It has long been obvious, to many people, that the government cannot establish the kind of low-cost access to space that will be necessary for mass exploitation of space. The reason for this is that all of the incentives for the government and its contractors are to make getting to space, and operating there, as expensive, difficult and time-consuming as possible, so as to preserve their jobs (in the government/NASA) or profits (in the space contracting businesses). The necessary goal, for mass exploitation to be possible, is to have flying into space be not much more rare, expensive or dangerous than flying from city to city.
This vision is still some ways off, but it has gotten perhaps a bit closer to reality. Scaled Composites, the company headed by Burt Rutan, and whose Voyager was the first aircraft to fly around the world without refueling, has developed Space Ship One. Developed entirely with private funding, this craft is designed for sub-orbital flights, but above the customary 50 mile boundary. In other words, making a trip on this spacecraft would make you officially an astronaut. This also makes the craft a contender for the $10 million X Prize, offered to the first team which gets the same 3-person vehicle to 100km altitude twice safely within two weeks.
Like Pioneer's Pathfinder, Space Ship One is attempting to solve the hardest problem, that of getting out of most of the Earth's atmosphere, by using the atmosphere, rather than fighting it. In a traditional rocket, 90% or so of its launch weight is oxidizer, and most of the rest is fuel. As the rocket's throw weight - that is, the payload weight to a given place - grows, the amount of fuel and oxidizer needed also grows, and along with that the weight of the rocket's structure grows. This means that a small increase in throw weight requires a large increase in rocket size. The Pathfinder lessens this problem by using both jets and rockets. The jets power to Pathfinder to altitude, at which point it meets up with a tanker, takes on oxidizer, then points its nose skywards and lights the rockets. This design means that for all practical purposes, Pathfinder is really a specialized aircraft. Space Ship One also uses jets to get out of the lower atmosphere, but in this case the jets are mounted on a carrier aircraft called White Knight. The spacecraft carries its fuel/oxidizer with it, but doesn't have to have the structure to fight through the lower atmosphere, so it is very small and light.
There are a number of interesting design features, including a hybrid rocket motor that burns tire rubber (HTPB) and laughing gas (NO2); tilting wingtips that "shuttlecock" the craft, for a low-speed reentry which makes reentry heating much less problematic; the development not of prototypes, but of working test articles; and the choice of viewport designs. The vehicle is designed for very low-cost operations, on the order of a Soyuz flight. With the ability to carry (externally) boosters to put microsats into orbit, the vehicle could have a built-in market ready to go (a lot of news organizations, for instance, would love to have additional capacity cheaply on call for satellite phones; and the military could probably use such a capability as well). I don't know how well this design will scale - can you use a larger version to orbit? - but I do know that if anyone can make this concept work, it's Rutan.
Since there is not any apparent attempt to actually use this spacecraft to start a space launch business, my guess is that Rutan intends to sell them to those organizations who could make use of them. In other words, he'll sell them like aircraft, albeit expensive and specialized aircraft.
UPDATE (4/21): More detail, for those who care about design, here
And here are the test updates.Posted by Jeff at April 20, 2003 10:51 PM | Link Cosmos