Most game jams have some kind of theme or limitation to consider.
Major questions would be:
1. Does the game have to be made during the time of the game jam, or can it be something made earlier?
2. Does the jam have a theme? I would assume it is space, but something like that should probably be stated.
3. Any limits on what kinds of resources we use? I.e. a particular game engine, only assets we made ourselves, some kind of screen resolution limit etc...
4. Will there be any kind of judging or prize for winners?
Sorry, don't mean to complicate things. But if there are none of these limits, it might also be good to state that in the description.