A rough guide for going back to the Moon

Unless humanity goes extinct in the near future this is certainly inaccurate.

People don't realize how rapidly fertility affects populations. Take a place with a fertility rate of 1. That means each successive generation (which tends to be about 20 years, or the the window of fertility for a gen - from age ~20 to ~40) will decrease in size by half, in a compounding fashion. So over 1 century, that's a 97% decline (0.5^5) in generational size. Extinction comes shockingly fast.

But the opposite is also true. So what's going to happen is that low fertility populations are simply going to go extinct. That's going to be just lovely for humanity as it also corresponds with higher income, higher education, higher liberalism, higher secularism, and so on. And the current high fertility groups will come to quickly dominate the world. So it's kind of amusing in a way that Biblical texts will indeed come to pass - you'll have groups like Amish or Haredi, the meek - who happen to have high fertility rates, indeed inheriting the Earth.

This is part of the reason fertility is, by far, the biggest crisis facing humanity today. All love to the Amish and Haredi, but I don't want the Earth to turn into a planet of overalls and sidelocks. Even that would probably be just liminal, but we need some sort of high tech, high intelligence, high fertility sect to emerge. It's probably going to require something to akin to a modern religion, though presumably without a deity. Or maybe the Mormons had it right all along.

> "ever" and "effectively infinite" are obviously exaggerations

I see no exaggeration, obvious or otherwise. Scientific consensus is that mankind's population is going to peak in the next century.

> mankind already needs more land than Earth has

By what basis? There's no shortage of land. There's a shortage of land close to popular population centers, and that tends to be the land that people want to live on most. But that's an inherent geometric and social problem which outer space definitely doesn't solve, in fact it makes it worse.

> more energy than Earth can spare

Earth doesn't provide energy, the sun does. Even fossil fuels, biomass and wind power were all originally energy from the sun. The exception is nuclear - Earth does have an unusually high concentration of heavily elements like uranium and plutonium.

The bottleneck has always been development and delivery, not availability of energy itself. On just the land the US currently uses to grow corn for ethanol gasoline, we could build enough solar panels to power the entire US. And I certainly don't need to tell you about nuclear - the only reason entire civilizations aren't already powered by it is the time and expense and risk of building the plants.

What energy does outer space provide? You have solar, which we have here, and nuclear, which we have here. (You also have a variety of ideas that exist in science fiction but not the real world, like dyson spheres - I surely hope you aren't referring to such as the basis of your arguments.) None of this is new, and none of this solves the problems of development and delivery, in fact it makes both problems significantly worse.

First Lunar flyby, first Lunar probe landing, first photos from surface, first Lunar rover - all Soviets.

Crewed landing is a massive achievement, but it being the finish line of the race is the US framing, primarily due to getting beaten in all other firsts.

According to [0], there's about 2% water by volume in Martian soil, and you need to heat it up to 800 degrees Celsius to extract it -- which means you need a power source capable of generating those temperatures on an ongoing basis, which is unlikely without massive solar arrays that would be constant covered with (and damaged by) Martian regolith. Oh, and Mars receives less than half the sunlight Earth does due to its greater distance from the sun, and dust storms could obscure them for weeks on end.

Or you could use hypothetical a nuclear power power plant that would be incredibly expensive to build, ship, run and maintain on a foreign planet.

You were right about the radiation! Kind of. There's "only" 50x more radiation on Mars' surface than on Earth's. You said this was less than what astronauts on the ISS are exposed to. How is that a meaningful comparison? You're talking about people living their entire lives in this environment, and presumably making babies who grow into adolescents and adults, all the while threatened by an amount of radiation we have no idea if a human child could live through.

The atmosphere on Mars is so thin that exposure to it will kill you. The level of radiation is so high that exposure to it will kill you, unless you lived essentially your entire life underground or in a bunker. The cold temperatures will kill you. The soil has perchlorate in concentrations that will kill you. There's basically nothing to do there -- no walks outside without a space suit, no nature to look at, no living beings (except perhaps soil microbes that would be instantly destroyed in the process of extracting water) -- nothing more available there than here on Earth except looking at the stars and dying. [1]

Every argument I've seen people make for colonizing Mars in the near term has been emotional. The arguments are all the more emotional for insisting that they are rational. We have no idea if we could grow food in a closed system indefinitely, or reproduce in space or on another planet, and the amount of research going into these literally existential questions is close to zero. Nor do the billionaires who claim to be obsessed with getting us to be a multi-planet civilization seem to give a shit about them. Colonizing Mars isn't a plan; it's a meme.

Finally, there's no thought given to how to deal with inevitable social problems that will arise if there are large (1000+) populations away from Earth: what to do with people who have psychological breakdowns? how do you prioritize if more people need to be sent home than there's space for on a return rocket? what are your responsibilities toward colonists who need expensive permanent care? what if they can't survive Earth's gravity due to physiological changes from growing up off-planet? What if an entire space colony will never be self-sustaining and they need to be supported with expensive shipments of food and supplies from Earth forever -- who will pay? Or will we?

Look, if you want to colonize Mars or other planets because you think it's a cool thing to do, at least that's an honest, personal opinion. But if you think putting a ton of resources into going to Mars anytime soon is a good investment -- when we aren't even mitigating an ongoing climate disaster here on Earth, the one environment to which we are exquisitely adapted and which is non-existent literally anywhere else in the known universe -- then you are fooling yourself.

[0] https://www.theguardian.com/science/2013/sep/26/nasa-curiosi...

[1] https://en.wikipedia.org/wiki/Mars