Even an ion engine needs fuel. We shot out Voyager 1 in 1977. It has traversed 47 years of distance. There has been the talk of solar sails as well, but gravit

Even an ion engine needs fuel. We shot out Voyager 1 in 1977. It has traversed 47 years of distance. There has been the talk of solar sails as well, but gravity assist propulsion is already so much easier to achieve for satellites.