Project Apollo for Orbiter
NASA's Apollo Space Simulation Project is an Addon for Orbiter which recreates the Apollo missions.
Background
NASSP was originally developed by Jean-Luc Rocca-Serra, who released the source code to version 4.x. Mark Grant then rewrote the code as C++, added an initial C++ implementation of the Apollo Guidance Computer and replaced the control panel bitmaps, releasing 'NASSP COSTAM' and a derivative which provided basic support for the Virtual AGC software.
Jean-Luc released NASSP 5.0, an updated version based on that source code, for the next release of Orbiter, including, for example, new particle exhaust support and a Skylab launch module.
With the 6.x release it became Project Apollo for Orbiter, an open source Apollo simulation add-on: for simplicity, both software variants are described here as NASSP. The latest 'stable' version is 6.4.3.
The 7.0 release is currently in Beta, including a near-complete simulation of the Command Module control panel and most of the internal systems, and support for new spacecraft. It is also capable of flying most of an Apollo mission using the Virtual AGC software.
Supported spacecraft
NASSP 7.0 supports a number of spacecraft.
'Apollo to Venus' Wet Workshop test
NASA's Manned Venus Flyby plans using Apollo technology would have used an SIVB stage to launch a three-man crew towards Venus, after which they would vent remaining fuel from the SIVB, extend solar panels and live in it as a Skylab-style space station. They would conduct generalised astronomical and zero-gravity experiments for most of their trip, and for a few days around the flyby they would conduct detailed observations of Venus.
NASSP 7.0 includes a simulation of the first test phase, in which the astronauts would use the SIVB to raise their orbit for a test of the 'wet workshop' of up to one month in duration.
Command/Service Module
NASSP simulates the Block II Command/Service Module, providing a home and life support for the astronauts in space.
Lunar Module
Two-stage lander used to land astronauts on the Moon and return them to orbit.
Lunar Rover
Electrically-powered rover used by the astronauts to drive around the lunar surface.
Saturn V
Three-stage launcher used to launch a Command/Service Module and Lunar Module towards the Moon.
Saturn 1b
Two-stage launcher used to launch a Command/Service Module into Earth orbit.
Saturn INT-20
Two-stage launcher used to launch a Command/Service Module and larger payload into Earth orbit.
Future spacecraft
There are a number of candidates for future additions to the spacecraft simulated in NASSP.
Command/Service Module
Support may be added for the proposed Block-III CSM with batteries for power in place of fuel cells, and the Block-IV CSM with batteries for power and LEM engines in place of the SPS.
Long-Range Flyer/Lunar Escape System
Simple two-man rocket using fuel from the LEM. This could be used for scouting missions to sites up to around 50 miles from the main landing site, or, in an emergency, to carry two astronauts from the lunar surface to rendevouz with the CSM.
Saturn INT-21
Two-stage launcher used to launch large payloads into Earth orbit. This was used for the Skylab mission.
Skylab
The NASSP 5.x Skylab sources were lost, so a new version will be required once the INT-21 support is added.