This is a pattern you see a lot in sechnology. Often the second version of something significantly learsnf rom the first. Take something like C#, which really corrected a lot of the problems Java had.

A more physical example is the rail network in the US. It's often asked "why don't we have high speed rail in the US?" Being a nation of autophiles obviously doesn't help but it's not as simple as putting higher speed trains on existing track. It's not even as simple as replacing the existing track with track that can take a higher speed train.

The rail network we had is an artifact of the performance constraints of 19th century trains for the most part. Top speed is the most visible constraint. But the grading, turning angles, etc are all a function of much lower constraint on top speed.

We'd probably be better off if we had no national rail network at all, which is pretty much the situation China was in. Admittedly there are other factors in China's rapid HSR deployments (eg streamlining planning and acquisition of land).

But I digress. Timing is hugely important in scaling.

The US low speed rail network works pretty well for freight. Despite some occasional bottlenecks and delays, it's still superior in certain ways to rail freight in China and the EU.

As for HSR, do we really need it? It might make sense in the northeast corridor but it's hard to make a business case elsewhere. The California HSR project has turned into the usual government megaproject boondoggle with long delays and cost overruns. Even if it actually gets built I'll probably never ride on it.

This is very true, and also reminds me of our telephone system, or Japan - which someone described as "living in a futuristic version of the 1990s".

Most accurate description of living in Japan I've read!

Yeah, but if we had just kept investing in faxtech innovation, it might have turned out pretty awesome. Just saying.

In rocketry one big needed technology before scale up can happen is reuse. Probably also intact abort and other technologies.

One should look at the operational capacity, not the theoretical capacity. Who cares if you have an airplane that can theoretically do Mach 3 if it's being repaired in the hangar and you need it now? In airplane lingo a plane like that is called a "Hangar Queen"

Falcon 9 is a huge step in the operational direction. But more is needed. Can one do two flights in 24 hours? Can one save the second stage too? Just the fairing? Or can one make the second stage cheaper? Or salvage it in orbit?

> In rocketry one big needed technology before scale up can happen is reuse.

There are other ways to reduce cost, such as cheaper rockets, more efficient fuels, etc. Whatever SpaceX does isn't the only possibility or a necessity.

Those also help, certainly.

This is why newer space startups like Stoke are aiming to produce totally reusable second stages. The goal is commercial airline-like refuel and relaunch.