Orekit is free software, it means you can use it as you want in your applications, but also that you can improve it and have your code included in the next mainstream release.
If you are interested in participating in the development effort, subscribe to the mailing lists and step up to discuss about it. The largest the community will be, 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.
