Digital Apollo – Thoughts on Automation

Digital Apollo cover. Book by David A. Mindell

I just finished reading a fascinating book that I learned of during a telephone interview with a PhD candidate in the history of flight simulation. During our chat about the Shuttle Mission Simulator and other ground-based trainers we used in the program, he mentioned this book (Digital Apollo by David A. Mindell) as something written by (I think) his PhD advisor at MIT. I immediately found a copy on Amazon and it showed up in a few days. While I am used to seeing books written by and from an astronaut’s perspective, or from that of a historian looking back on a particular space program, this was from a point of view I had not seen before – someone looking at the program by following the development of the Apollo computers and flight control systems developed by the Instrumentation Lab at MIT – a place we usually referred to as Draper Labs.

Charles Stark Draper was the leader of the team that did much of this development — a byproduct of which was the increased production of integrated circuits that form the basis for most of the electronics we have today. In my mind, these computer chips are one of the single, greatest products of our nation’s investment in the Apollo program. The need for a lightweight, compact, yet powerful computer to fly onboard the Apollo vehicles spurred the development of the nascent integrated chip industry and grew the technology that allowed the development of internet and the spread of global information systems.

The book goes into detail on the development of not only the computer hardware, but the software used to control and guide the Apollo spacecraft, and then describes how the man/machine interface worked for each of the six lunar landings. Even though I had learned the history of how the systems functioned and performed while working with many of the men who manned the consoles during those landings (as well as a few the astronauts that flew them), this book gave details I had never before heard. Detailed descriptions of how the guidance worked from Powered Descent Initiation to touchdown, the procedural aspects of how the crew worked the systems during the landing phase, and the exact programs that were rolled in and out of the tiny computer memory expanded my understanding of just how we landed on the moon.

The book reminded me of many of the stories I heard in my early days in Flight Operations as I was taught the skills and philosophy of flight control by the men who sat on console in Mission Control Center during those landings – tales that might go over the head of an average casual observer, but held many lessons for someone striving to become, as the saying goes, a “steely-eyed missile man”. The book stresses the blend of man and machine when it came to the piloting task – something that many either take for granted or don’t understand. While we often think of a flying machine as being controlled either automatically (by the computer) or manually (by the pilot), the truth is that when the machine becomes complex enough, manual control is really just a different kind of computer control, for the pilot isn’t simply operating control surfaces or thrusters using direct mechanical links – they are telling the computer what they would like the flying machine to do, and the computer is figuring out exactly what controls are needed to make that happen. Without the computer interpreting the human’s desired result, you have no control at all.

This process developed more fully as subsequent programs created more complex flying machines, and it was fully realized in the Space Shuttle, a completely fly-by-wire machine that flew at a pilot’s command by using carefully developed control laws acting as an interpreter between desire and the physical world. The pilot says “go left” at a certain rate and the computer figures out how to do that, a process that leaves the human more mental bandwidth to make good decisions, rather than occupying their mind with the trivia of how controls and actuators must move to get the desired result.

Many believe that this makes a human more of a “system manager” than a true pilot – but this really is a matter of how we define “piloting”. Piloting is the skill required to make a machine do what we want it to do, and exactly where the line between human and machine falls is simply not that important. Somewhere between thought and effect, the computer and the human make the desired result happen and finding (or defining) that line is less critical than getting where you need to be. Technology allows us to do more, with better margins, and less risk than doing without – and that is more important in achieving the goal than where the line between synapse and actuator is finally drawn.

Digital Apollo is a book I would recommend if you want to know the details of how humans landed on the moon – or if you simply want to explore and better understand the blending of human and machine to achieve a spectacular goal.

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