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#76 2019-10-14 12:21:13

SpaceNut
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Re: Colonizing / terraforming small asteroids

The issues for all locations aside from earth is using insitu materials and the chemistry to make use of them. These only change the reaction from the starting material source and the process methods to make what we would desire.

pg 11 of this shows the reactions for the moon of which if we have the same chemical make up we are using it in other locations.
https://ntrs.nasa.gov/archive/nasa/casi … 002987.pdf

What we are doing with the trials are finding which ones use the least energy or heat to provide the desired outcome for the element that we are trying to isolate from the inputs.

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#77 2019-10-15 15:33:41

Calliban
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Re: Colonizing / terraforming small asteroids

tahanson43206 wrote:

For Calliban ... this topic has languished for more than a month.

Please give it a boost with an insight about your chosen focus, or something related if you want to expand a bit.

(th)

Belter Lowda! I will rejoin this discussion soon.  Have been busy of late.


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#78 2019-10-15 18:25:42

SpaceNut
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Re: Colonizing / terraforming small asteroids

This one shows the thrusters in landing mode
images?q=tbn:ANd9GcRsOrk1ZsIg_dv3CKx_dBeHRsihBa2xaSRKa1sd0NHWmQTEwu1J&s

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#79 2019-10-15 18:34:49

tahanson43206
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Re: Colonizing / terraforming small asteroids

For SpaceNut re #78 ... thanks for finding that illustration!  Nice!

For Calliban re #77 ....

Thanks for the hint ... I was unaware of the existence of an entire branch of fandom!

https://expanse.fandom.com/wiki/Belter_Creole

As a creole language, lang Belta is primarily derived from English, with influences and contributions from languages of many different families, such as Germanic, Chinese, Romance, Indic, Slavic, and Niger-Congo.[3] Many of its words were derived from words or phrases in one or more of these languages.

I trust that Louis will absorb the message, that English (as we know it) will not survive far into the future.

It will become as Shakespearean English is today, an admirable curiosity.

(th)

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#80 2019-10-15 21:33:15

SpaceNut
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Re: Colonizing / terraforming small asteroids

Same tools for mars and other places

https://www.nasa.gov/centers/ames/engin … ature.html

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#81 2019-10-16 11:21:48

Calliban
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Re: Colonizing / terraforming small asteroids

Bad news regarding Apophis.  It appears to be an LL Condrite.  This is a breccia type material with no more than a few percent free iron.

https://en.m.wikipedia.org/wiki/99942_A … cteristics

The problem is that free iron is what platinum group metals, cobalt and nickel are dissolved within.  And they are the big paydirt when it comes to asteroid mining.  Really we need to be able to sell those things back on Earth, to at least subsidize the mission.

Last edited by Calliban (2019-10-16 11:23:00)


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#82 2019-10-16 12:50:04

tahanson43206
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Re: Colonizing / terraforming small asteroids

For SpaceNut re #80 .... That 2017 NASA web site sure does look close to what I was hoping for. Thanks!

For Calliban re #81 ... thanks for the link to that wiki article on Apophis. 

I noted this:

In July 2005, former Apollo astronaut Rusty Schweickart, as chairman of the B612 Foundation, formally asked NASA to investigate the possibility that the asteroid's post-2029 orbit could be in orbital resonance with Earth, which would increase the probability of future impacts. Schweickart also asked NASA to investigate whether a transponder should be placed on the asteroid to enable more accurate tracking of how its orbit is affected by the Yarkovsky effect.[35] On January 31, 2011, astronomers took the first new images of Apophis in more than 3 years.[36]

I hope that interest builds in placing such a transponder, because it would be understandable if the opportunity to place a probe on the object to collect detailed information about the material it contains.  The surface readings may reflect the contents of the entire object, but there might be material of value under the surface.

(th)

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#83 2019-10-26 15:58:15

Calliban
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Re: Colonizing / terraforming small asteroids

An energetically easy to reach asteroid with a diameter slightly less than 40m.

https://en.m.wikipedia.org/wiki/2000_SG344

This is small enough to enclose within a bag weighing just a few tonnes.  The asteroid weighs some 71,000 tonnes.  It would be interesting to plan a mission that could be carried out using a single heavy lift launch.

Last edited by Calliban (2019-10-26 17:20:40)


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#84 2019-10-26 18:01:24

Calliban
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Re: Colonizing / terraforming small asteroids

tahanson43206 wrote:

I hope that interest builds in placing such a transponder, because it would be understandable if the opportunity to place a probe on the object to collect detailed information about the material it contains.  The surface readings may reflect the contents of the entire object, but there might be material of value under the surface.

(th)

Agreed.  But without knowing it would be a leap of faith to commit resources to Apophis.  On the plus side, even iron magnesium silicates could be a valuable engineering material in Earth orbit.  Iron and magnesium are valuable metals and silicate materials can be used to produce semiconductor materials and basalt fibre.

It would be productive to consider options for reducing the required mass of the restraining bag needed to prepare Apophis for mining and colonisation.


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#85 2019-10-26 18:16:58

SpaceNut
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Re: Colonizing / terraforming small asteroids

No spectral data are yet available to shed light on its composition.

Mission planning will need this to show value for even going for other than a science mission.

It moves so far above and below Earth's orbit that the required change in velocity for a spacecraft to match its trajectory coming from Earth's would be 9.4 km/s, where as some other near-Earth asteroids require less than 4 km/s.

Earth, the escape velocity is about 11.2 km/s in which; escape velocity is v = sqrt(2GM/r). M is the mass of the earth, G is the gravitational constant, r is the earths radius, and v is escape velocity.

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#86 2019-10-27 07:33:41

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Calliban re topic in general, with a couple of questions:

First, have you had a chance to look at the YouTube video Louis posted about recently?  I'm wondering if you can see yourself as one of the trillionaires who are the focus of the story?  (I hope so)

Second, I had an idea recently that might fit into your bag concept.

However, the very persistence of vision that makes you so promising as a thought leader also guarantees that you will be disinclined to accept new information unless it matches perfectly with the existing vision.

In working with a person with those traits, I have found that a strategy that may allow new ideas to filter in is to ask the right questions.

To that end, I am curious to know how you are planning to fold your bag design for shipment from Earth in a cylindrical package.

(th)

Last edited by tahanson43206 (2019-10-27 11:08:46)

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#87 2019-10-27 10:35:32

SpaceNut
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Re: Colonizing / terraforming small asteroids

I would think that its going to be simular to the process that Bigelow uses to for the inflateable units which fit into the dragon truck for BEAM installation only on a larger scale. The bag for this has none of the inner workings that BEAM or other applications of an inflateable has so it should be easier to do.

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#88 2019-10-27 11:13:31

tahanson43206
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Re: Colonizing / terraforming small asteroids

For SpaceNut re #87 .... interesting idea, ...

My understanding is that Calliban's vision calls for a very thin fabric for his bag, since it is intended to encompass an entire asteroid. 

Planning for a mission along those lines would require computation of the spherical dimensions of the bag, and then deriving the mass of the material required to manufacture the bag.  With the mass number in hand, the mission planner can start to think about how to launch the package and deliver it to the target.

Related issues to be addressed would include deployment.  The Echo balloons were deployed by injecting gas into them, and they swelled up into spherical shapes which lasted for a time.  The asteroid bag could be inflated in such a manner, but the asteroid would not be inside the bag.

I'm hoping Calliban will address these issues and others that may come to mind as the forum audience considers the topic.

(th)

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#89 2019-10-27 12:31:58

SpaceNut
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Re: Colonizing / terraforming small asteroids

Earlier in the conversation the bag was wrapped around the asteriod but it evolved into a flat sheet that we can layer and seal around to using insitu material creation of the basalt fiber thread needed to weave around the asteriod. The after it would be slowly inflated to contain air but initially it was to keep the loose packed materials from leaving the asteriod as we work the small rock.

options
1. Bring heavy bag for encircling planetoid asteriod with an ability to automate and bag it robotically from earthnwhy mining the materials for use and export. Calculations were done ealier for a simular sized rock in topic for mass.
post #10 indicates

A 30m diameter restraining bag would weigh 2.6 tonnes

2. Bring a flat sheet approach to covering and seal the seems once its covering the asteriod from what was brought from earth to contain the loose asteriod why mining the materials for use and export. Calculations would not cchange all that much from what was done ealier for a simular sized rock in topic for mass only the means to seal.

3. Manufacturing the bag from insitu materials means loosing possibly some materials but allows for a reduction in shipped mass to be traded for the mining equipment which is still needed to allow for processing the basalt for fabication into the layers needed to wrap the asteriod.

Each has a different mass and need for deliverables for the operation to work.

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#90 2019-10-27 16:35:00

Calliban
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Re: Colonizing / terraforming small asteroids

I did not anticipate that an airtight bag would be a good idea.  Even if it started airtight; micrometeors would punch holes in it quite rapidly.  The idea was more about providing external compression to the asteroid, such that tunnels could be lined with a thin polymer membrane and pressurised without exploding a rubble pile asteroid.  Later, a strong enough bag would allow the asteroid to be spun to provide artificial gravity within the internal tunnels and voids.

I agree that ISRU is a good option for manufacturing the bag.  Given that it need not be airtight, a simple woven fibreglass would do the job.  Whilst a single sheet could be used, it might be more effective to use a number of hexagonal sections, connected using couplings that can later be tightened.  The purpose of the bag is to prestress the asteroid.

The larger the asteroid, the more important ISRU becomes.  For a small asteroid <100m in diameter, it is possible to use a heavy lift vehicle to deliver a Vectran bag to Earth orbit and then transfer the bag to its target using electric propulsion.  For anything much larger than 100m; the number of launches needed starts to grow excessive.

The feedstock for manufacturing the bag at target would be bulk silicates from the surface of the body.  This would presumably be melted, extruded into fibres and then spun into fabric.  Apophis, with its ll condrite composition would be a good candidate for this.  How it can be done, reliably on a low mass budget, is worth exploring.

Last edited by Calliban (2019-10-27 16:36:27)


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#91 2019-10-27 16:47:52

Calliban
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Re: Colonizing / terraforming small asteroids

Another potential candidate; about the right size (50m) and apparently in a suitable low delta-V orbit (0.81-1.01AU).

https://en.m.wikipedia.org/wiki/1999_AO10#

We could potentially begin by mining a small body like this using a restraining bag brought from Earth (which would weigh about 12 tonnes) and set up a bag factory (for want of a better phrase) within the excavated tunnels, where we would have access to a breathable atmosphere and artificial gravity (by spinning the asteroid) and could assemble the equipment and use excavated material as feedstock.  Hence, a bag manufactured from materials mined from 1999_AO10, could then be used to colonize a larger body like Apophis.  We could keep boot-strapping like this, using materials mined from one asteroid to begin settling another.  Start with tiny bodies and gradually build up to larger ones.

A 50m diameter asteroid like 1999_AO10, would mass around 150,000 tonnes, assuming a stony composition.  This is more than enough silicate material to construct a basalt fibre restraining bag for a 300m diameter asteroid like Apophis.  A 50m diameter asteroid has volume of 65,000m3.  If a sizable portion of this is excavated creating pressurised tunnels and voids; it would appear to provide ample space to set up manufacturing equipment for manufacture of new bags.  On this basis, only the very first bag would need to be lifted from Earth.  Presumably, this would be relatively small, with all subsequent bags for new missions being constructed in space from materials mined from asteroids.  With this in mind, it would be wise to begin with a very small asteroid, such that all of the equipment needed can shipped out using no more than a few heavy lifts, and preferably just one.

We would gradually mine the asteroid until it was just a thin shell of rock.  At this point, we would shift production elsewhere.

Last edited by Calliban (2019-10-27 17:08:47)


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#92 2019-10-27 17:51:35

SpaceNut
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Re: Colonizing / terraforming small asteroids

Another suggestion was to fill smaller bags with the scraps form the mining with which we would use them to create the meteorite shielding for the system to work and attach them to the outside cabling which is wrapped around the asteriods circumference. The cords would crisscross the asteriod allowing for the bags to over lap as the means to provide the barrier we need. One could wrap the entire asteriod again with another layer of insitu material blanket.

As usual the thoughts to make the tunnels that we have dug sealed such as to not leak the atmosphere we have built up possible by a Layers of fiberglass with epoxy reson would make for the hard shell to allow for the tunnels to hold there shape and becomed sealed.

You asked the question of how little can the mass of the production machinery for making the fiber. Which Robertdyck has posted about in a topic which we have and I will look for it and add that link to the conversation once found.

post #20 in "Underground vs Above Ground" (Both actually).
and again
post #12 for Rockwool in the same topic

PDT_003.gif

here is ISRU Polymers

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#93 2019-10-27 19:55:58

SpaceNut
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Re: Colonizing / terraforming small asteroids

NASA Asteroid 2019: 4 Asteroids, Including 393-Foot NEO, To Zip Past Earth Monday

NASA’s asteroid tracking system has detected four space rocks that are currently hurtling toward Earth. According to the space agency, one of the approaching asteroids is almost as big as the Great Pyramid of Giza.

The three are all different sizes and going at different speeds which makes picking them quite interesting to target if you are not planning for the chase in advance of starting a mission...

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#94 2019-10-28 11:07:34

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Calliban re topic in general ...

RobertDyck just posted about using Rhenium as a catalyst for removal of perchlorates from waste water on Earth.

Rhenium is (apparently) rare on Earth, but at the same time it appears (from Google results) to have many significant applications.

By any chance, have you found an asteroid (or other body) that has a measurable amount of Rhenium?

(th)

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#95 2019-10-28 11:13:27

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Calliban re topic in general ...

By now I've lost track of who said what in the forum recently, but since you've mentioned spinning asteroids more than once, I'd like to remind you of the inherent advantage of creating a torus inside the asteroid for artificial gravity.

Someone (I've forgotten who and it doesn't matter because they were wrong) expressed doubt about the practicality of building a rotating train inside such a torus.  However, several decades ago a gent named Barber patented a system for levitation of platforms on permanent magnets.  The dynamic magnetic levitation used by maglev trains around the world proves the practicality of the technology.  The wrinkle that Barber's patent provides is the nice option of setting a magnetic levitation train in motion without needing to expend energy maintaining the field. 

The principle of such an artificial environment is applicable to numerous off-Earth settings, of course, and not just asteroids.

Edit: I've seen the permanent magnet solution in a working high-school level science project.  However, in that instance, energy was expended spinning "feet" fitted with permanent magnets in order to cause them to interact with an aluminum plate floor.

The same principle would (I presume) work well if the magnet is moved relative to an aluminum coated floor.

(th)

Last edited by tahanson43206 (2019-10-28 11:16:02)

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#96 2019-10-28 13:04:59

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Re: Colonizing / terraforming small asteroids

As far as I'm aware, freefall doesn't have the same negative impacts on plant growth as it does on animals. Given the expense and complexity of centrifuges, it doesn't make much sense to incorporate farms (which take up a lot more than that cities do, here on Earth) into the non-freefall section of habitats.

A 500m diameter sphere would have a volume of approximately 60 million cubic meters, and 800 thousand square meters of surface area. If filled with 'air' (probably an O2/CO2 mix) at 50-100mb pressure, it would contain 6000 tonnes of air, which is a sizeable buffer for a small colony. Windows could let light in from the outside for the forest, or lights could be strung inside for the plants (which is what would probably be done further out than the asteroid belt - I'm thinking of the Trojans here). In the middle of the spheres would be the centrifuge towns, where people and their livestock would live. A 100m diameter ring that's 50m wide would have 1.5 hectares, enough space for a few hundred people. Spinning at 4rpm would give you 0.9g, dropping to 0.8g on the third floor/roof. You'd want to pair the ring with another, bringing it up to 3 hectares. Hopefully we'll be able to get away with less gravity, allowing us to drop the spin rate and/or diameter. 25m and 3rpm gives us 0.25g, and 0.75 hectares if scaled down in the other dimension. That's still a colony of over a hundred people, though.

In the outer solar system, the spheres could be built out of ice, using a plastic inflatable mould. Inflate with a little bit of gas, then pump water between the layers and let it freeze. The bag would mass on the order of 100 tonnes? Once the shell is established, it can be further worked on from the inside to insulate it and strengthen it for the full pressurisation. If in the Trojans, the colonies would be quite close to the others, maybe a few million kilometres from their neighbours. A chemfuel spaceship could make trips between them in weeks, even without tether assistance.


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#97 2019-10-28 14:21:25

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Terraformer re #96 ...

Your post contains several ideas which I find creative and certainly interesting!

Your vision of a rotating habitat inside an enclosed space reminds me of a series of stories published in Analog (ASF&F) several years ago. If the subject interests you, I'd be happy to try to find when the series was published.  It may well be available online for free at this point.  I thought the entire series was worked out very nicely, with lots of technical detail for the Analog audience, and plenty of story telling to go with it.

However, what I ** really ** like is your idea (which I have NOT seen before) of building a sphere out of ice.   While I am hoping someone on the forum with the required education will be able to compute the practicality of your idea, the first application that comes to mind is Calliban's plan to enclose asteroids in big bags.

On the assumption that water will freeze if sprayed on a surface in open space (in shade to prevent melting) I can easily imagine a robotic swarm making a sphere in (comparatively) short order.  In fact, a simulation of exactly that idea could (relatively easily) be rendered in an animation package, of which there are several candidates available.  I invite forum readers who have the necessary talent, and who may not be registered at the moment, to see if you can realize animation of the process.  That would be fun to see as a YouTube video (for example).

Your idea of using a form to provide a surface for freezing is also quite practical sounding (at least to me) but I'm not sure it is necessary, given the capabilities of robotics at this point in 2019.

(th)

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#98 2019-10-28 14:50:49

Terraformer
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Re: Colonizing / terraforming small asteroids

It's not about providing the surface (though that would still be necessary, to catch the ice that's sprayed on), it's about keeping the water liquid as the shell forms. That can't be done in a vacuum.

None of these are my ideas. The idea of ice spheres have been mentioned before on this forum. Five meters of ice provides the same amount of radiation shielding as the Terran atmosphere, so radiation isn't an issue inside them. If done right, they could even be transparent, allowing a view of the stars and making the habitat a large sphere filled with greenery. I'd call them terraria, but Kim Stanley Robinson already used that for hollowed out asteroid. Given the small size, perhaps vivaria works as a name. The purpose is to produce food, fibre, and oxygen. Like a Dyson tree, but not genetically engineered to take root in a vacuum.

There are hundreds of thousands of Trojan asteroids. There's opportunity for hundreds of thousands of independent colonies, with room for everyone. They may not even need fusion - big mirror farms and solar panels could still work, if scaled up 5 fold in each direction compared to Terra. But fusion does make things easier, and could bring trips between neighbouring habitats down to ~days rather than ~weeks. An 'isolated' spacestead could be a mere fortnight's travel from the big city.


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#99 2019-10-28 15:58:29

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 551

Re: Colonizing / terraforming small asteroids

tahanson43206 wrote:

For Calliban re topic in general ...

RobertDyck just posted about using Rhenium as a catalyst for removal of perchlorates from waste water on Earth.

Rhenium is (apparently) rare on Earth, but at the same time it appears (from Google results) to have many significant applications.

By any chance, have you found an asteroid (or other body) that has a measurable amount of Rhenium?

(th)

Some really excellent ideas here.  I will comment in more detail tomorrow.

Rhenium is a platinum group metal.  It is present as a natural alloying element in free iron within asteroids.  Overall platinum group concentrations are 100ppm.  That is about 20 times greater than Earthly platinum ores.

https://web.mit.edu/12.000/www/m2016/fi … roids.html


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#100 2019-10-28 16:16:30

Calliban
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From: Northern England, UK
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Posts: 551

Re: Colonizing / terraforming small asteroids

Terraformer wrote:

As far as I'm aware, freefall doesn't have the same negative impacts on plant growth as it does on animals. Given the expense and complexity of centrifuges, it doesn't make much sense to incorporate farms (which take up a lot more than that cities do, here on Earth) into the non-freefall section of habitats.

A 500m diameter sphere would have a volume of approximately 60 million cubic meters, and 800 thousand square meters of surface area. If filled with 'air' (probably an O2/CO2 mix) at 50-100mb pressure, it would contain 6000 tonnes of air, which is a sizeable buffer for a small colony. Windows could let light in from the outside for the forest, or lights could be strung inside for the plants (which is what would probably be done further out than the asteroid belt - I'm thinking of the Trojans here). In the middle of the spheres would be the centrifuge towns, where people and their livestock would live. A 100m diameter ring that's 50m wide would have 1.5 hectares, enough space for a few hundred people. Spinning at 4rpm would give you 0.9g, dropping to 0.8g on the third floor/roof. You'd want to pair the ring with another, bringing it up to 3 hectares. Hopefully we'll be able to get away with less gravity, allowing us to drop the spin rate and/or diameter. 25m and 3rpm gives us 0.25g, and 0.75 hectares if scaled down in the other dimension. That's still a colony of over a hundred people, though.

In the outer solar system, the spheres could be built out of ice, using a plastic inflatable mould. Inflate with a little bit of gas, then pump water between the layers and let it freeze. The bag would mass on the order of 100 tonnes? Once the shell is established, it can be further worked on from the inside to insulate it and strengthen it for the full pressurisation. If in the Trojans, the colonies would be quite close to the others, maybe a few million kilometres from their neighbours. A chemfuel spaceship could make trips between them in weeks, even without tether assistance.

A very interesting idea.  Given that the shell has negligible gravity, convection within it would also be negligible as a heat transfer mechanism.  This would allow a thermal gradient to form, whereby the air at the centre of the sphere is warmer than the air at its surface.  The centre of the sphere could be warm without the risk of melting the sphere.


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