Traditionally, regulators had insisted that all passenger aircraft be powered by at least three engines. But the development of more sophisticated airplanes eventually made twin-engine, long-distance travel feasible. A new standard was introduced, known as Extended-range Twin-engine Operational Performance Standards, or ETOPS.

The buzzword in the space industry now is tourism. Private companies have moved into space research, with the philosophy that the best way to extend man's reach into space is to promote it as a tourist destination.