Oh, yeah, I think you're literally on the Mars level...
Here's the basic layout of the map since you already got your immediate issue solved:
Red Dots are where Deus Ex Machina spawn (and frequently, I recommend using the big sniper rifle on them).
Iahel is close to the "Temple" I marked. I think "evidence" is in the "Federal Base."
You can get into the underground area either from the giant chasm or by hacking in the door in the Temple (it is a difficult hack). The Temple way in is one-way (in but not out).