[SEJeff]

Pretty sure this reason in specific is why SpaceX accepted the 1 billion USD investment from Google Ventures for their satellite internet constellation project in Seattle. If Musk's endgame plan is a serious Mars colony, there needs to be both location and communication over the entire planet (of mars). There also needs to be bidirectional communication with Earth. An orbiting constellation makes sense to do this.

https://www.nytimes.com/2015/01/21/technology/google-makes-1...

[Retric]

The important part of mars colonization is being able to produce 100% of all needed goods (from food to CPU's) on the surface of mars, not covering the planet with people. Really 2-3 redundant geosynchronous satellites on mars should be plenty for a very long time.

Musk wants satellite internet as it lets Space X lower cost per launch by launching a lot of satellites.

[monocasa]

> on the surface of mars

Why? Wouldn't it be easier to bootstrap by mining asteroids, and manufacturing in micro gravity, then dropping nearly finished goods onto the planet? That'd also allow you to use the same bootstrapping infrastructure for several surface sites.

[Retric]

Mining asteroids has a ton of issues even beyond the obvious cost and R&D problems. They are generally far from the sun so solar power is significantly less useful. You need to move a lot of bulk material which means heavy Delta V problems. Micro gravity means you can't have humans in the area for long without giant structures. Finally, economically resources are just not that scarce.

The delta V issues are more reasonable when you want stuff to end up in space. But, that's not an issue for a Mars colony. As to mining Mars's moon's they don't really have a lot of useful material that is not on Mars in the first place.

PS: Space X's slightly lower the cost to orbit actually makes Asteroid mining even less viable.

[gorkonsine]

>They are generally far from the sun so solar power is significantly less useful.

No, they aren't. There's tons of asteroids in Earth-crossing orbits. And Mars-crossing orbits too. It'll be a long time before we use those up.

>You need to move a lot of bulk material which means heavy Delta V problems.

No, you don't. You process the ores near the asteroids; you don't have to ship it all to the point-of-use.

>Micro gravity means you can't have humans in the area for long without giant structures.

So what? You don't need a lot of humans there; this stuff needs to be automated (or at least remote-controlled). And artificial gravity doesn't need a giant structure; you can do it with a small structure on a tether.

>Finally, economically resources are just not that scarce.

That depends on what resources, and where you want them. If you want a lot of platinum, it's very scarce here on Earth, but mining one Earth-crossing asteroid could provide a huge amount of it relatively cheaply.

>As to mining Mars's moon's they don't really have a lot of useful material that is not on Mars in the first place.

How do you know that? Mars's moons are really just captured asteroids and likely have no geological relation to Mars at all.

[Retric]

Basically, if you can mine it on earth you can do the same on mars excluding organic compounds.

Anyway, back to your argument. Processing ore is not light weight. Total mass of asteroids inside earths orbit is actually surprisingly low relative to planetary manufacturing needs. Sure the asteroid belt is ~4% of the moons mass, but inner planets have mostly cleared their orbits.

Yea, there are KM sized objects, which might be rich in stuff we want. But consider, Bingham Canyon Mine for example is 0.6 miles deep and 2.5 miles wide and that's just for copper. And even if you processed it all you still need Delta V on 19 million tonnes of copper.

Look at a periodic table. Mines can only really provide you with that stuff. Now exclude the useless elements and the stuff and what's abundant and there really is not a huge niche for asteroid mining. Futher ateriods regularly impacted mars after it had a solid surface so all the same elements are there much like they are on earth.

So, you really need asteroid mining to stand on it's own independent of colonizing Mars.

PS: Artificial gravity only gets you part of the way to dealing with micro gravity You need life support, food, water etc. Spin all that stuff and you need an even stronger tether with a larger counter weight.

[gorkonsine]

Luckily for us, a bunch of wealthy and influential people disagree with you and know more about this stuff than you do, and have started companies like Planetary Resources. All that stuff we're mining from the Earth's crust came from asteroids, not from the formation of the planet, and it's far better concentrated in asteroids than it is in the crust, so no, there really is a huge niche for asteroid mining or else there wouldn't be a lot of money put into exploring this. No, asteroids impacting Mars are going to have the same problem that they do on Earth: it reduces the concentration too much so you have to process a lot of dirt to get to the valuable ores; this isn't the case with asteroids.

>You need life support, food, water etc.

We figured all that stuff out ages ago. We can already recycle air and water and have been doing so on space stations for decades. Food can be supplied by resupply missions, and also grown on-site; it's not that hard. You're completely overstating the problem. If you think that running a small space station is somehow far harder than running a habitat on Mars (where you cannot control the gravity at all), which seems to be what you're implying here, you have no idea what you're talking about, and I think you're being intellectually dishonest to boot.

[vkou]

Why would you want to manufacture in microgravity? What are the practical advantages of this? I can't think of any, but I can think of a lot of disadvantages of this.

Also, a Mars colony would require millions of tonnes of raw materials. You can only get that in-situ.

[logfromblammo]

I think the largest problem in orbital manufacturing is actually rejection of waste heat. Otherwise, being able to run robots in an oxygen-free environment and move around large masses without conveyors sounds pretty good.

[vkou]

It's also an environment full of cosmic rays, which requires hardening of all your electronics, an environment where fluids don't flow through pipes, an environment where dust and powders don't settle, an environment where conveyor belts don't work because things float off them...

Almost every single industrial process that we have relies on a constant, freely available, predictable, unidirectional acceleration of 9.8 m/s^2.

Imagine trying to build a twenty-tonne steel smelter that will function in orbit - I'm sure working with tonnes of molten steel that won't stay where you put it would be a breeze.

There's also the part where many of our industrial processes are extremely water-hungry. Any kind of space industries would require complete reclamation of all waste water, stream, etc - with a large cooling cycle, to boot. And heaven forbid if the process consumes nitrogen, oxygen, or hydrogen in any appreciable amounts - unlike on Earth, you can't synthesize them in space.

[logfromblammo]

You're thinking of it the wrong way. The goal is not to transplant existing Earth manufacturing processes to orbit. That's currently impossible without a launch vehicle powered by nuclear bombs.

There is no 20 Mg steel smelter in orbit. The use cases are very different. First off, you're not starting with coke and iron ores and ending with flat carbon steel. Whatever you make is staying in orbit, to replace something that would otherwise have to be launched. You probably need to make 17-4 PH stainless steel, with synthetic thin-film silica surface coatings to prevent vacuum welding. And where is the raw material--iron, nickel, tantalum, chromium, etc.--coming from?

You can't just replace an existing industry with vertical conveyor belts 5 miles high and expect it to work.

Firstly, the raw materials: https://en.wikipedia.org/wiki/Mond_process , https://en.wikipedia.org/wiki/Carbonyl_metallurgy , https://en.wikipedia.org/wiki/Chemical_vapor_deposition .

You would likely be reacting powdered asteroid dust with CO + H2 (syngas), distilling the carbonyl vapors, and depositing nearly pure metals at higher temperature. The purified metals do not subsequently react with oxygen, because that is all kept bottled up for other purposes. Now you don't need the Bessemer process or oxygen converter process, because the iron is already pure, and also you don't have enough oxygen to waste on it. Since you're already using CVD in high vacuum to build up your ingot, you might as well just add the alloying elements and silica coating right there, on the asteroid, before you fling it to whatever orbit you want it to be in.

Metal carbonyl chemistry works at relatively low temperatures, below 250 degC. You don't have to worry about toxicity if you don't even have humans on site at the facility.

[valuearb]

It's far cheaper to send people to asteroids than Mars. Even those in the belt. And they have trillions of tons of easily accessible raw materials.