Walkthrough: Head down the path between the Ammo Recharge and Energy Recharge Station to reach the next area. Follow it as you defeat the oncoming enemies, reaching the next room with the Teleportation Statue and Save Station. Once you reach the next room, Screw Attack the floor. Jump up into the hallway on your right, and in the next room will find a regular Metroid. Defeat it, the first of ten normal Metroids you'll have to defeat in this Area.
You'll find one Metroid after the next in the ensuing rooms, with one or two Metroids in each room. You'll need to charge your Ice Beam Attack, and while the Metroids are frozen, shoot off five Missiles in order to defeat them. In the left most room you come to will be a Missile Expansion. At the end of the rooms will be a Save Station and Aeion Recharge. From there, face your final challenge by jumping through the hole on your right.
Missile Expansion: After defeating the last three Metroid in the left most room, shoot a Missile at the weak spot in the left wall to find the Expansion.