Orbiter is a spaceflight simulator based on Newtonian mechanics. Its playground is our solar system with many of its major bodies – the sun, planets and moons. You take control of a spacecraft – either historic, hypothetical, or purely science fiction. Orbiter is unlike most commercial computer games with a space theme – there are no predefined missions to complete (except the ones you set yourself), no aliens to destroy and no goods to trade. Instead, you will get a pretty good idea about what is involved in real space flight – how to plan an ascent into orbit, how to rendezvous with a space station, or how to fly to another planet. It is more difficult, but also more of a challenge. Some people get hooked, others get bored. Finding out for yourself is easy – simply give it a try. Orbiter is free, so you don’t need to invest more than a bit of your spare time.

Orbiter is now published as an Open Source project under the MIT License (see LICENSE file for details).

Get the Orbiter source repository from github

git clone [email protected]:orbitersim/orbiter.git

or

git clone https://github.com/orbitersim/orbiter.git

To configure and generate the makefiles, you need a recent CMake.

To compile Orbiter from its sources, you need Microsoft Visual Studio. Orbiter has been successfully built with VS Community 2019, but other versions should also work. Note that VS2019 comes with built-in CMake support, so you don't need a separate CMake installation.

Some configuration caveats:

• If you are using the Ninja generator (default for the VS built-in CMake), you may also need vspkg to configure the VS toolset.
• If you are using the VS2019 generator, you may need to set up Visual Studio to use only a single thread for the build. This is because some of the build tools (especially those for generating the Orbiter documentation) are not threadsafe, and the VS2019 generator doesn't understand the CMake JOB_POOL directive.

Orbiter is a 32-bit application. Be sure to configure vspkg and CMake accordingly.

If you want to build the documentation, you need a few additional tools:

• a filter to convert ODT and DOC sources to PDF, such as LibreOffice.
• a LaTeX compiler suite such as MiKTeX.
• Doxygen for building the source-level documentation for developers.

By default, the build is configured to create both graphics flavours of the Orbiter executable (although this can be configured with the ORBITER_GRAPHICS CMake flag):

• orbiter.exe is the standalone Orbiter application with built-in DX7 graphics.
• orbiter_ng.exe is a launcher for ./Modules/Server/orbiter.exe which is the graphics server version of Orbiter. It requires an external graphics client plugin to be loaded via the Modules tab of the Orbiter Launchpad dialog. The reference D3D7Client is included with the build with essentially the same functionality as the built-in graphics version. Use 3rd party client implementations to make use of more modern graphics engines.

See README.compile for details on building Orbiter.

The Orbiter git repository does not include most of the planetary texture files required for running Orbiter. You need to install those separately. The easiest way to do so is by installing Orbiter 2016. Optionally you can also install high-resolution versions of the textures from the Orbiter website. You should keep the Orbiter 2016 installation separate from your Orbiter git repository.

To configure Orbiter to use the 2016 texture installation, set the ORBITER_PLANET_TEXTURE_INSTALL_DIR entry in CMake. For example, if Orbiter 2016 was installed in C:\Orbiter2016, the CMake option should be set to C:/Orbiter2016/Textures. Alternatively, you can configure the texture directory after building Orbiter by setting the PlanetTexDir entry in Orbiter.cfg.

Help files are located in the Doc subfolder (if you built them). Orbiter.pdf is the main Orbiter user manual.

The in-game help system can be opened via the "Help" button on the Orbiter Launchpad dialog, or with Alt-F1 while running Orbiter.

Remaining questions can be posted on the Orbiter user forum at orbiter-forum.com.