Orbiter – Space Flight Simulator is a realistic simulation, using real world physics to provide a fun and educationally informative environment for flying spacecraft near the Earth, Moon, Mars and beyond. It was created by Martin Schweiger at UCL, and has been developed by him and many enthusiasts over the last decade. Many add on modules, spacecraft and mission are available. Very high resolution Earth and other planetary textures are available.
In 2006 I created an Orbiter compatible version of Gerry Anderson’s Supercar along with mission profiles for Earth to International Space Station (ISS) missions.
A relatively recent add-on spacecraft and mission is the X-Prize winning SpaceShipOne, the forerunner of the soon to be available Virgin Galactic Spaceship for actual tourist flights into space.
Mission planning, along with realistic take-off loads, fuel weights, take off timing and trajectories have to be planned in the advanced modes, e.g. for Space Shuttle missions to the ISS. But Orbiter can also be used in “fun” mode with lots of assisted flight control.
Much more detail, the free download of Orbiter, manuals and tutorials are available at http://orbit.medphys.ucl.ac.uk/download.html
Orbiter addons are available, for example, at https://orbithangar.com/