Review of A City On Mars (Part II)

Continuing on to the factual sections of the book.

Part I of this review can be found here.

After a polemic opening, the book gets on to two parts which cover scientific topics. There is some interesting stuff here for people new to the field, and lots of historical anecdote, but ultimately the book is still trying to make an argument against space settlement - in the near term, anyway.

Keeping Astronauts Alive

The book contains lurid descriptions of how exposure to space can kill, and of the trials of early spaceflight. None of this is contentious nor is any of it hugely relevant. The first thing they discuss which does apply to long term settlement is space radiation. They represent the current uncertainty around this but miss a few points.

• Regarding the secondary radiation produced by shielding (spallation) they state “if your radiation shield is super thick and is made from aluminum, you can end up being exposed to even more radiation than you would have if you had no shielding at all” without specifying what “super thick” means in this context. Most studies model aluminum shielding at most 1-2cm thick - which is a thick, heavy shield for current spaceflight due to mass limits, but such limits are being rapidly lifted to this aspect of the modelling is getting less relevant. Very thick shielding is a different proposition, although nobody plans to use aluminum for this. Shielding composed of low atomic number elements, such as water or polythene, are much better for not producing showers of secondary radiation

• They say of the Apollo astronauts “If these men had less cancer than you’d expect, perhaps it’s because they were just a little more robust than most of us.” - this appears to be complete speculation on their part. They don’t directly cite anything in the book, and for my previous review complained that I expected this for contentious claims. For a statement like this, if they have anything to back this up, they should have said so

• In various parts of the book they at unclear as to what protects us from cosmic radiation on the surface of the Earth. It must be stressed that its the atmosphere doing the majority of the work.

• There is lots of talk of living underground to avoid radiation exposure; on Mars at least this is somewhat misleading. The atmosphere does provide some shielding at low angles, so whilst it is important to shield the roof, having more open sides is possible without dangerous radiation levels, and several studies have exploited this in Mars architecture. The lack of attention paid to this is a significant oversight.

There are descriptions of various base architectures which are informative enough, but they seem mostly incidental to the main thrust of the science sections, which is to try and argue that everything is too hard and complicated for us to attempt for a long time.

The Gravity Prescription

A substantial portion of the science section of this book is on the impacts of weightlessness on humans - irrelevant to space settlement, as the authors admit, but takes up a number of pages anyway, and is decently entertaining. Readers looking for points to score against space settlement might use this information as a stick to beat us with, but that isn’t something the authors can control.

Knowing that humans suffer bad health effects from weightlessness, and that we can live well in Earth gravity, it is presumed there is some transition between the two. We have almost no data about partial gravity, as the book acknowledges. Some of the health impacts of weightlessness can be mitigated by exercise, but its worth noting that exercise is also required to maintain health in Earth gravity. I am myself concerned with this topic, as I have written about here before.

One of the Weinersmiths’ main focuses is on the risk to human reproduction in partial gravity. They cite the lack of multi-generational experiments on animals, and the limits of existing studies. They claim:

We are not saying that any of this is impossible to solve. But as with space medicine generally, getting the knowledge we’d need to have reproduction in space that is safe and ethical would be a massive, costly, decades-consuming affair, and strangely, among people advocating for vast space settlements in the next thirty years, nobody is doing the sort of enormous spending necessary to get answers.

Its not stated why this would take decades nor why it would be unduly costly. A single conjunction-class Mars mission could raise about 5 generations of mice in Martian gravity during the surface stay. Likely there will be continuous studies on mice as soon as Artemis establishes a lunar base. Larger organisms take longer, yes, but its not clear to me why we need 10 generations of Mars chimps before allowing humans to have children, if studies on lower animals are promising. If the Weinersmiths have a specific program in mind that would satisfy them, they should spell it out.

they continue

If there is no urgent reason to settle space, what is the ethical justification for a huge number of experiments on animals, including humans too young to consent?

This is a significant point which doesn’t get enough attention in the book. The authors assert there is no urgent reason to settle space (they are wrong) and thus imply that because of this it is the right of someone - themselves, society, the government, whoever - to determine for a woman whether or not she has a child in a certain time or place. They later level an accusation of eugenics at some space settlement advocates without a trace of self-awareness.

Whether the urgency justifies animal experiments - and you would have to be a militant animal rights activist to deny this - or whether it justifies having a child on a space colony before the Weinersmiths or their descendents are satisfied with your data, is a subjective view. Along with things like financial and relationship circumstances, it is just another decision someone has to make when choosing to become a parent. On what grounds do they presume to take that choice away?

Children born into poverty often suffer. Should we prevent the poor from having children? Children fed fast food, which never existed prior to last century, may suffer health problems as a result - do we consider this a dangerous and unethical human experiment? Neither of these things can be seen as good - but that is a far cry from saying that there should be a top-down ban on them. The implicit assumption here is that some benevolent bureaucracy must grant birth licenses when and only when it is convinced the matter is settled.

On the subject of abortion, the authors imply that aborting children with severe disabilities, as advocated in some proposals for early settlements, is somehow beyond the pale and indicative of a society that values life so little we should be frightened of it (from the wacky point of view of Daniel Deudney where the evil space men will drop asteroids on their biggest trade partner for no reason). Are the authors terrified of Iceland? This is a country that has used abortion to almost eliminate Down’s Syndrome. Whilst controversial this does not make the country fundamentally evil in most people’s estimation, and them having extremely slow and easy to intercept nukes would not pose an existential threat to humanity.

One strange omission from the discussion of space reproduction is the lack of any mention of c-section: A point is made of weakened pelvic bones as a threat to women in labour, but no mention is made of the obvious and existing workaround. A society with universal, or near universal, c-section births might seem alien or somehow frightening to many Americans, but in Brazil it is already they case that 56% of births are by this method, with the proportion being higher in the more developed parts of the country. There is no indication that this has made Brazil into some bizarre post-human society that we should fear, nor would it become so if the rate approached 100%.

None of this is to say that reproduction in space settlements is a trivial problem. But it can be solved as we go - initial bases doing animal experiments, building up knowledge, and then people themselves making the judgement of when it becomes safe to start having children. The Weinersmiths explicitly reject this kind of bootstrapping in favour of a managerial approach where a grand plan is concocted on Earth, and presumably a bureaucracy to implement and enforce it, and then its executed all in one go. The historical record of societies that have operated in this manner, either in terms of their efficacy or morality, is left unaddressed.

What about rotation?

The obvious solution to any potentially showstopping reproduction problems in low gravity is to use artificial gravity. I’ve discussed before how having this as a backup plan derisks going to Mars. The book is very negative about this concept being used in space settlement. For one thing, the authors exaggerate the issues with short radius rotation by cherry picking an edge case:

That sounds hard. Can we make these things a lot smaller perhaps? Probably not. In order to walk around the rim of a spinning wheel without getting nauseated, the wheel needs to be really really big. If it’s not clear why, consider an extreme case: you’re in space, and the radius of the wheel is precisely the same as your height.

They then go on to present 2 rotations per minute as standard for this, and 4 rotations per minutes as the “best case” scenario, when studies have already shown adaptation to higher rotations. Smaller designs than 112 metre diameter rings are thus ignored. A 6 rpm system, which in some studies has been shown to be adaptable to, would have a diameter of 50 metres, smaller than the ISS and yet far from the case where your head is close to the axis.

Tether based systems are dismissed in a footnote, on the basis that this would not represent a significant size habitat. It is not considered that larger habitats might be incrementally built up from smaller ones, such as in this 1977 NASA study (page 57 in the pdf):

Much is made of the issue of keeping a wheel-type habitat balanced, based solely on 1988 NASA study for a low-mass torus which would have used water ballast moving around to maintain stable rotation. The authors acknowledge that this would be less of an issue on a more massive stations, but elsewhere also make a big deal about how hard it supposedly is to refine the lunar regolith mined to build stations - unprocessed regolith works fine as ballast mass. Furthermore, it is really moment of inertia rather than mass per se that needs to be balanced, so ballasts further from the axis as proposed in the Kalpana One study for example can be used.

Generally, it seems that the authors either haven’t read a lot of the literature on space habitat design, or chose to ignore it. They decline to even bother with details they claim to know about, on the basis that to them its just obviously not worth it. They have not convincingly made that case. An example they use to try and promote these engineering issues as insurmountable hurdles ends up being somewhat ironic:

There are other issues we could get into, but the upshot is this: even a lot of the very basic aspects of rotating space wheels are difficult and dangerous and wildly expensive. While it is literally true that there is enough of the right stuff in space to build these things, it’s kind of like saying we can build solar panels on the Moon. What seems easy to the physicist may not work so well for the engineer, or the investor for that matter.

Likely at the time the book was written they were unaware of the Blue Alchemist program which has actually demonstrated a method of producing solar panels on the Moon. It turns out the engineers were able to handle it after all - so perhaps the authors aren’t as good as they think at gauging the difficulty of these things.

The case against space stations is in part made with a disdain for the 70s politics which Gerard O’Neill was immersed in. They say:

Many of the arguments made for space stations have their historical origins during a particular period of the 1970s when it appeared that environmental degradation was going to cause imminent worldwide famines, and when the price of space launch appeared to be falling rapidly. Also, renewable tech that we take for granted, like cheap photovoltaics, massive wind turbines, and advanced battery storage, were still decades away. If you combine all those constraints—resource calamity in the extreme short term, space access very cheap, and no other options—there might maybe have been a case for huge solar-power-collecting space stations with factories and artificial human habitats. But the widespread famines never came, renewables got cheap, and space travel has remained relatively costly, even accounting for recent changes.

As I pointed out in the previous part of this review, this is an incredibly shallow view of the environment. We don’t have to worry about food security because we have wind turbines? Do advances in battery technology prevent deforestation? The environmental issues have changed, but I can’t take seriously the notion that they have disappeared because solar panels became cheaper.

The Weinersmiths, however, consider these to be knock-down arguments - perhaps because the gravity prescription is their best case against near term space settlement, and they want to shove away any proposal that might blunt its impact.

Life Support

The book does present a good summary of Biosphere 2, beyond the normal “gotcha” view that it was a complete miserable failure. Given how overly complex it was, it worked reasonably well. Better designed and more successful experiments elsewhere such as the BIOS series and the Chinese Lunar Palace are also covered here.

Whilst interesting, closure or not is not as relevant to the viability of a settlement as in implied in the book. If a settlement requires X tonnes of material inputs to live, and has closure C of, say, 90%, then it can expand to require 2X of inputs if it increases to C=95% whilst receiving the exact same amount of supplies from Earth. An increase to 3X can be found by reaching C=96.7%, and so on. Aside from a total loss of Earth, there is no point at which a colony would have to jump to 100% - continuous refinement will work just fine. It should also be noted that disparate biospheres are unlikely to have closure in exactly the same things, and as such trade between them will increase mutual closure - so even though eking out the last few percentage points will get increasingly harder, there will be more chances to do it as the population has increased. Again, such an incremental approach is explicitly rejected by the authors.

Perchlorates in the Martian soil are raised as an issue; it is a problem, but one that is fairly straightforwardly solvable. There aren’t going to be people idly treading dirt through the airlock and into the greenhouses, and in any case the perchlorate ion is fairly reactive (its the oxidiser in solid rocket fuel…) and can be got rid of if some does get inside. The actual scale of the problem doesn’t really justify going at at length about Mars being horribly toxic.

Air quality on the ISS is mentioned, and it is for the ISS, but realistically a space settlement would have a vastly greater volume than the ISS and far less density of equipment and scientific experiments. In addition, CO2 levels on the ISS are higher than normal.

Such things as these are relevant details for designing life support systems, but they are presented as being extremely serious problems that need answers prior to settlement.

Psychology

On the issue of psychology, the authors do well to debunk a lot of tall tales about people going mad in confinement, with reference both to space travel and to environments such as submarines and Antarctic research stations. They thankfully call out as nonsense the notion of a moderately tense workplace dispute on Skylab being a ‘mutiny’ as some in the media have been fond of calling it.

However, because astronauts sometimes lie to flight surgeons to avoid being grounded, they declare all data invalid and assert their view that the non-problem might actually be a problem as the null hypothesis:

We do not believe self-reported astronaut data. Throw in the fact that we still don’t know if there are negative physiological effects on the brain due to long-term exposure to space conditions, and it’s reasonable to want a bit more science before we start building a Martian city.

The fact that a lack of evidence, in their mind, proves their already decided course of action is the best one is essentially information free. So whilst there are some interesting things in this part, it does not support the books thesis in the slightest.

Conclusion

Much of the science in the book is correct, but it really does not support the arguments presented. Topics which either aren’t useful to the central thesis, or even worse threaten to contradict it, are given short dismissive sections, whereas the parts the authors feel support their political arguments are expounded at length.

The implication throughout is that these authors are the first people to seriously think about these things, and that space advocates are somehow ignorant of the issues. A quick look at this very blog will show that is certainly not the case for me, and it rarely is for others. So far, the authors have yet to show a concrete instance of a space settlement proposal missing out on some detail that would in fact make it impossible (or incredibly hard). Merely stating “X is a problem” doesn’t qualify for this.

Humans are smart and resourceful. They are especially so when they are able to build and test their inventions rapidly in the environment in which they are deployed. So the discussion of challenges here - in some places quite valid - is not a reason to delay space settlement. Its a reason to get going, because pressing forward will accelerate the solutions to these problems by giving more people access to the appropriate environment, and hopefully with less of the slow managerial oversight they might find working on Earth for a space agency.

The final part of the review will be on the legal and sociological situation - which appears to be the primary interest of the authors, given how much of the book it occupies. To read that and more, consider subscribing: