Six(ish) years ago at the blog -- with Elon it's always déjà vu all over again

Starship will have a small spin on the way to Mars. Even a tiny gravity vector is better than none.

— Elon Musk (@elonmusk) March 6, 2024

With a radius of less than ten meters, any perceptible spin will only serve to make the crew sick. That's not to say that there aren't reasons why you might want a slight spin in an interplanetary flight, but based on past experience, we can be fairly sure Musk doesn't understand those reasons.

Wednesday, June 20, 2018

Elon Musk is a terrible engineer (and why that is important)

From Fortune:

In a tweet on Friday, Musk posted a GIF of Dr. David Bowman, the main character in 2001: A Space Odyssey running around a track in space. He said in the tweet that the BF Spaceship will feature a similar track and that running around on it “will look something like this.”

During the scene in the film, Bowman is running around a centrifugal device that creates enough gravitational force to allow him to run and get exercise. But when Bowman was running around in space, he was on the Discovery One spaceship and not the BF that SpaceX is working on.

First, a very brief and hopefully painless physics lesson (with apologies for any details I might screw up – – it's been a long time since I took a class in the subject). We are all familiar with the idea of centrifugal force. When traveling in a circle, the amount of the force you experience is a function of rpm's and radius. Increase either of those and you increase the force.

The ring shaped space stations you've seen in NASA proposals and science fiction movies are based on this principle. (The actual proposals might be more likely to referred to shape as a "torus," but let's not get technical.) Another design, which will get to in a minute, involves a tether and a counterweight. You see this in actual engineering proposals but it seldom seems to make it into the movies.

A big problem with using centrifugal force to get around microgravity is the Coriolis effect. Both volume and mass are at a premium with spacecraft, so we would like to trade speed for radius. Unfortunately, spinning rapidly in a tight circle messes with the inner ear in ways that cause dizziness, nausea, and disorientation. While there's evidence that people can adapt to this to a certain degree, if you want to avoid these effects, you need a very large circle (think hundreds of yards across) traveling fairly slowly (around 2 RPMs).

If you're using the tether and counterweight approach, radius isn't that big of an issue, but with ring-shaped craft increasing radius means proportionally increasing mass and the habitable space you need to maintain and the amount of radiation shielding you need. The specs for the BFR give a diameter of 30 feet making it impractical to squeeze a running track inside one.

Now, obviously this is a hugely complex question and you probably wouldn't have any problem finding serious and highly competent engineers (of which SpaceX has many) who are actively working on ring shaped designs for craft and stations, but that does not at all appear to be what happened here. Instead, we have yet another instance of Elon Musk going off script and showing a fundamental ignorance of engineering while confusing seeing something in an old science-fiction movie with having an idea.

After you follow Elon Musk for a while, his proposals start to fall fairly neatly into two categories: the silly and other people's. It is something of an open secret that Musk likes to take credit for employee's work. Fortunately, the ruse is seldom difficult to see through. The proposals for SpaceX and Tesla that actually make it into production and necessarily involve the work of multiple engineers and specialists invariably come off as professional and mainstream.

Then there are those times when Elon Musk decides to go off script. Musk without his engineers is a bit like a bad comic without his writers.  The concepts he "comes up with" are without exception standard elements from old science-fiction shows, be it the Hyperloop or the giant underground slot car track or the brain communication microchip or the super fast tunneling machine.

As for the engineering, any vestige of competence vanishes when Musk ventures out on his own. A good engineer looks at a problem and sees the complexity. A great engineer sees the complexity and when it's there, sees through the complexity to the underlying simplicity. Bad engineers propose simple solutions because they miss the complexity entirely.

This is a hallmark of Elon Musk's attempts to sound like an engineer. His "solutions" simply make other parts of the process more complicated and unworkable. The perfect example is his handling of thermal expansion with the Hyperloop. Having the terminal points of the line move hundreds of yards based on the day's weather creates far more problems than it solves. His go-to answer of saving money on infrastructure projects by making tunnels smaller falls in the same category.

I realize this seems awfully harsh. To be clear, Elon Musk is a man of extraordinary and extraordinarily valuable talents. As a charismatic leader, finance guy, and promoter, he has few if any equals. Without these talents, there wouldn't be a SpaceX or a Tesla and for that alone he deserves tremendous appreciation.

But there are real dangers to the hype and bullshit standard narrative of 21st century technology. The lies we tell ourselves are increasingly costly and, in that context, the myth of a real life Tony Stark is not one we can afford.