Today is a big day! The International Space Station turns 15! On this day, 15 years ago, nations united to build the mostadvanced space laboratory ever created—the International Space Station. A Russian spacecraft carried the first piece, Zarya, up into space in November 1998 with the module from NASA, Unity, joining it a couple of weeks later. It would be two years of preparation and building before the first crew would grace the ISS. But in November 2000, Expedition 1 arrived aboard a Soyuz TM-31. The space station marked an end to a rivalry between NASA and the Russian space agency. And the international participation now includes the Japanese space agency, the European Space Agency, and the Canadian Space Agency.