Ice evaporates in my freezer, why would it remain on the moon, where the Atm pressure is essentially non existant?
Very good question! The answer is that these cold parts of the moon are cold enough that ice does not sublimate/evaporate. There is some minor “heating” from sky UV background and starlight, but the thought is that there should be enough cometary impacts & such to bring water to the cold craters near the poles.
MD, who helped design, build, and test LAMP aboard LRO