mimantean

Of or relating to the giant Mimas in Greek mythology

Draughts from the fount of Nile [...] or the steep Mimantian height, Snow-capped

Of or relating to the Saturnian moon named for Mimas

This is puzzling because Mimas is closer to Saturn than Enceladus, and the Mimantean orbit is much more eccentric (out of round) than the Enceladean orbit.

a global thermal event early in Mimantian history erased all record of ancient impacts

An inhabitant of the Saturnian moon Mimas

I went back to the grind of reviewing that day's Cassini photographs. Imagine my shock when I noticed that Mimas, one of the inner moons of Saturn, had acquired a concave depression in it since the last fly-by! Of course, I immediately realized that the Mimanteans had constructed a fully armed and operational Death Star!