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Background:

The main asteroid belt between Mars and Jupiter is the closest and richest source of non terrestrial resources to Earth in the solar system. Even though it is vast its resources are obviously finite so mankind must choose between two projects to use it for:

  1. Terraforming Mars: Launching asteroids from the belt tangentially at Mars to increase its spin and mass and restart its core.

  2. Create a Dyson Ring: creating first satellites in the belt and eventually linking them into a ring. I'm not sure how much material there is but it could be this ring could be big enough to support habitable sections (much like a Halo ring).

Given only these 2 options, which option would result in the greatest enhancement for mankind: (relative plausibility should also be a factor in your answer)

Note: Any answer that seeks to scientifically discredit 1 possibility must provide mathematical evidence as to why it is not plausible.

Requested Criteria:

  1. Must select 1 of the 2 options.
  2. Enhancement to mankind can be quantified in living space, opportunity to improve technology, progression of space travel (man's reach), access to resources (materials, energy, infrastructure), and ultimately the security in continuation of our species (IE: the probability of a singular disaster being able to wipe us all out).
  3. If discrediting one possibility to select another, must mathematically discredit that possibility as part of that justification.
  4. In both scenarios Earth isn't acting a primary factory or resource supplier, the majority of resources and construction is to occur in the belt.
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    $\begingroup$ Can you give us some reasonably objective criteria by which we can judge how answers meet your "greatest enhancement for mankind" requirement? As it stands, I'm afraid this might still be a little too opinion-based (even though it's clear that you are trying). $\endgroup$ – a CVn Sep 28 '17 at 14:37
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    $\begingroup$ The rings from Halo aren't Dyson Rings. $\endgroup$ – sphennings Sep 28 '17 at 14:51
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    $\begingroup$ @sphennings No, but they do support habitable sections. That was the comparison OP was making. $\endgroup$ – AngelPray Sep 28 '17 at 14:55
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    $\begingroup$ there isn't actually that much matter in the asteroids belt. $\endgroup$ – A. C. A. C. Sep 28 '17 at 15:06
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    $\begingroup$ @sphennings I fear you may be misunderestimating the scale of space. (Don't worry; I think we both know that's easy to do.) Assuming our solar system (which seems a reasonable assumption to make here), 300M km diameter is pretty much exactly Earth's orbit; Earth has an orbital radius around the Sun of 150M km or 1 AU. Did you by any chance mean 300M km radius? That would put you a shade outside of Mars' aphelion which is at just under 250M km from the Sun, and (I'm guessing a little, here) probably smack in between Mars and the appreciable portions of the asteroid belt. $\endgroup$ – a CVn Sep 28 '17 at 15:12
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I'm not an astrophysicist, but I'm not sure why either of these options would limit the other.

First, Phobos, one of the moons of Mars, is probably going to collide with Mars in ~30 million years. Maybe... speed up that process and not waste an asteroid?

Assuming all we need to mine these asteroids for is solar panel materials, we shouldn't have too hard of a time telling which are prime targets for such use, and which simply do not have any valuable resources on them - at least, valuable to us now. So, mine the useful ones, slam the empty ones into Mars - best part of this is when you do want those resources back, you can find them on Mars.

If we truly must choose one over the other, I'd have to say make a Dyson Array first. The energy you get back from it is more valuable in both the short and long term than another Earth-like in the same solar system. Even if you're suffering over population, the self powering space colonies you could form on the parts of the array solve that problem. If you still need to terraform Mars, you can easily do it in the future thanks to all of the solar power you've farmed.

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A Dyson bubble can be made from the materials of just one asteroid, assuming you make gossamer solar sails to balance the light pressure from the sun against the Suns' gravity:

A 100% reflective statite deployed around the Sun would have an overall density of 0.78 grams per square meter of sail.[12] To illustrate the low mass of the required materials, consider that the total mass of a bubble of such material 1 AU in radius would be about 2.17×1020 kg, which is about the same mass as the asteroid Pallas.

enter image description here

Possible configuration of a Dyson Swarm

So this is the minimum mass needed to enclose the Sun and gather the available solar energy. Dyson swarms orbiting the sun are much more practical, and can be built incrementally using asteroids, moons and other astronomical bodies.

In terms of resources this is far more efficient than any terraforming scheme. It also has the advantage of collecting a large proportion of the available solar energy, which would give any future space faring civilization the means to do Terraforming of worlds if that is what they desire. There is plenty of material available (the moon Europa has 3X the liquid water as all the oceans of Earth alone), and with massive amounts of energy available, moving matter around is trivial.

enter image description here

Europa

enter image description here

Mars after terraforming

Build the Dyson bubble or swarm then you can do anything.

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  • $\begingroup$ Is this achievable with only resources from the belt. Sure there could be some from the Earth but the implied idea is that the Earth isn't the factory or primary resource provider. Others have argued that the belt's mass is minute so a whole sphere may not be realistic. Also if they are just simple reflective disks you have to consider collection as a construct of this array as the Earth would melt if it were the collection point. $\endgroup$ – anon Sep 28 '17 at 17:06
  • $\begingroup$ The mass you referenced is the maximum mass allowable for a Dyson Bubble not the minimum. That is the mass where a 100% reflective bubble will be kept in place by solar pressure and not collapse into the sun. $\endgroup$ – sphennings Sep 28 '17 at 18:04
  • $\begingroup$ Minimum mass for a sun girdling construct. You can make much bigger and more massive constructs, using more material. And yes. the Dyson bubble or swarm can be made with little or no input from Earth, and beam its energy output to anywhere in the Solar System, $\endgroup$ – Thucydides Sep 30 '17 at 1:24
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Even though one could aim carefully and drop all the asteroids tangentially on Mars, this would create a molten swimming pool on the surface, but would never reactivate the core.

Therefore, considering that option 1 just use resources to make a planet even less habitable, there is an easy choice: option 2.

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  • $\begingroup$ From posts across this stack and others, delivering a steady stream of impacts seems to be accepted as a theoretically plausible way of restarting the core. Do you have any math to disprove this theory? $\endgroup$ – anon Sep 28 '17 at 16:53
  • $\begingroup$ @anon Those are not proven and in the absence of proof, it is assumed to be false until proven. There isn't a reason to try and prove a negative. I actually don't know why people think that just bombing Mars with asteroids will start the core. $\endgroup$ – A. C. A. C. Sep 28 '17 at 19:12
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    $\begingroup$ @A.C.A.C. it is not assumed to be false, it is assumed to be unproven which is very different than false that's why its called theoretical. It remains theoretical till it is either proven or disproven. So if you are going to say that that theory which I am accepting at the moment (for my theoretical scenario) is false then you need to PROVE that. Welcome to the scientific method. $\endgroup$ – anon Sep 28 '17 at 19:16
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    $\begingroup$ @anon I don't know who taught you the scientific method but that is completely wrong. $\endgroup$ – A. C. A. C. Sep 28 '17 at 19:23
  • $\begingroup$ @A. C. A. C. If you instantly write off all theories as wrong absent evidence to the contrary you don't progress because you have already answered your question, potentially wrong. A theory is not much different than a postulation. It is neither right nor wrong till proven. $\endgroup$ – anon Sep 28 '17 at 19:26
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Larry Niven did some hard math in the Ringworld Engineers.. While a ringworld can be constructed with the mass of a solar systems worth of.planets, the energy required to move that mass would itself be the equivalent of a couple of solar systems, assuming 100% conversion of mass to energy.

The tensile strength of the supporting material for the ring would have to approximate neutronium.

Terraforming Mars is much more achievable.

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Well this is all a lot of effort, there's far easier ways, proposed by Dyson himself, and improvable since then:

MARS Problems: thin atmosphere, no core rotation to provide protective magnetic field, oxygen all locked up in rocks.

The atmosphere is easy to fix, you seed the planet with tonnes of bacteria that eat rust to liberate oxygen - such as the bacteria that have eaten the Titanic. You could even genetically engineer such a bacteria, or create a nanobot to turn the Ferric Oxide rocks into iron and oxygen. There's a caveat - the O2 levels must not rise above 20% or the planet becomes highly flammable. It will also need three or four times as much nitrogen, and some Carbon Dioxide, to create a self sustaining atmosphere and reasonable temperature.

The core is a bit trickier. You need to melt it, essentially, and then centrifugal forces and friction will take care of the rest. This is tricky, but may not be impossible.

Let me explain something here: Those people who say things are 'impossible' because 'physics says it cant be done', are usually wrong. This is because they base their judgement on the current level of knowledge. History shows that almost everything that has been declared 'impossible' at some stage has, in the light of later science, later discoveries, later technologies, been possible. if you think for one minute we are anywhere near a complete understanding of Physics, think again. There are VAST areas of science where we know nothing. And the areas of science we are aware of are mainly incomplete - both Relativity and Quantum Physics being two examples of theories with MASSIVE gaps in.

In 1890 it was declared 'impossible' to travel faster than 60 MPH as 'the air would be going past too fast to breathe'. In 1890 you could not possibly have foreseen airplanes, cars, rockets, satellites, lasers, computers, smartphones, the internet, relativity. quantum, physics, M theory, television, radio.... you would have had no idea of plate tectonics, Navier Stokes Equations, Genetic engineering, nuclear power, DNA, nanotechnology...in short, you cannot possible predict what is impossible, because you cant predict what we may know in the future to make it possible. (That include faster than light travel, BTW)

But I divert. In short, we can't get Mars's core rolling today, but maybe in 100 years we can pump enough fusion or antimatter power into the core to melt it. I'm confident we will crack the problem, since historically man has cracked every problem hes ever faced.

Venus has a similar core problem, and unsuitable atmosphere, but the solution is similar. The Runaway greenhouse on Venus is a consequence of the hydrocarbon atmosphere. Earth had a similar problem, until the Great Oxygen Catastrophe, when bacteria began producing masses of O2, breaking the Greenhouse grip. Read more here

https://en.wikipedia.org/wiki/Great_Oxygenation_Event

In short, we need hundreds of orbiting stations over Venus, mass producing and showering it with algae and cyanobacteria in a man made rerun of the GOC.

We still have the problem of the lack of magnetic field. Possibly we can build an extensive electromagnet to protect all or some of the planet until we solve how to melt and spin up the cores. It would not require a massive strength, but would need to be large to head off cosmic particles.

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