Orbital Airship

The orbital airship, also called the space blimp, is a proposed space transportation system that carries payloads to and from low Earth orbit. It is intended to achieve orbital altitude and orbital velocity using low thrust rocket propulsion by flying in the manner of an airship rather than a rocket, employing buoyancy and aerodynamic lift rather than vertical thrust to sustain flight during its ascent.

Read more about Orbital Airship:  JP Aerospace’s Airship To Orbit, Similar Proposals, Potential Problems, Potential Applications, Skepticism