The Moon is a Harsh Mistress is a 1966 sci-fi novel by Robert A. Heinlein that has set in the year 2075 in Moon, which is used as Earth’s penal colony. Agra, a city famous for Taj Mahal is the headquarters of the Lunar Authority on Earth and the book popularised the acronym TANSTAAFL (There Ain’t No Such Thing As A Free Lunch).