Spaceline Timeline

The more advanced of these spaceplanes will take years, and probably decades, to develop. As for the suborbital vehicles, they have already arrived. In fact, they have existed since the X-15 first flew in 1959. The natural maturing process of these suborbital spaceplanes was arrested for almost half a century by an intervening developmental eclipse by ballistic boosters. These "big dumb boosters," for their part, have already reached as mature a stage in their own development as they can, despite the fact that they never have (and probably never will) reached the same standards of safety expected of an airliner or a spaceliner.

When will the advanced spaceplane arrive, then? This is a question no one can answer at present, confounded by the fact that there is no consensus on how to go about developing them. There are many competing visions of the future, each with its own specific vehicle concepts and engine designs. Some envision a future without spaceplanes of any sort, a future of spaceflight that includes DC-X type vehicles only. Others see a future of two-stage-to-orbit spaceplanes as an intermediate step on the road to the mature single-stage-to-orbit spaceplane. Still others see a gradual improvement of suborbital spaceplanes until they achieve orbital spaceflight capability at some point.

Just as the Wright Flyer was incapable of transatlantic or supersonic flight, so SpaceShipOne was incapable of orbital or Lunar spaceflight. And yet the supersonic Concorde utilized the very same principles of aeronautics to fly across the Atlantic as the Flyer used at Kitty Hawk. By a series of small steps, punctuated by a few huge leaps, aviation progressed from the simple biplanes of yore into the hypersonic research vehicles of today. Similarly, by a continuous and sustained effort, the spaceplanes of today will grow into the advanced spaceliners of tomorrow. This process will accelerate when the first space tourists begin to fly on suborbital spaceplanes, because flight frequencies will increase, and with frequency, an ever-growing experience base.

The first advanced spaceplane, defined as one capable of taking off from a runway under its own power and accelerating into orbit (Fig. 9.12) with or without the

Fig. 9.12 The advanced Skylon spaceplane in a low Earth parking orbit (courtesy Reaction Engines Limited)

help of an aerial tanker, could fly sometime around the year 2030, give or take 10 years. As these words were written in late 2007, it was still very difficult to predict what might happen, given the fact that suborbital space tourism had not yet begun. But when this seminal moment arrives, a chain of events will unfold that will be wholly unlike anything we have seen before.

Orbital space tourism, it should be noted, has already begun. Since 2001, half a dozen space tourists have ridden Russian rockets to the International Space Station. Each of these space tourists has paid $20 million or more for the privilege of a few days in space, rubbing shoulders with professionally trained astronauts and cosmonauts. These flights have been relatively infrequent, and the funds have gone to the Russian government rather than to private spaceline companies. Therefore, they will have virtually no effect on the overall development of space technology, unlike the impact suborbital space tourism is about to have. As noted above, suborbital space tourism will cost the space tourist less than 1% of what the orbital space tourist today pays. This means there will be 100 times as many suborbital tourists, with the potential for much greater flight frequency, spaceflight practice, and spaceplane development. And it is the spaceplanes themselves - including their purchase, operation, and development - that the space tourist will gladly pay for.

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