We all know Project Apollo - NASSP as the Apollo add-on for Martin Schweiger's Orbiter space flight simulator. So why is there a new add-on "based" on Project Apollo - NASSP? And what is the Virtual AGC?

Virtual Apollo is based on Project Apollo - NASSP^[1] that means all the graphics and most of the code are used from Project Apollo - NASSP (and a few other add-on's, see Installation and Authors and contributors for more details) except one interesting and extremly important detail:

Unlike Project Apollo - NASSP an Apollo Guidance Computer (AGC) emulator is used running the original, authentic Apollo flight software (at the moment Colossus 1A, build 249 from October 28, 1968, probably flown with Apollo 8 and 9).

Figure 1. Apollo 11 on the Launch Pad

That means for example that all DSKY interaction is done by the real Apollo software and not by a NASSP-specific software with similar behavior. It does not try to mimic the superficial behavioral characteristics of the AGC, but rather to model the AGC's inner workings. In future versions all guidance, navigation and control operations could perhaps handled by the real flight software, so you can fly and operate the Apollo spacecrafts like the original astronauts.

I personally think that's really fantastic and very exiting, because I'm very interested in the historic Project Apollo. So for me Orbiter is mainly a "tool" to provide the physical universe for the AGC (and hopefully other internal systems in future). But of course if you are not interested in the details of the Apollo project and it's systems you will perhaps find all this boring...

The emulation of the AGC is done by using Ronald Burkey's Virtual AGC^[2]. Virtual Apollo is not the first attempt to do this, Mark Grant began this work with his NASSP_COSTAM2^[3] and the Virtual Apollo code is a further development of his work.

But Virtual Apollo don't want to be an add-on existing parallel or in concurrency to Project Apollo - NASSP. In fact Virtual Apollo is no add-on at all, it's more like a "proof-of-concept" study to show that it is possible to use the original, (almost) historical correct AGC but still to have a playable game like before. It has only a name of it's own to better can speak about it and to have a name for directories, documents and so on.

It is important to mention that Virtual Apollo is not written by me nor my affort. I only "screwed" a lot of existing components together.

In future I hope Virtual Apollo could be merged into Project Apollo - NASSP. So Virtual Apollo is planned as a only temporary existing add-on to discover the possibilities given by the Virtual AGC, it is an honor for me to contribute to Project Apollo - NASSP.