The Mars Genesis cards are "Non-Fungible Tokens" on Ethereum and ERC-721 standard that powers most digital art and collectibles.
No parcel has the same size or collection of attributes. Therefore, each has a different value. As a matter of fact, the topography, water data, temperature range, and colony conditions are accurate to the extent of human knowledge and from compiling state-of-the-art research.
Mars is finite. Therefore, once the 10,000 cards covering the planet are minted, the only way to acquire one is to purchase it from someone via the marketplace that is embedded in the blockchain. Via this market, you can buy, bid on, and offer cards for sale.