Ian McDonald's Luna trilogy is filled with fantastically detailed grace-notes that give his lunar society an uncanny veneer of reality; one of the most fascinating and thoughtful of these details is the cocktails that McDonald's clannish lunarians consume, each great house with its own signature tipple. In a new essay for Tor.com, McDonald describes the worldbuilding behind his booze, which is always a cocktail made from hard spirits because of the carbon budget needed to grow grain or fruit for beer or wine. But: spirit alcohol.