[tsimionescu]

Those are all ways to squander the Earth's limited resources while sounding forward thinking. Colonizing Mars will likely never happen, there is simply no upside: huge challenges, with no interesting resources. The Earth has plenty of space, we're limited by resources, and there are no interesting resources on Mars. I wouldn't be surprised to find out that we'll have a colony outside the solar system before a colony on Mars.

Asteroid mining is more plausible, but still extremely unlikely given our current technology. There are massive hurdles, and few things that would massively improve life on Earth - it's much more interesting from a profit perspective than a future of humanity perspective.

[__d]

Musk's motivation, which he has expressed repeatedly, is to make humanity resilient to an event that makes Earth uninhabitable.

Whatever that event might be (asteroid impact, nuclear war, environmental catastrophe, plague, whatever), I think the idea of having a second site of human habitation is not an unreasonable goal.

Which is not, as has sometimes been stated, "giving up on Earth and the rich moving to Mars" -- it's just an insurance policy.

The resources expended to achieve this are tiny. It's not a lot of money, and the consumables are ... literally drops in the ocean.

That's not to say that there aren't other problems that could be addressed using that money, but it's not really a question of either/or: humanity could very easily do both, should it choose to do so. It's just that Musk chooses to focus on this problem, and its solution. We're all certainly free to make a different choice ...

[tsimionescu]

Mars is already uninhabitable, so what would we gain from moving to Mars? The Earth is not going to become as bad as Mars with any possible disaster smaller than a planetary collision.

Also, a Mars colony that could survive indefinitely if the Earth is wiped out is almost certainly impossible, given the extreme conditions on Mars' surface. We don't even know if there is enough water ice on Mars today to sustain a human city, nevermind the huge network of cities that would be required to produce all high tech products on Mars. Also, with no fossil fuels, it's very unlikely that you could launch rockets from a Mars colony entirely cut off from the Earth.

Then, you'll also be missing nitrogen, and probably a lot of other nutrients. Oxygen will be in short supply, as will Helium. And remember, every time you leak water or other gases into the atmosphere, you've likely lost them forever, since there is no closed cycle of water on Mars, and solar winds are constantly stripping away Mars' atmosphere.

Also, the cost of building a self sustaining colony on Mars is well above the GDP of the world many times over. It would be many times easier to establish a second global trade network on Earth, completely isolated from any existing trade hub. Imagine building chip fabs and growing enough crops for food and bioplastics in Antarctica, and now remeber that on Mars it's much colder, there is virtually no air, and you have to dig tunnels everwhere, since any sort of prolonged exposure to the surface would irradiate you. Oh, and make sure you do this without any dependence on fossil fuels, except perhaps a few tons every few months.

[skissane]

> Also, a Mars colony that could survive indefinitely if the Earth is wiped out is almost certainly impossible, given the extreme conditions on Mars' surface.

Let's say you have a Martian colony of 100,000 people. It is self-sufficient in basic goods but still relies on imports from Earth for many advanced goods. Something terrible happens, and imports from Earth are no longer possible. Those 100,000 people have a choice – find a way to make do with what they have, or die. I don't think we should underestimate human ingenuity in such circumstances. They'll lose access to a lot of highly advanced goods – for example, they probably won't have their own leading-edge semiconductor fabs – but they may be able to survive without them, using more basic goods to take their place.

> Then, you'll also be missing nitrogen

The atmosphere of Mars is around 2.8% nitrogen. There are likely to also be nitrate minerals in the Martian soil and rock.

> Oxygen will be in short supply

Mars' atmosphere is 95% CO2. You can extract oxygen from CO2 by electrolysis. The MOXIE experiment on Perseverance has demonstrated this.

> and solar winds are constantly stripping away Mars' atmosphere

On human timescales (decades to millennia), Martian atmosphere lost to space isn't significant.

> Also, the cost of building a self sustaining colony on Mars is well above the GDP of the world many times over

I think Musk is going to try to establish a settlement on Mars, initially with tens of people, then hundreds, then thousands. And becoming fully self-sustaining is going to be their long-term goal. But I don't think actual full self-sustaining status is going to be achieved for several centuries.

[tsimionescu]

> Those 100,000 people have a choice – find a way to make do with what they have, or die. I don't think we should underestimate human ingenuity in such circumstances. They'll lose access to a lot of highly advanced goods – for example, they probably won't have their own leading-edge semiconductor fabs – but they may be able to survive without them, using more basic goods to take their place.

The answer will be die. There is no way to survive on Mars for any period of time without access to high technology, you will be dependent on it for electricity, for water, for farming, for pressurized ventilation, for air recirculation, for robots that can work on the surface (e.g. To keep solar panels clean, or for any kind of construction on the surface), to dig tunnels through rock to expand as resources dry up, and to produce the majority of the more basic goods you need. 100k people is very little for a functioning isolated economy on Earth, on Mars it would be much more complicated.

> The atmosphere of Mars is around 2.8% nitrogen. There are likely to also be nitrate minerals in the Martian soil and rock.

The much denser atmosphere ON earth is 78% nitrogen (see also my next point for a comparison), there is plenty of nitrogen accumulated in the soil, and still it is one of the major factors limiting plant growth. Any nitrite deposits on Mars are likely to be contaminated with other toxic chemicals, like much of the Martian soil and probably much of the water ice.

> Mars' atmosphere is 95% CO2. You can extract oxygen from CO2 by electrolysis. The MOXIE experiment on Perseverance has demonstrated this.

O2 is about 21% of the Earth's atmosphere. Mars's atmosphere is less than 0.6% of the Earth's atmosphere, even at the ridiculously low Martian surface temperatures. So even if you can convert CO2 to O2 with 100% efficiency, and even if Mars' atmosphere were 100% CO2, you would still only get 0.02 times the O2 you have on Earth.

This is extremely relevant not only for breathing, but because the only kinds of batteries we can imagine that have anything close to the power efficiency (Wh/kg) of fossil fuels utilize atmospheric oxygen to get most of the power.

> On human timescales (decades to millennia), Martian atmosphere lost to space isn't significant.

Fair enough, but it's still going to be impossible to recover water or helium or other gases we leak from Mars' rarefied atmosphere.

> I think Musk is going to try to establish a settlement on Mars, initially with tens of people, then hundreds, then thousands. And becoming fully self-sustaining is going to be their long-term goal. But I don't think actual full self-sustaining status is going to be achieved for several centuries.

I don't believe Musk will achieve anything more than tragically killing some volunteers on Mars. I also don't think a permanent self sustaining colony on Mars is actually possible or even desirable, for all of the reasons I listed, with any kind of foreseeable future tech (of course, paradigm changes in physics or chemistry could have completely unpredictable effects).

Edit to add: it's also important to remember that we do not know if humans can actually survive long term in 0.3g, or with what impact on their health. This will have to be tested on animals for years before actually attempting a human base.

[AngryData]

Humans surviving long term off of Earth, I think, is still just a pipe dream and pure sci-fi. I agree with the idea, I think it is something humanity should attempt, but it is atleast 100 years too soon to even attempt.

It is like trying to build a space station in the 18th or 19th century.

[skissane]

What's wrong with trying now? (By "now" I mean, "in the next 20 years".) So long as nobody gets killed, if it fails, at least we can say we've tried. Trying now may bring forward the date at which it is actually feasible compared to putting off trying.

Even if people die–and they may–if they make a free and fully informed choice to sign up to something which may risk their lives, and they end up dying as a result – wasn't it their right to take that risk? There are a lot of people out there, who will view being one of the first humans to attempt to live on another planet something worth risking death for.

[tsimionescu]

The problem is that it's a massive waste of resources, in terms of fossil fuels, production capacity, engineering talent, research talent. There are much more pressing and likely to be fruitful avenues of exploration. Launch or build telescopes to explore space, and engineer green energy and carbon capture solutions on Earth.

[relativ575]

> The Earth has plenty of space, we're limited by resources, and there are no interesting resources on Mars

There are new discoveries on Earth even today, after hundreds of thousands year of mankind history. What make you think we have known all we need to know about Mars?

> I wouldn't be surprised to find out that we'll have a colony outside the solar system before a colony on Mars.

Mars is a 8 month journey. Alpha Centauri, the nearest star, is a 296,000 year journey using the current propulsion technology. We'll have colonized every single colonizable planets in the Solar System before then.

> it's much more interesting from a profit perspective than a future of humanity perspective.

Future of humanity depends on advance in science. Space exploration has always been a major force that drives science forward, asteroid mining included. So many examples to list, but just to pick one:

https://astronomy.com/magazine/ask-astro/2019/06/how-do-scie...

[tsimionescu]

> Mars is a 8 month journey. Alpha Centauri, the nearest star, is a 296,000 year journey using the current propulsion technology. We'll have colonized every single colonizable planets in the Solar System before then.

Sure, but there is nothing on Mars. We have no reason to colonize places that lack even the basic resources necessary for life, or some precious resources that are scarce on Earth. At least with a different star system, you can imagine that in some far flung future we may need to escape the expansion of the Sun (though assuming humanity survives for some billions of years is indeed unlikely).

> Future of humanity depends on advance in science. Space exploration has always been a major force that drives science forward, asteroid mining included. So many examples to list, but just to pick one:

I'm not sure what the article was supposed to show, is spectroscopy a technology invented as part of the space program?

It's true that a product of the spave program are advanced materials and other factors that can be re-used on the Earth. But this is more a question of the vast resources which were invested in the space race, which could as well have been invested in Earth programs and would have likely yielded similar results.

Teh most valuable results of the space programs have been communications satellites and things like the hubble space telescope - which has done far more for scientific space exploration than the entire Apollo program, as have the Voyager probes, Mars rover etc.

Manned space exploration may still serve an inspirational purpose, though. I absolutely admit that the social and inspirational impact of seeing a human on the Moon/Mars/in outer space is hard to beat.

[relativ575]

> Sure, but there is nothing on Mars. We have no reason to colonize places that lack even the basic resources necessary for life, or some precious resources that are scarce on Earth

You don't know what Mars can offer. Not without extensive exploration that can only be done effectively with human presence. We still don't fully understand Earth.

Human once couldn't survive on the desert. We might still not if we never explored it in the first place. Technologies or knowledge we take for granted today may never exist either. The same will happen with Mars. I don't know what the future hold thousands years from now. We may have terraformed it, human body may have adapted to Mars environment, or we may have found it indeed not suitable. We'll however have permanent presence on Mars, and we'll make major leap in science and technologies thanks to Mars exploration.

> I'm not sure what the article was supposed to show, is spectroscopy a technology invented as part of the space program?

You wondered the role of space exploration in the future of humanity. I reckon that our future lies in the advance of science. Spectroscopy would be much less developed without its application in astronomy.

> Teh most valuable results of the space programs have been communications satellites and things like the hubble space telescope - which has done far more for scientific space exploration than the entire Apollo program, as have the Voyager probes, Mars rover etc.

I'm not sure what points you're trying to make it here? some programs have more short term return than others? We are doing both, right? not only that, investment for something like communication satellite dwarf that for outer space programs.

[AngryData]

What is the benefit of living on Mars, rather than a space based habitat that can attach to and mine asteroids or small moons for extra resources? Living in a "large" gravity well seems like all negatives to me in terms of expansion and resource extraction.

[tsimionescu]

To be fair, living in 0g is even less plausible than living in 0.3g long term. In particular, there is a good chance that animals can't reproduce in 0g - those that have been tried have definitely been unable (including insects and chicken - there is still a chance mammals could).

[AngryData]

You can spin for artificial gravity out in space though, which would be relatively simple to do provided you had any sort of space manufacturing capabilities.

[tsimionescu]

It's not actually simple at all. You need a massive station to actually spin in such a way that humans don't get dizzy just by crouching (you need the acceleration to be almost constant for the ~1.5m difference between a person lying down and a person standing up). You also require lots of fuel to actually maintain this constant acceleration. The larger everything is, the more problems you have with shielding and energy expenditure. Any malfunction of the spinning mechanism is likely to be catastrophic, as suddenly losing 'gravity' is can easily cause massive damage if people are living without care for this constant possibility.

Not to mention, this would not feel like living on Earth - there are many effects of spinning that do not approximate gravity well, such as the fact that forces acting on you depend on the direction of your movement relative to the direction of spin.