Most likely is for component testing - would explain the secrecy, the low flight rate, and the long (2 years or so) mission duration. EDIT: And, in fact, the o

Most likely is for component testing - would explain the secrecy, the low flight rate, and the long (2 years or so) mission duration. EDIT: And, in fact, the one publicly-released payload I'm finding was a test of a new heat pipe.