Shortly after defeating the first two Hunters, go inside the building and check underneath the main ramp.
After your HUD starts to flicker and Cortana says it's because of her, it's at the base of a Forerunner structure.
After meeting up with fellow USMC soldiers, turn around before running outside and the terminal is directly behind you.
Near the very end of the level, you will pick up Cortana and trigger a long cutscene. After the cutscene, you will backtrack a little and a lightbridge will take you to the right. Do not enter the elevator triggering the end of the level! After the lightbridge, turn right to find the terminal.
After killing the 2 hunters, turn around and face the lightbridge that took you to that platform. Backtrack across the lightbridge and go to the right to a new platform. The terminal is on the backside of the isolated platform.
After killing the hunters and then going outside after a cutscene, look for the word "Atrium" written big up on a wall. The terminal is located in some small rocks near Atrium.
After the flying sequence is over, you'll fight your way through some large Promethean hallways. In the 4th large room, look behind the central structure for the final terminal.