Colonization of Ceres instead of the moon or Mars

[catloaf]

For some reason colonization of Ceres is just not as widely discussed as the moon or Mars, despite the planet's¹  unique advantages in comparison to the moon or mars. These include being closer to the outer planets and low surface gravity makes Ceres ideal for outer solar system exploration. In addition ice on its surface means plenty of fuel and oxygen from isru. The other arguably more important reason is that it's close proximity to mostly metallic asteroids means that there is a monetary reward that will occur within the investors lifetime. Although distance and micro gravity are worse than the moon and Mars, artificial gravity or rigorous exercise are not are probably still necessary for those destinations anyway, and the distance is just a harder version of Mars. Because this is colonization not exploration this isn't a big problem since the low gravity of Ceres will reduce costs and the residents are permanent. Ceres also makes sense from the stepping stone to the outer solar system due to lower transfer times, although the rarity of good transfer windows could reduce this by a lot, and Mars's moons may be preferable for that. (I don't know how to end new topics but please discuss it...)

¹ I consider dwarf planets to be a subset of planets, as red dwarfs are to stars. Versus asteroids which are to planets, how brown dwarfs are to stars

Edited August 17, 2020 by catloaf

[DDE]

1 hour ago, catloaf said:

These include being closer to the outer planets

As an inverse, it's further from Earth. This is a problem for dV-constrained programs.

1 hour ago, catloaf said:

In addition ice on its surface means plenty of fuel and oxygen from isru.

No advantage over Mars.

1 hour ago, catloaf said:

The other arguably more important reason is that it's close proximity to mostly metallic asteroids means that there is a monetary reward that will occur within the investors lifetime.

Don't even try.

https://www.thespacereview.com/article/3586/1

1 hour ago, catloaf said:

artificial gravity or rigorous exercise are not are probably still necessary for those destinations anyway

That's a pure unknown at this point, put permanent damage in but a few years is suspected.

1 hour ago, catloaf said:

the residents are permanent

See above

1 hour ago, catloaf said:

Ceres also makes sense from the stepping stone to the outer solar system

Given the associated costs, that would mean jeopardizing the Mars colony project, which is far less risky.

1 hour ago, catloaf said:

(I don't know how to end new topics but please discuss it...)

So long as you don't beg us to clap, you're fine.

[Bill Phil]

Eh. 

I’d forego any surface settlements at all. No real point to it. 

We can build orbital habitats instead. Once such a technology is mature they could even be used as vehicles to emigrate populations to other places. Settlements built with material from the Moon and some asteroids may find themselves in orbit over a far off planet. 

Ceres might make a decent destination for such an emigrating habitat - if it can self replicate and build more habitats at Ceres then it could be worthwhile. 

But to get to that point we’d need to develop orbital habitat technology.

[DDE]

3 minutes ago, Bill Phil said:

But to get to that point we’d need to develop orbital habitat technology.

Or, to put it in other terms: where we're going we won't need planets.

[CFYL]

2 hours ago, catloaf said:

being closer to the outer planets

For this, I gotta say that:

1. If ΔV is still a major problem in space flight, then this Ceres base would not benefit. In fact, on the Earth you could even have a bonus of Obert effect. The additional orbital energy provided by a longer SMA will not make up for this loss of Obert in terms of Uranus and Neptune, obviously; while (reaching) Saturn or Jupiter may be a bit easier, if starting from Ceres instead of Earth. So, I would actually prefer bringing an near-Earth asteroid (or brown dwarf of planets, as you said) to a circular Earth orbit of, say, 2000km, with its inclination turned to the plane of planetary orbits around the Sun. As long as it is not controlled by terrorists to hit the Earth. And then move poisonous industries or those requiring minimal gravity there, with some mining.

2. If ΔV is finally a marginal concern compared to time, then humans can literally populate every single planet, in whatever kind of habitation modules. For a practical base, though, I suggest the use of Pluto-Charon system. A binary system is not just fun, but Pluto is rich in methane. (That, was the topic of a Nature article in 2016, if I didn’t forget) METHANE. The substance of life. I don’t mean there’s any identified life forms there, but we have something to burn. Ah, the burning releases water and carbon dioxide, to flourish (brought-there) life. As long as you have oxygen, of course. Pluto is even closer to the Solar System’s edge, you know that.

Spoiler

Consider the barycenter of planetary systems orbiting the sun, the only one known to be out of the more massive body is the Pluto-Charon system. The closest to this? The Earth-Moon system! With its barycenter only halfway down the Earth! (About 3000km below the ground, that is.)

 

2 hours ago, catloaf said:

Although distance and micro gravity are worse than the moon and Mars, artificial gravity or rigorous exercise

Why not spin entire dwarf planets fast enough, or comets or asteroids, to make an outwards “artificial gravity”? Just do some planetary reinforcements.

 

2 hours ago, catloaf said:

it's close proximity to mostly metallic asteroids means that there is a monetary reward that will occur within the investors lifetime.

Space is not for mining, mind you. The Earth is rich in many resources, including diamond and gold, but some just had their prices controlled by giant corporations or even governments, to gain more profit. You may consider that the same as fake moon landings or flat Earth(s), but the fact is that some resources are simply rich AND easy to mine, and so they have a mass production rate, but still costly. Mining from space would probably be practical only when space has a mass population.

 

2 hours ago, catloaf said:

Ceres

And finally, what about Vesta

 

2 hours ago, catloaf said:

low surface gravity

I surly agree with this. Low g is better, despite the hardness of orbital maneuvers to intercept.

18 minutes ago, Bill Phil said:

We can build orbital habitats instead.

I wanted to say, why bother building, when you have some built by nature? Use asteroids and comets as a replacement may be more preferable. Just have giant engines or on a larger scale, maybe giant propelling mechanics, to be clear. Dig tunnels(easy with little G, huh), and live in caves. For gravity? Spin it on the roll axis, with carefully-designed RCS for heading control and reinforcements to prevent breaking it. This is suggested to be done in the outer solar system, to prevent your base becoming a chunk of burning, evaporating ice.

Edited August 17, 2020 by AllenLi

[Spacescifi]

24 minutes ago, Bill Phil said:

Eh. 

I’d forego any surface settlements at all. No real point to it. 

We can build orbital habitats instead. Once such a technology is mature they could even be used as vehicles to emigrate populations to other places. Settlements built with material from the Moon and some asteroids may find themselves in orbit over a far off planet. 

Ceres might make a decent destination for such an emigrating habitat - if it can self replicate and build more habitats at Ceres then it could be worthwhile. 

But to get to that point we’d need to develop orbital habitat technology.

 

I have never understood what people mean when they speak of self replicating machines that humans will build in the future 

The closest thing we know of that self replicates are tiny blood cells.

They are living things though, AND they rely on fuel to replicate.

To build a nonliving thing in the real world that self-replicates is hard enough, to build one that does so in space with questionable fuel sources is harder still. What have we got? Asteroid rock? Space radiation? The orginal replicator?

I would. Also point out that the very idea of smelting metals and manufacturing inanimate stuff in space has been well researched.

The research indicates that without bringing suitable resources with you from elsewhere, you can never just 'live off the land' so to speak building whatever you want. Like to make many metal that are useful they need to be alloys, and finding a roid with everything you need?

You won't know till you dig, and I doubt it will be that convinient either. Given tgat roids are not like earth rock.

Like I can't write this off as completely impossible, but it certainly is nigh up there.

Edited August 17, 2020 by Spacescifi

[DDE]

6 minutes ago, Spacescifi said:

I have never understood what people mean when they speak of self replicating machines that humans will build in the future 

Well, fortunately this is on such a scale that we can plausibly create such "self-replicating machines". They're called tools factories.

[Spacescifi]

Just now, DDE said:

Well, fortunately this is on such a scale that we can plausibly create such "self-replicating machines". They're called tools factories.

Thought you were going to mention self-replicating nanomachines in space, which are a scifi trope that really is pitted against thermodynamics hard.

Want performance? Go big? Less? Go small. That's just how it is in space. Since small stuff simply cannot handle performance energies without obliterating.

This arricle is also interesting:

https://en.m.wikipedia.org/wiki/Space_manufacturing

[Hannu2]

5 hours ago, Spacescifi said:

 

I have never understood what people mean when they speak of self replicating machines that humans will build in the future 

Self replication is obvious solution to problem of huge area under exploration. It makes exponential growth of exploring ability possible. It makes possible to chart every planet on every star in whole galaxy in geologically or biologically relatively short period.

 

5 hours ago, Spacescifi said:

The closest thing we know of that self replicates are tiny blood cells.

They are living things though, AND they rely on fuel to replicate.

To build a nonliving thing in the real world that self-replicates is hard enough, to build one that does so in space with questionable fuel sources is harder still. What have we got? Asteroid rock? Space radiation? The orginal replicator?

Practical solution would be some kind of robot colony which send smaller mining probes to asteroids and assemble robot factories on suitable orbits. Every solar system has materials and energy needed. All humans's machines are made from few tens of elements by using electric and thermal energy.

 

5 hours ago, Spacescifi said:

I would. Also point out that the very idea of smelting metals and manufacturing inanimate stuff in space has been well researched.

The research indicates that without bringing suitable resources with you from elsewhere, you can never just 'live off the land' so to speak building whatever you want. Like to make many metal that are useful they need to be alloys, and finding a roid with everything you need?

What is the material you think is so special in our solar system? As far as I know everyone of them (at least which are used in industry) have been detected from space and there is also theoretical base why we can expect to find them everywhere.

 

 

5 hours ago, Spacescifi said:

You won't know till you dig, and I doubt it will be that convinient either. Given tgat roids are not like earth rock.

Like I can't write this off as completely impossible, but it certainly is nigh up there.

It is completely impossible with current or foreseeable technology. But there is no known restrictions from known natural laws. It is very much like interstellar traveling, which is many orders of magnitude away but no clear impossibilities are known. I am quite sure that we can build automated self replicating process and test it in asteroid belt before we can transport such system to nearby star system. Probably interstellar crafts will need some kind of intelligent and self repairing robot swarm to maintain them during very long trips. It is easier solution to believe than exotic energy shields against damage or near light speed propulsion at least for me.

[Spaceception]

This isn't about Ceres colonization, but it is about our first mission there http://rascal.nianet.org/themes/ which talks about a mission in the 2040s. I don't know if it'll happen (probably not, the timeline is pretty far out), but it's basically an envisioning if Artemis continues, and they're able to move onto Mars, Venus, and Ceres.

 

As for colonization itself, I think the Moon and Mars will be first. The Moon is close, and has the resources for a decent settlement to support Cislunar activities, likely with supplements from Earth (Carbon and Nitrogen come to mind). Mars, afaik, has the resources for an industrial city-state (and eventually nation). My personal thoughts when it comes to building habitats, is that since those can be many tens of thousands or hundreds of thousands of tonnes in mass on the smaller end (If you want habitats that can hold hundreds to thousands of people), that is both a lot of upfront investment in resources before they can even settle in, and a lot of infrastructure that has to be developed and brought to that location to assemble those resources.
Once you have the habitat, you also need regular cargo delivery since there's no immediate resources to maintain the station and do useful work as if you were on a planet. So depot docks, and manufacturing bays will be needed. Both will be expensive to wholly maintain from Earth. Especially if habitats are around the Moon for example, because if Lunarians can't stay on the surface, they will need to live in habitats some of/most of the time. Having direct access to the Moon may be preferred if resources can largely come from there.
A Lunar or Mars settlement will be important to allow for wide-scale manufacturing in space for the long-term. Once you're no longer building everything on Earth, and your launches are largely just people and associated cargo, you likely have a sufficient industrial base. So Habs can begin to go under construction around this time.

Edited August 17, 2020 by Spaceception

[Spacescifi]

1 hour ago, Spaceception said:

This isn't about Ceres colonization, but it is about our first mission there http://rascal.nianet.org/themes/ which talks about a mission in the 2040s. I don't know if it'll happen (probably not, the timeline is pretty far out), but it's basically an envisioning if Artemis continues, and they're able to move onto Mars, Venus, and Ceres.

 

As for colonization itself, I think the Moon and Mars will be first. The Moon is close, and has the resources for a decent settlement to support Cislunar activities, likely with supplements from Earth (Carbon and Nitrogen come to mind). Mars, afaik, has the resources for an industrial city-state (and eventually nation). My personal thoughts when it comes to building habitats, is that since those can be many tens of thousands or hundreds of thousands of tonnes in mass on the smaller end (If you want habitats that can hold hundreds to thousands of people), that is both a lot of upfront investment in resources before they can even settle in, and a lot of infrastructure that has to be developed and brought to that location to assemble those resources.
Once you have the habitat, you also need regular cargo delivery since there's no immediate resources to maintain the station and do useful work as if you were on a planet. So depot docks, and manufacturing bays will be needed. Both will be expensive to wholly maintain from Earth. Especially if habitats are around the Moon for example, because if Lunarians can't stay on the surface, they will need to live in habitats some of/most of the time. Having direct access to the Moon may be preferred if resources can largely come from there.
A Lunar or Mars settlement will be important to allow for wide-scale manufacturing in space for the long-term. Once you're no longer building everything on Earth, and your launches are largely just people and associated cargo, you likely have a sufficient industrial base. So Habs can begin to go under construction around this time.

 

Eh... consider what resources the moon has to offer.

Then afterward, consider what it DOES NOT OFFER.

Then you know all.

 

 

Lunar surface chemical composition^[11]

Compound	Formula	Composition
		Maria	Highlands
silica	SiO2	45.4%	45.5%
alumina	Al2O3	14.9%	24.0%
lime	CaO	11.8%	15.9%
iron(II) oxide	FeO	14.1%	5.9%
magnesia	MgO	9.2%	7.5%
titanium dioxide	TiO2	3.9%	0.6%
sodium oxide	Na2O	0.6%	0.6%
		99.9%	100.0%

Solar power, oxygen, and metals are abundant resources on the Moon.^[12] Elements known to be present on the lunar surface include, among others, hydrogen (H),^[1][13] oxygen (O), silicon (Si), iron (Fe), magnesium (Mg), calcium (Ca), aluminium (Al), manganese (Mn) and titanium (Ti). Among the more abundant are oxygen, iron and silicon. The atomic oxygen content in the regolith is estimated at 45% by weight.^[14][15]

Solar powerEdit

Daylight on the Moon lasts approximately two weeks, followed by approximately two weeks of night, while both lunar poles are illuminated almost constantly.^[16][17][18] The lunar south pole features a region with crater rims exposed to near constant solar illumination, yet the interior of the craters are permanently shaded from sunlight, and retain significant amounts of water ice in their interior.^[19] By locating a lunar resource processing facility near the lunar south pole, solar-generated electrical power would allow for nearly constant operation close to water ice sources.^[17][18]

Solar cells could be fabricated directly on the lunar soil by a medium-size (~200 kg) rover with the capabilities for heating the regolith, evaporation of the appropriate semiconductor materials for the solar cell structure directly on the regolith substrate, and deposition of metallic contacts and interconnects to finish off a complete solar cell array directly on the ground.^[20]

The Kilopower nuclear fission system is being developed for reliable electric power generation that could enable long-duration crewed bases on the Moon, Mars and destinations beyond.^[21][22] This system is ideal for locations on the Moon and Mars where power generation from sunlight is intermittent.^[22][23]

OxygenEdit

The elemental oxygen content in the regolith is estimated at 45% by weight.^[15][14] Oxygen is often found in iron-rich lunar minerals and glasses as iron oxide. At least, twenty different possible processes for extracting oxygen from lunar regolith have been described,^[24][25] and all require high energy input: between 2-4 megawatt-years of energy (i.e. 6-12×10¹³ J) to produce 1,000 tons of oxygen.^[1] While oxygen extraction from metal oxides also produces useful metals, using water as a feedstock does not.^[1]

WaterEdit

Main article: Lunar water

Play media

Images by the LCROSS orbiter flying of the lunar south pole show areas of permanent shadow.

The image shows the distribution of surface ice at the Moon's south pole (left) and north pole (right) as viewed by NASA's Moon Mineralogy Mapper (M³) spectrometer onboard India's Chandrayaan-1 orbiter

Cumulative evidence from several orbiters strongly indicate that water ice is present on the surface at the Moon poles, but mostly on the south pole region.^[26][27] However, results from these datasets are not always correlated.^[28][29] It has been determined that the cumulative area of permanently shadowed lunar surface is 13,361 km² in the northern hemisphere and 17,698 km² in the southern hemisphere, giving a total area of 31,059 km².^[1] The extent to which any or all of these permanently shadowed areas contain water ice and other volatiles is not currently known, so more data is needed about lunar ice deposits, its distribution, concentration, quantity, disposition, depth, geotechnical properties and any other characteristics necessary to design and develop extraction and processing systems.^[29][30] The intentional impact of the LCROSS orbiter into the Cabeus crater was monitored to analyze the resulting debris plume, and it was concluded that the water ice must be in the form of small (< ~10 cm), discrete pieces of ice distributed throughout the regolith, or as thin coating on ice grains.^[31] This, coupled with monostatic radar observations, suggest that the water ice present in the permanently shadowed regions of lunar polar craters is unlikely to be present in the form of thick, pure ice deposits.^[31]

Water may have been delivered to the Moon over geological timescales by the regular bombardment of water-bearing comets, asteroids and meteoroids ^[32] or continuously produced in situ by the hydrogen ions (protons) of the solar wind impacting oxygen-bearing minerals.^[1][33]

The lunar south pole features a region with crater rims exposed to near constant solar illumination, where the craters' interior are permanently shaded from sunlight, allowing for natural trapping and collection of water ice that could be mined in the future.

Water molecules (H
₂O) can be broken down to its elements, namely hydrogen and oxygen, and form molecular hydrogen (H
₂) and molecular oxygen (O
₂) to be used as rocket bi-propellant or produce compounds for metallurgic and chemical production processes.^[3] Just the production of propellant, was estimated by a joint panel of industry, government and academic experts, identified a near-term annual demand of 450 metric tons of lunar-derived propellant equating to 2,450 metric tons of processed lunar water, generating US$2.4 billion of revenue annually.^[23]

HydrogenEdit

The solar wind implants protons on the regolith, forming a protonated atom, which is a chemical compound of hydrogen (H). Although bound hydrogen is plentiful, questions remain about how much of it diffuses into the subsurface, escapes into space or diffuses into cold traps.^[34] Hydrogen would be needed for propellant production, and it has a multitude of industrial uses. For example, hydrogen can be used for the production of oxygen by hydrogen reduction of ilmenite.^[35][36][37]

MetalsEdit

IronEdit

Common lunar minerals^[38]

Mineral	Elements	Lunar rock appearance
Plagioclase feldspar	Calcium (Ca) Aluminium (Al) Silicon (Si) Oxygen (O)	White to transparent gray; usually as elongated grains.
Pyroxene	Iron (Fe), Magnesium (Mg) Calcium (Ca) Silicon (Si) Oxygen (O)	Maroon to black; the grains appear more elongated in the maria and more square in the highlands.
Olivine	Iron (Fe) Magnesium (Mg) Silicon (Si) Oxygen (O)	Greenish color; generally, it appears in a rounded shape.
Ilmenite	Iron (Fe), Titanium (Ti) Oxygen (O)	Black, elongated square crystals.

Iron (Fe) is abundant in all mare basalts (~14-17 % per weight) but is mostly locked into silicate minerals (i.e. pyroxene and olivine) and into the oxide mineral ilmenite in the lowlands.^[1][39] Extraction would be quite energy-demanding, but some prominent lunar magnetic anomalies are suspected as being due to surviving Fe-rich meteoritic debris. Only further exploration in situ will determine whether or not this interpretation is correct, and how exploitable such meteoritic debris may be.^[1]

Free iron also exists in the regolith (0.5% by weight) naturally alloyed with nickel and cobalt and it can easily be extracted by simple magnets after grinding.^[39] This iron dust can be processed to make parts using powder metallurgy techniques,^[39] such as additive manufacturing, 3D printing, selective laser sintering (SLS), selective laser melting (SLM), and electron beam melting (EBM).

TitaniumEdit

Titanium (Ti) can be alloyed with iron, aluminium, vanadium, and molybdenum, among other elements, to produce strong, lightweight alloys for aerospace. It exists almost entirely in the mineral ilmenite (FeTiO₃) in the range of 5-8% by weight.^[1] Ilmenite minerals also trap hydrogen (protons) from the solar wind, so that processing of ilmenite will also produce hydrogen, a valuable element on the Moon.^[39] The vast flood basalts on the northwest nearside (Mare Tranquillitatis) possess some of the highest titanium contents on the Moon,^[29] harboring 10 times as much titanium as rocks on Earth do.^[40]

AluminiumEdit

Aluminium (Al) is found with a concentration in the range of 10-18% by weight, present in a mineral called anorthite (CaAl
₂Si
₂O
₈),^[39] the calcium endmember of the plagioclase feldspar mineral series.^[1] Aluminium is a good electrical conductor, and atomized aluminum powder also makes a good solid rocket fuel when burned with oxygen.^[39] Extraction of aluminium would also require breaking down plagioclase (CaAl₂Si₂O₈).^[1]

 

SiliconEdit

Photo of a piece of purified silicon

Silicon (Si) is an abundant metalloid in all lunar material, with a concentration of about 20% by weight. It is of enormous importance to produce solar panel arrays for the conversion of sunlight into electricity, as well as glass, fiber glass, and a variety of useful ceramics. Achieving a very high purity for use as semi-conductor would be challenging, especially in the lunar environment.^[1]

CalciumEdit

Anorthite crystals in a basalt vug from Vesuvius, Italy (size: 6.9 × 4.1 × 3.8 cm)

Calcium (Ca) is the fourth most abundant element in the lunar highlands, present in anorthite minerals (formula CaAl
₂Si
₂O
₈).^[39][41] Calcium oxides and calcium silicates are not only useful for ceramics, but pure calcium metal is flexible and an excellent electrical conductor in the absence of oxygen.^[39] Anorthite is rare on the Earth^[42] but abundant on the Moon.^[39]

Calcium can also be used to fabricate silicon-based solar cells, requiring lunar silicon, iron, titanium oxide, calcium and aluminum.^[43]

MagnesiumEdit

Magnesium (Mg) is present in magmas and in the lunar minerals pyroxene and olivine,^[44] so it is suspected that magnesium is more abundant in the lower lunar crust.^[45] Magnesium has multiple uses as alloys for aerospace, automotive and electronics.

Rare-earth elementsEdit

Rare-earth elements are used to manufacture everything from electric or hybrid vehicles, wind turbines, electronic devices and clean energy technologies.^[46][47] Despite their name, rare-earth elements are – with the exception of promethium – relatively plentiful in Earth's crust. However, because of their geochemical properties, rare-earth elements are typically dispersed and not often found concentrated in rare-earth minerals; as a result, economically exploitable ore deposits are less common.^[48] Major reserves exist in China, California, India, Brazil, Australia, South Africa, and Malaysia,^[49] but China accounts for over 95% of the world's production of rare-earths.^[50] (See: Rare earth industry in China.)

Although current evidence suggests rare-earth elements are less abundant on the moon than on earth.^[51] NASA views the mining of rare-earth minerals as a viable lunar resource^[52] because they exhibit a wide range of industrially important optical, electrical, magnetic and catalytic properties.^[1]

 

[kerbiloid]

Then rare-ceres.

[Bill Phil]

On 8/17/2020 at 12:48 AM, DDE said:

Or, to put it in other terms: where we're going we won't need planets.

Not necessarily. Certain planets would make excellent sources of raw materials like Mercury or Mars, provided civilization is suitably energy rich.

On 8/17/2020 at 12:55 AM, AllenLi said:

I wanted to say, why bother building, when you have some built by nature? Use asteroids and comets as a replacement may be more preferable. Just have giant engines or on a larger scale, maybe giant propelling mechanics, to be clear. Dig tunnels(easy with little G, huh), and live in caves. For gravity? Spin it on the roll axis, with carefully-designed RCS for heading control and reinforcements to prevent breaking it. This is suggested to be done in the outer solar system, to prevent your base becoming a chunk of burning, evaporating ice.

Actually using asteroids and comets as habitats isn't a great idea. It seems great at a surface level, but consider that asteroids aren't all that structurally sound. And even if they were, the amount of material that you'd excavate would be large enough that you could build more habitat space.

On 8/17/2020 at 1:08 AM, Spacescifi said:

 

I have never understood what people mean when they speak of self replicating machines that humans will build in the future 

The closest thing we know of that self replicates are tiny blood cells.

They are living things though, AND they rely on fuel to replicate.

To build a nonliving thing in the real world that self-replicates is hard enough, to build one that does so in space with questionable fuel sources is harder still. What have we got? Asteroid rock? Space radiation? The orginal replicator?

I would. Also point out that the very idea of smelting metals and manufacturing inanimate stuff in space has been well researched.

The research indicates that without bringing suitable resources with you from elsewhere, you can never just 'live off the land' so to speak building whatever you want. Like to make many metal that are useful they need to be alloys, and finding a roid with everything you need?

You won't know till you dig, and I doubt it will be that convinient either. Given tgat roids are not like earth rock.

Like I can't write this off as completely impossible, but it certainly is nigh up there.

It's not self-replication in the context of microscopic things. It's self replication on an industrial scale - that is, using industry to self replicate industry. All you need to bring is a population to provide labor and the means of production for them to work on. If every space habitat has its own industrial block that can build another space habitat (with another industrial block) then said habitat can self-replicate, provided the population is large enough to provide the labor necessary and the needed inputs are provided. This isn't nanomachines, but rather more conventional machines (though adapted for use in the free fall environment if necessary).

So really it's a symbiosis of nonliving things and living things that work together to self-replicate, provided the right energy and material inputs. 

The only strict problem with orbital habitats is material resources. The fuel will be solar energy (or nuclear energy if necessary). Even then, with enough energy this problem becomes rather solvable by sourcing materials from places that have those materials. Some places will have everything in varying quantities and others won't. But to build a space habitat 95 to 99% of the mass will be shielding, so it can be basically anything. It's still desirable to place habitats near material sources though, in energy terms. So in orbit over a planet or large asteroid. Possibly bring some other asteroids with good resources nearby. 

On 8/17/2020 at 3:33 PM, Spaceception said:

My personal thoughts when it comes to building habitats, is that since those can be many tens of thousands or hundreds of thousands of tonnes in mass on the smaller end (If you want habitats that can hold hundreds to thousands of people), that is both a lot of upfront investment in resources before they can even settle in, and a lot of infrastructure that has to be developed and brought to that location to assemble those resources.
Once you have the habitat, you also need regular cargo delivery since there's no immediate resources to maintain the station and do useful work as if you were on a planet. So depot docks, and manufacturing bays will be needed. Both will be expensive to wholly maintain from Earth. Especially if habitats are around the Moon for example, because if Lunarians can't stay on the surface, they will need to live in habitats some of/most of the time. Having direct access to the Moon may be preferred if resources can largely come from there.

How is that any different from settlements on Earth? They need regular resupply as well. No space settlement should ever be considered to be an isolated system and no large human settlement should be expected to be entirely self-sufficient. Every settlement is but one part in a much larger whole, and should be considered as such. Even settlements that are sent to other planets to then self-replicate won't be completely isolated unless they're going on an interstellar voyage. In fact, you could send a cluster of settlements at once along with a decent cache of necessary resources to use while en route and shortly after arrival. No human settlement is ever completely self-sufficient. Even a Moon or Mars settlement would require the infrastructure to receive regular cargo and manufacture things. Not to mention large scale infrastructure to build the settlement.

Not only that but the vast majority of the mass of orbital habitats is just that: mass. It can be anything. This is because most of it is radiation shielding. So in terms of mass that provides living space, it'll likely be quite similar to the mass requirements for any settlement on a planet/moon, but this one can provide a full 1g. 

No one should live on the Moon. People can work there - to provide resources for orbital habitats and other purposes - but no one should live there. The gravity could be much too low for healthy development. But it can be a decent source of some materials. 

Space habitats are basically housing (with some more stuff but that's basically what they are). Resources can be gathered from other places, and manufacturing can be done either on a space habitat or wherever is convenient. But housing should be as comfortable and healthy as possible. These requirements necessitate 1g. And the only way to get that is rotation. This could also be done on a surface but that's highly complex in comparison and the surface itself limits expansion. So building such habitats in space would be the best option.

[Spacescifi]

3 hours ago, Bill Phil said:

Not necessarily. Certain planets would make excellent sources of raw materials like Mercury or Mars, provided civilization is suitably energy rich.

Actually using asteroids and comets as habitats isn't a great idea. It seems great at a surface level, but consider that asteroids aren't all that structurally sound. And even if they were, the amount of material that you'd excavate would be large enough that you could build more habitat space.

It's not self-replication in the context of microscopic things. It's self replication on an industrial scale - that is, using industry to self replicate industry. All you need to bring is a population to provide labor and the means of production for them to work on. If every space habitat has its own industrial block that can build another space habitat (with another industrial block) then said habitat can self-replicate, provided the population is large enough to provide the labor necessary and the needed inputs are provided. This isn't nanomachines, but rather more conventional machines (though adapted for use in the free fall environment if necessary).

So really it's a symbiosis of nonliving things and living things that work together to self-replicate, provided the right energy and material inputs. 

The only strict problem with orbital habitats is material resources. The fuel will be solar energy (or nuclear energy if necessary). Even then, with enough energy this problem becomes rather solvable by sourcing materials from places that have those materials. Some places will have everything in varying quantities and others won't. But to build a space habitat 95 to 99% of the mass will be shielding, so it can be basically anything. It's still desirable to place habitats near material sources though, in energy terms. So in orbit over a planet or large asteroid. Possibly bring some other asteroids with good resources nearby. 

How is that any different from settlements on Earth? They need regular resupply as well. No space settlement should ever be considered to be an isolated system and no large human settlement should be expected to be entirely self-sufficient. Every settlement is but one part in a much larger whole, and should be considered as such. Even settlements that are sent to other planets to then self-replicate won't be completely isolated unless they're going on an interstellar voyage. In fact, you could send a cluster of settlements at once along with a decent cache of necessary resources to use while en route and shortly after arrival. No human settlement is ever completely self-sufficient. Even a Moon or Mars settlement would require the infrastructure to receive regular cargo and manufacture things. Not to mention large scale infrastructure to build the settlement.

Not only that but the vast majority of the mass of orbital habitats is just that: mass. It can be anything. This is because most of it is radiation shielding. So in terms of mass that provides living space, it'll likely be quite similar to the mass requirements for any settlement on a planet/moon, but this one can provide a full 1g. 

No one should live on the Moon. People can work there - to provide resources for orbital habitats and other purposes - but no one should live there. The gravity could be much too low for healthy development. But it can be a decent source of some materials. 

Space habitats are basically housing (with some more stuff but that's basically what they are). Resources can be gathered from other places, and manufacturing can be done either on a space habitat or wherever is convenient. But housing should be as comfortable and healthy as possible. These requirements necessitate 1g. And the only way to get that is rotation. This could also be done on a surface but that's highly complex in comparison and the surface itself limits expansion. So building such habitats in space would be the best option.

 

I tend to agree with you on space habitats being the most viable option for a permanent presence in space.

However I also think it is quite possible from an engineering standpoint to create a 1g centrifuge on the moon's surface.

However the cons may outweigh the pros due to gravity losses via propellant EVERY time one delivers stuff there.

With space habitats you can afford to spend less propellant for shipping since everything  is weightless more or less.

 

EDIT: It would be nice if there were a such thing as a thin rad shield.

Even if heavy.

I once toyed with a scifi idea of fictional engineered metal that could absorb a ton of liquid hydrogen per cubic inch.

Called hydron. While spacecraft using it would be incredibly heavy and dense, the propulsion system would be exotic anyway... diametric drive.

A theoretical drive that would work very well in scifi.

Spoiler

https://www.daviddarling.info/encyclopedia/D/diametric_drive.html

 

Edited August 24, 2020 by Spacescifi

[kerbiloid]

Quote

Seven types of hypothetical space drives were suggested by Marc Millis of the Breakthrough Propulsion Physics Program at NASA's Glenn Research Center. Three are speculative and closely-related varieties of space sail: the differential sail, the diode sail, and the induction sail. The four others are the bias drive, the diametric drive, the disjunction drive, and the induction ring.

It's great that the NASA engineers propose actual things instead of freaking around.

[Nuke]

On 8/16/2020 at 9:48 PM, DDE said:

Or, to put it in other terms: where we're going we won't need planets.

i think its a good place for mining infrastructure though. also great for tunneling into for radiation shielding and thus capable of continuous habitation, perhaps with the addition of subterranean centrifuges. its escape velocity is a mere 510 m/s, so its great for launching construction materials and fuel into orbit. likewise more exotic ores from asteroids can be processed on the surface. eventually you will want to move this to orbital colonies. large sections of such a colony can be manufactured under ground in a shirt sleeve environment and launched in a mostly completed state with all of its structure and rad shielding in place and merely docked in orbit. 

On 8/16/2020 at 9:44 PM, Bill Phil said:

Eh. 

I’d forego any surface settlements at all. No real point to it. 

We can build orbital habitats instead. Once such a technology is mature they could even be used as vehicles to emigrate populations to other places. Settlements built with material from the Moon and some asteroids may find themselves in orbit over a far off planet. 

Ceres might make a decent destination for such an emigrating habitat - if it can self replicate and build more habitats at Ceres then it could be worthwhile. 

But to get to that point we’d need to develop orbital habitat technology.

a fully kitted out space colony built in earth-lunar space is going to be massive and hard to move to a good place in the belt. barring some serious advances in propulsion technology. 

Edited August 24, 2020 by Nuke

[Spaceception]

2 hours ago, Bill Phil said:

How is that any different from settlements on Earth? They need regular resupply as well. No space settlement should ever be considered to be an isolated system and no large human settlement should be expected to be entirely self-sufficient.

I may not have been clear enough. I do agree, Earth will be too big in population, resources, and energy not to have widescale interconnectedness, but I think autarky should be a soft goal for our space settlements, at least our first ones. There are a handful of nations that could achieve this already, the US included, despite having lots of international trade. And I think space settlements should be included in that group. The first part will be to just stop relying on basic imports from Earth, like food, water, and shelter. Then eventually things like energy, and essential medicines. Finally, working to make sure there's a large enough population to maintain and grow their infrastructure and nation so it doesn't break down at the first long gap in resupply.

2 hours ago, Bill Phil said:

Not only that but the vast majority of the mass of orbital habitats is just that: mass. It can be anything. This is because most of it is radiation shielding. So in terms of mass that provides living space, it'll likely be quite similar to the mass requirements for any settlement on a planet/moon, but this one can provide a full 1g. 

My point is that settlements on a planet can be modular. If they need more space, they can build new habitats as needed, and get them up and running. They don't have to build an entire city or large town for a few hundred people, or the shell of one. So the upfront time and cost isn't as sharp. I don't know of any concept to expand a rotating habitat as needed (since they'd probably need to stop the drum, which could become a problem), but if you know of any, I'd be interested to read about them. But I can see strings of small habitats being built as lunar settlements are developed, which can hold hundreds or thousands of people each.
How much would it take to build one of those, vs an equivalent planetary base? There needs to be a structure which can rotate stably without tearing itself apart, surrounded with radiation shielding, with internal levels where people can live. Only then can they pressurize and spin up. But now that I think about it, this could start out as a 0-g workshop, as a temporary bay for work to protect probes, and service satellites from potential debris. It can also prevent tools from being lost. Then once its finished, the bay is moved out, and the front is built over so it can be spun up.

 

[Spacescifi]

38 minutes ago, Spaceception said:

I may not have been clear enough. I do agree, Earth will be too big in population, resources, and energy not to have widescale interconnectedness, but I think autarky should be a soft goal for our space settlements, at least our first ones. There are a handful of nations that could achieve this already, the US included, despite having lots of international trade. And I think space settlements should be included in that group. The first part will be to just stop relying on basic imports from Earth, like food, water, and shelter. Then eventually things like energy, and essential medicines. Finally, working to make sure there's a large enough population to maintain and grow their infrastructure and nation so it doesn't break down at the first long gap in resupply.

My point is that settlements on a planet can be modular. If they need more space, they can build new habitats as needed, and get them up and running. They don't have to build an entire city or large town for a few hundred people, or the shell of one. So the upfront time and cost isn't as sharp. I don't know of any concept to expand a rotating habitat as needed (since they'd probably need to stop the drum, which could become a problem), but if you know of any, I'd be interested to read about them. But I can see strings of small habitats being built as lunar settlements are developed, which can hold hundreds or thousands of people each.
How much would it take to build one of those, vs an equivalent planetary base? There needs to be a structure which can rotate stably without tearing itself apart, surrounded with radiation shielding, with internal levels where people can live. Only then can they pressurize and spin up. But now that I think about it, this could start out as a 0-g workshop, as a temporary bay for work to protect probes, and service satellites from potential debris. It can also prevent tools from being lost. Then once its finished, the bay is moved out, and the front is built over so it can be spun up.

 

So basically this?

Spoiler

 

On the moon? 

[DDE]

53 minutes ago, Spacescifi said:

So basically this?

  Hide contents

On the moon? 

I'm more partial to this one, to be perfectly honest.

Spoiler

 

[Bill Phil]

4 hours ago, Spacescifi said:

 

I tend to agree with you on space habitats being the most viable option for a permanent presence in space.

However I also think it is quite possible from an engineering standpoint to create a 1g centrifuge on the moon's surface.

However the cons may outweigh the pros due to gravity losses via propellant EVERY time one delivers stuff there.

With space habitats you can afford to spend less propellant for shipping since everything  is weightless more or less.

 

It is possible. And it may be done one day. But it's something that is considerably difficult compared to orbital habitats.

3 hours ago, Nuke said:

a fully kitted out space colony built in earth-lunar space is going to be massive and hard to move to a good place in the belt. barring some serious advances in propulsion technology. 

Indeed. Such a project would be quite a challenge.

But it's a question of scale. Escape velocity in high Earth orbits can be on the order of hundreds of meters/sec. At 1 hundredth of a gee such a maneuver wouldn't take too much time. Of course, for a habitat (and some other stuff) massing around 50 million tonnes, that's still a lot of force. Something like 5 giganewtons. But again, that's a question of scale. We can use a huge cluster of rocket engines, or we could use mass drivers. Or perhaps some nuclear pulse drive system. Not too crazy, really. Indeed nuclear pulse drives generally work better at larger scales, though this doesn't apply to all such drives. Though one based on Mag-Orion could do it well, and at high ISP too. Though you wouldn't want it to use actual bombs. Doesn't seem any more advanced than the settlement itself to me.

2 hours ago, Spaceception said:

I may not have been clear enough. I do agree, Earth will be too big in population, resources, and energy not to have widescale interconnectedness, but I think autarky should be a soft goal for our space settlements, at least our first ones. There are a handful of nations that could achieve this already, the US included, despite having lots of international trade. And I think space settlements should be included in that group. The first part will be to just stop relying on basic imports from Earth, like food, water, and shelter. Then eventually things like energy, and essential medicines. Finally, working to make sure there's a large enough population to maintain and grow their infrastructure and nation so it doesn't break down at the first long gap in resupply.

Sure, there's a minimum degree of self-sufficiency. But what I was getting at is that the individual settlements themselves will be more akin to cities or even neighborhoods than nations. A nation-state could be capable of self-sufficiency, but could that be said of the cities within it? Or individual neighborhoods? As a whole system the space settlements and space based industries could be self sufficient, but individual settlements need not be. That's too much to ask. I think it's reasonable to expect them to grow their own food, but even that would require some regular inputs over time. 

2 hours ago, Spaceception said:

My point is that settlements on a planet can be modular. If they need more space, they can build new habitats as needed, and get them up and running. They don't have to build an entire city or large town for a few hundred people, or the shell of one. So the upfront time and cost isn't as sharp. I don't know of any concept to expand a rotating habitat as needed (since they'd probably need to stop the drum, which could become a problem), but if you know of any, I'd be interested to read about them. But I can see strings of small habitats being built as lunar settlements are developed, which can hold hundreds or thousands of people each.
How much would it take to build one of those, vs an equivalent planetary base? There needs to be a structure which can rotate stably without tearing itself apart, surrounded with radiation shielding, with internal levels where people can live. Only then can they pressurize and spin up. But now that I think about it, this could start out as a 0-g workshop, as a temporary bay for work to protect probes, and service satellites from potential debris. It can also prevent tools from being lost. Then once its finished, the bay is moved out, and the front is built over so it can be spun up.

Even settlements on a planet have a limit to their modularity. The question is what is the optimum size for a given module?

This is a limitation of orbital settlements, but it isn't a deal breaker. We can start small as we build up the infrastructure. Some rather small designs exist but still have reasonable populations. And over time the size of new colonies grows until we reach the optimum for size and ease of construction. 

There are concepts for expanding rotating habitats but I am not too familiar with them. However, it is definitely possible to inhabit a small portion of the colony and not pressurize the rest until you need it. Beyond that there are a few ideas where a cylinder can be lengthened while under rotation. I personally don't like that idea since it's overly complicated. 

It definitely requires more infrastructure, but I would argue that it's not that much more. The industry in space can be bootstrapped to an extent and once it reaches the necessary size building space colonies can be done without too much trouble. It's essentially a giant pressure vessel - and cylinders are well suited to having a huge number of identical parts. Once the industry reaches a certain point building a new colony could become easy enough that doing it for just a few hundred people isn't seen as a problem. Especially since you'd want to have a continuous production of colonies - maybe even with a stable population.

Don't get me wrong, using the Moon as a resource is definitely great. But I don't really think the Moon or Mars are suitable for human habitats. We can do much better with artificial environments built in space.

[Spacescifi]

52 minutes ago, DDE said:

I'm more partial to this one, to be perfectly honest.

  Hide contents

 

 

Where are the centrifuges? Those two domes are too small to house many 

[DDE]

6 hours ago, Bill Phil said:

Sure, there's a minimum degree of self-sufficiency. But what I was getting at is that the individual settlements themselves will be more akin to cities or even neighborhoods than nations. A nation-state could be capable of self-sufficiency, but could that be said of the cities within it? Or individual neighborhoods? As a whole system the space settlements and space based industries could be self sufficient, but individual settlements need not be. That's too much to ask. I think it's reasonable to expect them to grow their own food, but even that would require some regular inputs over time. 

Soviet industrial experience suggests it is quite possible to run a factory without supplying it with spare parts. This merely requires an inordinate investment into the repair department's machine shop - a better option than to wait through several years of red tape. This up to and included rigging replacement circuit boards.

Combine that with certain plants being so well known for quantity over quality that any equipment supplied by them was sent straight to garbage, and you get an explanation for the Union's ridiculously low productivity of labor and capital.

The point being, self-sufficiency is possible even on a relatively small scale. It can, however, be horrendously inefficient.

[kerbiloid]

14 hours ago, Spaceception said:

The first part will be to just stop relying on basic imports from Earth, like food, water, and shelter. Then eventually things like energy, and essential medicines. Finally, working to make sure there's a large enough population to maintain and grow their infrastructure and nation so it doesn't break down at the first long gap in resupply.

I would expect that all this will get possible when the serial fusion-powered autonomous space yachts will be available on eBay.
I.e. long before than a team of sociopaths can build a really autonomous Martian village.

So,

14 hours ago, Spaceception said:

settlements on a planet can be modular

will be an axiom.

The settlements will be trailer parks for yachts.

You live in your yacht for a half-year on Ceres, then move to Mars, etc.

11 hours ago, Spacescifi said:

Those two domes are too small to house many 

Depends on their military rank. The privates are pretty compressible.

Edited August 25, 2020 by kerbiloid

[DDE]

1 hour ago, kerbiloid said:

long before then a team of sociopaths can build a really autonomous Martian village.

Hey, don't judge my social distancing habits!

[CFYL]

15 hours ago, Bill Phil said:

Actually using asteroids and comets as habitats isn't a great idea. It seems great at a surface level, but consider that asteroids aren't all that structurally sound. And even if they were, the amount of material that you'd excavate would be large enough that you could build more habitat space.

Hmmm...

Yeah I agree that asteroids aren’t exactly stable. But excavations are not quite hard:

1. Push the digger in.

2. Dig a tunnel.

3. Throw out the dirt to space.

4. Reinforce the asteroid with steel (for moderate temperatures) or solid water ice (for extremely cold temperatures). Inserting long steel strings right at the “surface” of the tunnel.

Then people can live in the tunnel.

I haven’t learned deep into Physics, so I don’t know about the theory of relativity that well.

But I suggest:

Spoiler

Leave some tunnels vacant. Make sure they’re in a straight line.

Then build particle accelerators based on these tunnels. Supported by fusion reactors or electricity.

I suppose a length of about 20km is enough to move particles close to the light speed. Guess what?

You shoot them out, at high velocities. That is very high a specific impulse.

Then you have a source of propulsion. The TWR won’t be high, though.

Also, electricity isn’t needed so much, as in space it’s easy to keep cold, so make use of superconductors.

With Ceres, on the other hand, tunnels are much longer, so velocity can be really close to speed of light. So the particle gets a higher mass. Not sure if it would be significant.

 

 

 I only “think” about this thing, and I am open to criticism that this thing won’t work.

 

So with Ceres we basically can dig longer tunnels.