Space shuttle Discovery docked with the international space station early on Wednesday. NASA said the Discovery's seven-person crew now joins the six-person space station crew for more than a week of work together. It will be for the first time that four women are in space at one time. Discovery lifted of on Monday morning from the Kennedy Space Center in Florida. The shuttle's 13-day mission includes three planned spacewalks, replacing an ammonia tank assembly and retrieving a Japanese experiment from the station's exterior. It is scheduled to return to Earth on April 18.