Orbiter - A Free Space Flight Simulator
- A realistic 3D flight simulator that uses proper physics for the modelling of planetary motion, gravitational fields, free space, and atmospheric flight.
- http://www.medphys.ucl.ac.uk/~martins/orbit/orbit.html
Orbit Hangar Mods - A general repository of contributions submitted by third party add-on developers. - http://www.orbithangar.com/
Orbital Mods - An addon repository focused in the Russian space flight program. It also features a database of known bugs in the simulator. - http://www.orbitmods.com/
Orbiter Mars - Includes concise tutorials that explain the procedures and the planning stage of interplanetary missions. - http://www.orbitermars.co.uk/
Project Alpha - An ongoing project to simulate the International Space Station Alpha. - http://www.f-a-d.co.uk/
Dan's Orbiter page - Find the module plug-in that enables sound in the simulation. Includes a support forum for frequently asked questions and general discussion. - http://orbiter.dansteph.com/