What is the status today of O'Neill's vision today?

Void · 2016-09-17 17:12:14

I guess that's why we communicate, because someone else may think of something more. Yes, ideas. But I will let you champion your own interests.

As for myself, I asked for the gravitation of Ceres, as an arbitrary selection originally. Might as well find out what is a tolerable or ideal gravitational environment for working, particularly with large objects. Yes indeed.

For my part now, however, I see that we have some options to support. Luna & Ceres, or Mars, or Venus.

One of these schemes is likely to be the winning ticket, if effort is applied to it.

For Mars, I have misgivings. I have long had a conspiracy suspicion that the reason that our space program was diverted from the Moon to Mars, was that the conspirators were worried that we were getting too close to success. With Mars, they have options to cut the process short, either by claiming the protection of life, or by cutting the budget, or arranging for a dead crew.

Of course that is the paranoid view. It would require a class of people who live by manipulating populations, and their objective in this case would be to capture the spinoffs of the process, but to cut short the process when it threatened to set their servant class free from their power.

And I am not totally paranoid, I just list it as a possible reality.

So, the cycling spaceship proposed with Ceres & Earth/Mars/Moon synthetic gravity, would be a purpose in itself, but could also be assistive in settling Mars itself, if that is allowed, or if Mars is said to have life, it could allow human access to the moons of Mars to study that life on Mars.

But it would also study how to use Luna & Ceres, if Mars is ruled off limits for humans.

Ceres itself appears to not be as I thought it would be.

Instead it is not completely differentiated, so the crust it seems may be 60% soil/rock & 40% ice.

And its materials include Nitrogen.

So, Ceres has a very large palate of the materials one would want in space.

Therefore, in considering O'neill machines, perhaps one should consider all possible understood future options, or as much as possible.

If you could do the Ceres & Earth/Mars/Moon gravity synthesis on such a cycling spaceship then you could also do it on Ceres, but you would not need synthetic gravity for Ceres itself, since it supplies that. You would instead want a network of double torus devices with Earth/Mars/Luna synthetic gravity, and greenhouses under Ceres ambient natural gravity.

It should not be forgotten how relatively easy it would be to export materials from Ceres, once humans were established there.

For instance Ice. I have no references, but I believe that you can crash a block of ice onto the Moon on the dark side at very high speed, and probably 60% of it will remain long enough to be collected.

Therefore if we are blocked from using Mars, Luna & Ceres would be quite a good objective. And cycling spaceships? Why not?

Last edited by Void (2016-09-17 17:28:45)

Tom Kalbfus · 2016-09-17 18:51:52

You ever see this movie?
http://www.bing.com/videos/search?q=O%2 … ORM=VDFSRV
What do you think? It is a variation on O'neill's idea with artificial illumination of the interior. I wonder how close one can get to those light sources without getting fried? My guess is they are giant florescent light tubes or LEDs, what do you think? In the middle of it is a model of the island of Manhattan and its surrounded by countryside. Not a soul is to be seen, although the fields appear to be cultivated. One can see the Twin towers in the model of Manhattan.

Void · 2016-09-17 19:08:04

That is certainly a good dream, and so it would seem your heart has value.

Strange, you have New York +, and also wide spread farm fields as some of your re-occurring notions, your reference points.

My background has to do with figuring out how to run your life without extreme guidance from a hiearchy.

That in theory is how Americans are supposed to be. Some of our highest politicians seem to love to criticize people like me because we do not want to associate with predatory cultures such as the very old world. (Those cultures in my opinion only run on hierarchy). To me they are deadly poison. Like being forced to co-exist with rotting corpses of the living dead.

I suppose I had better get to a point.

In my mind there is no chance that the sort of people we are dealing with as enemies these days would leave such a machine unmolested. They are creatures that crave power and control. So, a wonderful dream, but only if somehow you can keep the demons out.

It is a wonderful aspiration however!

And that is why I prefer smaller work oriented machines, where a small community pulling together to accomplish a profitable living. Such communities are less likely to foster degenerates of the sort that crave control of large populations. Rather such an environment will favor people who manipulate physical objects for profit, not other people.

Last edited by Void (2016-09-17 19:29:56)

Void · 2016-09-17 22:13:08

And terraformer said before our B.S. Avalanche:

Before all that, I'd like to find out how much gravity is required for plumbing to function normally. Now *there's* something we can do using parabolic flights, without needing to go into space at all.
If it turns out 0.1g is sufficient to be make a lot of things significantly easier to do, even if it doesn't provide much health benefits, then we could look at sending some small, ~8m diameter centrifuges to whatever space station we're using at that time.

A very important question terraformer. That, and what is the need to maintain health benefits.

The ideal work place gravity field.

Tom Kalbfus · 2016-09-18 06:02:18

Void wrote:

That is certainly a good dream, and so it would seem your heart has value.
Strange, you have New York +, and also wide spread farm fields as some of your re-occurring notions, your reference points.
My background has to do with figuring out how to run your life without extreme guidance from a hiearchy.
That in theory is how Americans are supposed to be. Some of our highest politicians seem to love to criticize people like me because we do not want to associate with predatory cultures such as the very old world. (Those cultures in my opinion only run on hierarchy). To me they are deadly poison. Like being forced to co-exist with rotting corpses of the living dead.
I suppose I had better get to a point.
In my mind there is no chance that the sort of people we are dealing with as enemies these days would leave such a machine unmolested. They are creatures that crave power and control. So, a wonderful dream, but only if somehow you can keep the demons out.

You are not going to build this without Artificial Intelligence, there is a reason why the streets are vacant, and the landscape is empty, humans haven't moved in yet! That is why at the end of the movie, you see a space shuttle approaching.

It is a wonderful aspiration however!
And that is why I prefer smaller work oriented machines, where a small community pulling together to accomplish a profitable living. Such communities are less likely to foster degenerates of the sort that crave control of large populations. Rather such an environment will favor people who manipulate physical objects for profit, not other people.

Void · 2016-09-18 07:34:27

Well Tom, this will be a pointless argument if we go down that path.

We do not really know what A.I. will be like. Therefore your assertion that it will comprise a benovelent and competent protector of such a giant machine is not testable at this time and all we really could do is make tiresome counter assertions.

I will say that even now computers are hacked.

Also when multiple life forms interact, they always seem to split into groups, and eventually one group becomes the prey, and the other the predator.

But again we do not know what such A.I. will be like. If they are not like humans, then they might behave in an insane manner from our perspective, and that could be quite dangerous to the continuation of our patterns. If they are like humans, what have you gained?

I don't think I will talk on this subject anymore because the argument presented is untestable at this time. It would be an exasperating interaction. Already is.

Terraformer;

I suggest you start a new topic dealing with your question on the ideal work functional (Plumbing) synthetic gravity. Otherwise it will just die here.

Last edited by Void (2016-09-18 07:39:13)

Tom Kalbfus · 2016-09-18 09:47:01

I'll just say this, if AI destroys us, then all the talk about building space colonies will be moot, if it does not, then they'll be needed, even Gerard O'Neill assumed as much. He assumed that his larger colonies would be build with robotic workers and that he population density would go down as a result, and that was back in the 1970s when he said this, he said that his O'Neill Cylinder Island Three could support a population of up to ten million people, but because of all the robot labor involved in its construction, it probably wouldn't have to, that is also why his colonies, when depicted in art have that "suburban feel."

space.colony.jpg
This is not a teaming metropolis you see here. Who would build such a thing? You see a town off in the distance. I think if it was built entirely by humans, it would b jam packed with skyscrapers, you wouldn't get such a rural landscape as depicted here.
The top one is similar to the cylinder depicted in Rama.

Last edited by Tom Kalbfus (2016-09-18 09:51:17)

GW Johnson · 2016-09-19 08:24:50

Addressing the issue raised by Terraformer: how much gravity is required to make conventional infrastructure like toilets work?

Without actually having attempted such, I think it's a matter of time constant you can tolerate. The dynamics and fluid dynamics of all sorts of processes slow down in low gravity. We've already seen a little bit of this during the moon landings.

In a water treatment operation for example, the bubbling and settling operations are going to need much larger exposure or residence times as gravity weakens.

Such things would be very slow on Ceres with 2% class gravity, but if you can tolerate the slowness, conventional stuff should work even there. If in some process, slowness is intolerable, then you have to devise something that will accomplish the function some other way.

GW

Tom Kalbfus · 2016-09-19 09:24:57

On Ceres you would need much bigger toilets to generate the water pressure under 2% gravity. Also under low gravity toilets would flush more slowly, you would need more water to get the same job done of removing the waste. I rather think it would get quite messy with water and fecal matter splashing out of the bowl in slow motion when you flushed it! You probably would need a deeper bowl so the water and what you put into it wouldn't splash out!

Void · 2016-09-19 12:11:02

Nice.

I guess we want to segregate our eating, breathing, and emissions behaviors. In this case, it is a good thing to do.

Ceres if rehearsed with O'neill artificial hab methods, would reveal if Ceres itself could be successfully and prosperously habituated.

It could also contribute to the distribution of humans to Venus and Mars and Luna as well.

So, I am interested in a two level synthetic gravity for such artificial habs.

If it works out, then perhaps a great deal of the surface of Ceres could be simply habed, with some of it being natural Ceres gravitation, and some with multiple centrifuge rings, linked together, to allow a very flexible life style for the inhabitants.

Such a Ceres, if possible/practical, could become a hub for an early solar system civilization.

A place for human spiritual growth as well, I think if the material needs are satisfied.

Last edited by Void (2016-09-19 12:21:36)

Antius · 2017-05-15 08:13:46

O'Neill's vision for solar power satellites is the only remotely plausible suggestion I have seen for space colonisation. Not because of the enormous space colonies he proposed, but because it involved producing something that could be sold to folks back on Earth, something that had enough value and sales volume to fund the sorts of investment needed.

O'Neill's vision is more plausible today than it was in 1976. As a start-up, the lunar side of the operation could be largely automated or teleoperated. It could start small and gradually increase in scale as more money comes in. The most massive component of the lunar base is the power supply to the mass driver. Space solar power systems are much lighter now. According to Louis' recent information, power-weight for solar power may soon exceed 1Kw/kg. Mass drivers would also benefit from super-capacitors.

The space based operation would also be a lot more streamlined. In 1976, O'Neill was talking about building solar dynamic power plants which would have required a lot of moving parts and working fluids. A 10GW station would have weighed a hundred thousand tonnes. Now, the satellites would be thin film PV, would have a minimum of moving parts and a 10GWe satellite would weigh perhaps 10,000 tonnes.

The mega fantasy space colonies are something for further into the future. In the near term, an SPS manufacturing operating can be started as a relatively small scale effort, using compact facilities making use of 3D printing of simple repeatable components. Build-up of facilities can occur incrementally as more SPS sales come in.

Last edited by Antius (2017-05-15 08:40:21)

Terraformer · 2017-05-15 12:45:12

I wonder if very thin film solar cells could be used with coverings manufactured from Lunar resources? So Lunar glass would be used to protect them from degradation, with the only thing being imported from Terra being the ultra-thin cells which would be attached to the rest of the satellite in orbit.

RobertDyck · 2017-05-15 13:30:55

Antius wrote:

O'Neill's vision for solar power satellites is the only remotely plausible suggestion I have seen for space colonisation. Not because of the enormous space colonies he proposed, but because it involved producing something that could be sold to folks back on Earth, something that had enough value and sales volume to fund the sorts of investment needed.

Solar Power Satellites are a dumb idea that has already been debunked. Sorry.

Start by asking: Why space? Why not solar power on Earth? The advantage to space is no clouds and no night. But the best power transmission technology has been able to deliver 30% of power transmitted. Solar power on Earth can do just as well. On Earth there's no power from solar roughly 50% of the time due to night, and more power loss due to clouds. That results in about the same. Building a solar power system on Earth requires a truck to deliver parts, and repairs require a technician in clothing driving a pickup truck. Building one in space requires a multi-million dollar launch vehicle, and repairs require an astronaut in a spacesuit delivered via spacecraft launched by another launch vehicle. Ground based solar is a lot more cost effective.

Next look at technology. I keep talking about a paper I read in year 2000. A US federal government laboratory called the Los Alamos National Laboratory did a theoretical study and found a new photovoltaic chemistry that should have a solar absorption spectrum that almost perfectly matched the Sun. So it should be extremely efficient. They looked for someone to build one for them, so they could see if reality matched their theory. They went to the materials lab at the University of California in Berkeley. They found it does work, and it's transparent to any frequencies of light (colours) that it doesn't convert to electricity. That shouldn't be a big surprise considering space photovoltaics already use 3 junctions (sub-cells), the top 2 are transparent to colours they don't absorb. The top junction of current space cells is gallium-indium-phosphate, this new one is gallium-indium-nitride, so only the doping agent is different. Furthermore, the absorption spectrum can be shifted by using a different concentration of nitride. Current space cells use a different chemistry for each junction (sub-cell), but this new one allows each sub-cell to use the same chemistry, just a different concentration. U.C. Berkeley found a 2 junction cell produces 56% conversion of sunlight to electricity, 3 junction 64%, and 36 junction 72%. Another scientists studied this and produced optimized junction combinations for 2 through 8 junctions. He found the same results for 2 and 3 junctions, and 8 junctions would produce 70.2%. One excuse this hasn't been developed is implanting nitrogen deeply enough into the cell, but every blue LED is gallium-indium-nitride just with a different configuration. And every white LED is actually 3: red, green, blue. So every LED light you have already has this, implanting nitrogen has already been solved.

Build a house with the entire roof as one big solar array. Not just a couple small solar panels attached to the roof, the solar array *IS* the roof. Include a geothermal heat pump (aka ground source heat pump), windmill, batteries, and the house is 100% energy independent. Size the system for the worst case in that city or location, the rest of the year the house will sell surplus power to the grid. So no heating bill, no electricity bill, instead the power utility pays the home owner. This won't work in high-rise buildings such as apartment buildings or downtown office buildings, but those are the customers who will buy the power.

This is far more practical than solar power satellites.

Antius · 2017-05-18 08:27:37

RobertDyck wrote:

Antius wrote:
O'Neill's vision for solar power satellites is the only remotely plausible suggestion I have seen for space colonisation. Not because of the enormous space colonies he proposed, but because it involved producing something that could be sold to folks back on Earth, something that had enough value and sales volume to fund the sorts of investment needed.
Solar Power Satellites are a dumb idea that has already been debunked. Sorry.
Start by asking: Why space? Why not solar power on Earth? The advantage to space is no clouds and no night. But the best power transmission technology has been able to deliver 30% of power transmitted. Solar power on Earth can do just as well. On Earth there's no power from solar roughly 50% of the time due to night, and more power loss due to clouds. That results in about the same. Building a solar power system on Earth requires a truck to deliver parts, and repairs require a technician in clothing driving a pickup truck. Building one in space requires a multi-million dollar launch vehicle, and repairs require an astronaut in a spacesuit delivered via spacecraft launched by another launch vehicle. Ground based solar is a lot more cost effective.
Next look at technology. I keep talking about a paper I read in year 2000. A US federal government laboratory called the Los Alamos National Laboratory did a theoretical study and found a new photovoltaic chemistry that should have a solar absorption spectrum that almost perfectly matched the Sun. So it should be extremely efficient. They looked for someone to build one for them, so they could see if reality matched their theory. They went to the materials lab at the University of California in Berkeley. They found it does work, and it's transparent to any frequencies of light (colours) that it doesn't convert to electricity. That shouldn't be a big surprise considering space photovoltaics already use 3 junctions (sub-cells), the top 2 are transparent to colours they don't absorb. The top junction of current space cells is gallium-indium-phosphate, this new one is gallium-indium-nitride, so only the doping agent is different. Furthermore, the absorption spectrum can be shifted by using a different concentration of nitride. Current space cells use a different chemistry for each junction (sub-cell), but this new one allows each sub-cell to use the same chemistry, just a different concentration. U.C. Berkeley found a 2 junction cell produces 56% conversion of sunlight to electricity, 3 junction 64%, and 36 junction 72%. Another scientists studied this and produced optimized junction combinations for 2 through 8 junctions. He found the same results for 2 and 3 junctions, and 8 junctions would produce 70.2%. One excuse this hasn't been developed is implanting nitrogen deeply enough into the cell, but every blue LED is gallium-indium-nitride just with a different configuration. And every white LED is actually 3: red, green, blue. So every LED light you have already has this, implanting nitrogen has already been solved.
Build a house with the entire roof as one big solar array. Not just a couple small solar panels attached to the roof, the solar array *IS* the roof. Include a geothermal heat pump (aka ground source heat pump), windmill, batteries, and the house is 100% energy independent. Size the system for the worst case in that city or location, the rest of the year the house will sell surplus power to the grid. So no heating bill, no electricity bill, instead the power utility pays the home owner. This won't work in high-rise buildings such as apartment buildings or downtown office buildings, but those are the customers who will buy the power.
This is far more practical than solar power satellites.

Robert, I cannot comment on your information regarding recent solar cell improvements, as I am not familiar with multi-junction research. But your assessment of microwave power transmission is somewhat subjective.

The efficiency of beamed microwave power transmission is a function of the relative sizes of the antenna and rectenna, their distance apart and the frequency of beam. A frequency of 2.45GHz appears to be optimum in terms of minimising interaction with Earth’s atmosphere, but requires a relatively large rectenna (~10km in diameter) in order to avoid efficiency loss due to beam diffraction. Because of these variables, the transmission efficiency through the Earth’s atmosphere is dependent upon the scenario. This Chinese reference estimates transmission efficiency to be ~66%.

http://www.sciencedirect.com/science/ar … 6516310013

An experiment carried out by Raytheon under the supervision of JPL in 1973, demonstrated a DC-to-DC conversion efficiency of 54%.

http://ieeexplore.ieee.org/document/113 … eload=true

Whilst transmission losses are relatively high, it must be remembered that only about 60% of sunlight hitting the top of Earth’s atmosphere reaches the surface, about 70% across the visible spectrum. So arguably, the real efficiency of an SPS is about 80-90% of the same solar power system on the ground.

There are three big advantages that an SPS has over a ground based system:
1. It is in full sunlight for 99% of the time. It therefore gathers roughly three times as much solar energy as the equivalent area of panels at Earth’s equator. For a North European country, it would be exposed to 8-12 times as much energy in 1 year. If dynamic cycles are used, the advantage is greater still.
2. There is no intermittency, aside from the 1% of time in Earth’s shadow. That is a major advantage, as renewable energy systems here on Earth require a combination of energy storage (which is inefficient) or back-up power, which basically means having a whole extra power station on standby to cover the downtime. With the SPS, some 72 minutes of back-up would be needed and it would be required at predictable times. Open cycle gas turbines can do this cheaply and with negligible impact on whole system efficiency.
3. In space, without wind or gravity, the structure of the power plant can be relatively slender.

Collectively, these advantages are significant. But the economics of the concept clearly rely upon the ability to use extra-terrestrial resources for manufacture of the satellite.

Last edited by Antius (2017-05-18 08:30:26)

Mars_B4_Moon · 2023-02-22 20:49:49

A legend Bible story or Noah's Ark Tevat Noaḥ

Only a Scifi concept and Space Art?

O’Neill Cylinder Space Settlement
https://space.nss.org/o-neill-cylinder- … ettlement/

Norway's 'Noah's Ark' seed vault chalks up a million crop varieties
https://www.thelocal.no/20180227/norway … varieties/

A Bizarre Study Says People Can Live in Asteroids. It's Actually a Brilliant Idea.
https://www.popularmechanics.com/space/ … cylinders/

Mars_B4_Moon · 2023-03-19 00:15:23

'Muscle Scans, Bone Study Cleanup as Next Spacewalk Nears'

https://blogs.nasa.gov/spacestation/202 … alk-nears/

'Artificial Gravity Space Stations Just Got One Step Closer To Reality Thanks To Vast Space'

https://www.slashgear.com/1206172/artif … ast-space/

Today, one solution to zero gravity involves rotating the facility that a team might live and work in. This would provide a centrifugal force that mimics the gravitational pull that an individual feels while tethered to the ground beneath their feet. This option has been rendered in science fiction, but it's often seen in gigantic ships traveling between solar systems. This use in the arts is grounded in the fact that the larger a spinning object is, the slower it has to move to create the binding force required to fake internal gravity.
Therefore, a relatively small space station would have to spin rapidly to deliver this sensation, rendering it virtually useless and potentially inducing sickness in the crew. Another option is through electromagnetic charges that move around a field. This might be best visualized in the gravity boot concept for science fiction characters. However, this option doesn't defeat the gravity-dependent body liquid problem. One very real bodily problem can already be seen in ISS astronauts who come home with eye troubles.
Vast Space's acquisition is sure to infuse the bolstered company with a new spark of energy as the team pursues grants within NASA's Commercial low Earth orbit Development program (CLD). Jed McCaleb has set his sights on the next phase of space exploration rather than the problem of "getting out there" in the first place. "For me, the compelling thing is to push humans out into the solar system," he told TechCrunch. For Max Haot's part, he notes that his team was highly motivated to merge operations. "Our Launcher team jumped at the chance to join Jed's vision of moving beyond Earth and advancing humanity's exploration of space," he offered in the press release from Vast.

Last edited by Mars_B4_Moon (2023-03-19 00:17:23)

Calliban · 2023-03-20 09:21:41

If Starship can indeed be scaled sufficiently to reduce launch costs to $2million for a 100te to LEO payload, then I would say O'Neill's vision would be credible. What killed it was the failure of space shuttle economics. The O'Neill vision would have required tens of thousands of tonnes of people and equipment to be delivered to High Earth Orbit and lunar surface. The $30,000/kg launch cost of the shuttle, left his plans dead on the ground. If Starship does indeed become the cheap reusable launcher that Musk anticipates, then it could be the key enabling technology for a HEO industrial revolution. Needless to say, having HEO manufacturing industry based upon lunar materials would do wonders for Mars colonisation. We could build interplanetary liners propelled by mass driver engines.

Ironically, Musk has been critical of Bezos vision for a HEO industrialisation. The Bezos vision is essentially the O'Neill vision. Despite his objections, Musk's rocket could be the key enabling technology for what Bezos has in mind.

Last edited by Calliban (2023-03-20 09:24:47)

tahanson43206 · 2023-03-20 09:39:05

For Calliban re #117

For readers of your posts who might not be familiar with the history of the interaction that may have occurred between Jeff Bezos and Dr. O'Neill, here is a snippet Google found that may set the stage for further investigation if anyone is interested.

In 1976, four years before Bezos arrived on campus, Princeton physicist Gerard K. O'Neill published a book detailing plans to move into space — "The High Frontier." Bezos attended some of O'Neill's seminars.Oct 29, 2021

I can confirm from personal experience that Dr. O'Neill was a charismatic leader who inspired creation of the Space Studies Institute, and inspired a number of conferences on Space Manufacturing held at Princeton University.

Hopefully other NewMars members will contribute snippets or perhaps personal recollection of the many individuals who were inspired by Dr. O'Neill, and who went on to become leaders in various aspects of the space movement.

(th)

Void · 2023-03-20 19:29:04

That is very impressive (th).

I have a feeling that over time the concept of Mars Direct and Moon Direct will merge with the O'Neill Vision.

We have several big hitters doing big things. They each have their own peculiarities but that is a good thing.

Elon Musk has several activities that can relate, ships and robots.
Jeff Bezos has had a lot of put down for Blue Origin, but I do respect that they figured out how to make solar panels from Moon materials.
Strangly Bill Gates seems to back the new type of method, that Stokes Space is trying. And he is into high temperature solar mirrors, and also nuclear reactors.
Relativity Space is doing Terran-R.
Rocket Lab is working towards the Neutron. I am wondering if that could eventually give birth to a larger vehicle in some years hence.

So, really good chances to have the right tools to do Mars, the Moon, and the Asteroids, and also of course space platforms.

Done.

Last edited by Void (2023-03-20 19:36:00)

Mars_B4_Moon · 2023-08-08 06:35:02

A New Paper Shows How To Change An Asteroid Into A Space Habitat – In Just 12 Years

https://www.universetoday.com/162697/a- … -12-years/

The basic idea of turning an asteroid into a rotating space habitat has existed for a while. Despite that, it’s always seemed relatively far off regarding technologies, so the concept hasn’t received much attention over the years. But, if you’re retired and have an underlying interest in researching space habitats, developing a detailed plan for turning an asteroid into one seems like a great use of time. And that is precisely what David W. Jensen, a retired Technical Fellow at Rockwell Collins, recently did. He released a 65-page paper that details an easy-to-understand, relatively inexpensive, and feasible plan to turn an asteroid into a space habitat.

tahanson43206 · 2023-08-08 07:12:41

For Mars_B4_Moon re #120

Thanks for the link to the article about the work of David W. Jensen ....

The use of glass to make structural elements able to sustain the air pressure inside the torus, and to hold the entire structure together against the force of 1 G of artificial gravity is one I've not seen before.

It is possible the source paper provides engineering detail to support that conjecture.

I'd appreciate seeing someone's report on the actual paper, if anyone has time to investigate.

(th)

Calliban · 2023-08-10 03:12:45

tahanson43206 wrote:

For Mars_B4_Moon re #120
Thanks for the link to the article about the work of David W. Jensen ....
The use of glass to make structural elements able to sustain the air pressure inside the torus, and to hold the entire structure together against the force of 1 G of artificial gravity is one I've not seen before.
It is possible the source paper provides engineering detail to support that conjecture.
I'd appreciate seeing someone's report on the actual paper, if anyone has time to investigate.
(th)

The old L5 society did some research into the development of glass-glass composites. The basic idea is to have high melting point ceramic fibres embedded in a matrix of lower melting point glass. These composites can be enormously strong. But the glass matrix remains brittle. The fibres serve the additional function of interupting crack growth.

The composites could function as tensile members. But the design needs to allow inspection and incremental replacement of these members.

The other option is to use iron to make a tensile shell. This is ductile and has a forgiving stress cycle. Iron is abundant in most asteroids. It is also easy to reduce. You start with a mass of iron oxide rich powder and blow hydrogen or carbon monoxide through it at 900°C. Reduced iron can then be removed with a magnet. Put the reduced iron powder into an electric arc furnance, melt it and blow oxygen through it using a lance, to burn off sulphur, phosphorus, hydrogen and other impurities. Add a little carbon powder to the melt and you have carbon steel.

Last edited by Calliban (2023-08-10 03:17:10)

tahanson43206 · 2023-08-10 06:18:51

For Calliban re #122

Thanks for your explanation for how glass might be used for tensile members in a rotating habitat.

Jensen's proposal is to make a specific habitat from a specific asteroid, which (apparently) contains no iron.

Perhaps iron can be procured from another asteroid.

Someone in the forum could help the discussion by taking the time to read the actual 65 page paper.

In the absence of knowledge of the specific proposal, we are speculating.

Update after preliminary visit with the paper (dated February 2023)...

Glasses and ceramics generally work well under compressive loads but not well under tension stress. It may be possible to reinforce glass structures with asteroidal nickel-iron
steel and enhance them to withstand a wide range of both
tension and compression. This complexity may not be necessary with the additional tensile strength produced with the
anhydrous, vacuum-produced glass [Blacic 1985] [Prado and
Fraser 2018]. Glass produced in the absence of hydrogen or
water has significantly better mechanical properties [Prado
and Fraser 2018]. It may be possible to substitute this glass
for structural metals [Blacic 1985] [Carsley, Blacic, and
Pletka 1992] [Soilleux 2019]. This glass is called anhydrous
glass. On Earth, water and hydrolysis weakens the strength
of the silicate bonds by about an order of magnitude [Blacic
1985]. Production on the asteroid will be in a hard vacuum
and water is extremely limited. Quickly cooling this glass
could further increase the tensile strength [Yale 2013]. Researchers believe it may be possible to substitute this anhydrous glass for structural metals in a variety of space engineering applications [Blacic 1985]. They note that this glass
would be competitive or superior to metals [Carsley, Blacic,
and Pletka 1992]. A study in 2012 found that anhydrous glass
could attain a tensile strength of 13,800 MPa [Bell and Hines
2012]. A 2019 report claims a bending strength of over 100 (quote stopped here)

The author proposes to capture any metal atoms that may be present, for more important uses than structure.

Examples of such higher priority uses would include electronics and the robots that are intended to self-replicate in order to carry out the ambitions construction program.

(th)

Void · 2023-08-10 10:02:03

I would like to offer this suggestion:

Starting with an egg-shaped bag as an alternative to a cylinder.

Making a tensile shell to re-enforce that, perhaps fiberglass?

Making a low pressure window at an end, to allow sunlight inside.

Then building more than one torus inside.

Then creating a transparent shell for higher pressure, that shell able to use compressive force and centrifugal force to maintain a differential pressure. Although the high pressure area may leak a bit, the low pressure barriers will allow the recapture of much of the leakage.

Each Torus having individual rotational abilities they may match the beehive shell or an adjacent torus in variable configurations to dock in different ways over time.

The Torus on average will spin in reverse of the beehive shell and at higher speeds to provide significant spin gravity.

With this I hope that gyroscopic flipping can be avoided.

This build process allows for transformation from egg to frog, sort of with tadpole between.

I think that the beehive shell may give fair radiation and impactor protection to the Torus devices.

Of course there will be room for improvements on this notion.

If we have windows on the ends of the egg/beehive, then we intend to conduct sunlight into the interior of the beehive, of course at least at times. Mirrors are a likely provision for that. The mirrors are not shown in the drawing.

Done.

Last edited by Void (2023-08-11 05:27:38)

tahanson43206 · 2023-08-10 13:22:05

For Void re Post #124

My intention is to try to encourage your creativity.

This is the first time I have read anyone who offers the idea of making a huge egg shaped bag as an enclosure for a set of habitat rings.

The closest I can think of was a vision by a science fiction author, but that vision was for a "balloon" so large that multiple rotating habitats were drifting around inside. Naturally, the "balloon" was created by aliens, and I suppose the humans inside the volume were there as a kind of study subject.

Your vision is less grand than that, but it is quite grand on our present scale.

It occurs to me that there are a great number of advantages to your proposal, and I hope you will continue developing your ideas. Can I try to stimulate your imagination? If you will allow yourself to read part of the paper by Mr. Jensen, just discovered and reported by Mars_B4_Moon, then (I think) you are likely to gain a number of ideas for how to approach building the structure.

One great advantage is you can put radiation protection and solar energy gathering into the mission of the egg shell.

The rotating habitats can run just fine within the volume you have created, if the power from a solar source is used to illuminate the interior with LED lighting.

You have imagined high and low pressure, but the reason for that eludes me. That is of no consequence, if the reason is clear to you.

(th)

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