Howdy!
Additional planets and crewmates are planned, but will likely come in updates post-release. Currently, the game is heading for a huge Quality Pass, where existing systems are going to be expanded upon, new areas added, etc, and the focus is very much going to be on making current stuff even better.
Procya as a 'true' location is planned, too, likely as part of aforementioned Quality Pass, so stay tuned for that!
Thanks for playing! :)