Space tourism company to launch revolutionary flights by 2024 – but they won't come cheap

There are exceptions to the rule, such as NASA and the US Air Force, which consider space to begin just 50 miles up (80km).

By this standard, customers on Virgin Galactic’s jaunts aboard the VSS Unity spaceplane get to earn their astronaut wings.

World View Enterprises is, however, confident its rocketless journeys will be spectacular enough in its own right.

From an altitude of 18 miles (29km), the company said customers will have a chance to see the planet’s curvature and experience the darkness of space.