Digital Apollo – Mindell (2008)

Digital Apollo is a excellent sociological and technological study of the uneasy alliance between the astronauts who commanded the Apollo missions, and the computers which actually controlled the spacecraft systems. It traces how pilots, who first resisted the incursion of computers into their domain, gradually and grudgingly accepted the important role the computers played in making spaceflight possible.

I had this book sitting on my shelf for about four years. I finally got around to reading it and I was hooked. I read it cover to cover over a period of several nights. It is a very good book if you are interested in the topic of human computer interaction and the general question of automation vs manual control of machines.

As Mindell recounts, in the manned space program, most of the astronauts came from a test pilot background. They were expecting to fly the spaceships in the same way they flew their planes – by the seat of their pants. Yes, truly, the first astronauts were expecting to fly the rocket off the pad with a joystick. I found this absurd, but thanks to Mindell’s book I see the pilots point of view.

The engineers building the rockets and spaceships came from a career of building ICBMs, which flew autonomously to their targets, immune to any jamming or tampering after launch. They wanted to automate the entire mission, with computers flying the humans safely and accurately to and from the moon. They had done the math, and the margin of error was tiny, and the time scales miniscule. It only took a few minutes for these giant, powerful rockets to lift off from the launch pad and insert into orbit. There was not enough time for a pilot to hold the rocket to its trajectory, or to react correctly in case something went wrong.

It took a long time for the pilots to accept this. There was a great deal of back and forth between the pilots and the engineers about how much and what the computer would control and often very heated discussions whose basis was very existential – why were we sending men to the moon if all they would be doing would be punching buttons – one which said “take off” and another which said “land”.

Modern fighter aircraft are built to be unstable, making them more maneuverable, but harder to fly. Computer control of, say, the F-22, is what makes it actually flyable. In level flight the aircraft does not want to keep flying level and true, like the earliest piston engined aircraft. It wants to buck and jump and tear itself apart. Only the computer, fusing readings from a variety of sensors and quickly actuating various control surfaces, can react fast enough to keep the F-22 flying.

When the pilot moves the stick, or pushes on the throttle the computer integrates all the sensor information, infers what the pilot wants the aircraft to do,  and performs the appropriate actions to make that happen.

Not only do we have fly-by-wire, but we have drive-by-wire. I remember reading, back in the day, about the Toyota Prius and how the accelerator pedal was more a “demand pedal” which instructed the computer what speed or acceleration the driver was expecting, and it was the computer that then “managed” the car systems to give that speed or acceleration. I believe this is now commonplace in modern cars, for sure in the electric ones, though my old junker has a physical, stranded wire cable that snakes out from a hole in the firewall, from the passenger compartment, to the valve in the engine. I find that reassuring. But I am old fashioned.

To my mind, fly-by-wire, or drive-by-wire, is not really, fundamentally, different from what humans have done all along – developed technology to make end goals achievable by removing the burden of some of the more routine and demanding tasks, freeing up the human for more executive functions.

Take the governor for example. No one would today argue that because a steam engine has a governor, the train driver’s role or prestige was lowered. However, the governor did take over some of the skill of an operator. Without the governor, an operator would have to pay attention to the state of the engine and manually calibrate valves to keep the correct engine speed. The invention of the governor reduced the skill needed by the driver, but it also freed up the driver to devote attention to other, more high level things, like steering.

To me the Apollo computer was just like the governor in a steam engine: a tool that reduced the pilot workload for uninteresting, purely reactionary tasks – like adjusting the engine gimball to ensure the thrust passed through a buckling center of mass – so that they were free to do things like scan for an appropriate landing site, or take photos and make scientific observations.

On the other hand, a skilled train driver who had mastered the art of keeping his engine nicely purring through all kinds of load demands, would feel a bit of loss when the governor was introduced. Perhaps he enjoyed the challenge of fiddling with his engine to keep it on even keel.

The astronauts in the manned space program probably felt that some of their joy, their raison de etre, was being robbed, by off loading the complexity of the flight control to the machines. But this is a sentiment of pure ego. The apollo flight computers, in the end, were what enabled man to get to the moon in the first place. They made the rocket flyable, they made the lunar module landable.

The book ends by making a connection to the modern age when fly-by-wire aircraft are common and where there are similar discussions that pop up, especially after accidents, about how much control pilots actually have over the aircraft, and how they may be forgetting how to “actually fly” the aircraft.

Mindell throws in some side details along with the main narrative that intrigued me and made me want to look for further details. One of these was the mention of the landing simulator. These days our kids are used to the idea of photorealistic graphics of breathtaking interactive imaginary worlds in computer games, but in those days computer graphics were very primitive.

Though there is mention of someone being tasked to simulate the view out of the lunar module window in software (I think – but I don’t see how they could do this, given the primitive state of graphics at that time) what really caught my attention was a few paragraphs of an actual physical visual simulator that was set up.

Skilled craftsmen would craft a clay model of the lunar surface and mount it upside down on the ceiling. As the astronauts played out a lunar landing in their LM simulator, a small computer controlled camera would video this model, and the display would be projected onto the simulator windows in real time. I found this very cool.

Mindell remarks that no one has written a book about this simulator, and I really hope someone does. As you can imagine, doing a web search for “lunar landing simulator” brings up all the wrong hits.

One of the great things about the book is that Mindell cites his sources in fair detail. This allowed me to shortlist some other books I may want to read. Among them were Journey to the Moon by Eldon Hall.

Overall, it is a great book. You should read it.

Also, you should play this:  http://moonlander.seb.ly/