# What Is Comanche055 and Its Role in the Apollo 11 Mission? > Discover Comanche055, the Apollo 11 guidance software. Learn how this open-source code managed navigation, attitude, and re-entry for the historic mission. Explore the chrislgarry/Apollo-11 repository. - Repository: [Chris Garry/Apollo-11](https://github.com/chrislgarry/Apollo-11) - Tags: deep-dive - Published: 2026-03-04 --- **Comanche055 is the open-source release of the Command Module guidance software (also known as Colossus 2A) that controlled navigation, attitude, and re-entry for the Apollo 11 mission, archived in the chrislgarry/Apollo-11 repository.** The chrislgarry/Apollo-11 repository preserves the original source code for NASA's Apollo Guidance Computer (AGC). Comanche055 represents the specific program version that operated the Command Module (CM) during the historic Apollo 11 lunar mission, offering a rare look at the assembly-level instructions that flew humans to the Moon. ## What Is Comanche055? Comanche055 is the publicly released source code for the **Command Module's** Apollo Guidance Computer software. Originally designated **Colossus 2A** in NASA documentation found in [`README.md`](https://github.com/chrislgarry/Apollo-11/blob/main/README.md), this program governed every automated function of the CM, from launch through lunar orbit and splashdown. The code resides in the `Comanche055/` directory of the chrislgarry/Apollo-11 repository and is available under a public domain license, allowing developers and historians to study, assemble, and emulate the exact software used during the 1969 mission. While Comanche055 specifically supported Apollo 11, subsequent revisions of the Comanche codebase served later flights, including Apollo 12, making this archive the foundational reference for Command Module flight software evolution. ## The Role of Comanche055 in Apollo 11 During Apollo 11, Comanche055 executed critical flight phases aboard the Command Module *Columbia*. The software managed: - **Orbital navigation and guidance** calculations that maintained the spacecraft's trajectory - **Attitude determination** through vector cross-product routines - **Integration loops** for state vector updates and re-entry planning - **Interface management** between the AGC and the CM's thrusters and sensors Unlike Luminary099, which ran the Lunar Module, Comanche055 never executed the landing sequence, but it was essential for maintaining lunar orbit, rendezvous maneuvers, and the trans-Earth injection that brought the crew home. ## Exploring the Comanche055 Source Code The repository provides the complete assembly source for analysis and emulation. ### Key Source Files The `Comanche055/` directory contains the modular AGC source files: - **`CONTRACT_AND_APPROVALS.agc`** – Houses the official NASA contract metadata and program approval documentation, providing historical provenance for the software release. - **`INTERPRETER.agc`** – Implements the interpretive execution engine that processes high-level AGC instructions; this file serves as the primary entry point for understanding how the software processes commands. - **`INTEGRATION_INITIALIZATION.agc`** – Contains the initialization routines for the integration loops that drive continuous navigation and guidance calculations throughout the mission. ### Assembling Comanche055 To build the source into executable binary format, use the **YaYUL** assembler included with the Virtual AGC project: ```bash # Clone the repository git clone https://github.com/chrislgarry/Apollo-11.git cd Apollo-11/Comanche055 # Assemble an individual source file (e.g., the interpreter) yaYUL INTERPRETER.agc -o INTERPRETER.bin ``` The assembler translates the 1960s-era Assembly language into binary compatible with AGC emulators. ### Running on Virtual AGC Once assembled, execute the binary in the Virtual AGC emulator to simulate Command Module operations: ```bash # Launch the emulator with the assembled Comanche binary virtualagc -c INTERPRETER.bin ``` This command initializes the emulator environment, allowing you to step through instructions, inspect register states, and observe the same computational sequences that guided the Apollo 11 CM. ### Core Routines Within `INTERPRETER.agc`, navigation routines such as the vector cross-product calculation demonstrate the mathematical foundation of spacecraft attitude control: ```asm ; Cross-product routine excerpt VXV UNIT ; Compute unit vector of R(CM) × V(CM) ``` This instruction sequence calculates the unit vector of the cross product between position and velocity vectors, a fundamental operation for determining spacecraft orientation. ## Summary - **Comanche055** is the open-sourced Command Module software (Colossus 2A) from the Apollo 11 mission, archived in the `chrislgarry/Apollo-11` repository. - The program controlled navigation, attitude, and orbital mechanics for the Command Module *Columbia*, distinct from the Lunar Module's Luminary software. - Source files reside in the `Comanche055/` directory, with critical components including `INTERPRETER.agc` and `INTEGRATION_INITIALIZATION.agc`. - Developers can assemble the code using **YaYUL** and run it on the **Virtual AGC** emulator to simulate 1969 flight conditions. - The codebase is released into the public domain, serving as the authoritative reference for Command Module AGC operations in Apollo 11 and subsequent missions. ## Frequently Asked Questions ### Is Comanche055 the same as Colossus 2A? Yes. According to the [`README.md`](https://github.com/chrislgarry/Apollo-11/blob/main/README.md) in the chrislgarry/Apollo-11 repository, Comanche055 corresponds to the NASA internal designation **Colossus 2A**, the specific revision of the Command Module software flown on Apollo 11. ### How can I run the Comanche055 code? You can run Comanche055 by cloning the repository and using the **Virtual AGC** toolchain. First, assemble the desired `.agc` files using the **YaYUL** assembler, then load the resulting binaries into the `virtualagc` emulator to execute the code in a simulated Apollo Guidance Computer environment. ### What is the difference between Comanche055 and Luminary099? **Comanche055** operated the Command Module (the spacecraft that remained in lunar orbit and returned to Earth), while **Luminary099** controlled the Lunar Module (the vehicle that landed on the Moon). They share the same AGC hardware architecture but execute distinct mission phases and vehicle-specific guidance routines. ### Is Comanche055 legally open source? Yes. The code in the chrislgarry/Apollo-11 repository, including Comanche055, is released into the public domain, meaning there are no licensing restrictions on its use, modification, or distribution for educational, research, or commercial purposes.