That’s one small step for man, one giant Leap for mankind. — Armstrong

That’s one small step for man, one giant leap for mankind. — Armstrong

Neil Armstrong, astronaut of Apollo 11, spoke the first words after man first set foot on the moon.

The Apollo program was a series of manned missions to the moon conducted by the United States between 1961 and 1972.

The Apollo spacecraft used for lunar missions in the late 1960s and early 1970s were actually two different spacecraft, the Command Module (CM) and the Lunar Module (LM).

CM was used to send three astronauts to the moon and back. While CM was in lunar orbit with one astronaut, the LM was used to send two other astronauts to the moon.

Every spacecraft needs to be able to navigate through space with the help of astronauts, so there needs to be a “navigation system”. The navigation system was developed by MIT’s Instrument Laboratory, now an independent company called Charles Stark Draper Laboratories.

An important component of the navigation system is the Apollo Navigation Computer, or AGC. On any given Apollo mission, there were two automatic gain control systems, one for the command module and one for the lunar module.

The two automatic gain control systems are identical and interchangeable, but they run different software because the tasks the spacecraft must perform are different.

In addition, the software run by the AGC has evolved over time, so the AGC software used on subsequent missions like Apollo 17 is slightly different from that used on earlier missions like Apollo 8.

The AGC can be considered a severely impotent computer by modern standards.

 

The occasional joke is that the AGC is more like a calculator than a computer. But to say that is to grossly underestimate the complexity of the AGC. For example, AGC is multitasking, so it looks like it can run multiple programs at the same time.

Another important part of the navigation system is the display/keyboard unit, or “DSKY” for short. The automatic gain control system itself is a box with an electrical connection, with no built-in way for astronauts to enter. DSKY provides astronauts with an interface through which they can access the AGC.

The lunar module has only one DSKY, which sits between two astronauts and can be operated by either of them. The command module actually has two DSkys. One of CM’s DSKY is just the main control panel, while the other is located near optical equipment used to mark the location of stars or other landmarks.

 

The GitHub project is associated with the website of the Virtual AGC Project, which provides a virtual machine to simulate AGC, DSKY, and other parts of the navigation system. In other words, if the virtual machine we call yaAGC was given the same software originally run by the real AGC and fed back the same input signals encountered by the real ACG during the Apollo mission, it would respond in the same way as the real ACG.

The current version of virtual AGC software is designed for Linux, Windows XP/Vista/7, and Mac OS X 10.3 or higher (but preferably 10.5 or higher). It also works on at least some versions of FreeBSD. The main author is Linux version, so interested partners, you can try to choose Linux version.

It’s going to look something like this

GitHub address: github.com/virtualagc/…