Why Is Making A Reusable Rocket So Difficult? Elon Musk

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SpaceX CEO & Chief Designer Elon Musk discusses the difficulty of making a reusable rocket. Filmed at The National Press Club.

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  Science & Technology

[Clint Johnson]

To those confused about the context, this isn't about "the space program", it is about Elon Musk's company working hard on a difficult engineering problem. You may feel that people should "scrap" a project because it is difficult. Well, I am filled with joy and relief there are people like Elon who are ready, willing and able to put their time and money on the line to open space; not because it is easy OR because it is hard... but because it is the most important thing that it is possible to do.

[Ian Kennedy]

Space-X is the future of space access. It's great to see someone finally doing this right.

Make no mistake, I love NASA. I love their heritage and what they want to do. But since they are seen by elected officials as, essentially, and "jobs program" you do not see the kind of efficiency from them that SpaceX has demonstrated.

I'm glad to see the private sector pick up the orbital trucking task. NASA should be about bold, bleeding edge technology right on the edge of feasibility.

[Clint Johnson]

The first stage is only traveling about 4100 mph when it separates, not the 17,000 mph that their Dragon spaceship successfully reenters at. They know the structural capabilities and what it should be able to handle so they know how much they have to slow it from that. Some of the best aerospace engineers on the planet have looked at all of your concerns and they believe they can work them out. They will have failures on the way, but it is reasonable to expect a reusable first stage before 2020.

[drumchakra]

The heat of the rentry and braking will deteriorate  the structured frame of the chassis. Fail prediction right now.

[Clint Johnson]

You seem confused about what Spacex is developing. Currently, the first stage doesn't go to space, but separates on the edge of space then falls to its destruction. A wide safety margin for fuel means there is generally a lot of fuel left in the tanks. Elon plans to use that fuel, and a bit more if needed, for an apogee burn to slow and orient the stage, then a near ground re-ignition to slow the stage for a survivable water landing or gentle strut landing. Saving tens of millions each launch.

[drumchakra]

Has this rocket ever left Earth's gravity and returned?

[Clint Johnson]

You use the word "impossibility's" (sic), but since you are emphatically incorrect in its usage, it appears you have no idea what it actually means. Feeling sad at your embarrassment, I've include the actual definition for your edification so you do not make such a fool of yourself in the future. You're welcome.

impossibility

/imˌpäsəˈbilitē/

Noun

The state or fact of being impossible.

An impossible thing or situation.

[Joseph Stern]

You are correct about the speed requirements for stable orbits, but nuclear-powered rocketry would not be used to inject spacecraft into planetary orbits, or maintain them in such orbits; it would be used to traverse interplanetary space (as, for instance, on a Mars mission). Such traversals can be made along ballistic trajectories, where a single initial velocity vector is obtained by firing the main thruster, and the trajectory is only corrected with smaller thrusters from then on.

[Joseph Stern]

Again, I don't follow. You replied to a post in which I was conversing with someone else about the possibilities for Orion-type rockets, which work by exploding nuclear bombs behind a shock-absorbing pusher plate. I chimed in that expecting Orion-type rockets to be approved anytime in the foreseeable future is probably foolish, but that perhaps an NTR might eventually become politically feasible. The conversation was originally about specific impulse and mass-to-orbit, NOT about speed.

[Joseph Stern]

I'm afraid I don't follow. What's "my rocket"? Do you mean NTR's (nuclear thermal rockets)? If so, you may want to look up NERVA, a lab-tested nuclear rocket engine designed by NASA in the late 1960s and early 1970s. The technology for this has been well-understood for decades, but with the Cold War over and the space race defused, and with all things nuclear being made into political poison by the radical Green movement, there just isn't the will to see it through. One can hope, though.

[drumchakra]

The dude is wasting his money so guys like you and him can jerk off over impossibility's