(Clic on the image to access at the website)

Welcome aboard the "Flagship" of Orbiter.ch

The most successful of space flight simulator, created and developed by Martin Schweiger, this simulator allows you to simulate all missions you want, be it the launch of the shuttle Atlantis in a mission or exploration of the solar system.

http://orbiter.jimdo.com/

ORBITER is a free flight simulator that goes beyond the confines of Earth's atmosphere. Launch the Space Shuttle from Kennedy Space Center to deploy a satellite, rendezvous with the International Space Station or take the futuristic Delta-glider for a tour through the solar system - the choice is yours.

Here's a addon's "Home Made by Orbiter.ch". As is my habit, I put it friendly available for free download!