After preventing a meltdown in Sector 3, Adam tells you to search for possible survivors in the Habitation Deck.
Go to the Habitation Deck
After you go up the Main Elevator, you will be in the area where the SA-X bombed the wall early in the game. Go through the door on the right, and go to the far right of this room, then run to the left to do a Speed Boost. After you break through some Boost Blocks, take the Missile Tank.
Run to the right while shooting your beam, and you will Speed Boost through the damaged wall up ahead. Go to the right and go down the shaft. You can optionally go through the door on the left to see what is there. Then go to the right and go through the Navigation Room (no need to use the Navigation console this time), and in the next room go up to the top of the shaft. Go through the door on the left, then go up the elevator to reach the Habitation Deck.
You can go through the door on the right to reach a Save Room. In the elevator room, go through the door on the left. Some free-floating X will tranform into a Fune and a Nahime. Make the Fune come out of the wall and freeze it, and jump up to the ledge above and to the left. Make the Nahime come out and freeze it, then jump on it to reach the door at the top. Go through it.
Through the window, you will see the sources of the bio-signs that Adam detected: Etecoons and Dachoras. Samus originally met them on Zebes in Super Metroid.
Go to the left and bomb the block in the floor that is near the left side of the window. Stand where the block was and you will fall through some Pit Blocks. Shoot the left wall to break it open. The block to the left can be broken with a Speed Boost, so run to the right, open the gate, and run to the left while shooting your beam. After you fall down below, open the gate on the right and take the Missile Tank.
Go to the left and jump up against the left wall to enter a hidden passageway. Make your way up the shaft by freezing the Fune when they emerge. At the top, go through the exit on the right. Go to the right and use the console to release the Etecoons and Dachoras.
Go back to the elevator and go down.
In the elevator room, go through the door on the right, then go down to the bottom of this shaft and go through the door on the left. In the Navigation Room, Adam tells you to go back to Sector 5 and use the Data Room there to get Power Bombs.