M2SL Recovery Station
From Halopedia, the Halo wiki
The M25L Recovery Station was a UNSC medical station. This is the station that Spartan-117 and Sergeant Johnson went to for medical checkout and debriefing after the events on Installation 04, and Operation: FIRST STRIKE. It is probable that Spartan-043, Spartan-104, and Spartan-058 recovered on this station as well.
Cassandra, a Spartan too wounded to continue active duty, lives on the station. She and John 117 seemed to be close as she often writes to him[1].