The Ancient Turbine is the Karakorum Power Plant: a massive Axum water-power facility far to the east — a fully submerged giant turbine plus smaller structures, once the alien civilisation’s primary energy source, long damaged by unknown causes.
Repair sequence: scan the damaged section with a Bioscanner, then use the Habitat Builder with 10× Mangalloy Ingots, 10× Strontium and 10× Titanium Ingots. Repairing it reignites the plant, powers nearby facilities, and unlocks the Observatory Museum. It requires the Axum Vision adaptation (obtained from an Angel Comb in Root Canyon below) to interact with the alien tech. This is a core mid/late story gate, patrolled by heavy fauna including the Twin Sitaray and Great Jaw.