This article is to study to what extent the liability and responsibility regime developed under the UN space treaties could reasonably address private activities of the Moon and Mars using a hypothetical case and state practice of the UN registration of satellites deployed from the International Space Station. The survey shows that neither the liability regime nor the unique international responsibility regime would be sufficient to address “newspace” activities, and it is concluded that the nationality for space object is needed for the orderly exploitation of the Moon and Mars, as it is not necessarily possible to identify the nationality of a private person who is responsible for a business activity due to the inevitably complicated investment and operation schemes and persons of various nationalities staying in one self-contained space station or facility.