Conventional rocket engines have reached a high level of efficiency. However, the space industry is always working on improving the propulsion systems used in space flight.
Until recently, the exploration and exploitation of space was a dominated by national governments which could bear the tremendous expense of launching payloads to orbit and beyon
Currently, exploration of space is governed by the U.N. Outer Space Treaty of 1966 which covers scientific exploration and commercial exploitation of orbits and bodies in space.
Space is not a friendly place. As the human race has sent explorers beyond the atmosphere into space, we have been discovering just how unfriendly it is.