You return to B.S.L research station to investigate an explosion that took place there.
Receive Your Objective
Your computerized CO (commanding officer) tells you to go to the Quarantine Bay to investigate the explosion. Your first destination is the Navigation room en route to the Quarantine Bay.
Exit the Docking Bay to the left, then jump the platforms to go up the tall room. Ignore the red hatch on the way (it's locked) and exit through the door at the very top.
Just keep going left and you'll reach the navigation room. Stand in the middle of the room to use the computer. It tells you that there are life signs in the Quarantine Bay ahead. Afterward, go to the left.
The door to the left is locked, so go to the top of the tall room. Exit through the open door at the top.
There is a broken wall to the left that you can't go past. Go down to the lower part of the room and go through the door there.
Go to the left, jumping over the boxes. A Hornoad is hopping around. Shoot it with your beam until it dies. It will turn into an X parasite. Since you were vaccinated against X, you can collect the X by touching it. Yellow Xs will restore 10 units of energy.
Return to the Navigation Room. You learn that the X can transform into creatures that it has infected. The computer tells you that it has detected bio signs and orders you to investigate. The computer unlocks Level 0 hatches, which will be blinking.
Exit to the right and go up the tall room until you see a blinking grey door. Shoot the grey door to open it. (The doors above are locked.) The X in this room turns into a Hornoad. Go right to find the first Save Room. Stand on the floating platform to save your game. Exit to the right.
In the next room, go up to the top, killing the Zombie on the way, then go through the door on the right to reach another Navigation Room. The computer tells you that you can go to a Data Room to regain your Missile ability.
Exit to the right, then go up and go through the door at the top. Stand on the glowing spot and press up to go up the elevator. During the elevator ride, Samus decides to refer to the computer as "Adam," after her former commanding officer, Adam Malkovich. (Adam's story is expanded upon in Metroid: Other M for Nintendo Wii.)
When the elevator stops, go through the door, then go to the left. In this big room, there is a Recharge Room and Save Room on the bottom floor, and there is a Navigation Room and Data Room on the second level. Go into the Data Room and stand in front of the glowing machine to receive your Missile ability. To use missiles, hold R while shooting.
Afterward, go to the right. You will hear the power turn off. In the Navigation Room, the computer tells you to find an alternate route to investigate the bio-signs.