(OPEN SOURCE)
The MERCURY birds are still active.
I haven’t bothered to listen to any Zulu net traffic in a while or any Blue Grass for that matter. I have a HF-GCS station about two miles from the house - hard to miss them while I am SWL.
I would guess it was a ‘spare’ NAOC bird loaned out to FEMA? Ok by current rules and the bird is in the inventory.