The idea of methods of passage between this dome and others along an ice plane interests me greatly. By going further along in that vein, it becomes obvious that aliens, if they exist, would not come from above, but from the side (or the south pole, if you still believe in a round earth).
This opens a good number of questions. If aliens could enter from the side, then a very good way to disguise that fact would be to hide the existence of that side entirely. Conspiracy nuts the world over are looking for how NASA is covering up having made extraterrestrial contact and are pointing their telescopes upwards - that would make it a lot easier to hide something along the ice wall!!