"Disenchanting is much fiddlier than enchanting," says Pattern. "You basically have to be a better enchanter than whoever did the original enchantment. Which has obvious problems if you do your own. Some spells are pretty amenable to editing, or come with unraveling mechanisms, but I don't want the habitability of my colony to be readily unravelable - for all we know, enchanting could be contagious, like Matilda's magic - and editing can only do so much if there's something the matter with the core."