545 karma · joined January 26, 2021
It is actually a great example which shows the difference between cobbling something together in a garage, to produce a one-off demonstration, and having a mini-fab which is capable of delivering the results reliably. The difference in the required effort is many orders of magnitude.
The "RAM in a shed" guy started with a Ph.D. in semiconductor technology, and was running a company before he made the improvised lab at home and started to make videos about it. He uses the lab to test some of the steps for the specialty devices which he invents.
But simply making something smaller is not synonymous with it automatically becoming more accurate or capable of achieving higher resolution. If anything, very high precision machines are typically larger in size than the less accurate ones.
In rockets, there is a so called "aerospike" engine [1], which does not have any bell-shaped nozzle at all, but instead uses the ambient air to always shape the flow for an ideal expansion ratio. In theory it is great, but in practice it remained mostly a pie in the sky.
How fast the gas expands through an opening depends on the pressure ratio between entrance and exit, and for ordinary air the flow reaches the speed of sound at the narrowest part when the pressure ratio exceeds about a factor of two. The flow never becomes supersonic in the constriction itself, but after the constriction the flow can continue to accelerate to supersonic speeds, especially if the constriction is followed by an expanding nozzle (converging-diverging, or de Laval nozzle), although this is not strictly necessary. For example, one can observe shock diamonds in the air coming out of an ordinary plastic bottle filled with slightly compressed gas: https://www.youtube.com/watch?v=61tsXGUc6nU
The cables can go the entire distance between the data centers. The satellites probably connect to their closest neighbors, and any long distance transmission would have to make multiple hops, and share the bandwidth with everything else in the system going through the same nodes.
Since there are hundreds of undersea cables, with a dozen fiber pairs or so each, the cable system has several orders of magnitude greater throughput compared to the current constellation of satellites.
Although one could randomly stumble on some interesting anecdote here and there in the NRO archive, overall that collection was not made to be easy to navigate, and one would have to be very patient to sift through it thoroughly. Maybe the situation is better now.
[1] https://www.nro.gov/foia-home/foia-declassified-nro-programs...
So we are talking about a reasonably high stability crystal to begin with, and a very narrow adjustment range. In an atomic clock, the feedback loop uses the electronic frequency adjustment to more or less completely remove the aging. This requires a very tiny and a rather slow acting feedback.
In the atomic clock, the output of the crystal is used as a reference for a microwave sweep generator, which then scans the spectrum of atomic transitions. The absorption peak in a cesium clock is something like a kiloherz wide, but with a good signal to noise ratio and with a lot of averaging, one can measure the position of the peak to a very tiny fraction of its width. Comparing the measured and the expected positions reveals the deviation of the reference frequency from its design value, and that is what generates the tuning feedback for the crystal. I do not know off the top of my head how slow the feedback is exactly -- it is something that one could look up in the Hewlett-Packard service manual, but I am sure it is slow enough to be irrelevant for the cycle-per-cycle jitter.
An exception is an active hydrogen maser, which directly outputs the frequency of atomic transition. It has very good phase noise, but is a rare beast, which is only used where it is absolutely necessary.
There are very good illustrations of this if you search for "Super-Kamiokande Cherenkov ring." That's a Japanese neutrino telescope with a bunch of huge photomultipliers lining the walls of a giant underground cistern filled with water. Ice Cube has similar light detectors, probably from the same Japanese manufacturer, that were lowered on strings into wells melted into ice.
One of the consequences of this was the meteoric rise of the young Will Roper [1], who in a span of a few years went from a theoretical physicist to being in charge of the Air Force procurement program, and then tried to facilitate the access of startups to defense contracts, through AFWERX and "Defense Pitch Days".
Whether this worked or not is debatable, but the itch to change things was there. One example of a startup which was an early beneficiary of this top-down attention is Ursa Major [2], a rocket engine company. Unless one looks at them in the context of these military programs, their existence would seem quite puzzling.
[1] https://www.af.mil/About-Us/Biographies/Display/article/1467...
"This project is a collaboration with Miles Segal (Gotham Silicon), whose mission is to make microchip fabrication more broadly accessible. Creating ultra high resolution micron-scale imagery is the very first step in this process."
"Those are clips of Miles in the Columbia University Nano-fabrication Facility where he is developing a workflow to make the technology required to build microchips more accessible."
Another mention of the same: https://x.com/JoinEdgeCity/status/1966180823129878656
"Miles Segal is building an ASIC foundry by repurposing vintage nano-fab gear to deliver custom chips in 24–48 hours."
"During the week he was at @EdgeEsmeralda, he focused on making new connections – leaving with new energy, confidence, and momentum from countless serendipitous convos."
So it seems to be one very young dude passionate about revolutionizing semiconductor processing. Whether there is an actual market for a super fast turnaround at 1 um node, and whether he has the experience and the support to pull this off, is somewhat dubious.
But of course wonderful things do sometimes happen. While he was a student, Sam Zeloof became a legend by building a chip fabrication lab in his garage, using surplus and home-made equipment. Now he has a serious team, working on developing mini-fabs: https://fab2.com/ That looks pretty serious.
Although the original OneWeb satellites were assembled in the USA, they were developed in Europe and the components were always sourced predominantly from Europe, Canada, and Africa, with only some parts produced by the European companies in the USA, and even fewer parts sourced from the US companies. It is a very European satellite.
Rocketry may be much more talked about, but in terms of headcount is was a tiny thing compared to the number of German experts who were "invited" into all Allied countries after the war. Just France and UK had brought in about 3 thousand persons each. If one had said that this did not happen, that would have been an error. But simply not bringing this up at all because it is not very relevant to the discussion of Isar is fine, I think.
Debating who "won" the space race, and who "used" Germans "better" is not something that I want to do.
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.