 # Orekit > An accurate and efficient core layer for space flight dynamics applications [Orekit](https://www.orekit.org) is a low level space dynamics library written in Java. Orekit is designed to be easily used in very different contexts, from quick studies up to critical operations. As a library, Orekit provides basic elements (orbits, dates, attitude, frames, ...) and various algorithms to handle them (conversions, propagations, pointing, ...). ## Download ### Official releases [Official Orekit releases](https://gitlab.orekit.org/orekit/orekit/releases) are available on our [Gitlab instance](https://gitlab.orekit.org/). They are also available in the [Maven repository](https://mvnrepository.com/artifact/org.orekit/orekit). ### Development version To get the latest development version, please clone our official repository and checkout the `develop` branch: ```bash git clone -b develop https://gitlab.orekit.org/orekit/orekit.git ``` __Note:__ Our official repository is [mirrored on Github](https://github.com/CS-SI/Orekit). ## Documentation Project overview, architecture and development, detailed features list, tutorials, Javadoc and a lot of other information is available on the [Maven site](https://www.orekit.org/site-orekit-development/). ## Getting help The main communication channel is our [forum](https://forum.orekit.org/). You can report bugs and suggest new features in our [issues tracking system](https://gitlab.orekit.org/orekit/orekit/issues). ## Contributing Orekit exists thanks to the contribution of [many people](https://gitlab.orekit.org/orekit/orekit/graphs/develop). If you are interested in participating in the development effort, subscribe to the [forum](https://forum.orekit.org/) and step up to discuss it. The larger the community is, the better Orekit will be. The main rule is that everything intended to be included in Orekit core must be distributed under the Apache License Version 2.0 (you will be asked to sign a contributor license agreement). More information is available in our [development guidelines](https://www.orekit.org/site-orekit-development/guidelines.html). ## Building Detailed information on how to build Orekit from source either using Maven or Eclipse is provided in [building.md](src/site/markdown/building.md) file. * The [src/main/java](src/main/java) directory contains the library sources. * The [src/main/resources](src/main/resources) directory contains the library data. * The [src/test/java](src/test/java) directory contains the tests sources. * The [src/test/resources](src/test/resources) directory contains the tests data. * The [src/tutorials/java](src/tutorials/java) directory contains sources for example use of the library. * The [src/tutorials/resources](src/tutorials/resources) directory contains example data. * The [src/design](src/design) directory contains pieces for a UML model of the library. ## Dependencies Orekit relies on the following free software, all released under business friendly free licenses. ### Compile-time/run-time dependencies * [Hipparchus](https://hipparchus.org/) from the Hipparchus project released under the Apache Software License, version 2 ### Test-time dependencies * [JUnit 4](http://www.junit.org/) from Erich Gamma and Kent Beck released under the Eclipse Public License, version 1.0 * [Mockito](https://site.mockito.org/) from Szczepan Faber and others, released under MIT license. More detailed information is available in the [Maven site](https://www.orekit.org/site-orekit-development/dependencies.html). ## License Orekit is licensed by [CS Systèmes d'Information](https://www.c-s.fr/) under the [Apache License Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.html). A copy of this license is provided in the [LICENSE.txt](LICENSE.txt) file.