History of Biosphere Explorer

Biosphere Explorer is a Titan ritual armor set. Its pieces, including the Biosphere Explorer Helm, drop from ritual activities, the same way as the Hinterland set for Hunters.

The item pages on the Destiny 2 wiki list the helm as a Season 24 item whose vendor is Xûr. Some reports instead place the ritual sets in Season of the Witch (2023), with pieces dropping from Vanguard Operations, Crucible and Gambit. Check the in-game acquisition for the current source.