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Comment by cyberferret | Hacker News Reader

Some might argue that having an unlimited budget, and nearly a million people working on a project, and utilising 'throwaway technology' would be arbitrarily easier than trying to do it with private funding.

Moon travel is not a common everyday thing now, because the original effort wasn't geared for that - it was primarily to put a man on the moon as fast as possible, before the Russians did it.

If the aircraft industry worked the same way and airlines had to throw away a 747 after each flight, it wouldn't be an every day thing like it is now.

SpaceX are essentially setting up the future building blocks for far more affordable and common space flight now. It is a longer path, and IMO no less difficult than what NASA was doing back in the 50's and 60's.

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>SpaceX are essentially setting up the future building blocks for far more affordable and common space flight now.

What exactly is the breakthroughs/discoveries that Spacex have made that will justify the claim.

Please note that landing the rocket does not count. Because I don't think it involved something new, some new technique that was unknown before.

Landing the rocket is the first step in figuring out reuse. Its irrelevant that it probably did not involve some scientific breakthrough - in fact it makes it all the more sadder that no-one bothered to do it before. Same situation with Tesla. No breakthroughs there either. Now imagine all the things we can do right now but aren't because no-one is interested in funding it.

If you arbitrarily dismiss things because you "don't think it involved something new" that's a fairly random criteria.

>What exactly is the breakthroughs/discoveries that Spacex have made that will justify the claim.

The breakthrough is actually doing it. A lot of space engineers were saying before Falcon 9 that what SoaceX were trying to do was impossible.

Hindsight is 20/20. It's easy to see now what steps were required to pull this off and that clearly those steps were possible. But if it's so clear, why wasn't it done before? The ottoman line is only Must and SoaceX were prepared to get the job done. Nobody else was even trying.

>The breakthrough is actually doing it...

That is not a breakthrough.

Not all breakthroughs are just theory. If you can show me someone actually managing to land a launch-capable rocket, and not just some testbed demo capable of throttling to less than hover, I'm all ears.

The only other player in this space is Blue Origin, and they are still working on their commercially-viable engines. Everybody else throws away their rocket after the launch.

> If you can show me someone actually managing to land a launch-capable rocket, and not just some testbed demo capable of throttling to less than hover, I'm all ears.

Are you saying only SpaceX is capable of doing this? Seriously?

Are you saying that only USA were able to put a man on the Moon in 1960-s? Seriously?

No. That would be an utterly moronic claim if someone made it..

Here's what they actually did that was novel:

- Building an engine capable of multiple restarts while facing into a supersonic headwind, which are necessary for any kind of successful propulsive landing.

- Designing a mass-thrifty first stage simultaneously lightweight enough to be able to accommodate the added weight of landing equipment, but strong enough to handle the tensile stress and buffeting of atmospheric reentry.

- Developing ultralight landing legs to enable stable landings at low mass cost.

But most of the innovation has been in the realm of integrating existing technology in new ways. They brought together cold gas thrusters, grid fins, and thrust vectoring - none of which were new - into a complete package capable of precisely controlling the flight of a 15-storey first stage from the upper atmosphere to the ground. It's the act of getting technologies to work together that is often the source of the greatest gains.

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Actually there was a lot of new stuff learned especially in the transonic regime.

> Please note that landing the rocket does not count. Because I don't think it involved something new, some new technique that was unknown before.

"Answer my question despite my imposition of arbitrary criteria that intentionally make it unanswerable"

Well, despite what you think landing the rocket was a breakthrough. Sure it involved the application of standard techniques in the industry but a combination so executed becomes more than the sum of its parts.

If you want something where SpaceX has blazed trail in science as well as engineering then there's thir work on CFL and more importantly supersonic retro propulsion. It turns out that the bow shock created by the engines is enough to serve as an ersatz heat shield and it protects the rocket when it would otherwise be destroyed during reentry. NASA's studying the data they've recorded for the purposes of applying it to Mars EDL. It's given them a chance to investigate an entirely new EDL technique which is important seeing as the Low-Density Supersonic Decelerator seems to be going nowhere.

>bow shock created by the engines is enough to serve as an ersatz heat shield

Source pls. Google search yeilds no results.

It's an over-reach of me to say that they discovered it. This talk gives a good outline of SRP. https://youtu.be/GQueObsIRfI?t=983

Their unique breakthrough is relighting rocket engines in a hypersonic airflow. Everything else is shoulders-of-giants and design iterations and good project management, but relighting rocket engines like that was an unknown.

Landing is a critical prerequisite to reuse: we can't reuse what we discard.

But the important reusability breakthrough comes in a few months when they do the first reflight of an orbital booster.

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