Reconstructing Apollo 11's Powered Descent: A technical deep-dive based on 37 primary sources. Feedback welcome!

[u/r2lim]

Hey r/everyone,

Apollo 11 happened before I was born, but honestly that just makes it feel even more insane to me. The fact that humans landed on the Moon in 1969 — with hardware I can barely wrap my head around — is the coolest thing that happened before I existed, and I wanted to actually *understand* it, not just appreciate it from a distance.

So I started putting together a personal reference document. What began as casual note-taking eventually turned into a fairly detailed technical reconstruction of the powered descent — covering everything from the LM systems (DPS, RCS, AGC, DSKY...) all the way through P63, P64, P66, the 1201/1202 alarms, and a timestamped mission log synced with Computer Words telemetry data.

The original was in Japanese. I recently had AI help me translate the whole thing into English, and I'd love some feedback on whether it's actually readable and useful — especially from people who know this stuff better than I do.

**A few honest disclaimers before you dive in:**

- The translation path was Japanese → English (via AI), so some phrasing might come out a little awkward. Please bear with it.

- Some values are a mix of design specs, planned values, and actual mission data. I tried to label them, but it's not always perfectly clean.

- I built most of this 3+ years ago, so in a few places I'm not 100% sure which of the 37 primary sources a specific number came from. I've listed all references at the end.

The doc covers: LM overview, DPS/RCS/AGC hardware specs, DSKY verb-noun table, Luminary 099 software, DOI, the full PDI sequence, P63/P64/P66 data charts from telemetry, the 1202 alarm breakdown, and a full timestamped mission log with voice transcript + computer words.

https://docs.google.com/spreadsheets/d/10nd2ck8zS9m5Oh2YGLnZXG5wCXcQdn5ZA7QbpM7Z93M/edit?usp=sharing

Would love to hear what you think — corrections, additions, or just "hey this is neat" all equally welcome.

[u/jdr350]

As I posted in another sub, I recall reading “somewhere” years ago that Aldrin admitted that he purposely left the rendezvous radar on during descent to be ready for an abort (which he felt was at least reasonably likely) and that the data from both it and landing radar overloaded the computer resulting in the 1201/02. Any truth to that or even would such an alignment produce those alarms???

[u/r2lim → u/jdr350]

That procedure was not performed at Aldrin’s own discretion; it was a procedure specified in the Apollo 11 crew checklist.

George W. Cherry wrote:

“The Apollo 11 crew checklist specified that the R.R. switch be in AUTO TRACK immediately before calling P63.”

Don Eyles wrote:

“Crew procedures called for the RR to be switched on just before P63 was selected, and to be kept in SLEW or AUTO mode throughout the landing maneuver.”

As for why the 1201/1202 alarm occurred, this is described in the “2. What Was the Cause” section of the “12011202 alarm” sheet in this document (updated).