This is an expansion! A copy of Terraforming Mars is required for play. 

Our world has widened before us. Corporations expand their operations to all corners of the solar system in pursuit of minerals and resources. Most places are not suited for terraforming, but building colonies may greatly improve your income and your possibilities in achieving that higher goal — the terraforming of Mars. Send your trade fleet to distant moons! Colonize the clouds of Jupiter! And let your Earth assets propel you to success!

Terraforming Mars: Colonies, an expansion for Terraforming Mars that can be played with only the base game or with any combination of expansions, lets you visit the outer solar system. It features colony tiles where you can build colonies and send your trade fleet. It also includes new cards and corporations.