Rocket Launches Are Surprisingly Successful

> The number of components in rockets and IC transistors are probably roughly comparable.

Unless you are counting the payload, I really doubt it.

ICs are only possible because people create some way to mass manufacture those features, and people don't even design the features by themselves.

If people created them at the traditional route of "manually design|manufacture this -> encapsulate into component -> use components to manually design|manufacture that -> encapsulate again...", it would be impossible to create chips as complex as we have now. But there still aren't better way to produce rockets.

All the problem with rockets is that they are created by joining a big number of things that don't really like to stay together (or, in a few cases, don't like to stay by themselves either). I doubt they have more bare complexity than a modern car.

The way I've heard this explained, fuel is 3% of the mass of a modern car, 45% of the mass of a passenger jet, and 90% of the mass of a rocket. That means the structural engineering margins of safety for a rocket are much smaller, as there's very little mass fraction available to build redundancy into. There just isn't a lot of 'rocket' in a rocket. That, not complexity, is the root cause of why rockets aren't so reliable.

There's an even more basic physical reason why 'rockets are hard'. It's easy to explain in energy units of kT, the approximate energy of a gas molecule at room temperature. A carbon-carbon bond has an energy of 140 kT, while the gravitational potential energy of a carbon atom on Earth is 300 kT. If the Earth's gravitational potential were much closer to kT, room-temperature gas molecules would be able to diffuse out, we would have lost our atmosphere to space, and humans wouldn't exist. But that means that for a chemical system to escape Earth's gravity, needs a clever arrangement whereby most of the energy contained in its chemical bonds goes to a small fraction of its molecules. In a way, it's surprising not that chemical rockets are hard, but that we're lucky enough to be able to use them at all.

> e.g. if a high-end CPU has bad transistors in a section of the cache, that section of the cache is disabled and the CPU can carry on its life as a Celeron

For me, that's the part that is really fascinating about the fab industry. We have a statistically-reliable method of fabbing, but we build in the necessary fallbacks in the chip design itself that if a chip partially fails quality control, we can scale it back and sell it as lower-end product. It's intriguingly analogous to the quality process in gemstones, except that chips aren't found---they're made via mechanisms that we can't perfectly control.

Pretty sure that SpaceX is focused on reliability. One of the analogy that Elon Musk used is comparing a Honda Civic versus a Ferrari, asking which is more reliable.

Historically, rockets are focused on performance, not cost.

SpaceX's focus on producing cheaper rocket and launching more of them will yield more reliability. You make more of them, you make more mistakes, more opportunities to correct them.

Eventually you'll have a system for making very reliable rockets.

Accepting lower reliability of rockets doesn't buy you as much cost reduction as you might expect. Payloads are usually very expensive, so even a moderately increased risk of losing one can be pricy.

What SpaceX is doing is accepting worse performance in exchange for lower cost. Hopefully that'll make things more reliable in the long run, rather than less, since they won't be pushing the envelope quite as much as competing designs. (Remember the Space Shuttle Main Engines, which had to be practically rebuilt after each flight? That was done in order to get the amazing performance needed to make the Shuttle work at all.)

Incorrect orbit of a secondary payload is also included in the failure count (I was thinking of a 2012 Falcon 9 launch, where the primary payload was successful but the secondary payload didn't reach its intended orbit).