jumpjack / dskysim2

Tiny and simple simulator of DSKY interface for Apollo Guidance Computer (AGC)

DSKYSIM2

Replayer of Apollo 11 mission telemetries on DSKY interface of LEM Guidance Computer (LGC)**

• Live page: https://jumpjack.github.io/dskysim2/
• Raw telemetries in PDF: https://www.ibiblio.org/apollo/Documents/apollo_11_computer_words.pdf (other link , raw imnages )
• Transcripted telemetries: see .js files

(Original idea of dskysim by Ron Noteborn, 2001).

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In 2022 I found by chance this tiny page on internet:

It's dated 2001, more than 20 years ago; probably github didn't even exist at that time. But that page and its source look very interesting: tiny, simple, completely standalone, and easily extensible with further functionalities.

Original functionalities are indeed very simple, and summarized in the short help in the page itself, which you can find here.

Original Apollo 11 telemetries of descent

Telemetries of Lunar Module 5 of Apollo 11 mission are available here; I am trying to decode them here.

High resolution scans of single pages are available here.

Exposed methods of DSKYSIM

But the exposed methods allow to easily interface the DSKY to any external javascript source, so I plan to write an "Apollo 11 LEM descent AGC replayer", which will replay status of lamps and registers of DSKY as recorded on july, 20th, 1969.

I list in this page the highest level methods available to the developer; this is all you need to know to attach this interface to your program.

DSKYSIM2

My idea is to upgrade and extend DSKYSIM and turn it into a "DSKY replayer" or "AGC replayer": using the original Apollo 11 telemetries recently discoverd by VistualAGC team, I will try to make my DSKY simulator show the real status of AGC during the Apollo 11 powered descent: lamps, messages, data, everything. Around a hundred of telemetries were sent by AGC to ground every 2 seconds (*); although the found document does not contain all of them, it contains:

• status of all the DSKY lamps
• contents of all AGC registers
• values of nouns and verbs selected by crew
• status of DSKY keyboard

This is all I need to bring DSKY/AGC replayer to life.... but there are a lot more:

• values of computer flagwords from 4 to 11 (15bit x 12 = 180 bit, 1 bit unused in each flagword)
• values of computer channels 11-14 and 30-33
• status of RHC (joystick which controlled rotation of the LM)
• status of THC (joystick which controlled translation of the LM)
• orientation of the main engine gimbal (Descent Propulsion System - DPS, or Engine Control Assembly - ECA, aka "the bell" for friends)
• spacecraft roll, pitch and yaw (in CDU data)
• alarms status (1201, 1202....)

Other sources of data

There are other projects showing "realtime" data for Apollo 11, mostrly focused on transcripts; only "first man on the moon" shows some telemetries (commander heart rate, spacecraft pitch), but they are not available as raw data and there is no source available:

• https://project.exploreapollo.org/
• https://apolloinrealtime.org/11/
• https://www.firstmenonthemoon.com/

My repository Apollo11LEMdata, derived from the apparently abandoned jamescarruthers/Apollo11LEMdata , contains all the telemetries charts I was able to find aorund in some documents "hidden" on several server around nthe world.

Other javascript AGC/DSKY simulators

• Moonjs
• iDSKY (Exposed methods of iDSKY: here)

(*) "OUTPUT - EVERY 2 SECONDS 100 DOUBLE PRECISION WORDS (I.E. 200 LGC COMPUTER WORDS) ARE TRANSMITTED VIA DOWNLINK" --> see original AGC source