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First Words Spoken on the Moon: Probably Not What You Think

Blog Post created by benz on Aug 10, 2017

  How about “ACA out of detent

Some people of my generation viewed the 1960s race to the Moon as an alternative to a military conflict, with the astronauts as the point of the spear. They were the space equivalents of fighter pilots, doing a more civilized kind of combat. Or maybe they were modern-day cowboys, taming the wildest frontier.

I was too young to be thinking explicitly about engineering as a career, but I viewed those on Earth and those flying the ships mainly as engineers. I still do. Consider the first words spoken by Buzz Aldrin and Neil Armstrong after the first lunar touchdown:

   Shutdown. (Armstrong)

   Okay. Engine stop. (Aldrin)

   ACA—out of detent. (Aldrin)

   Out of detent. (Armstrong)

   Mode control—both auto. Descent engine command override—Off. Engine arm—Off. (Aldrin)

   413 is in. (Aldrin)

By contrast, what we almost always hear in news or documentary coverage after “contact light” (when a probe extending from the lander footpads has touched the surface, but the spacecraft has not yet landed) is a pause and something rather more stirring:

   Houston, Tranquility Base here. (Armstrong)

   The Eagle has landed. (Armstrong)

Some people contend that the “real” first words were Neil’s announcement of Tranquility Base, but I disagree. In so many ways, the Apollo program and its predecessors were fundamentally engineering efforts. It was engineering of the first order, performed by thousands of people, that directed construction and testing, which was performed by hundreds of thousands.

The space program encompassed almost all engineering disciplines, especially electrical and computer engineering. Electrical engineers pioneered systems for control, telemetry, navigation, communications, and tracking. Computer engineers made astonishing advances in both miniaturized (for the time) hardware and real-time, fault-tolerant programming that did an extraordinary job of managing priorities.

Those first words reflected an engineering foundation and the mission planning that it drove. The first priority of the astronauts was to execute those plans, to maximize safety and the chances of mission success. When asked what dominated their thinking, astronauts don’t say much about fear or excitement, but rather a focus on avoiding messing up, and using their wits to solve the problems that came up (see also Apollo 13).

Most astronauts were engineers, and later engineering test pilots. Many had advanced degrees, and all had considerable engineering training. For example, Aldrin’s first degree was in in mechanical engineering, and he pioneered rendezvous technology that was essential for the Moon missions.

It’s no surprise, then, that Armstrong and Aldrin first uttered technical jargon, supporting the essential aspects of completing the landing and handling contingencies for a possible immediate abort back to lunar orbit. The ACA-detent discussion referred to a way to tell the guidance system that they were stable on the lunar surface, stopping any useless thruster activity. The “413 is in” comment refers to a command telling the computer that their orientation was horizontal on the surface, removing drift error ambiguity that could endanger any return to orbit.

After the triumphant announcement of the landing, Armstrong, Aldrin, and the Mission Control team immediately returned to the technical essentials, with Armstrong radioing, “Okay. We’re going to be busy for a minute.” Mission Control spent an intense 90 seconds going through the Stay—No stay decision process, while corresponding efforts on the lunar surface took even longer. If you’re interested in more detail, an annotated transcript is available.

The technical effort behind the Moon landing inspired a generation of engineers of all kinds, and recently some have virtually revisited the landing site. On the 45th anniversary of the landing, NASA used the cameras of its Lunar Reconnaissance Orbiter to generate a 3-D survey.

Recent overhead picture of the Apollo 11 landing site, showing the descent stage of the lander, scientific equipment left behind, and tracks of the astronauts.

This annotated composite image shows the reexamination of the first manned lunar exploration site by the cameras and stereo digital elevation model from the Lunar Reconnaissance Orbiter.  (Image from NASA)

All this certainly inspired my own efforts in engineering and science, and I’ve found that the unvarnished details are always plenty exciting, interesting and even inspiring. If you’d like to make your own virtual visit, rich online resources are now available anywhere there’s an Internet connection.

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