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The basic idea is to not have all your eggs in one basket. We are one asteroid strike away from losing all human life on earth. Having 2 habited planets spreads the risk. Obviously having those planets in different solar systems would be even better, but we don’t have the technology for that, yet.

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You're presenting a false dichotomy. Our options aren't only (a) live only on Earth, and (b) live on Earth and Mars and potentially other planets. There is, for example, (c) live in man-made structures orbiting the sun at a distance of 1AU, which is debatedly much more sensible than trying to live on Mars.

Hmm. With Starship's lifting capacity, that might become a side project. Maybe they could even sling something to become part of the orbital station and continue to Mars

How many tons would you need to get out of the gravity well before you had enough orbital manufacturing capacity to begin building that sort of thing? I mean, I love the dream, but I don't know how you can make it a reality.

In the video Elon makes an estimate of a million tons to Mars (if I remember correctly) in order to establish an entirely self-sufficient colony there. Building orbital manufacturing would be a different kind of problem, but in some respects it's kind of similar. I suspect it'll make sense to establish a foothold on Mars first (which has a lot of necessary resources and less gravity means you can transition from the planet to orbit much more cheaply) and then maybe use Phobos and/or Deimos as manufacturing hubs for space-based hardware like habitats. Or maybe it makes sense in the short term (before Mars has the necessary infrastructure for big projects) to do manufacturing on the moon.

That's true, but there is no fuel source out in space. Outside of Earth orbit, eg Lagrange points, you need fuel deliveries.

On Mars they can make methane with the Sabatier process.

So you have:

- LEO/MEO - vulnerable to asteroid impact ejecta

- GEO/moon/L-points - avoid ejecta, but need regular refueling. If Earth is toast, there goes resupply

- Mars - close enough to the sun for solar, able to conceivably bootstrap in a few centuries

Actually there is fuel in space - water and sunlight.

You can split water into hydrogen and oxygen using electricity from sunlight.

In long term, most likely both Hydrolox and Methalox will be in use.

I think the parent comment meant to say there is no propellant in space.

There are comets in space, so there is water and water can be made into propellant.

Ceres also seems to have a lot of water: https://astronomy.com/news/2020/08/ceres-an-ocean-world-in-t...

Solar sails can get you to anywhere in the Solar system. Not very fast, but essentially free. So a swarm of drone ships with solar sails can transport an almost infinite amount of propellant to your refueling bases from mining sites.

It is much easier to get protected from radiation on mars, than in the outer space. Nobody knows for certain how would childbirth look like in zero g and it's just the one of many problems. Mars is much more hospitable than pure vacuum.

By building underground structures?

Technically, every structure encapsulating space makes that space "underground" - the distinction between natural rocks or poured concrete as a ceiling is negligible when it comes to radiation protection. Whenever we set up a sunshade, we are protecting ourselves from harmful radiation.

Putting more material between you and radiation by burying into the ground is a good idea, especially when your concrete-pouring capabilities are limited.

Better rockets and better spacecraft serve all space exploration and colonization efforts.

Mars is difficult of course, but it does have resources. You can get water, oxygen, rocket fuel, various ores, etc. It's also not a vacuum, and there are places where the temperature profile is vaguely similar to Earth.

None of that is true in space, unless you're thinking of something I'm not, but like another poster has said, none of this is zero sum. The technology developed to try to settle on mars can be devoted to building large, habitable objects in space if people think that's a better plan. We should also have a moon base, etc. etc.

> live in man-made structures orbiting the sun at a distance of 1AU, which is debatedly much more sensible than trying to live on Mars.

The resources still need to come from somewhere. Either we mine them on Mars, asteroids, or the moon. Mining is a lot easier when you have gravity you can push against to apply force. Rather than move the resources off-body though, its easier and cheaper to use them directly in-situ.

> much more sensible than trying to live on Mars

It's more sensible if you plan to keep a bunch of people there with constant supply from Earth. Elon wants to build a *self-sustaining* city on Mars. There isn't any other choice of location, be it man-made, or in the solar system:

- that has enough resources, atmosphere, gravity, water to allow a non-trivial population to survive without help from Earth

- that is hospitable to life

I suggest you watch his previous presentation where he talks exactly on why Mars is the destination, and not somewhere else.

Yes, we are talking about permanent, Earth-independent settlement in space. I didn't mean to imply that the settlements in the man-made structures would be Earth-dependent.

Atmosphere is possible in man-made structures.

Gravity can be simulated in man-made structures.

I don't believe water is particularly scarce, and it is reusable except for when it's used to create fuel.

With the Sun + plants a lot can be done.

Mars, on the other hand, has low gravity and is far away from the Sun.

Your proposed alternative would also benefit from something like Starship.

Of course, we can (and should, eventually) do both.

> We are one asteroid strike away from losing all human life on earth.

We're one asteroid strike from losing all human life in the solar system even if you had a bunch of people living on Mars. It would take a very long time to get even a single Mars colony self sufficient. Without resources of Earth supporting the colony it would die out the first time the air conditioner broke.

Putting people on Mars isn't putting our eggs in a second basket. It's putting an egg in a wet napkin on a mouse trap positioned under a precariously balanced boulder.

Musk says basically this in his presentation. Very very hard.

You have to start building the basket at some point. If you never start working on the colony you'll always have an excuse ("it'll take a long time!", "it'll be too expensive!", "the technology doesn't exist" and so on).

The technology to be self-sustaining won't exist without demand for it, and starting to setup a colony creates a lot of demand.

By that logic we will never leave Earth. Let’s say it takes 200 years to get a fully self sufficient colony on Mars. If we start now, it could be self-sufficient by around 2222. But, according to your logic, we shouldn’t start since the colony won’t be immediately self-sufficient. Instead we should wait until… until when? Assuming it will always take 200 years to make the colony self-sufficient, do we wait until 2222 to start so that it is self-sufficient by 2422?

A 200 year timeline is likely far too short. There's nowhere on the planet a human (or any multicellular Earth life) can survive without an active life support system. Every square meter of living and farming space needs to be enclosed with powered life support. There's no lubricants, easily accessed water, or even raw materials for heavy industry.

Even if Starship was ready to go tomorrow zero percent of any of the infrastructure needed to keep humans alive on Mars exists. The infrastructure needed to let some Martians be self sufficient only exists in artist renderings.

Getting a hundred tons of crap to Mars is the easiest part of the problem. Building a reliable toilet that won't clog and kill everyone or an air filter that never breaks is hard. Having enough food and medical supplies to keep people alive after a crop fails is hard. Building a factory that doesn't need a huge supply of oil-based lubricants is hard. Crowing crops in shitty soil is hard. Shit just building a big sealed structure is hard.

I don't find any claims of colonizing Mars believable because there's only lip service paid to boring infrastructure. Infrastructure can't just be patched in later.

So… give up and don’t even bother trying, because failure is probable but not certain. Got it.

That's not what I said. I do not find any claims of "colonization" believable because there's absolutely zero interest in solving or even realistically addressing the Hard Problems involved. There's little interest in solving the easier but boring problems.

If the toilets on a Starship get clogged [0] the crew can't wear diapers for a year and a half on their way to Mars. In space a clogged toilet has the fun side effect of aerosolizing feces that the crew will then breathe in, likely killing them.

Big talk about colonizing Mars is just talk without any actual movement on important infrastructure. A big rocket is only the first tiny step on a very very long road and itself is not really all that useful.

If you want to make pithy statements about not trying, direct your energy towards everyone fantasizing about Mars colonies with zero intent to tackle any of the Hard Problems involved.

[0] https://futurism.com/the-byte/spacex-tourist-toilet-alarm

Gonna be interesting to see how many people actually pony up to really take part in that kind of vision.

Are there any economic incentives for colonizing Mars? Asteroid mining makes sense and bases on and around the Moon make some kind of economic sense at least. I don't know how Mars fits into that picture in the 50-100 year "medium" term picture.

Economic incentives include government-funded basic science, mining, tourism, real-estate speculation (i.e. claim a bunch of land while it's cheap), entertainment (sports and movies/TV shows), the ability to do things in a presumably lax regulatory environment that might not be allowed on Earth, and long-term care for those who have disabilities that would require a wheelchair in full gravity but not on Mars, and the establishment of Mars as a more convenient source of food/fuel/raw materials for any human presence in the belt or outer solar system.

A lot of that assumes an already functioning economy on Mars. We're not going to be sending anyone other than the richest people up to Mars in their old age. And for stuff like food and hydroponics you could have that on the Moon which is the natural waystation to the Asteroids. The Asteroids are going to be where all the mining is. Entertainment also assumes an already existing economy. Space tourism is the only thing that seems viable in the short term.

About all I can see is producing methane for rockets in Asteroids and being in a much shallower gravity well than Earth. That assumes having an economy established in the Asteroid belt already though, and the cost of sustaining a colony on Mars is going to be its own kind of high overhead. It may be expensive to ship fuel off of Earth, but the people to support the refinement process already exist.

At some point there will be a flip where a Mars economy becomes self-sustaining, but so far I'm not seeing it during my lifetime. My guess is that we're going to be tethered to the Earth for a lot longer.

(Basic science is also great but that's the kind of things that governments support and its not self-sustaining any more than Antarctica is -- which I suspect is closer to the model for Mars in the next 50 years).

The ability to make methane on Mars is pretty huge, though. If you're mining the asteroid belt and need to refuel your ships, it's a lot easier to ferry fuel from Mars to the belt than haul it all the way from Earth. And methane/oxygen production is likely to be one of the first things we get going on Mars because we'll want our rockets to be able to make return trips back to Earth and we really don't want to haul the extra fuel and oxygen we need all that way.

Most of the economic incentives I suggest don't really start paying off until you have at least some decent infrastructure and a population of semi-permanent residents, though. It might not happen in our lifetimes, but you never know. Once the technology exists, it's just a matter of whether someone has deep enough pockets to make human settlement of Mars a reality. Once someone has a foothold, it gets easier for others to expand on that.

Again though lifting methane off of Earth is expensive, but ships from the Asteroid belt will naturally be coming back to Earth, so refueling around the Earth or Moon doesn't go out of the way. Mars is a detour, and you have to sink the costs to sustain the colony which offsets the smaller gravity well.

I figure that any large-scale asteroid mining operation is likely to employ a fairly complicated supply chain that doesn't ship everything to or from Earth.

Earth would probably continue to manufacture high-value, complex machines like rocket engines and computers and robots. Earth would receive high-value minerals from the asteroid belt like gold or platinum or silver. Maybe nickel or copper. Iron wouldn't be worth it unless shipping costs were really low, aluminum would probably be the same. On the other hand, iron and aluminum might be worth enough on Mars to be worth shipping there. It'd be cheaper than shipping from Earth, anyways. And hauling rocket fuel/oxygen all the way from Earth really doesn't make sense if you can get it on Mars.

Basically, you'd have ships going back and forth between Earth and the belt delivering equipment and bringing back high-value metals, and you'd have another set of ships going back and forth between Mars and the belt hauling fuel and oxygen and maybe bringing back low value metals to be used on Mars. If there are people living in the belt, the ships can bring them whatever else is easier to make on Mars than in space. Maybe food.

It's kind of a weird thought, but I would suggest that a lot of the output of industrial infrastructure in space is going to be used in space rather than returned to Earth. What's the point (you might ask) if it doesn't come back to Earth? Well, people on Earth might for various reasons want to expand their foothold in space, and then once it reaches a certain critical mass those footholds in space become their own thing. Like Europeans coming to America and eventually rebuilding more-or-less what they left behind, but with some differences.

> The basic idea is to not have all your eggs in one basket.

A moon base is the precursor to a base on Mars and having humans get anywhere near Mars in the next 50 years (if they return or not) is a PR stunt.

Planning for mars is making the moon shot significantly better. Starship can basically replace the whole complicated and expensive orbiter lander situation with a fast, cheap, reusable craft with a fantastic payload capacity. That craft is being designed and built with Mars in mind. It’s also going to be fantastically useful for other things.

From a species POV sure, from an individual POV living on Mars would be miserable..

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