Imagine researchers on Mars want to know about life on earth (in order to understand how they might attract more visitors, scientist ...) – they set up an analog station to find out – on earth.
Sometimes visitors with children came along – „Are you playing to be on Mars?“ the child asks. And of course, if I said „yes“ they would ask for the space suit, the space ship etc. – „No, we are playing to be on earth, playing that we are on Mars.“ The child laughs. Only his father doesn‘t understand.