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August 19, 2011

Elon Musk is interviewed by NPR about Spacex going to the Space Station

The SpaceX company has gotten approval to launch its Dragon spacecraft this fall. If all goes well, the 'craft will dock at the International Space Station nine days later, making it the first private spacecraft to do so. SpaceX CEO Elon Musk discusses plans for the launch.

Elon -
Falcon 9 is - it's a pretty big rocket. It's about a million pounds of thrust, which is four times the thrust of a 747. It weighs about as much as a fully loaded 47 - 747 on takeoff. The nine refers to the nine engines on the base. It's designed for super-reliability so that you can lose any of the engines, including right after lift-off and still complete your mission. It's really the only rocket that can do that. And then later in flight, you can actually lose more than one engine and still complete the mission.

So I think that's a pretty significant reliability improvement. It's designed to have higher structural safety margins than other rockets, so we designed our rocket to 40 percent above flight loads instead of 25 percent.



The escape system is actually on the Dragon spacecraft. So Falcon 9 is the booster that delivers the spacecraft to orbit, and then the Dragon spacecraft maneuvers over to the space station, docks and comes back here with people or with a cargo. The - but we are doing something that is very new. We are pushing the state of the art with Dragon, which is we're building the launch escape engines into the sidewall of the Dragon spacecraft.

So rather than having this big solid rocket motor tractor on the nose of the spacecraft, which is how it's been done in the past, we're actually integrating the engines into the spacecraft.

Dragon spacecraft has on-board propellant for orbital maneuvering and de-orbit and for controlling its re-entry. And - but you either need to do - to escape - to do launch escape or you need to do orbital maneuvering, but not both. And so we're getting dual use of the propellant. And it ends up being a much lighter, I think, much more reliable system by doing that. And it solves two reliability issues that (unintelligible) from the past. One is that that launch - that tractor tower, escape tower, has to always be jettisoned on every mission or all the crew will die.

It's sort of like having a fighter jet with an ejection seat that's got to work on every flight or you die. And that - I think that's unwise. And then because that tractor tower is so heavy, it has to be discarded a few minutes into the launch. And so you don't actually have escape capability all the way to orbit. But in our case, with the integrated engines, we avoid those issues. And then there's an added advantage, which is we can use those same engines to do a propulsive landing. So you can actually land Dragon with the accuracy of a helicopter, and anywhere on Earth.

Dragon ... well, I think we'd want to do some upgrades. But in the current configuration, we could probably do a launch a week, I guess, with Dragon. But we do need to make the rockets reusable as well, the first and second stage of the rockets.

The Holy Grail in space is to have a fully and rapidly reusable rocket. No one has ever achieved this. The space shuttle is partly reusable, but the main tank is thrown away every time. And even the parts that are reusable are extremely difficult to refurbish. And so the space shuttle costs about well, anywhere from four to eight times as much an expendable rocket of equivalent payload capability.

So it's - yes, it's - so there's - and all the other rockets are just fully expendable. So whether it's SpaceX or some other company, whoever invents the first fully and rapidly reusable rocket will have - that'll be a huge, huge breakthrough because it would allow the costs of launch to drop by about 100.

That is our aspiration
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