In addition, it functions as a safe haven from the Halo network's strategic pulse and as a facility to construct replacement Halos.
Located 218 (about 262,144) light-years outside the Milky Way galaxy, it is safe from the Halo effect (as it is referred to by the Forerunners in the terminal transcripts) that kills all sentient lifeforms, the main Forerunner behind its use was Didact. The purpose of the ark is to remote activate every halo ring, from outside the blast radius. This is a failsafe system that is only activated by an aborted firing such as the one that occurred at the end of Halo 2