'Space train' means holidays to the stars will be here within 20 years
Space-based solar power would be used, making the technology far more cost-efficient than fuel-dependent rockets.
The 'Startram' railway that would be driven by superconducting cables suspended in the air by magnetic forces.
The inventors say that a cargo-only version, which would cost around $20 billion, could be completed within 10 years.
Nasa scientists say the technology is feasible, but its creators say that the Startram Project, which they claim is 'the next step in human civilisation' would have be an international programme rather than country - specific.
On its website, its creators say: 'Startram will necessarily be an international program, otherwise the potential for an expensive and dangerous arms race between nations is too great... This is simply too important to leave up to individual nations and militaries."