The Galactic Federation Special Squadron was sent to SR388 by the Galactic Federation to make sure there were no Metroids left on the planet. Shortly after, contact with the ship was lost. A search and rescue party was later sent, and then a special combat group, but none of them came back alive. Samus Aran was then sent to SR388 to exterminate the Metroids, setting in motion the events of Metroid II: Return of Samus.
Their remains are never encountered in the game.