New Scientist: You claim to be getting away from the government-assisted model of spaceflight engineering and the lack of innovation that approach entails. Yet your website says your Falcon 9 rocket’s main Merlin engine design is inspired by the Apollo lunar module main engine. So you still depend on government-inspired inventions?
Elon Musk: Heh (laughs). We should probably change that text, it’s probably not the best in the world. That’s a bit like saying a modern day car is based on what Daimler and Benz did. We’re in fact using something that’s far more advanced than they had on the Moon, which was a type of injector called a pintle, a large signal coaxial injector - and that was the basic architecture we used. We said that originally because it had to be super safe - it was a single point of failure - and it’s a type of engine architecture that is naturally stable and is not subject to combustion harmonics that can cause a combustion chamber to explode.
NS: What kind of technology do you really want to advance, given the freedom you have to do it your own way?
EM: The really big advance, the fundamental breakthrough that’s needed, is a fully reusable rocket system. There was an attempt at that with the space shuttle but it failed. The space shuttle was only ever going to be partially reusable as the main tank - the primary flight structure to which the orbiter and booster were attached was discarded on every mission. And the parts that were reused were so difficult to reuse that the shuttle ended up costing four times more to run than an expendable rocket of equivalent payload capacity. The space shuttle was often used as an example of why you shouldn’t even attempt to make something reusable. But one failed experiment does not invalidate the greater goal. If that was the case we’d never have had the light bulb.
NS: Can you outline the economics?
EM: The fuel, oxidiser and pressurant on a Falcon 9 rocket accounts for about 0.3 per cent of the cost of the mission, about $200,000. But each mission costs $60 million because we have to make a new rocket every time.
NS: And SpaceX manages that by doing everything possible in house, without significant outsourcing?
We are trying to make a huge difference - by advancing space technology substantially. To do that we had to design the Falcon rockets from scratch because the space supply chain is just not an effective one. At SpaceX we make the engines, the avionics, the primary structure - I think we’ve got a fundamentally better design: our airframe, engines, electronics and launch operations are much lower cost.
NS: What about performance though? Anyone can cut costs..
EM: Our engine has the highest thrust to weight ratio of any engine in the world, our airframe has the best mass fraction of any rocket in the world - and our electronics are the lightest and have have the most computing power over that of any other rocket.