UNC: Listening Post Theta
From Mass Effect Wiki
An Alliance base in the Acheron system in the Styx Theta cluster may be in danger. Get to the base and find out what is going on.
[edit] Acquisition
One way to acquire this assignment is to simply enter the base on Altahe. Alternately, if you enter the Erebus system first, this assignment will be given to you after you have fended off the rachni in the first part of the UNC: Listening Post Alpha assignment on Nepmos.
[edit] Walkthrough
After landing on Altahe, head to the Alliance base and kill the rachni emerging from the nests around it. Then enter the base and kill all the rachni inside. Fight your way to the back and access the terminals to hear a distress call from Lt. Durand and get the UNC: Listening Post Alpha assignment. If you have completed the other listening post mission already, you will be given the UNC: Depot Sigma-23 assignment.
