That's what rockets basically do today, use multiple stages optimized for the area they're operating in. The issue with rockets is that they have to use a cert

That's what rockets basically do today, use multiple stages optimized for the area they're operating in. The issue with rockets is that they have to use a certain amount of energy to go up, and they have to carry their own fuel which adds weight and means it need to consume even more energy and so on. For certain values of gravity and type of fuel, this becomes hard, to impractical, to impossible.