That's "passive daytime radiative cooling" for the curious. Supporting sweat, durability, non-toxic, existing textile tech, etc, gets hard. Or perhaps, like rad

That's "passive daytime radiative cooling" for the curious. Supporting sweat, durability, non-toxic, existing textile tech, etc, gets hard. Or perhaps, like radiator-free ships in The Expanse, Dune just didn't want to show Fremen looking like butterflies.