Move Upstairs to Operations | Mission 4: No Hope in Hadley's A: CM Guide

Explore the colony (if you don't want to wait until someone opens the door, use the control panel yourself). Follow your teammates again, there are no aliens to run into. Take a look inside the first room on the left to find the only Audio Log in this mission, pictured above.

Backtrack to the main corridor and move forward, past some other rooms. When you find the stairway, move up to the first floor. Your destination is the door illustrated above, which you need to open using the welding torch.