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Comment by ClumsyPilot | Hacker News Reader

The entire point of construction in space is to avoid launching from earth. It takes 36 times less energy to get a ton of material from moon surface, and can be done without rockets at all - a space elevator can be built on the moon with 'normal' materials.

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> The entire point of construction in space is to avoid launching from earth

This is true, but avoiding launching from earth could be done for one of two reasons:

(1) to increase the efficiency of what can be built

(2) to increase the possibility of what can be built

Your point is (1), and I agree with it. The point mentioned above is (2) — even if all the materials for the ISS were from earth, it still could not be constructed on earth and then launched as a whole, and so construction in space is viable.

It would still be a good stepping stone to complete off-world industry; one of the reasons current space launches cost a lot is because you don't only want things in orbit but you want something in orbit intact and functional. A pallet of dumb steel ingots could be lopped up with something with much more generous tolerances ala the Big Dumb Booster[0], with any orbital maneuvering once up there accomplished by space tugs.

[0]https://en.wikipedia.org/wiki/Big_dumb_booster

Why is Elon Musk aiming for Mars if building a solar panel array and all of the subsequent manufacturing industry on the moon could potentially be way more productive?

Is there something I am missing?

Musk has been talking more and more about the moon lately. Maybe he's thinking the same.

The fact that NASA has a clear directive to spend an absolutely humongous amount of money on the moon over a relatively short time frame may have something to do with Elon Musk's interest.

US military uses quite a ridiculously larger amount yearly. Nasa budget for going to the moon is insignificant compared to what is spent on war.

False dichotomy. Military budget that can be spent on Elon’s business is probably less than what NASA is prepared to spend on a proven Earth-Moon-Earth service.

It's not a perfect false dichotomy, between people getting to keep their wealth and all of the things it could be spent on, there actually is a sum that has to balance to zero.

Robert Zubrin argued that Mars has more lightweight bulk resources (water, carbon dioxide) twenty years ago, and at the time the moon was thought to be barren of such resources that are useful for starting a human colony.

Recently (in the last decade) water has been discovered on the moon, frozen in areas of cold permanent shadow in craters.

Also the current US vice president wants to go to the Moon. The previous president wanted to go to Mars.

Mars is a more hospitable, Earth-like environment for humans. It has an atmosphere, a normal-length day-night cycle, less extremes of temperature, and closer to normal gravity.

Mars and the moon both have pros and cons. Mars would be an easier place to survive, but the moon is easier to get to.

"Mars would be an easier place to survive, but the moon is easier to get to. "

Since it takes 6 months to get to mars and only 3 days to the moon and the only advantage for surviving on mars is the mini gravity, I really think we should start with the moon.

It's not just the gravity. On the moon, you have to deal with 2 weeks of day and 2 weeks of night, which means having to deal with wide temperature swings and if you rely on solar you need very large batteries.

Mars also has an atmosphere which contains CO2, which is useful for making methane. It also has a lot of water. (The moon has water too, though it may be less abundant/accessible.)

Could some of those downsides be mitigated by putting your base on a "pole"?

That is, are there locations on the Moon's surface where the sun is perpetually visible?

There are just a few crater rims where this happens, not the full pole - but those do indeed get sunn almost all the time & border areas in perpetual darkness, which is also pretty useful (cryogenics, temperature gradient, etc.).

Sort of; there are some spots that get sunlight almost all the time. (The moon has quite a bit of wobble, so it's hard to get to 100%.) That greatly restricts your choice of base locations, though. There may be other resources or geological features you might want to be close to that aren't convenient (lava tubes, water deposits, flat places to land, minerals that can be used as building materials, etc...).

I suppose if our base is extensive enough, we could use those locations primarily for power generation and then transmit that power to more desirable locations for other tasks. Though I do realize that I'm talking about a lot of effort/time/money/resources.

Day and night cycle is an issue yes, and sure, for a long term self sustainable settlement, mars looks much better.

But in terms of setting up a base soon and building rockets for example ... the very short travel distance to the moon offsets any advantage the mars has

The habitability difference is not relevant at this stage - both will kill you instantly. The ISS orbit has no atmosphere or gravity, but it's easier to keep people alive there than on Mars.

For a Moon base locations, look up peaks of eternal sunlight. We also have space-grade nuclear reactors and RTGs ready to go.

On the Moon you can have realtime communication, bring way more equipment, have robots remotely controlled from Earth, and get help or evacuate quickly. NASA and China will be able to land people on the Moon, other nations can get rovers/supplies there.

Anything goes wrong on Mars - you are dead. I would pick Moon any day.

Mars has more resources available to work with and is a less extreme environment than the moon or space. There's definitely a trade-off between quick and easy access to the moon versus an easier environment to work with.

No one can survive in any of these places without a space suit, but on Mars you have easier access to the various natural resources you'd need in order to survive and build additional infrastructure. Light for solar power is consistently available on a normal day/night cycle, as is CO2 and water, which can be used to make methane fuel and liquid oxygen. It has concentrations of sulfur, which can be used to make a form of concrete. The gravity is more conducive to long term human health. All this is relevant.

Surviving on the moon or in LEO is also quite possible, it's just that you'd need to bring more equipment and all the resources you can't find on-site.

Mars is absolutely a better place to live, it's an actual planet.

But for industrial hub, the fact that we have the moon is an absolute miracle. We can build and refuel ships that dwarf our current ones. And we will need moon based factories if we are to make any meaningful progress is settling the solar system. The only things that should ever be lifted off earth is People/ other life, and super high-tech goods like microchips.

The Moon is also close enough to Earth that you can get help, or go back in case you suddenly need surgery. Good luck with that on Mars.

Settling Mars with our current ships is like settling Australia with a canoe.

Indeed, yet there are various challenges inherent to Moon colonization, such as continuous direct surface impacts due to no atmosphere, extreme temperature surface environment due to 14 day days, lack of various elements (such as carbon or nitrogen), etc.

Still super useful & the short distance overrides much of the downsides.

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