Asked by: Anonymous
So long as we rely on chemical propulsion to lift us into orbit, space travel will never be cheap. The Tsiolkovsky equation shows that a rocket needs between 10 and 25 times as much propellant as the mass that it’s lifting into orbit. To partly get around this, all rocket designs use multiple stages that are discarded during flight to reduce the dead weight as you ascend. But replacing – or recovering and then reusing – these stages isn’t cheap either. We’re also only just beginning the first generation of commercial passenger spaceflight, so there are all the R&D costs to pay off, still.