The author said somewhere, (maybe in the comments) that they had purchased ready made iron oxide of required particle size.

If the chip is subjected to a few thousand g's of shock the wires can bend and short.

This failure mode is quite low on the list among others, but it is something that people did investigate. For example: "Swing Touch Risk Assessment of Bonding Wires in High-Density Package Under Mechanical Shock Condition" https://asmedigitalcollection.asme.org/electronicpackaging/a...

Jonathan is very knowledgeable and is usually right. But in this specific instance, everything points out that this is indeed a component of a rocket.

The eyewitnesses describe that the object fell with a high velocity, with a loud noise, and was hot when it landed.

The better angles in the video [1] show molten metal on the outside, and a typical aerospace bolt pattern with carefully machined pockets around the bolts.

This kind of construction is typical in rockets, for example at the top and the bottom flanges of some stages of the Indian PSLV rocket [2]

[1] https://youtu.be/Wr1t8CE1FpQ?t=60 [2] https://upload.wikimedia.org/wikipedia/commons/6/67/PSLV_C50...

Vishay is one of the large manufacturers of discrete semiconductors and passive electronic components. They maintain a significant manufacturing presence in the USA, with about a dozen of factories.

The legendary ATC (American Technical Ceramics), belongs to AVX which belongs to Kyocera. It also apparently manufactures all their high frequency capacitors in the USA.

So if we look at US manufacturing proper, it exists, though compared to the greater China, it is of course quite small, as one would expect, considering where most of the electronic assembly happens. However, if we look at the component manufacturing which is "not in China", then the situation is fine, with the dominant companies having hundreds of factories in Japan. Specifically, lots and lots of ceramic-based components (capacitors, resistors, filters, magnetics, etc) are manufactured in Japan (Murata, Kyocera, TDK) and to some extent by their subsidiaries in the USA and elsewhere. If we include Mexico, Eastern Europe, Israel, Philippines, a few factories in Western Europe, then the situation is quite balanced.

Here is an interesting article regarding capacitors: "Japanese companies hold a dominant market share of 56%, significantly ahead, while mainland Chinese MLCC manufacturers account for approximately 7% of the global total." https://www.cytechsystems.com/news/top-mlcc-manufacturers

There is additional nuance here. Not all of the MRI machines are the same.

The USA typically uses machines with higher magnetic field strength, which are more expensive but produce higher spatial resolution. These machines are based on large superconducting solenoid magnets.

In Japan, there are many MRI machines with lower magnetic field, which makes them much more affordable while still quite useful. Some of such machines even use ordinary permanent magnets, which have much lower upkeep costs compared to the large superconducting devices.

That is a rare level of cunning!

A simpler, somewhat common version is when one dog pretends that there is something interesting outside, so that the other dog would drop the toy and would run to the window hoping to bark at the mailman, while the trickster picks up the left behind toy.

Some dogs actually learn to see through this ruse. It can be very amusing to watch them darting instinctively, then suddenly realizing what is about to happen, returning back to pick up the toy and only then going to the window more leisurely.

Dogs are amazing. And human brains/minds are without doubt even more complex than those of dogs. But it is typical for humans to not be aware of the true reasons of behaving or even feeling in the way they do.

When asked about causes of our behavior, we readily make up an explanation, and we believe our own explanations completely whether they are true or false. There is a considerable literature demonstrating in an experimental setting how easily the behavior is controlled by the factors that are not consciously perceived, and how it is rationalized post factum in plausible but arbitrary ways. More informally, many fiction writers show characters, for example falling in love and showing that through their behavior, but refusing to admit that they are in love, even when explicitly confronted with the facts.

Of course one can say that an adult human can at least in principle, sometimes, examine what is going on, while a dog is probably much less capable of such complex analysis and is more like a small child. This seems plausible.

CRT tubes usually have stern safety labels warning to not exceed specified voltage, not because there will be an electric breakdown, but because this will generate vastly more X-rays.

So the quotation "glass formulation limits the voltage" is probably correct, but it is supposed to mean: "glass formulation determines how opaque to X-rays the tube is, and what acceleration voltage can be safely used while remaining in compliance with the health regulations".

I think this is what it is supposed to be. Lead based glass is so common in CRTs precisely because of this reason.

Indeed. My mistake.

The author is Peter Bloem, and the html is compiled from these sources: https://github.com/pbloem/gestalt.ink

with the help of mathjax: https://www.mathjax.org/

The font seems to be Georgia.

Making any kind of a rocket that works is already nontrivial (once one goes beyond Estes models), but in terms of complexity of the challenge, making some kind of a hopper that goes up and down is a task that ambitious amateur groups with a few members and under $1M in funding were demonstrating even before SpaceX was founded. There is no need for a highly efficient engine, there is no need for lightweight structures. Many other concerns, such as low frequency structure oscillations, aerodynamics, etc are practically nonexistent.

Making a space launch vehicle is a task for a group with at least x100 more resources and experience. Reaching orbital velocity is pretty hard. Most startups do not succeed.

Making a space launch vehicle which does not spend the fuel entirely, while carrying extra hardware to also land after the launch is another step up in how hard this is. Very serious institutions worked on this problem since 1970s but lots and lots of people were skeptical. Shuttle was impressive, but also very expensive. Then SpaceX has shown that it was not only possible, but even practical to make ordinary rockets reusable. That was amazing. Even now, almost a decade later, nobody has shown anything like that -- though a number of Chinese startups are working on it.

It is great that the author of the video helps to introduce the topic to the general audience. This is a vast and a fascinating subject with lots of material available for a further more systematic study.

It becomes more technical, if one is specifically interested in the methods used by SpaceX. But there are some overviews that describe the general idea. Here is one presentation by Behçet Açıkmese: https://nescacademy.nasa.gov/video/eda2b96bddf945629be2c9d2e...

Note that before joining SpaceX to lead their autonomous landing software development, Lars Blackmore worked at JPL, where together with Behçet Açıkmese they developed the autonomous precision landing algorithms based on real time optimization methods. So, even though SpaceX has undoubtedly developed additional nuances to match their needs and capabilities, they were building on this prior work at JPL.

As the article explains, with a well designed procedure, the required navigation accuracy is quite modest. Even the latest consumer IMUs and GPS would do, and SpaceX is using even slightly more accurate "tactical grade" units, typical for all launch vehicles.

Good article. It is nice how it goes through all the points systematically.

Falcon-9 uses radar altimeters for determining vertical "distance to go" during landing.

While a sideways position error of even ten meters is not fatal, it is critical for the rocket to be quite close to zero altitude when deceleration brings the velocity to zero. (Any residual error must be dealt with by the shock absorbers, and their capability is modest.)

Starlink satellites use on-board GPS receivers for extremely accurate (centimeter level) measurements of their position. The orbits which SpaceX reports to the world (for collision avoidance) are based on these measurements.