Review of A City On Mars (Part I)

I've been searching for quality criticism of the project of space settlement for some time, and found mostly uninformed snark. Could this book be different?

Parts two and three of this review are now available

In this newsletter and elsewhere, I have often locked horns with critics of space settlement and found them lacking. They get facts critical to their argument wrong, and won’t back down when this is demonstrated. They are arrogant and condescending. They are hostile and often dishonest. So I’ve put the call out for an actually competent, honest critic of settlement to engage with.

A lot of people have been eagerly anticipating A City on Mars by Zach and Kelly Weinersmith as being able to provide just that.

Having apparently started out pro-settlement, the Weinersmiths became increasingly skeptical of the project as they researched their book, and have thus published a somewhat anti-settlement book - perhaps better described as an attack on the advocates of settlement than the general concept itself. So, I am going to review it at length, in several parts, as I read the book.

The Introduction

Because there is some good science in this book, which comes after the introduction, the confrontational tone it opens with is unfortunate. Here the authors describe their position:

After a few years of researching space settlements, we began in secret to refer to ourselves as the “space bastards” because we found we were more pessimistic than almost everyone in the space-settlement field, and especially skeptical about the most grand plans of space geeks. We weren’t always this way. The data made us do it. Frankly, we are cowards and would very much like to agree with the consensus. We didn’t like being this pessimistic, especially about an endeavor that so many people think embodies the best of human nature. It makes one feel like, well, a bastard.

“The data made us do it” will turn out to be somewhat overstating their case - they often freely admit there is very little data to go on. But the implication is that others haven’t looked at the appropriate data. They also say “Detailed treatments that are honest about the severe difficulty of these things are almost invariably left out of books and documentaries about space settlement” - seemingly casting themselves as brave (and smart) truth tellers in a world of dishonest hacks who haven’t bothered to properly look into what they advocate.

It sounds as if they see themselves as parents patiently explaining to ignorant children why they can’t have ice cream for breakfast - to talk down to people in such a way surely requires them to be very certain of their position, and based on their initial arguments they ought not to be.

The introduction is peppered with this sort of language - “straight-talking”, “realistic” etc. They describe many space advocates as ‘nonexperts’ but themselves draw on the work of people whose actual expertise is somewhat suspect. For instance, the Weinersmiths present as authoritative the work Daniel Deudney, who they admit is not taken seriously by settlement advocates, but don’t seem to explore why other that implying settlement advocates are being somehow unfair.

The most detailed treatment of the issue comes from international relations scholar Dr. Daniel Deudney and his book Dark Skies: Space Expansionism, Planetary Geopolitics, and the Ends of Humanity. It’s an involved argument, but the basic idea is this: humans being what we are, the move into space creates at least two forms of existential peril: the risk of nuclear conflict on Earth due to a scramble for space territory, and the risk of heavy objects being thrown at Earth if humans are allowed to control things like asteroids and massive orbital space stations.

Robert Zubrin reviewed this book and found it fatally lacking in technical aspects as well as its grim anti-technology tone. The aspects quoted here are touched on in that review but I shall also add my own retort.

We have lived with nuclear missiles for decades. An asteroid thrown across space does much the same thing, except it takes months or years to reach its target, is much easier to detect and much easier to stop. The idea that space could increase the risk of a nuclear exchange on Earth is also bizarre, as if the logic of MAD will suddenly stop applying? I am reasonably confident that having a Moon base, or even losing one to the Americans, will not make Xi Jinping suddenly become suicidal. There is a reason Deudney’s work has been largely ignored - its just a bit silly.

The Weinersmiths likewise scorn Robert Zubrin for ignoring space law in his seminal work The Case for Mars. I don’t really blame him though - there are no courts and no police on Mars, so there is no law there. Space law, as applied to human activity on other planets, seems terribly premature, and tends to gloss over how such laws would be enforced. Later sections of this book apparently cover this matter though, so I will address that in a later part of the review once I’ve read the arguments.

Back to the text, they are as dismissive of the concept of free floating space colonies as they are of the plans of the Mars Society:

Jeff Bezos likely got his theory of space settlement from Dr. Gerard K. O’Neill, a professor at Princeton whose lectures Bezos attended as a young student. O’Neill’s philosophy for space oriented around large solar-powered space stations as the way to save Earth’s economy and ecology. This argument may have been plausible circa 1970, when it was widely believed that space would keep getting cheaper and that energy and food crises would result in unprecedented worldwide famines by the 1980s. Today you can do a much better job of saving Earth’s biosphere with Earth-based solar and wind power. Even if we thought space settlements could take pressure off of Earth’s seas and lands, they will absolutely not arrive in time to thwart any environmental calamity.

These are bald statements without argumentation or citation. For one thing - solar and wind power can only solve one particular problem, that of anthrogenic CO2. What do they do for nitrogen pollution? deforestation? The balance between human needs and the biosphere is a complex and difficult topic, which deserve more than to be waved off in a single sentence. Admitting that, though, would admit to the continued relevance of the O’Neillian argument - or at least that it deserved to be discussed at more length. The discussion below in the preamble doesn’t really add much more either.

There is some good stuff in the introduction; the notion of billionaires using space as an escape hatch is rightly rejected by the authors. The affirm they really are in favour of settlement, but choose a “wait and go big” approach. In other words, do a huge amount of research on Earth and wait until the technology makes it trivially easy to do. This seems an incorrect way to do just about anything though. A better approach to this idea of endless planning before executing anything is iteration, when you plan only what you need to and then try something, and revise and retry. Ironically, it is SpaceX choosing the latter approach over the former that has provided the astonishing advancement in rocket technology that has made this whole debate relevant.

The Space Myths

Following the introduction there is a preamble, where the book introduces and assesses what the authors consider the leading arguments for space settlement, and then largely judge them lacking

Argument 1: Space Will Save Humanity from Near-Term Calamity by Providing a New Home

I do think that sometimes this argument is overstated, but this books objection to it overlooks a significant point

An Earth with climate change and nuclear war and, like, zombies and werewolves is still a way better place than Mars. Staying alive on Earth requires fire and a pointy stick. Staying alive in space will require all sorts of high-tech gadgets we can barely manufacture on Earth.

This is all true - but doesn’t account for population. When we talk of planetary existential threats, like climate change, we aren’t suggesting they would make Earth less inhabitable than Mars - we are pointing out that they would make it unable to support 8 billion people. Mars, even in Elon Musk’s very optimistic projection, would have a million people on it at best. Nobody is claiming the environment would ever be easier there - putting aside terraforming which I think has to come a long time after colonisation. The claim is that the a catastrophe would make it harder to share the Earth’s output, and tempt people into not sharing it at all and turning to violence.

Still, this is one of the weaker arguments for settlement, and I don’t tend to use it myself.

Argument 2: Space Settlement Will Save Earth’s Environment by Relocating Industry and Population Off-World

The Weinersmiths point out that 220,000 people per day would have to be shipped off Earth permanently in order to even keep the planets population static, let alone reduce it. This in itself, though, does not refute the argument for a few reasons

• Reducing population growth would relieve pressure on the ecosystem even if growth is not entirely reversed

• Population growth is slowing, so on the timescale of space settlement the break even figure will drop

• It isn’t actually argued why that figure is impossible, it is merely presented as self-evidently absurd.

I have done actual calculations on how much carbon dioxide emissions can be saved by migrating humans permanently off Earth - its a small gain, not something that will really help our near term problems, but that doesn’t preclude it being worthwhile long term.

As for the viability of shipping out 220,000 people per day - according to the FAA, 2.9 million passengers fly out of airports in the US alone each day, out of 12.5 million daily passengers globally pre-pandemic, so such a herculean effort would still be dwarfed by the scale of the airline industry. Spaceflight, of course, has a very high energy cost - but that too can be calculated. Lets assume a Starship flying 220 people (roomy for LEO flight), that gives 1000 flights per day each burning around 1000 metric tonnes of methane. Assuming 15 kWh/kg, that gives a total annual consumption of about 5500 TWh, about 14% of current global consumption. Whether this is practical or wise, what it certainly is not is impossible.

I’ve addressed some more of the practical details of cheap mass human spaceflight here for a deeper dive on this matter.

How long would it take us to ramp up to such a huge flight rate? Currently, Falcon 9 is flying roughly once ever 4 days, and if you put a Dragon capsule on it could take 4 people into space. To fly Dragons every time would need many more of them to be built, and cost a lot, but we can say that the absolute maximum rate of evacuation currently possible is around 1 person per day.

Currently, the rate at which Falcon rockets are throwing mass into space is accelerating at a fair clip - around 45% per year for the last couple of years. If this can be maintained beyond the life of Falcon - which Starship and future projects have a decent chance of doing - then mass-to-orbit can double every 2 years. Scaling passenger numbers with this would mean that 220,000 per day would be achieved in a little under 36 years. These people would need a place to stay - at the density of London and about 2 tonnes/square metre of shielding, you would need about 300 tonnes per person, or about 24 billion tonnes per year - roughly the amount of aggregates produced annually in China, which is a good proxy as most of this mass would be shielding. This is a huge amount of mass that is likely too much to be thrown from Earth, and would be sourced from the Moon or asteroids, which makes it hard to model how feasible it is. Bear in mind in this scenario, there would be millions of people working in space towards this.

Can this sort of increase in mass be maintained? Can human spaceflight capability, and space habitat capacity track it? The above calculations are simple because more detailed ones aren’t possible at this stage, so the honest answer is that I don’t know. The Weinersmiths don’t either - they just assume the number itself answers with a resounding ‘no’ and move on.

Following this is an argument about whether or not its economically to manufacture 3.5 billion tonnes of cement (total global demand) on the Moon and ship it to Earth. Of course it isn’t economical, but nobody is proposing it. It seems to be a straw man of a statement Jeff Bezos made about moving heavy industry off Earth - but it seems obvious to me that he wasn’t intending current industrial consumption to be shipped back here, and it seems uncharitable to pretend he was.

The authors state that space based solar power cannot support this sort of endeavor, which is probably true. I have not seen a business case for it that I would put my own money in. This is best left on the shelf as an idea that looked better in the 1970s - my own view is that the solar energy in space is abundant and useful, but it should be used more or less where it is collected, rather than attempting to beam it around.

Argument 3: Space Resources Will Make Us All Rich

The Weinersmiths make good points here about asteroid mining - but I feel they have missed the point of this type of argument. Myself and most other advocates of settlement cite the abundance of energy and raw materials in the solar system not as something to be returned to Earth, but to be used to build a far larger civilisation out there. If the form of the argument that promises lucrative returns from bringing back metals is seen as the dominant one, that is a failure of the advocates to communicate well.

They also argue here that mining Helium-3 from the lunar regolith for profit is essentially nonsense. They are correct.

Argument 4: Space Settlement Will End, or at Least Mitigate, War

I don’t personally believe this, but it might be true. The notion is essentially that there is enough space and resources for everyone and nobody has to contest anything. Intractable disputes can in principle be resolved by colonists branching out and finding separate spaces.

I wouldn’t dismiss this argument as casually as they do, and I certainly wouldn’t make comparisons to “White Flight” as their source De Witt Kilgore does. Do the Weinersmiths agree with his implication that it is somehow racist to want to colonise space? I have not read Kilgore’s work, but he comes across as quite politically radical and polemical. Perhaps he has something to add to the debate, but surely on a factual question such as this some balance would be nice?

Argument 5: Space Exploration Is a Natural Human Urge

This one they claim is not very convincing because “most of us are not in fact famous explorers”

Well, no, but some of us are, and that is all that really matters. Nobody is suggesting the entire human race migrate to Mars - only those who want to. Just because an urge or a deep human truth is not shared by literally every human, does not mean it is invalid.

They also dismiss in this part the notion that any sort of stagnation is occurring in terrestrial societies because of all the cool stuff that has happened since the 1950s. First, most people date the start of the stagnation much later, and secondly they focus in on advances in computing (which proponents of stagnation specifically exclude, see Peter Thiel’s famous quote “We wanted flying cars, instead we got 140 characters”) and space launch technology. The reason Musk has become so renowned as a technologist is that he has bucked a trend of the world of atoms falling behind the world of bits. The Weinersmiths say they can’t imagine a serious argument for stagnation - instead of imagining, why not find someone who makes such an argument, quote it directly, and try to refute it?

Argument 6: Space Will Unify Us, and Argument 7: Space Travel Will Make Us Wise

I don’t myself make these arguments, and can’t really defend them. I do agree with the authors that the “Overview Effect” is greatly overhyped, most recently in Virgin Galactic marketing materials. The efficacy of that message can maybe be gleaned from a recent earnings call.

Argument 8: Creating Nations in Space Will Reinvigorate Our Homogenized Bureaucratic, and Generally Wussified, Earth Culture

This is dismissed - specifically with reference to linguistic diversity, which to me has never been central to the argument - with the claim that Mars would remain strongly connect to Earth because it “is going to have Netflix”. Really? The authors clearly understand the latency issue (which might make selecting a film take a significant fraction of the films running time) but perhaps they are unaware of the cost of sending data over this distance? Here is DSS 43, the antenna that us currently communicating with NASA spacecraft around Mars at time of writing:

Its a 70 metre antenna that can transmit in the X-band and in the absolute best case could maybe provide broadband on Mars for a few dozen homes. The size and power of such an antenna is driven by physics and whilst there are ways the situation could be improved, its not at all clear that Martian colonists will ever have broadband speeds we are used to and the book doesn’t address this technical detail.

So even those willing to wait 40 minutes for their entertainment to start are probably not going to want to pay for HD streaming over interplanetary distances. This issue applies to other forms of internet activity too. Whether it is good or not, there will be meaningful separation from the densely connected planet we currently live on.

It is hard for me to believe that a spawning of dozens or hundreds of effectively new nations would somehow not be more diverse than the established ones on Earth. It would require positive effort to replicate terrestrial nations exactly, and wouldn’t make a lot of sense in the new environment. If media led to these nations sharing basically the same language, that in itself doesn’t preclude a diversification in other aspects of culture. So I don’t find their linguistic rebuttal very convincing.

They then turn to the “Frontier thesis” which attributes American success to the harshness of the new nations Western frontier. First they say it has been rejected by historians since the 1980s, which given institutional biases in academia isn’t a surprise - the thesis is a fairly conservative reading of history and US colleges were becoming increasingly liberal at the time. Using its rejection by the humanities as an argument is akin to saying its wrong because the liberals disagree with it, which is not a valid epistemology. The reasoning by which it was rejected by academics may well be valid - but that reasoning not presented here at all, even in the footnote. They then go on to claim that if it were true it would be in part due to a need to organise against the natives, and Mars has no natives. Why, though, would the harshness of the environment there not also force such organisation? I am not claiming the thesis is proven, or that it matters much to me as a non-American, merely that what is offered here does little to disprove it.

To further attempt to refute the thesis as applied to Mars, the Weinersmiths consider creating an equally harsh environment in a “necrosphere” on Earth:

Why did we build it? In the sure knowledge that we can stick engineers inside who, due to the harsh environment combined with their need not to die, will spew forth valuable ideas like a spigot spews forth pressurized water. If this sort of thing seems implausible to you, you should ask yourself why anyone would expect a Mars base to generate all these supposed benefits. You should also ask yourself why it is that so many innovations on Earth come not from anarchic wastelands but from cities where an engineer’s main hardship is eight-dollar espressos.

This does not really address the argument made, for the same reason they later point out that Mars sims on Earth have limited applicability to psychology in space - the participants know they aren’t on Mars. If the harshness of the frontier does spur creativity, out of need for survival, then surely we would only expect it to work if one is actually on the frontier. There is a huge psychological difference between harsh conditions arising naturally and them being intentionally and unnecessarily inflicted on you by a person, and it isn’t considered here.

The Weinersmith Way To Space

The book presents two arguments the authors consider good: “The Cathedral of Survival” and “The Hot Tub Argument”.

The first of these two envisions and multi-generational endeavour to ensure the very long term survival of the species, done in the knowledge that it would take longer than our own lifetimes to get to this stage. This is all well and good - but it seems to overlap with arguments they claim to have just refuted:

• Argument 1 differs only really in the phrase “near term”

• Argument 2 also seeks to alleviate long term catastrophe by decoupling us from the biosphere

• Argument 3, in the form it is properly expressed, is about generating wealth in space - and a cathedral building project would certainly do that

I’m not sure why there is a line drawn between these arguments here - is it merely a question of how they are being expressed? The Weinersmiths don’t seem to have noticed the same connections as I have and thus don’t address them. However their version of the argument is expressed though, it is a reasonably good one. I don’t see how it removes all urgency from the project, as they seem to think though - you have to be reasonably urgent in adding your bricks to the cathedral, or nothing will ever get built.

The second argument equates the desire to settle space with consumerism

When you want to buy a hot tub, nobody says “It is the destiny of Man to put His butt in bubbly hot water.” Nobody tries to convince you that a hot tub–less humanity is bound to stagnate. Nobody tells you the proliferation of toasty warm outdoor bathtubs will end human conflict. It’s just that you want a hot tub and someone is selling it, and nobody has any right to stop you.

the underlying sentiment is fine, but the humorous analogy seems designed to trivialise anybody else’s motivations, if they can’t justify them to your satisfaction. Maybe they find some of the dismissed arguments more compelling than you do? Maybe they have reasons that you haven’t addressed? Perhaps they have different values to you, and thus what may be rational for them is not rational for you? These things don’t make their choices frivolous. I don’t suppose it matters if you are intending to leave people alone in their choices.

However, the authors then return to the previous dubious argument about space settlement being akin to acquiring a nuclear weapons, and thus gives others a right to stop you owning it. Looking over at the AI debate, this kind of fear mongering seems quite a popular way to bypass liberal principles these days.

Throughout this introduction and preamble, the Weinersmiths have cited very left leaning figures - Daniel Deudney, Erika Nesvold, De Witt Kilgore - and presented them as objective expert sources. Whilst decrying the bias of space settlement advocates writing about space settlement, they do nothing to address the bias they bring to the table by drawing on these writers. This is not necessarily a left wing thing - I know liberals, socialists and even communists who are enthusiastic about space settlement - but it is something peculiar to a part of the western left that, in my view, sees confinement of humans on Earth in perpetuity as a way to force zero-sum competition and thus reach their goal of perfect equality. The fact that the space race is now being led by billionaires probably contributes somewhat to their motives and biases too.

On To Actual Science

This preamble was just their argumentation, and honestly not well supported by evidence. The following three sections deal with scientific aspects of space settlement, and are considerably better - but I will still have things to say there.

It is possible that elaborations on the above arguments may be made in chapters I have not read yet - if so I will talk about that when I get to them. But surely then the strident statements must come after the presumably watertight evidence that backs them up, and not precede them? Unless the intention is to provoke, and I have fallen for literally trolling?

Part two can be read here

I shall resolve the issue soon enough - please consider subscribing with the button below if you want to read the rest of the review as it comes.