# 21

In certain corners of the astronautics community, there’s a real and substantial debate over whether to prioritize Mars or Luna when planning out the future of human spaceflight. There are good arguments on each side, but I think that neither side makes the correct case.

Luna is attractive because it is close. We know how to land on Luna; we’ve done it before. Building bases on Luna would offer the opportunity to really understand how humans live and operate in space over the long term. It would provide a test-bed for certain technologies that would enable more advanced missions to the planets. If things go wrong, it would be easier to get support from Earth, or to head home if need be.

The counter-argument put forth by the pro-Mars camp is that Luna is a very different world from Mars, and thus wouldn’t provide really all that much advantage for testing Mars-specific technologies. Life support systems on Luna would necessarily use a very closed loop; aside from some water deposits at the poles, astronauts would want to recycle as much as possible. Mars, on the other hand, has water and carbon dioxide and organic molecules in abundance. It offers much better options for building self-sufficient outposts.

There’s also disagreement about the efficacy of using Luna as a refueling stop, so to speak, en route to the Red Planet. From an orbital mechanics standpoint, it’s not a slam-dunk idea, but the argument in practice depends heavily on the specific logistics. In-situ fuel production might just make such a configuration worth it.

In any case, both camps miss the main question when it comes to long-term off-world development: where’s the money coming from?

While Mars is obviously the more attractive target for colonization, we are a very long way from building colonies on other celestial bodies, no matter how good of an idea it is. The reason is very simple: space colonization is an unspeakably expensive proposition. The off-world economy as it currently exists is entirely constructed around servicing needs on Earth, and there are no terrestrial markets which demand colonies on another planet.

I have yet to think of an economic need which a self-sustaining population on Mars would fulfill, that innovative strategies could not fulfill on Earth. Farming food on Mars? We can do hydroponics here. Running out of room to house people? We’re nowhere near that kind of population density. New legal environments to test out social engineering concepts? Seasteads and charter cities are way safer and less expensive. Climate change? Just tax carbon and build nuclear power plants, sheesh.

No one will front the money to build Mars colonies until there’s an economic incentive to do so. I see no such economic incentive. I would love to be wrong about this, because Mars is the best colonization target by far. But I don’t think I am.

Nevertheless, there are profits to be made in space.

There are needs on Earth which off-world industries can satisfy. Currently, most of the needs which we’re satisfying relate to information on or near Earth’s surface: passing data quickly between two points, or observing the location of moving vehicles, or watching the development of weather systems—things in that vein. There’s been a lot of discussion of space tourism, but that has yet to make any real money without piggybacking on government-funded flights. Scientific probes and the like are great, but largely a public service. They don’t represent the sort of self-sustaining economic sector that successful space colonization requires.

What self-sustaining options are there? Honestly, that’s very difficult to predict. Modeling the profitability of a venture depends heavily on the assumptions we make. How far will launch costs fall over the coming years? Will other space technologies follow suit? What will the tax and regulatory structure look like in twenty years?

Some things are simply impossible to know at this point: how materials behave in microgravity, what resources are available in space, and in what forms—and how much will everything cost? Will there need to be humans involved, or not? These are impossible to know without further investigation; basic research is, in many cases, a part of the capital investment. Publicly-funded space agencies have done a great deal in this area, but the private sector is going to have to carry some of its own weight before turning a profit.

We can still speculate, of course. I think in-space manufacturing and resources from space are potentially tremendous markets. That said, many people get these aspects wrong. For instance, many will point to the nominal value of precious metals in asteroids, ignoring the fact that introducing such quantities would immediately and permanently crash the market. In that particular regard, what’s far more interesting is the possibilities that open up when platinum, say, becomes cheaper than aluminum is now.

The real value of off-world industry will come in the things we can do in space that we can’t do on Earth. This includes all sort of material processes (though, of course, gravity makes a great many things easier), and the lack of environmental concerns. As the people of Earth demand an increasingly high standard of living and simultaneously a cleaner environment, I suspect that this may prove to be the ultimate driver of off-world industrialization. Again, though, speculation.

Towards that end, staying near Earth is much more attractive logistically than going all the way to Mars. Orbital space stations are preferable to Luna is preferable to asteroids. considerations eat up the profit margins, to the extent that off-world resource extraction has yet to enter even the demonstration phase. The cost of even basic space technology is currently prohibitive.

Those costs will fall, at least to some extent, but the basic logic remains. If all we need is microgravity, there’s little reason to go above low Earth orbit. If we desire some degree of gravity, Luna will probably do. Asteroids may be useful targets for mining, but I would need to see actual numbers before deciding whether to pursue particular resources on Earth, Luna, or smaller bodies.

Critically, space industrialization is different from space colonization. Developing an off-world economy is a pre-requisite for seeing a large, permanent population above the atmosphere.

Certainly astronauts can visit Luna and Mars. We might even establish permanent research bases. This, however, is a public-spirited endeavor. Governments may choose to pay for scientific missions to other planets; they will not front the costs of developing entire planets quite literally from the ground up. Whatever outputs space agencies may build, they will not be colonies. People won’t live there, the way that human populations have whenever establishing themselves in a new locality. There won’t be families and new businesses and the like, not for a long time.

Instead, we’re probably going to see many largely-automated operations, with minimal and possibly intermittent human presence. Over time, these will expand, and eventually we may see actual colonies in orbit and on Luna. But that will come only once there’s a profitable market for goods manufactured or processed in space. These industries will beget new markets, which may be satisfied by other off-world industries. At some point down the road, there very well may be demand which can be more profitably supplied from Mars than Earth (from a perspective, it’s easier to reach Luna from the surface of Mars than Cape Canaveral). But I think that it’s unrealistic to expect that to occur particularly soon.

As we push towards human settlement in space, our focus should therefore be the development of new industries and new technologies to enable and motivate working above the atmosphere. Between the two targets of Luna and Mars, the former clearly comes out ahead for this purpose. Proximity wins over hospitality, though many of the disadvantages Luna has as a world are significantly less serious in the context of production rather than settlement.

One day, our species will span three worlds. That day remains very far away. Rather than fixate on terraforming dreams, we should chart a course carried by the currents of economic necessity. With the correct regulatory environment and technological investments, we can begin building sustainable off-world industries in a realistic timescale. Such industries will carry us to the planets in the pursuit of profit—a far more reliable motivator than any humanitarian spirit from politicians.

That, I suspect, is what the future of space travel is going to come down to. Do we pursue an incremental strategy that eventually carries us to the ends of the Solar System, or do we wallow on this one planet, fantasizing of an amazing future no one has any incentive to hand us? Are we going to fixate on self-sustained colonies and settle for nothing less, or shall we go to Luna first, but not to live there?

# 21

New Comment

I would like to take the complete opposite position and argue that self-sufficient space colonies will happen long before Earth reaps any benefits from industrial activities in outer space, if ever. The reason I believe this is that outer space activities won't be economically driven for a long time, because there is no profit to be made.

It is important to clarify what sort of propulsion technologies you are basing your analysis on. I subdivide propulsion technologies into 3 categories:

• Level 1: current non-reusable rockets; ~$10,000 per kg to LEO • Level 2: reusable rockets, space planes; ~$100 per kg to LEO
• Level 3: space-elevators, orbital rings, fusion drive; <$1 per kg to LEO and beyond With level 1 tech delta-v is absolutely crucial for any activity in outer space because every kg of fuel in LEO is worth its weight in gold. With level 2 tech, delta-v becomes a much less important consideration; there are plenty of equipment whose value exceeds$100 per kg, and the cost can be further reduced with dedicated tanker spacecrafts highly optimized for re-usability. Fuel itself is cheap, after all. And finally, with level 3 tech, delta-v becomes utterly trivial; simply climbing higher on a space-elevator can eject you straight out of the solar system.

We have been stuck on level 1 for half a century now, and there has been no outer space activities beyond a few space probes here and there. If we stay on this level, there is no reason to expect more activities in the future, either. If we ever reach level 3, setting up shop anywhere in the solar system will be just as easy as on Earth. So level 2 is the only scenario worth discussing with regard to colonization vs industrialization in my mind.

Currently, our best bet to reach level 2 by far is SpaceX, which was founded with the explicit goal of colonizing Mars. It is way ahead of the competition both in terms of currently operational re-usable rockets (having sucked up most of the global non-governmental launch market) and pushing re-usability tech further. It is in the process of becoming a space-based internet broadband provider which has the revenue potential dwarfing the satellite launch market, with no competition in sight. It is also a privately-held company and intentionally so, so that profit incentives don't get in the way of its mission.

Their road map is to lower launch cost enough such that private citizens, the government or Elon Musk himself (most likely a combination of the above) could fund a Mars homesteading campaign. Low enough that economic drives are unnecessary. I would like to hear why this plan is unrealistic.

One major advantage Mars has over the moon (regardless of colonization or industrialization) is the availability of carbon. The only fuel that can be produced in-situ on the moon is hydrogen, which is not ideal for re-usability due to its low boiling point and hydrogen embrittlement. There is good reason all next-gen re-usable rocket engines use methane as fuel.

But far more importantly, you have not argued why industrializing the moon is a good idea in the first place. I wholeheartedly agree with the idea that operations on Mars will never turn a profit for Earth, but that hardly supports your point. Putting factories on the moon might make (marginally) less losses than putting factories on Mars, but so what, there is always the option to stay home and make no loss.

Level 2: reusable rockets, space planes; ~$100 per kg to LEO The economics that Elon predicts are more ~$10 per kg to LEO then ~$100. But far more importantly, you have not argued why industrializing the moon is a good idea in the first place. I wholeheartedly agree with the idea that operations on Mars will never turn a profit for Earth, but that hardly supports your point. Putting factories on the moon might make (marginally) less losses than putting factories on Mars, but so what, there is always the option to stay home and make no loss. Industrializing space is desirable because industrializing Earth has had a number of negative side effects on the biosphere, so moving production outside the biosphere would be a positive development. My argument is that the option of staying home is clearly economically preferable for now, and will be unless we see major cost reductions in space technology. Whether SpaceX and other launch vehicle organizations can reach the Level 2 threshold you describe remains to be seen, and LVs are only part of the pricetag. Materials, equipment, and labor represent a large segment of space mission cost, and unless we can also drive those down by similar degrees do the economics of colonization start making sense. Note, too, that is non-trivial, even when we start getting to high specific-impulse technologies. Industrializing space is desirable because industrializing Earth has had a number of negative side effects on the biosphere, so moving production outside the biosphere would be a positive development. My argument is that the option of staying home is clearly economically preferable for now, and will be unless we see major cost reductions in space technology. I thought your argument is that we should industrialize space because it's economically viable? Putting that aside, environmentalism is just about the last reason for space activities. Space travel has had a negligible impact on the environment thus far only because there has been so little space travel. But on a per-kilogram payload basis, even assuming the cleanest metholox/hydrolox fuel composition produced purely from solar power, the NO2 from hot exhaust plumes and ozone-eating free radicals from reentry heat alone are enough make any environmentalist screech in horror. You'd have to go to the far end of level 3 tech to even begin making this argument, and even then it still isn't an economic incentive. You can't seriously dismiss space tourism as a driver for space travel and then propose environmentalism as an alternative. Whether SpaceX and other launch vehicle organizations can reach the Level 2 threshold you describe remains to be seen, and LVs are only part of the pricetag. Materials, equipment, and labor represent a large segment of space mission cost, and unless we can also drive those down by similar degrees do the economics of colonization start making sense. Space is hard, sure, but how does that help your point exactly? Colonization doesn't have to (and won't) make economic sense. Industrialization does. Note, too, that ΔV is non-trivial, even when we start getting to high specific-impulse technologies. Not really. This isn't relevant for the Moon vs Mars debate, but even for the outer planets I would argue • Short travel time isn't necessary for colonizing or industrializing outer planets • Nuclear fusion can realistically go up to 500,000s Isp, dwarfing any reasonable requirement for travel time inside the solar system Also, all the analysis with hyperbolic orbits are kind of unnecessary as the solar gravity well becomes trivial for short transfers. You could just as well assume the target planets to be fixed points and get the Δv requirement from distance divided by desired travel time (x2 for deceleration). This includes all sort of material processes (though, of course, gravity makes a great many things easier), and the lack of environmental concerns. If you want something like gravity you can easily get it by rotating your space station. Whether you want less or more then there is on earth space stations can easily get it. You can create your crystals in zero G and then fly them to a earth-like pseudo gravity to give them to mice for animal testing. When it comes to your wider argument I don't see an articulated reason for why we should go to the moon. You didn't lay out anything that space stations can't provide. This is not articulated, but from other reading I have done on the subject the argument is this: It is well understood that space stations provide most of the value. The significance of a moon base is that it makes the intermediate work of constructing multiple space stations more efficient, especially when it is built for that purpose. Traffic between the moon and a space station, or space station construction site, is much cheaper than between the earth and those sites. Plausible advantages include: • Helium-3 for a fuel and/or energy source • Depot for storing fuel, equipment, and supplies in bulk • Warehousing for stockpiling extracted resources or manufactured products • Basing for space-drones which mine asteroids, build space stations, etc. Traffic between the moon and a space station, or space station construction site, is much cheaper than between the earth and those sites. Other than delta-v, I don't see any reason to think that. However, to exploit even that advantage, you'd have to build the space station on the moon using local materials in bulk. This is at least as hard as colonizing the moon since space stations require lots of high-tech manufacturing to produce, whereas colonization just requires air, water, food and construction materials in bulk which are much lower-tech. Helium-3 for a fuel and/or energy source He-3 fusion is way harder (higher Coulomb-barrier) than D-T fusion which itself hasn't been cracked. The only advantage Helium-3 provides over Deuterium-Tritium is aneutronicity, which doesn't matter if you're just building a power plant. Aneutronicity is only important if you want to use direct thrust from the fusion products to propel your spacecraft, and at that sort of tech level it's better to mine He-3 from the gas giants which have way more supply. Depot for storing fuel, equipment, and supplies in bulk Where do those fuel, equipment and supplies come from? If they come from Earth, there are no delta-v savings. If they come from the moon itself, the argument becomes circular. I've long thought homesteading was an attractive idea. Free launch costs to anyone with a business plan. Heavily subsidized grub stakes: standard living quarters, food, raw materials, tools, etc. A core assumption is that we mudfeet will lack the motivation, experience, and insight to solve all the problems pre-emptively. Colonists will find problems and solutions we can't even dream off. Setting priorities must be left to those who will live with the consequences. But here's the rub: mated pairs only, the ladies expected to bear their first child within, say, 18 months. And, key point: No return ticket. The Up and Out is your home for the rest of your life. Expect a steep learning curve and heavy losses for the first two or three generations. This doesn't really address my basic question, which is why the government or private sector would want to sink the necessary funds into setting up such a project. Government: Ask Kennedy Private sector: Ask Musk There’s also disagreement about the efficacy of using Luna as a refueling stop, so to speak, en route to the Red Planet. From an orbital mechanics standpoint, it’s not a slam-dunk idea, but the argument in practice depends heavily on the specific logistics. In-situ fuel production might just make such a configuration worth it. I think it's pretty much a slam-dunk that refueling on the moon is a bad idea. Adding lots of complexity (thus failure points) and the cost of establishing the necessary infrastructure for what can be accomplished by a few re-fueling trips in LEO seems unnecessary, especially considering it's not even the right fuel. And if you're talking about expendable rockets, well, Robert Zubrin has done detailed analysis on why refueling on the moon is utterly counterproductive and Mars Direct is better. delta-v ≠ money saved. While Mars is obviously the more attractive target for colonization, we are a very long way from building colonies on other celestial bodies, no matter how good of an idea it is. Very much disagree on space colonies as hedge against human extinction. I could write a more detailed critique, but the bottom line is there is no x-risk severe enough to wipe out all (not merely 99.999%) humans on Earth but at the same time not severe enough to also wipe out all moon/Mars colonies. The reason is very simple: space colonization is an unspeakably expensive proposition. Not necessarily. Senate-run space program is definitely an unspeakably expensive proposition, though. I have yet to think of an economic need which a self-sustaining population on Mars would fulfill, that innovative strategies could not fulfill on Earth. Farming food on Mars? We can do hydroponics here. Running out of room to house people? We’re nowhere near that kind of population density. New legal environments to test out social engineering concepts? Seasteads and charter cities are way safer and less expensive. Climate change? Just tax carbon and build nuclear power plants, sheesh. Agreed, except the part about sea-steading. Staying home is even more safe and less expensive. Put in a less tongue-in-cheek way: The difficulty of reaching Mars is why a Mars colony has a chance to become an independent civilization in the first place. Sending supplies to Mars is so difficult that the colonists would be better off building up their own supply chains in the long term for anything but the most value-dense equipment like microprocessors. The same isn't true for a sea-stead; sure you could in theory build your own economy, but realistically you'll just end up importing everything because it's easy, become heavily reliant on the outside world and be independent in name only. You're also within reach of any tax-collecting naval power of the world. No one will front the money to build Mars colonies until there’s an economic incentive to do so. I see no such economic incentive. I would love to be wrong about this, because Mars is the best colonization target by far. But I don’t think I am. Depends on what amount you're talking about. If it's <$100 billion mere prestige would be enough incentive, otherwise Apollo could have never happened.

As the people of Earth demand an increasingly high standard of living and simultaneously a cleaner environment, I suspect that this may prove to be the ultimate driver of off-world industrialization. Again, though, speculation.

Very far-fetched argument. To relocate the vast amount of industry required to make a significant positive impact on the environment, you'd need to lower launch costs close to maritime shipping costs today. And at that point, supplying off-world colonies would be just as easy.

Critically, space industrialization is different from space colonization. Developing an off-world economy is a pre-requisite for seeing a large, permanent population above the atmosphere.

A dubious conclusion. Do you propose relocating entire supply chains off-world, or just small bits? If it's the former, it's no easier than founding a self-sufficient colony. If it's the latter, it's not worth it due to exorbitant transportation costs back and forth from Earth.

Governments may choose to pay for scientific missions to other planets; they will not front the costs of developing entire planets quite literally from the ground up. Whatever outputs space agencies may build, they will not be colonies.

colony ≠ terraforming

People won’t live there, the way that human populations have whenever establishing themselves in a new locality. There won’t be families and new businesses and the like, not for a long time.
Instead, we’re probably going to see many largely-automated operations, with minimal and possibly intermittent human presence.

I think you're seriously overestimating the capability of robots. Compare what the Apollo astronauts were able to do on the moon and what Mars rovers have done.

As we push towards human settlement in space, our focus should therefore be the development of new industries and new technologies to enable and motivate working above the atmosphere.

This sounds like a call to action, but if human settlement in space was profitable, it would happen anyway? Also, who's "we"?

One day, our species will span three worlds. That day remains very far away. Rather than fixate on terraforming dreams, we should chart a course carried by the currents of economic necessity. With the correct regulatory environment and technological investments, we can begin building sustainable off-world industries in a realistic timescale. Such industries will carry us to the planets in the pursuit of profit—a far more reliable motivator than any humanitarian spirit from politicians.
That, I suspect, is what the future of space travel is going to come down to. Do we pursue an incremental strategy that eventually carries us to the ends of the Solar System, or do we wallow on this one planet, fantasizing of an amazing future no one has any incentive to hand us? Are we going to fixate on self-sustained colonies and settle for nothing less, or shall we go to Luna first, but not to live there?

Again, colony ≠ terraforming, and again, curious to hear your thoughts on why Mars Direct/Elon Musk's plan won't pan out. In any case, whatever your vision for future human space exploration is exactly, the only thing that matters right now is lowering launch costs.

Very much disagree on space colonies as hedge against human extinction. I could write a more detailed critique, but the bottom line is there is no x-risk severe enough to wipe out all (not merely 99.999%) humans on Earth but at the same time not severe enough to also wipe out all moon/Mars colonies.

I think this is a good point. Civilization may eventually recover from some catastrophic risks (e.g. nuclear war). And some risks are so severe that even Mars would not be safe (e.g. UFAI).

But are there no risks that could wipe out humanity on Earth that wouldn't also kill a Mars colony? A comet impacting the Earth might be at the right scale for that. Or maybe a runaway greenhouse effect triggered by our carbon emissions.

And what do you think about using space colonies as a hedge against the collapse of civilization (rather than extinction)?

But are there no risks that could wipe out humanity on Earth that wouldn't also kill a Mars colony? A comet impacting the Earth might be at the right scale for that. Or maybe a runaway greenhouse effect triggered by our carbon emissions.

I have thought about both scenarios and, no, I don't think either is plausible. I find natural x-risks not worth defending against in general due to their unlikelihood and lack of severity. If a planet allows complex but non-technological life to exist for hundreds of millions of years, it has nothing to throw at us in the next few hundred years.

Regarding meteor impact specifically, I think a comet would have to be significantly bigger than the one that caused the Chicxulub crater and failed to wipe out the dinosaurs. Birds are not close cousins of dinosaurs, they are the direct descendants; and had that meteor missed the Earth, dinosaurs would likely have evolved into something that looks very different than what walked the Earth 65 million years ago anyway, just like how we look very different to early mammals.

We, like the dinosaurs, are spread all over the Earth across every climate zone. Unlike the dinosaurs, we have technology at our disposal from stone tools to computers. Even the ruins of our civilization will provide many useful tools to ensure the survival of at least the tiniest fraction of humanity. I believe we are far more resilient than dinosaurs which again, survived the Chicxulub impact.

Since the distribution of meteor sizes follows a power law, it's unlikely for Earth to encounter a comet/asteroid large enough to wipe out humanity outright until the sun becomes a Red Giant, let alone the next few centuries.

But if we were to hedge against such an impact, the most cost-effective way would be to create large underground bunkers with infrastructure and industry to keep a small isolated civilization running indefinitely. If we can build a self-sufficient colony on Mars, we sure as hell could do it on Earth.

Regarding runaway greenhouse effect, we have geological records testifying CO2 concentrations above 1000 ppm in the Cretaceous period which didn't cause a runaway greenhouse, and I expect climate catastrophes to limit our ability to pump more CO2 into the atmosphere well before then through regional economic collapse. Since it's a gradual process, there is also time for negative feedback like plant growth to kick in, and for drastic geoengineering efforts such as deliberately setting off a nuclear winter.

My favorite example of a one-planet x-risk (at first glance) is a microscopic black hole swallowing the Earth. Since a black hole with Earth's mass would follow the same orbit, you'd think it won't have any effect on the rest of the solar system. (Un)fortunately, there is 1) no physics grounding for the thesis that such a black hole would be stable and 2) the energy released in such an event would be akin to setting off a supernova inside the solar system and nuking everything from here to Pluto.

Finally, I'm not sure what you mean by "hedging against the collapse of civilization". A Mars colony doesn't stop civilization from collapsing on Earth. It would help avoid a delay in technological progress, but in the long run a delay of a few centuries is of no particular importance.

Another important benefit of our moon's closeness is the short ping. We still don't have an AGI we can send to industrialize other planets, but I do think we are at point where we can do remote controlled industry where humans don't have to be at the site but still need to monitor and manage everything. Even if it's not commercialized yet, the technological frontier is already there - think Boston Dynamics showcase robots with humans telling them what to do doing the work of human workers in a mostly automated modern factory.

If we do this on the moon, communication round trip is just a few seconds (between 2.4 and 2.7, but maybe we'll need to route it via some satellites so let's round it up to 3 seconds). Not instant feedback, but good enough to be effective. Mars, on the other hand, has a ping of between 6 and 44 minutes - which is much harder to work with.

Imagine a robot doing something wrong in a martian factory. The control center on Earth will see it after 3 minutes at best - and by that time the robot proceeded with its wrong actions, doing 3 minutes worth of damage. The humans send the command to stop - which arrives after 3 more minutes of damage. On the moon, on the other hand, that's only 3 seconds of damage (not counting the humans' reaction time) which is much better.

Space travel is largely impractical with current tech. There are technologies which would make space travel practical. So humans will stay on earth and research until we find those technologies.

Suppose that sooner or later we get supersmart AI. The AI will spread out at near light speed. whether or not we have a fledgling Mars colony by this point is largely irrelevant.

Could tourism become an economic engine of the space colonisation? For example, Moon has 6 times lower gravity and this allows new types of sport. Older people can jump again there!

The important question isn't the desirability of going, but the costs of getting there. Space tourism at it currently stands means paying at least \$20 million, going through a condensed astronaut training program (and passing), and then spending around ten days in low Earth orbit. Unsurprisingly, only a handful of extremely rich individuals have paid that much.

Lunar surface tourism would be considerably more expensive. Building a small space station in low Earth orbit where tourists can experience weightlessness for an extended period would probably pay off better. Right now, we're still waiting for suborbital hops.

There's another cost, as well: the same age that makes low gravity attractive also makes a rocket launches precarious. (Sure, if we had a space elevator, that wouldn't matter, but if we had the technology and funding to build a space elevator I wouldn't have written this post.) Not coincidentally, a lot of astronauts retire in their 50s or early 60s. I don't know how much this would depress the demand, but it would certainly depress it some, and also raise the legal and operational costs to prevent liability.

Tourism might be a big market once the infrastructure is there, but I'm not sure how well it will serve to fund the infrastructure and technology development itself. As with the other potential markets I mentioned, whether we would like to do it has relatively little bearing on whether there's sufficient willingness-to-pay such that we actually can do it.

If Musk's Starship will work, it will lower price of Moon tourism. If a launch will cost 1.5 mln USD and there will be 100 people on board, it means 15k a person for a ticket.

You need more then one launch to get to the moon with Starship as it's designed. It needs refulling in between.

Even when it costs 15k to low-earth orbit you might pay 100k to the moon.

There are more than 1 million households in US which have 10 mln usd capitalisation, and they could afford such travel without damaging their wealth. No all will go, but may be a 10 thousand a year will. This gives 1 billion a year for tickets and they will spend at least the same amount on the Moon. So it is 2 billion dollar a year tourist economy. Not much.

OP addresses space tourism in the post.