to determining present position as accurately as possible and how it related to the future destination. Control referred to directing the vehicle’s movements, and in space the directions related to its attitude (yaw, pitch and roll) or velocity (speed and direction). MIT’s expertise centered on guidance and navigation, while NASA engineers—especially those who had experience working on Project Mercury—emphasized guidance and control. The two worked together to create the many maneuvers that would be required based on the gyros’ and accelerometers’ data, as well as to determine how to make the maneuvers part of the computer and software.
NASA and the Lab at MIT decided the astronauts traveling to the Moon and back would need a telescope to periodically align the inertial guidance system to the stars, as well as to make navigation measurements with a sextant by observing the direction of the Earth and Moon against the background stars. The digital computer was required to handle all the data, and part of the computer would have a fixed, non-erasable, indestructible core-rope memory—an upgraded version from the Mars Probe. Another part of the computer would consist of erasable memory that would allow astronauts to input information. That meant the astronauts would need an arrangement of displays and controls to operate the system.
A Block II Apollo Guidance Computer component and the DSKY (display and keyboard). Credit: Draper.
“Ramon Alonso was responsible for the core-rope memory,” said Battin, “and he stopped me in the hall one day and he said, ‘Hey, I’ve got a great idea of how to communicate with this computer.’ He came up with a noun-verb communication, the design of the display panel and the keyboard, and he showed it to me. He said, ‘What do you think of this?’“
Battin looked it over and said, “Well, it sounds good.” He knew it would take some detailed, painstaking work to create a user interface that would integrate successfully into the computer.
With NASA’s decision to attempt LOR, the Lab and the industrial contractor tasks were expanded to include the GNC for the
Lunar Module. NASA chose Grumman Aircraft Engineering Corporation to build what was initially called the lunar excursion module; the name was later changed to just Lunar Module (LM) because the word excursion connoted a leisurely trip.
In early 1963, coordination meetings took place with Grumman for the LM and North American Aviation for the Command and Service Modules (CSM). The Lab decided on a self-imposed ground rule that the guidance computer hardware elements in each spacecraft should be as similar as possible. That decision would later pay off in manufacturing, testing and astronaut training. This ended up being one of the few systems that were the same on both the CSM and LM, although the software would need to be entirely different.
Wernher von Braun visits the MIT Instrumentation Lab in March, 1964. Left to right: unknown, Milton Trageser, von Braun, Dick Battin and Ed Copps. Credit: Draper.
Knowing they would need to expand their operations to work on Apollo, the MIT Instrumentation Lab made arrangements to move into new facilities, a former underwear warehouse in Cambridge next to the Charles River. Battin thought they could maybe get by hiring 20 to 30 more people. What he couldn’t possibly fathom in 1963 was that by 1968, the lab would need to employ approximately 350 people in order to complete their work for Apollo.
“It was a whole change in point of view, that this project was not really just a few of us working, like on the Mars Probe,” Battin said. “It was a much bigger job, and we had to have lots of people whose only function seemed to be to keep everybody happy, not just NASA, but the spacecraft builders too. And we had to have firefighters to put out the fires.”
Eight Years to the Moon Page 8
