By the year 2025 there will be a base or bases or settlement(s) on the Moon, or in an orbit around the Moon, with an average total population of at least 20 persons. The average will be taken over any one-year period, starting by Jan 1, 2025.
Standard ambiguity clause: If the wording is found to be ambiguous I will judge on the basis of the obvious intent. If the intent is ambiguous I will judge on the basis of precise wording. If both are ambiguous or if both are clear but conflict, I will look for a solution that causes the least damage to FX as a market and game.
I assume the usual meanings of the words in the claim: persons are human, and the earth is not in orbit around the Moon in the usual frame of reference. While the intent appears to be that the base or moon-orbiting station be permanent, for the sake of definiteness the claim will be closed after the first year of 20+ average population regardless of the stated future plans of the occupants.