The development of space tourism may also contribute to lower launching costs for small, low-mass satellites.

Satellites are just packages of electronics, and the price of electronics is falling without foreseeable end. It is the launch cost ($20m a time) that restricts their use. A successor to the SpaceShip/White Knight combination could deal with that. First, the whole system is more economical than using throw-away rockets. Second, rather than having to wait ages on the ground for the right launch window, an air-launcher can fly to a better location. Such changes could bring satellite ownership to cities, universities and companies. Ultimately, it may bring it within the purse of individuals. Who could resist having their own, private window on the world?

It is famously difficult to predict the market for disruptive technologies, whether they be computers, muskets, jet engines or digital cameras. But cheap access to space, and to the other side of the Earth, is likely to be revolutionary.