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Jan 07 2015

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Elon Musk “Ask Me Anything” Reddit interview

Entire interview on Reddit.

This was probably the best, most informative AMA I’ve ever seen. Summary:

  • When the Falcon 9 booster returns to the Autonomous Spaceport Drone ship, it is secured mostly by gravity (the booster has a low center of gravity), but they’ll also weld steel shoes over the booster landing feet to ensure it is secure for transit back to port.
  • The Mars Colonial Transport (MCT) is going to use the Big F&#*ing Rocket, which will like use a single monster boost phase instead of a scale up of the Falcon Heavy.
  • Turns out that his 50% chance of success of landing on the drone ship estimation is just his hunch, not backed up by any hard science or math.
  • For re-entry, they use the grid fins instead of thrusters because “the aerodynamic forces are way too strong for the nitrogen thrusters. In particular, achieving pitch trim is hopeless. Our atmosphere is like molasses at Mach 4!”

Falcon 9 grid fins

  • Instead of working on making 2nd stage recovery for Falcon 9, Musk has made engineering on the MCT the priority. The Falcon 9 2nd stage could be reused if they wanted to work the issue.
  • “With sub-cooled propellant, I think we can get the Falcon 9 upper stage mass ratio (excluding payload) to somewhere between 25 and 30. Another way of saying that is the upper stage would be close to 97% propellant by mass.”
  • Raptor engine performance: “Looks like a little over 230 metric tons (~500 klbf) of thrust per engine, but we will have a lot of them :)”
  • Looks like, for the Falcon Heavy, a sea landing on the drone ship will be the preferred landing place in most instances due to the high speed of reentry.
  • The MCT is going to be a completely new architecture, which SpaceX plans to unveil by the end of this year.
  • SpaceX plans to unveil its new space suit by the end of this year.
  • MCT’s goal is 100 metric tons of useful payload to the Martian surface.
  • The life cycle of a Merlin 1D is 40 cycles (firing the engine and turning it off). Some components may need to be replaced after 40 firings, but most of the engine would not have to be refurbished at the end of its life cycle.

Some questions were so good that they and their answers need to be quoted in their entirety:

TL;DR: What needs to happen to grow SpaceX to the point where you can afford to enable the colonization of Mars?

Even Mars Direct, which would only involve temporary stays on Mars rather than colonization, would cost ~$1.5B/year. SpaceX is worth <$10 billion as a company, and the launch industry is only a ~$6B/year industry. Growing SpaceX’s profit margin by a couple orders of magnitude will be difficult due to low market elasticity; you’re betting Mars (the fate of the human race) that lowering launch prices will trigger a large increase in demand, allowing SpaceX to grow.

  • Given that the only growth and market elasticity seems to be in the small satellite and CubeSat launch industry, why did you cancel Falcon 1 after only 2 successful launches?
  • How specifically do you intend to increase SpaceX launch revenue by orders of magnitude?
  • Will cheap/reusable launches have a similar profit margin, or will profits/launch fall?
  • Is the SpaceX WorldVu partnership an attempt to grow the satellite industry, or for SpaceX to branch out into a more lucrative industry? (The satellite industry is a ~$200B/year industry)
  • What other approaches (by SpaceX or others) might grow the industry by orders of magnitude?

[–]DashingLeech 27 points

Having just seen a series of papers on the economics of launch costs and space business in general, at the International Astronautics Congress in September, you’ve hit some key points.

Growth in space ventures is coming not from reduced launch costs, but more generally from reduced payload costs, size, and power requirements thanks to things like smartphones and tablets. Hence the growth of smallsats, cubesats, nanosats. They are able to launch for cheap because their small size allows them to become secondary and tertiary hitchhikers on existing launches, and that brokerage market is another area of growth.

So I agree. For a wide range of operations, launch costs are not the most significant issue, and while launch costs can certainly shrink (a la SpaceX), they tend to be incremental and eventually limited. For example, you can’t shrink a human payload, and that means a certain amount of metal and fuel to lift them.

That being said, game changers like additive manufacturing might produce some wonderful cost reduction measures, opening up space tourism, for instance. I think that’s about the only growth opportunity with recurring income. It’s not like reduced costs means there will be an order of magnitude more planned satellites or space missions.

It’s a tough problem to crack, but predictions are hard.

Permanent link to this article: http://www.newspaceraces.com/2015/01/07/elon-musk-ask-me-anything-reddit-interview/

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