In this task you should enable reactor attractors on the reactor terminal, then lure the core (wandering orb) into the reactor, which is placed in center of this chamber, using an anomaly sensor switched to attractor mode. (If you lost both sensors, there's another one in the gravity anomaly)
Then you can activate the reactor using the terminal, and proceed to the gates marked with large "C" letter. The gates can be opened using the terminal near them.