There was a confluence of several factors which helped SpaceX to succeed, and not the least of these was the employee number one. For many years, Tom Mueller has been working in his free time on rather large liquid fuel amateur rockets, which he was building in his garage and which he was launching from some amateur rocketry facilities in the desert. In terms of regulation it was a relatively accessible hobby in the US. At the time Musk found him, he was working on the original "BFR" -- a very large liquid fuel amateur rocket. So the deal was to invest serious money into the project and scale the same no nonsense approach to a small orbital launch vehicle. They were in LA, the center of US aerospace manufacturing, so through Tom's professional connections and knowledge of who was who in the industry, they were able to source the necessary materials, components, and to find the key personnel for their company. Significantly, NASA has already spent probably a decade or more trying to get somebody to produce a cheap small launch vehicle. This did not directly affect SpaceX, but it did fund the R&D for example at Barber-Nichols, which enabled them to offer a turbopump for SpaceX engine at a much lower cost than it would have been possible otherwise.

At first, Musk and Co thought that they would be able to develop the rocket for a few million dollars. But even in the US regulatory environment it turned out that doing everything in compliance with regulations raised the costs to well over a hundred million dollars.

So, Tom's hobby + Musk's activism + industrial ecosystem in the area + NASA's prior support of component vendors + being at the right time to snag the International Space Station delivery contract were all important for SpaceX thriving where so many others have failed.

In fact, after the war the USSR has briefly reconstituted the manufacturing of V-2 in Germany, employing thousands of people, before transplanting this entire industry to the USSR. This dramatically lifted the level of Soviet manufacturing and relevant metallurgy.

von Braun's dissertation was on engine design and testing. But when he built the Redstone missile in the USA, he ordered the engine from a US company -- the engine which was already a generation ahead, compared to the imported German engines which the US engineers studied after the war.

Meanwhile, the Soviets have developed even better engines, completely on their own, though with the important parts built using the materials and the equipment brought from Germany.

So it is debatable whether having the German higher-ups and having a greater continuity with German design philosophy was a good thing or a liability.

It is less well known, but France have also imported a significant number of ex-Peenemunde engineers for their program. And their engines developed in a way different from both the American ones and the Soviet ones -- which definitively shows that although internalizing the German know-how was the starting point for everyone, it did not define the path of subsequent development.

Of course, the engines were not the whole story. The Germans took to the USA the advanced prototypes of the inertial guidance systems which were developed for the missiles that were supposed to come after the V-2. And the Soviets got Helmut Gröttrup. This did have its effects in both cases.

That pushed their main NZ investor away, and they somehow hooked up with the US intelligence community, which facilitated a rather unique series of inter-government arrangements for launching US reconnaissance satellites from NZ. That was probably always the appeal -- to launch over China with very little warning. A cheap, rapidly launchable vehicle was always a dream of the US agencies -- in 2003 this was FALCON program (Force Application and Launch from CONUS) run by DARPA and the Air Force, and today it is the Space Force's "Victus".

So, although the bulk of work was done in NZ, Rocket Lab functioned rather intimately with the US spooks from the very early on, including getting some funding from In-Q-Tel. Then in 2013, for the bulk of investment they just had to become a Delaware Corporation, for all the usual reasons. Very soon they moved engine manufacturing to a facility in California. More recently, with the large rocket (Neutron), their main manufacturing operations are in LA and the launch facility in Wallops. All in all, they are an international outfit.

Dostoyevsky subtly advocates that Western rationalism, materialism, and utopian socialism lead to failure, and only spiritual communion of people bound together by love and Orthodox faith can give hope. This idea of specialness of "messianic Russian soul" and of Orthodoxy is extremely in vogue today in modern Russian ideology. But that is a different subject.

But as a flip side of this, Boston Dynamics developed certain idiosyncratic interests in getting the hydraulic valves just right, etc. Their machines required a lot of tender care, (expensive!) and were dangerous to be around.

When Google acquired them, many things were mismatched. Andy Rubin, the VP at Google who advocated for BD, got fired for alleged sexual misconduct. This cast a shadow on the whole plan that he was trying to implement. DARPA finding did not sit well with Google's ethics. They pushed BD to stop getting grants from DARPA.

Expensive and dangerous robots were not an ideal fit for AI experimentation. Google was buying cheap and much safer tabletop robots for that. All in all, there was no good fit, and after spending tons of money on it, Google have gotten rid of them. They did encourage BD to develop a cheaper, safer electric robot, and this became Spot Mini.

The question was whether during this test the stage was loaded with the same amount of fuel as for an actual flight, or only a small fraction of that.

The heat from combustion of this amount would be about 3.4 kt, which is roughly the same as the heat in the late fireball of the Trinity test.

The mushroom cloud from the New Glenn explosion was also substantial: https://photos.app.goo.gl/a7uPVjsB5n453SJA7

Some reports say that this means "running all seven BE-4 engines at full thrust for up to 38 seconds".

In flight the engines fire for 190 seconds.

So what the full duration means, and whether they fill the tanks with just enough fuel for the firing, or with a larger amount to help the clamps to hold the stage down, all this we will probably only find out from the investigation, if the results are ever published.

This serves as a basis of comparison for this deflagration. If we are considering specifically the appearance of the late fireball, the heat output is the relevant figure of merit.

Assuming about 10-15% of the total bomb energy remained in the heat of the late fireball (with the rest spent on the blast wave, peak thermal radiation and neutron/gamma radiation), the fireball of this rocket deflagration could have exceeded the late fireball from the bomb. But this assumes the tanks were fully filled, which we do not know yet.

The energy of the detonation wave in rocket explosions is typically 1-2% of the energy in the fuel, at least that is the ballpark of what people use for estimating the effects of mishaps.

We also do not know if the tanks were fully filled -- it the past, rocket companies have called 10 second static fire tests a "full duration static fire test." We will probably find out later what it actually was meant to be.

The first atomic bomb had yield of 20 kt TNT, of which about half was in heat, and the rest in the blast and radiation.

Depending on how full the rocket tank actually was, the fireball from the rocket explosion was in the same ballpark, or possibly even larger in the size and duration of afterglow compared to that from the Trinity nuclear test.

https://scholar.google.com/scholar?q=NASA+Data+Acquisition+S...

https://scholar.google.com/scholar?q=Design+of+Electrical+Sy...

A typical test stand would have maybe a thousand channels of relatively slow data (pressures, temperatures, flow rates, valve states, etc), and maybe up to a few hundred of channels for essentially audio data from vibration sensors. This amounts to sub-gigabit per second data rate overall.

If very high speed video / multiple video cameras are used, this could generate massive data rates, but unless something interesting happens it is not clear how important this data is.

In flight, the telemetry data rate from the entire Falcon-9 used to be measured in megabits per second per stage, plus the video stream. It was not a huge amount of data. Presumably now with Starlink they send a lot more telemetry from Starship, but in flight the engines typically have far, far fewer sensors compared to the ground testing.

A good cold gas thruster produces a lower density, more expanded flow, which looks blue for the same the reason the sky looks blue.

One can compare this to the exhaust from various Falcon-9 engines and thrusters when it is illuminated by the sun on the backdrop of the night sky: https://youtu.be/JRzZl_nq6fk?t=193

The booster not completing the return part of the flight was disappointing. They had a similar incident in one of the previous flights, when they tried to maneuver the booster too aggressively immediately after stage separation which caused problems with the fuel supply. If it was something similar this time, it might be solvable by changing just a few details of the maneuver. So, maybe it is not that huge of a deal.

There were many cool things in the webcast, from them showing the catamarans that are deployed at the landing site, to the views form the cameras on-board of the "satellites". The first few minutes after liftoff were just amazing visually.

"Always/Never: The Quest for Safety, Control, and Survivability." (part 1) https://www.youtube.com/watch?v=DQEB3LJ5psk

They cover both the technology itself and its history, including the incidents you are reading about. These people are the ones who developed the methodology and the technology for nuclear device safety, or at least a significant chunk of it. I think it has recently become much more mathematically heavy, with zero knowledge proofs and other fancy stuff used to talk to the locks in the devices.

To teach this more conveniently to his students, he wrote the original version of MATrixLABoratory to allow interactive exploration of the library functions without having to compile FORTRAN code. The original version was about 2000 lines of code in FORTRAN.

Engineering students loved it so much that he decided to make a company around this product. His buddy expanded and rewrote the interpreter in C, for a PC, and the rest is history:

"In 1983 Jack Little suggested the creation of a commercial product based on MATLAB. I said I thought that was a good idea, but I didn't join him initially. The IBM PC had been introduced only two years earlier and was barely powerful enough to run something like MATLAB, but Little anticipated its evolution. He left his job, bought a Compaq PC clone at Sears, moved into the hills behind Stanford, and, with my encouragement, spent a year and a half creating a new and extended version of MATLAB written in C. A friend, Steve Bangert, joined the project and worked on the new MATLAB in his spare time."

User guide for the original version of MATLAB: https://blogs.mathworks.com/cleve/2018/02/05/the-historic-ma...

The source code of the very early (1982?) FORTRAN version of MATLAB: https://github.com/johnsonjh/matlab

The origins of the first PC version: https://blogs.mathworks.com/cleve/2018/03/09/matlab-history-...

Accurately casting explosive in odd shapes, without different ingredients separating, and without producing voids when the melt solidified, required developing a whole new technology with careful gradients of temperature in the molds.

They tried lots of different commercial and handmade detonators to find which ones would work most consistently. That took an awful lot of time.

The electronics itself was probably least difficult -- a microsecond was already a very long time for the electronic circuits even in 1945. One could use an off the shelf oscilloscope to see if the detonators worked simultaneously or not. Incidentally, 2/3 of the cables in the famous picture of the "Gadget" are not the detonators, but the simultaneity sensors -- reporting the difference between the earliest and the latest detonation fronts.

Everything was tested extremely extensively. Tremendous resources were spent on testing and test equipment. All in all somewhere between 20000 and 40000 explosive tests were performed at Los Alamos during the project.

It is not often emphasized how much of the work was done in the explosives laboratory in Pittsburgh before passing it on to Los Alamos. They have developed the slow explosive. They also reproduced from the earlier British work and further developed and tested the concept of the lenses, together with many other more advanced things which did not find an immediate application in the bomb. The director of the laboratory, George Kistyakowsky, took over the explosives work at Los Alamos, once the implosion became the main focus of the project.

And then of course there are versions making it into a much more dramatic story.

When they were working on the fusion bomb (and Edward Teller was working on fusion full time already during the Manhattan project), it took some years to establish that even the "easy" to fuse deuterium cannot be set of by simply blowing up a fission bomb. The reaction simply did not propagate for any reasonable dimensions of the system. For any other material the energy balance would have been orders of magnitude short of what was required for a propagating fusion burn.