Groombridge 34 system
From Halopedia, the Halo wiki
The Groombridge 34 System was a system controlled by the UNSC in 2531. It was the resting place of Construction Platform 966A after the platform was decomissioned. It was here that Spartan-051 went missing after a mission to investigate rebel activity on the platform. Despite exhaustive search efforts from the frigate UNSC Tannenberg and prowler Circumference, they were unable to find him. The UNSC Point of No Return then picked him up.