Samus Aran goes to a planet called SR388 when the Galactic Federation told her to exterminate the Metroids that live on it . To ensure that the Space Pirates can never obtain any more Metroids , the Galactic Federation sends several teams to the Metroids ' home planet , SR388 , to destroy them once and for all . However , when none of the teams survive , the Galactic Federation contracts Samus to finish the mission .