There are currently 6 active halos. No one knows the origin of Guilty Spark's name, but we do know that the monitor of each halo's designation number is the previous number × 7. For example: The monitor of installation 01 has a designation number of 001, installation 02's is 007, the monitor of 03 is named [u]049[/u] Abject Testament because 7 × 7 is 49. 49 × 7= 343, therefore we get the monitor of installation 04: [u]343[/u] Guilty Spark. Get it? Normal question: Sargeant Johnson volunteered for what spartan program before the Human-Covenant War?