Beneath Enceladus's icy crust churns an ocean, acting like a perfect heat pump. It pushes heat from the equator to the poles, spending a thousand times less energy than it transports — like a perpetual motion machine built into the moon. The secret lies in salt. If there's too little or, conversely, way too much, the currents abruptly speed up, as if someone cranked the pump to the max.
That's why the polar ice is thinner than the equatorial ice — the Cassini probe confirmed this anomaly. Models show: tweak the salinity just a bit, and the polar cap either melts completely or expands all the way to the equator. The balance is so delicate that scientists see it as a possible hint of life.
Enceladus's geysers shoot water into space, and the Cassini probe found salt, organics, and hydrogen in it — potential food for microbes.
A frozen moon with an ocean inside brings to mind Europa from Clarke's '2010: Odyssey Two', but with its own geysers.