Twenty years ago, three astronauts took up residence at the International Space Station (ISS) and became the first crew to call the floating space lab home.

The members of Expedition 1—American commander Bill Shepherd of NASA (above center) and Yuri Gidzenko (left) and Sergei Krikalev of Russia—arrived on the ISS on November 2, 2000. Their historic mission as the first crew to live aboard the ISS marked the beginning of an era of international teamwork in space that continues today.

The idea for the ISS was proposed in the 1990s as a research laboratory where scientists from countries around the world could live and conduct experiments. The Expedition 1 team performed two dozen experiments while also working to get the station running for future crews. (Just activating the ISS food warmers reportedly took a full day!)

To date, approximately 240 astronauts from 19 nations have lived on the ISS. Scientists residing there today are studying ways to help send humans to Mars.