Far Europa

Still on the Alfvén constraint, let's try some speculation. We are here to revisit Trefils-Sommers, Imagined Life.

Propose a world in the upper-HZ of a M star, like LHS 1140 b. Eyeball planet; but here terran in mass, so not LHS 1140 b. Also unlike that world, I'm going subAlfvén (as most are), so: no atmo.

This planet will like LHS 1140 b remain cold enough for ice; not as much ice, to be sure, but ice on the darkside. Liquid water needs an atmo, but solid water doesn't. And on the darkside nobody cares about stellar flareups.

Basically what we need from Imagined Life is to promote that tidally-locked world as, in part, a dead end. Instead it leads to its under-ice ocean world - here, perhaps several under-ice seas each shallower than Europa's, which turns out better for life than Europa; or its ice world, where are cracks.