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Comment Re:Am I reading this right? (Score 2) 78

No, the liquid Oxygen is delivered as liquid on trucks, and stored in large tanks at the pad as liquid. The Helium would be cooled to LOX temperature by virtue of being inside a tank full of the stuff. This would lower the pressure of the stored helium, allowing you to put more in the tank, but it's not cold enough to liquefy.

One possible failure mode is something preventing the Helium from cooling down, in which case it could overpressure the tank and it blows up. That could be a problem with getting the LOX into the tank, bubbles around the He tank, etc. Or it could be something simple like a flow valve fracturing. They have all the telemetry data, so I can only speculate.

Comment Re: Huh. (Score 2, Interesting) 78

Nah, that's too obvious. A sniper rifle fired by a CCAFS security person with money troubles is less conspicuous. Security staff have a reason to be on the base, even patrolling the launch pad area. On the other hand, there's a whole lot of nobody else around the launch pads, for safety reasons. So all he has to do is find a good spot, pop off a shot, then drive over to the launch pad like a concerned security guy would do when something goes boom.

Why money troubles? The people with a motive, like United Launch Alliance, could pay off someone for a whole lot less than what they stand to lose by SpaceX eating their business. Even a six month delay and a few customers moving payloads to "spread their risks" is worth a billion or so in revenue.

Comment Re:40 years in a box (Score 2) 289

Luxembourg is a forward-looking country. They invested in communications satellites in the 1980's, and now operate the largest commercial constellation of satellites. Recently, they started investing in asteroid mining, and they are also a SpaceX customer. I don't think Musk is so dumb he didn't know a big rocket could go other places than Mars. I think what's happened is he has a customer who is *interested* in going other places than Mars. And he needs lots of commercial customers to help pay for the big rocket he wants to build.

Comment Re:Wacky? Maybe, but at least he's got vision. (Score 1) 289

Look, he's developing the Raptor engine ( https://en.wikipedia.org/wiki/... ) Assuming he uses 9 of them in the first stage, like the Falcon 9 has, that's 20.7 MN of liftoff thrust. Liquid rocket T/W on liftoff is typicall 1.3:1, which gives 2100 tons liftoff mass. A good chemical rocket typically has 4% payload mass, so 84 tons payload to LEO. All of that follows directly from the engine size and how many you use.

If you can put that much mass into Low Earth Orbit, you can get variable amounts of payload to different higher orbits. This is obvious to anyone who has much experience with rocketry. User handbooks for different launch vehicles have graphs showing the payload as a function of mission velocity, and that velocity is set by where you are going and the trajectory you follow. Perhaps Musk is slow to realize this, because of his focus on colonizing Mars, but it's no surprise to people in the industry like me, and probably to a lot of the people working at SpaceX either. I can imagine the staff meeting at SpaceX:

Musk: You mean this giant rocket we're building can go other places than Mars?
Staff in unison: No shit, Sherlock.

Comment Re:Recursive Manufacturing (Score 2) 209

> we don't even have a Wikipedia page on it yet?

We have a WikiBook half written about it: https://en.wikibooks.org/wiki/...

There's a Wikipedia page on self replicating machines: https://en.wikipedia.org/wiki/...

But "fully automated self-replication" is both a limiting concept, and *hard*. There is no reason you can't make different machines than the ones you start with, or different sizes. So a "starter set" can be smaller and simpler than the final factory. All the complexity is in the stored computer files that tell it what to build. There is also no reason that it has to be 100% automated and make 100% of its own parts. Those are theoretical ideals like 100% efficiency. We can tolerate some manual labor and buying parts and materials from outside. The only real requirements are to be efficient enough to compete with conventional manufacturing, and have enough surplus production to pay for the things you can't make on your own.

Comment Re:Seed Factories (Score 1) 209

We currently have $95,000 of income producing assets and a 3 acre R&D location being developed. We are an *open source project*, not a venture capital startup, so we don't have paid staff, at least not yet. People contribute their time and funds to the project, and we do the best we can with it. Our workshop won't house all the machines and tools we need to build our prototypes. For that we rely on a network of makerspaces, individually owned equipment, university labs, etc.

We don't have a timeline for reaching a complete prototype factory, we haven't even finished conceptual design. For the moment the work is fleshing out the concepts, and renovating the workshop space on our property, so when we do have hardware to test, we will be able to. Things like solar furnaces need sunlight, which is why we have 3 acres. You can't test them indoors.

I'm a retired aerospace engineer. I devote my spare time to this project because it interests me. Other people's motivations are their own, I can't speak for them.

Comment Re:Why is this easier in space than on Earth? (Score 1) 209

> Until such a thing exists this is just fiction. As far as I can tell, at the moment all plans for building a self-bootstrapping automated factory on Earth, much less the actual operating factory, are fiction also.

Industrial automation is a thing, and has been for decades. We don't have to reinvent that part. What makes a seed factory different is the CAD/CAM files include making parts for more machines, besides the salable end products that any factory makes. Again, most of this has already been done, machine tool makers use their own machines that they made to produce more machine tools to sell to others. Robot makers use their own robots in their robot factories to make more robots. So our design problem is coming up with a growth path from a small and simple starter set (we presently have 8 elements in the starter set) to a complete factory capable of producing new starter sets.

And because people like you justifiably question the ability to do this, our project goal is to design and build prototypes to prove it can be done. We are not done yet, far from it. But you have to start somewhere, even if it takes 10 or 20 years to reach the goal. You will note that unlike Mars One (who I criticized myself, here on Slashdot) we don't give some fictional completion date. All we say is "here's the idea, here's what we've done so far, we are working on it".

Comment Re:pipe dream (Score 1) 209

Any aerospace engineer, but apparently no member of Congress, knows the right approach to get most of the cost reduction:

* Stop throwing away several kg of aerospace hardware @ ~$1000/kg every time you launch. *

There's roughly 160 MJ/kg of fuel energy in a good conventional rocket, which results in 1 kg of payload with 31 MJ of orbital energy, so around 20% energy efficiency at best, and often 10% in not so good designs. But propellant is *cheap*, around $1/kg. By far most of the cost is the hardware.

Outside of NASA, most of the new rocket development involves re-using the hardware. The Space Shuttle was intended to save money by reusing most of the hardware, but the program was poorly designed and run and didn't achieve cost savings. They did, however fly hardware multiple times.

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