Building up is vastly more difficult than hanging something. The best engineering on earth is still under a km in compression. To hang a steel cable 150km all

Building up is vastly more difficult than hanging something. The best engineering on earth is still under a km in compression. To hang a steel cable 150km all you have to do is make it skinnier towards the bottom. The engineering issues of the bit at the top might be a bit eye-watering. A 100% reliable maglev sled supporting 100s of tonnes coasting on a catenary supported by centripetal force sounds like a recipe for the world's largest whip. Launch loops start to sound less scifi as a space megaproject (although then we're back tosuper weapons)