Survive Sevastopol with Prima’s Alien: Isolation Walkthrough.
When this mission begins, your objective will be to Find a Way to Contact the Torrens. Exit the shuttle and head to the Reception door, using your Security Access Tuner to gain access. Follow the corridor a short ways until you find an unmarked door on the right, choosing the option to Use Ion Torch to open it and pass through.
Go down the stairs in front of you and take a left, passing under the Comms Control sign and following this corridor all the way to the end. It will loop to the right and you want to keep moving even after that. You're going to take it all the way to the room where you snagged the Motion Tracker way back in Mission 4: Seegson Communications, turning into the room on the right side of the hall just before you get there. Be very careful making this journey. There are security personnel who mean to cause you harm. Try distracting them with a Noisemaker to sneak by.
Head up to the top of the stairs and save your game, then go through the door and turn right, following the corridor as it curves. When you reach some stairs on your left, go up them to reunite with Ricardo, as well as update your objective to Find the Sevastopol Observatory.
Wait for Ricardo to open the door, then follow the corridor straight and all the way to the end. Choose the option to Call Elevator when you reach it, then hop on and push the To Comms Control button. When the elevator arrives, move into the middle of the room and turn to your left, continuing on and through the door labeled Observatory Chamber. Just watch out for evil doers wandering the area.
After moving through a short corridor that curves to the right, choose the option to Use Ion Torch to open the only door you can pass through, then approach the ladder and Climb. This will update your objective to Use the Tracking System to Find the Torrens, and allow you to Activate Observation Platform on the console behind you. When that's done, move on to the next console and choose to Commence Deep Space Scan, and then on to a third to do the same thing.
Doing all of this will update your objective to Manually Input Torrens Coordinates, so Climb back down the ladder and backtrack out the way you entered. Turn left into the E.V.A. Preparation room and step onto the platform, then choosing the option to Use. When you reach your destination, step off and save your game just to the right.
After saving your game, you'll need to approach the glass with the space suits behind it and choose the option to Change. When you're done, pass through the External Array, turn right and go through the door at the end of the short corridor. Once the second door unlocks, step outside and start making your way across the catwalk.
When you reach the other side, you'll see a sign that says Dish Maintenance with a lift behind hit. Step on and choose the option to Use, then step off when you arrive and continue to follow the catwalk as the Dish Maintenance signs guide you. When you pass through a door into a dark area, look for an press the button to Reboot Array Clamp Controls.
This is another situation where you have to press a bunch of buttons to make something happen. Keep looking from one to the other until you can choose Power Up Clamp Release, then move to your right and repeat the process two more times. When that's done, move back to your left and choose to Unlock Emergency Clamp, then backtrack out the way you came, going up the stairs as they curve to the right. When you reach the top, look to your right and choose the option to Input Torrens Coordinates. Move the first marker to 35 and the second marker to 75... assuming the game gives everyone the same coordinates.
This will allow you to contact the Torrens, and after a brief conversation your objective will be to Find a Way for the Torrens to Dock, which is really, really far away.
Start by using the lift to descend, then following the catwalk all the way back to where you originally started. Head back inside, change out of your space suit and then save your game. Take the lift back up just in time to spot the Alien in action, but be very careful not to let it catch sight of you.
Exit the room, turn to your left and make your way back to the elevator. Step inside and press the button to go To Comms Security Surveillance. When you arrive, step off and follow the corridor back to Ricardo's last known location, then go down the stairs and turn to your right. Follow the hallway as it curves to the left and then through the Reception door on the left. Make your way down the stairs and back into the corridor with all the security personnel.
You need to follow this corridor all the way around as it loops to the left. Take it all the way back to the area where you started Mission 4: Seegson Communications, then pass through the door labeled Departure Bay, turning right and taking the elevator To Systech Upper Transit. This will conclude the mission.
Continue to Alien: Isolation - Mission 17: Desolation.