Think "cheap". The cheapest vacuum is right above us: at 35 km up there's only 1% the air pressure at the surface. It takes some energy to get there, but if you're on a rail you can recoup it on the way down.
Think "cheap". The cheapest vacuum is right above us: at 35 km up there's only 1% the air pressure at the surface. It takes some energy to get there, but if you're on a rail you can recoup it on the way down.