M2SL Recovery Station
From Halopedia, the Halo wiki
The M25L Recovery Station was a United Nations Space Command medical station.
Background
This is the station that MCPO John-117 and SgtMaj Avery Johnson went to for medical checkout and debriefing after the events on Installation 04 and Operation: FIRST STRIKE. It is probable that William-043, Frederic-104, and Linda-058 recovered on this station as well.
Cassandra, a SPARTAN-II too wounded to continue active duty, lived on the station. She and John-117 seemed to be close as she often wrote to him [1].