Learn English – ‘Earth-based’ adjective counterpart to ‘Lunar’ or ‘Solar’

Prerequisite springs to mind.

• It would be immediately intelligible to anyone who has attended an American university or played Dungeons and Dragons.

• It can be deployed as either an adjective or a noun.

• Its upstream and downstream scopes can be expressed economically (T’s prerequisites are S₁ and S₂, S₁ is prerequisite to T).

This is a good question. I'm sure at least one sci-fi author must have coined such an adjective, and I feel like I must have come across one in the past, but I can't remember any right now.

One option that I've found in scientific contexts is circumstellar. It is used primarily in reference to circumstellar disks, such as the asteroid and kuiper belts, but it could be used to refer to anything in orbit around a star (or in orbit around a binary star system.)