Hm. You know, I guess it is illegal to visit the moon without permission. From the 1979 Agreement Governing the Activities of States on the Moon and Other Celestial Bodies:
1. States Parties to this Agreement shall bear international responsibility for national activities on the moon, whether such activities are carried on by governmental agencies or by non- governmental entities, and for assuring that national activities are carried out in conformity with the provisions set forth in this Agreement. States Parties shall ensure that non-governmental entities under their jurisdiction shall engage in activities on the moon only under the authority and continuing supervision of the appropriate State Party.
OK, I take back my little rant. I am still not entirely thrilled about the world’s governments extending their control to celestial bodies, but the US is acting in accordance with international law. Mind you, the US hasn’t ratified the 1979 treaty, but we have ratified the 1969 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space. And Article VI in that document is nigh identical to Article 14 above. Oh, and here’s a list of signatories (PDF) to all five UN space law documents. Now I want to go work in Vienna.