The Metroid could leech life from victims, was impervious to most weaponry, and could be cheaply cloned by exposure to beta rays for 24 standard hours. The Pirates had already tested their potential in a three-way simultaneous act on several Federation worlds, which were a stunning success for the Pirates’, with no casualties to their side at all. This was a grave threat to the fate of the Federation. With hundreds of Metroids under their power, the Space Pirates would inevitably begin a campaign to conquer the rest of the universe. Galactic Civilization would end. After a long and harrowing search, the Federation Police tracked the Pirates to Zebes. They launched an invasion but Pirate resistance was strong. After much debate, the Federation decided to turn to Samus to infiltrate the base at Zebes. She was given two objectives.
Destroy all Metroid organisms. & Defeat the Mechanical Life-Form