AviraDeArah,
“the mitzvos are all earth-centered; zmanim, 4 minim, all food related mitzvos, etc, are all based on earth. It’s untenable that they would go to a place where they can’t keep mitzvos properly”
Not Earth centered, but E”Y centered. Zmanim are challenging north of the Arctic circle. In past generations when transportation was harder, the arba minim were hard to come by in much of Europe, as citrus trees do not grow in cold climates. We start saying mashiv haruach by Shemini Atzeres and stop by Pesach because that is the beginning and ending of E”Y’s wet season, but Florida’s rainy season tapers off after Shemini Atzeres and picks up after Pesach. And the seasons and agriculture in the Southern Hemisphere are flipped from the Northern, meaning they plant when E”Y harvests, and harvest when E”Y plants. Your argument could be applied to living on Earth as well. And until we have the Beis Hamikdash, we cannot keep the mitzvos properly anywhere, even in E”Y.