The shiny metal ball is used at the spaceport in Arnika, which is also where you find the orbital tracker (literally -- the ball fixes the tracker). You only get the real top security pass if you are on the Alliance mission to blow up the DS's ship. In order to perform the last mission from the general, you need to go back to Marten's Bluff and do two things down in LMB - one near Z'ant and the other in the room with the two weird glassed-in chambers on either side that had guards but who didn't challenge you going in.
If you want to get your hands on the fake pass but don't want to kill Kunar, just tell him "Destiny arrives tonight" (at least, I'm pretty sure that was the phrase) and he should give you the pass.