Ceres

Terraformer · 2011-12-29 20:24:24

Gravitational decrease is countered exactly by the increase in volume of the atmosphere, so ignoring centripetal force, we can ignore the decrease in gravity. Doubling the radious results in gravity decresing by a factor of four, but the total volume of atmosphere, and so force, doubles... it compensates. The end result is that we only have to deal with centripetal force...

Actually, we only need to deal with centripetal force above the equator. Perhaps, if we can select a suitably ionisable gas, we can use a magnetic field to recapture the atmosphere which escapes?

The trouble with any kind of hydrocarbon is the formation of petrochemical smog - the CH bond breaks too easily. While I think we want something that will ionise easily to make retention easier (Argon is a possibility), it's got to reform itself.

I think Sulfur containing compounds might be a possibility? Hmmm. It ought to be something that can easily be found ready made...

JoshNH4H · 2011-12-29 20:41:59

That's actually a really interesting effect, about the increase in volume of the atmosphere being counteracted by the decrease in gravitational force. Truly fascinating.

I wouldn't say that centripetal force is only relevant at the equator, but it is the strongest there. IMO that means that you could do some kind of rough approximation of how much higher the pressure can be at GCO at the equator than what you actually want. For example, say you want 10 microbars planetary average, you might be okay with as much as 30-50 microbars at GCO at the equator.

Terraformer · 2011-12-30 12:58:25

Right, I've worked it out. What we need is a really, really low temperature, around 100K, with an atmosphere that has a molar mass of around 40g/mol... Since v is proportional to r, and centripetal force = V2/r, centripetal force is proportional to r, right? Hmmm, this means that, since the atmospheric volume increase is proportional to the square of the increase in r, and the effective gravity decrease is inversely proportional to r^3 (r^2 due to gravity and r due to centripetal force), the decrease in force we have to deal with is directly proportional to r, which makes things a lot easier, since the effective scale height is then simple 2x the scale height for a non-rotating planet. I think. Anyone care to follow my logic and check it?

We may be able to source enough Argon, though CO2 ought to do the trick (could the radiatior properties of CO2 be enough to cool it this low?). I'm thinking of a mixture of N2O and CO2, with Argon, could serve as a buffer for the atmosphere. Effective scale height, if I'm correct, should be about 150km, so the atmospheric pressure will decrease by a factor of 150 by the time it reaches Ceres Synchronous Orbit (CSO). Grr, that still leaves 1mb there if we go for a minimally breathable atmosphere, with the prospect of CO2 clouds blocking sunlight... depending on how ionised these gases become, we may be able to recover them using a magnetic field (though Oxygen is less important, if we can get enough H2O above the cold trap to keep production and loss rates balanced).

So, all in all, more suited to a hybrid worldhouse further out... still, if we monkey around with different gases...

Last edited by Terraformer (2011-12-30 13:10:45)

Terraformer · 2011-12-30 15:55:09

Regarding the low temperatures required to maintain the atmosphere, would it be possible to have habitable temperatures on the ground with frigid temperatures above? Certainly with a hybrid worldhouse this ought to be possible, but without one?

An interesting thing to note about Ceres is, if a hybrid worldhouse with a roof several km high is used, the lower gravity may permit trees to reach all the way to the top. Perhaps the entire world could be englobed in a dyson tree of some variant.

We do need to get quite low temperatures though, and it might be that we need to tap a lot of Argon for the atmosphere then.

Or we could just encircle the planet with an orbital ring and force the atmosphere back down...

JoshNH4H · 2011-12-30 23:07:59

If you take a look at Earth, the temperatures drop to pretty low values once you get out of the troposphere. I would say that the real problem on Ceres is to get the surface to a temperature near room temperature, as opposed to keeping the troposphere cool.

Just wondering, though, what the issue is with the mid-sized hydrocarbons. It is my understanding that they're not overly toxic, unless you have a source saying otherwise?

I would be quite surprised if you found enough argon on ceres to make an atmosphere out of.

Terraformer · 2011-12-31 06:04:48

It's not that they are toxic - more that UV tends to cause them to form longer and longer chain hydrocarbons, forming a tholin smog which obscures the surface (see Titan as an example).

The amount of Argon-40 depends, of course, on the amount of Potassium-40 the planet contained at the beginning. There may well be abundant clathrates on many gases which simply need to be destablised to form a H2O-NH3-CH4-CO2-Ar atmosphere, which would be turned into an O2-N2-CO2-Ar atmosphere by solar action.

We just need one heck of a magnetic field...

JoshNH4H · 2012-01-02 00:25:58

Well, if you want to have an actual viable biosphere, there's no reason you couldn't build in an organism that gets its energy by reacting (solely) the heavier hydrocarbons with oxygen to CO2, and then another organism that synthesizes the pentanes or hexanes.

Another wacky idea is to have towers that suck in the air up high and drag it down into the troposphere.

karov · 2012-01-06 06:41:24

JoshNH4H wrote:

Another wacky idea is to have towers that suck in the air up high and drag it down into the troposphere.

... + colling it. The towers could be alive ( like trees ) or "biosignatures" like the ant hills, termite cities or coral reefs.

Terraformer · 2012-01-06 07:07:16

Well, the possibility of making a bioengineered hybrid worldhouse can't be discounted...

Terraformer · 2012-02-08 04:46:06

Given the difficulties inherent in open Terraforming, I think Ceres will follow a hybrid worldhouse model, with a dense (CO2?) atmosphere at low pressure (10mb) above the worldhouse room - this will deal with small impactors and provide sufficient shielding for the world below, though I'd still like to build UV protection in to the actual worldhouse skin. Bonus points if it can use the extra energy to repair and maintain the envelope, which could be some kind of organism. We'll have to puncture it in places to dock spacecraft, of course, and to allow the elevators to reach the surface.

I can forsee the Cererean system being quite well developed, with the "Paratially" terraformed planet providing food and raw materials, and colonies in orbit, with a Torus around the equator where the elevators attach...

karov · 2012-02-09 13:47:02

a Hybrid worldhouse terraformed dwarf planet will have at least 100km thick habitable under-layer --> more than enough room to put all the rotating structures one needs.

The over-layer - yes, it must be low temperature, high density, low pressure one. The foamy "tent" will have to reside in zero pressure gradient hight: i.e. buoyancy exactly as much higher than the air bellow than the air above.

The ships will pass right throught it - density of the foam cover won't be higher than as if smooth through-air ride -- i.e. smart cellular mini-aerostatic multifunctional world skin won't be an obstacle. The skin may even rain down food and oxygen to support the biosphere bellow. NOt to speak that as with the original J. Storrs Hall's design it will control the illumination / irradiation with resolution as high as square meter.

Terraformer · 2012-02-09 15:08:28

I'm not entirely sure what you're suggesting here... are you proposing we make the layer effectively out of foam? I'm a bit leery of proposals to use active nanotech in maintaining terraformed worlds, when failure means nearly instant death of the biosphere, not least due to the fact that I like to base it on what we can reasonably expect from an extrapolation of our current technology, with no major breakthroughs but plenty of development.

I don't see why the pressure gradient has to be zero, since that would defeat the point of the exercise. The outer layer is only there for radiation and meteorite protection, as well as braking any ships which can afford the delta-V to make a propulsive entrance to the system (though this would be rather minor, since we can expect to be able to brake them with one of the tethers and dock them at the Torus).

The first step, therefore, is to create the atmosphere. Best way to do this, if we can't devolatilise clathrates, might be to import the entire atmosphere with comets, impacting small chunks in such a way that they will vaporise but not escape. Hmmm, it would be best if we can devolatilise clathrates. Once we've got a suitable ~10mb atmosphere, I'd begin to build a greenhouse all around the equator, and keep expanding it towards the poles until it's covered.

Maybe a few docking stations in the roof could allow craft to enter directly into the inner atmosphere without stopping? As for the roof itself, I was thinking it would be multilayered, with a dual layer that's under tension and a suitable reservoir for immediate repair in case of damage. Or maybe a living layer that's 0.1-1m thick could take care of it (but it's got to allow sufficient light into the main part)...

karov · 2012-02-10 05:41:17

well, see the link for J. Hall Storrs -- study the Utility Fog and Weather Machine concepts.
I think that the volatiles trapped even in the Main belt's dwarf planets are enough to produce decent atmospheres. Even nitrogen won't be an issue.
Why living foam structure(?), because the kinetic structures are the most robust given a flow of energy through the system. Compare a plastic bottle as a liquids container and a population of living, evolving and multiplying cells for the same purpose...
Thus the whole set of geosphere, illuminosphere, hydrosphere, atmosphere becomes united alive conglomerate which can withstand even much harsher changes in the energy flux. Such animated-spheres world will last times more than normal planet with primitive "non-multicellular" biosphere.
I believe the encephalization trend which brought homo sapiens here, is universal trend -- the technosphere which follows as a consequence of the culture, on its turn result of the advanced neurology, is namely the means for indeffinite survival of the planetary biospheres. The next stage of evolution.

Antius · 2012-08-17 08:44:28

This website went down for ages and I lost track of it. It is good to see it up and running again and that the same people have kept their enthusiasm!

On the subject of terraforming, I have come to realise that the most effective material will not be flourocarbon gases, heavy noble gases or CO2 but...carbon steel. Think about it: An inch of carbon steel weighing 200kg/m2 can contain an atmosphere as effectively as a 100 mile thickness of flourocarbon gas weighing 100's of tonnes per square metre.

My guess is that by the time people living on Ceres have enough resources to consider terraforming, the world will already be paraterraformed with tens of thousands of glass & carbon steel structures, each containing a small ecosystem. These people probably will not have any incentive or motivation to build a fully terraformed world. It simply would not offer value for money.

Spaniard · 2012-08-20 06:08:40

Titan has a thick atmosphere, as dense as Earth, and it not lose it.
What is the key? It is very cold and it has molecules too heavy to reach escape velocity at that temperature.

Could we have a moon at the Titan's atmosphere pressure but at Earth temperatures and breathable?

To the question of temperature, some methods could been proposed, like the active towers. The Earth's temperature is required in the layers near the ground, where they are living beings, while the loss of the atmosphere occurs in the outer layer, where the molecules are unlikely to collide with each other, and it could get up escape velocity and lost forever.

This issue can become so deep that it could lead to the development of a future branch of geoengineering. About how the heat is distributed by the layers of the atmosphere, and as radiation, convection and conduction between the gas creates the gradient.

Assume for a moment that this is not a problem. Ganymede dense atmosphere, for example, would isolate the heat generated by light from artificial fusion reactors. Escaping most as radiant heat, the last layer being the more "transparent" to these, so that the heat escape transparently maintaining very cold the upper.

The second is more complicated. Molecules? Heavy? A "unsolvable" problem occurs. Heavy molecules tend to be lower in the atmosphere, so that would probably unbearable for earthlings. And the necessary O2 and N2 would remain light, rising up and losing equally.

Here is an idea that has been haunting me. What if we make very large molecules ... heavy, but simultaneously form a very light gas?
Is that possible?

The first question you must understand is that the gas density depends on the space between molecules, not only of these. These molecules are separated from one another by various fundamental forces, creating a "rejection space". Is your weight, divided into the space, which will form the density. Another thing is that the molecules usually tend to create a similar space, since the effective space is much larger than the molecule, so they tend to create similar areas. So, normally, we could considerate that density depends only of molecular weight.

But this need not be so.

Imagine a sphere totally made of graphene. The area would be very small. I'm talking about hundreds of thousands of carbon atoms, not more. Inside, just empty space. Its effective space is huge, because they are areas "impenetrable". The number of carbon atoms grow with surface. The effective space of the "molecule" with the volume. With an area of sufficient size, density would be lower even than the less dense molecule ... hydrogen.
Yet this "molecules" would be very heavy! With lots of atoms.

So, these molecules tends to be at the top of atmosphere, but at the same time, it would be too heavy to reach scape speed. It could be a wonderful tool to make dense atmosphere relative stable in time. When a "molecule" of this kind breaks, it probably turns into a broken ball more dense and drops to the low atmosphere.

It may have defects. It is possible that the material proposed (graphene) did not have the right properties. For example, you may not be able to sustain its vacuum state for long because other molecules could pass through the graphene using tunnel effect. But it is possible that may exist other alternatives for the same purpose. For example, with larger areas, although some molecules enter the density molecules take longer to go down. The issue is not that they are always empty, but its state of lighter molecules that hydrogen could be sustained long enough. The location of a graphene layer could perhaps use a multilayer model with some technology that would allow these layers remain in a stable state.
The question would be to have these "balls" lighter than hydrogen stable long enough to need little repleshing.

Spaniard · 2012-08-20 09:41:55

Sorry. A obviusly error in my last post.

Graphene spheres could be lighter that any gas, but the weight of the gas depends on pressure. So and certain altitude, it had the same density and the light gas cross easily.

But it could be a useful tool. By the same reason the pressure don't change, these balls don't change with the temperature, so it could be useful in a active cooling system, because the layer was stable no matters which temperature has. With a layer under the temperature for make oxygen liquid at that pressure it would create a freeze floating "wall" (a compact "gas" made of balls) that force oxygen to go down again.

Terraformer · 2013-04-15 08:34:42

Whether Ceres can retain an atmosphere will depend, in a large part, on whether the atmosphere will rotate with the planet. If the upper atmosphere does not, then we won't have to worry about losing it at the stationary orbit point to any kind of sprinkler effect. Do atmospheres usually rotate at the same rate (which would mean increasing velocity as you increase in altitude), or do they typically shear to the point where only the ground level atmosphere is rotating at the same rate, with the upper atmosphere appearing to have quite strong winds opposite to the direction of rotation?

I doubt that we'll have an appreciable atmosphere at that point, so we shouldn't be having to deal with much drag on our stations up there.

We just might be able to get away with using CO2 as our main gas to get Ceres to the point where genetically engineered plant life can exist on it's surface...

Void · 2013-04-15 18:52:59

I don't want to be a drag, but I would rather wonder if their is fusion fuel in the ices of Ceres, or perhaps Helium 3 in the regolith covering it.

Having that and eventually fusion power, could you not build chambers within and light them with solar or fusion power?

No nock on the atmosphere thing, but it is a very hard achievement I think.

But in a more direct answer to your query:
Maybe with a magnetic shield that rotates, and drags the upper atmosphere in the character you want you could make it behave, and also block the solar wind. The upper atmosphere could have magnetic properties, if it is ionized?

StarDreamer · 2013-04-16 07:45:40

This is an interesting discussion. If memory serves, Ceres is warmer now at its surface than Mars? I am trying to find the relevant posts in this thread, but it's a lot of reading. Can anyone point me to some?

Terraformer · 2013-04-16 08:18:38

I don't remember anything along those lines...?

Void, there'll be less He-3 than at Luna, because the solar wind is weaker there, but Deuterium is a good fusion fuel on it's own, and where there's water, there's usually Deuterium. But why use fusion lit underground bunkers? You might as well use the materials to build lots of space colonies, which can be lit with solar energy...

Magnetic fields only work on ions, so almost the entire atmosphere would have to be ionised. Besides, I wouldn't want to make it rotate, since that would cause it to escape into space...

StarDreamer · 2013-04-16 08:22:42

Wikipedia says: "The Cererian surface is relatively warm. The maximum temperature with the Sun overhead was estimated from measurements to be 235 K (about −38 °C, −36 °F) on 5 May 1991."

Terraformer · 2013-04-16 15:11:57

Mars at it's warmest point is above the melting point of water...

Void · 2013-04-16 21:07:12

Terraformer said:

Void, there'll be less He-3 than at Luna, because the solar wind is weaker there, but Deuterium is a good fusion fuel on it's own, and where there's water, there's usually Deuterium. But why use fusion lit underground bunkers? You might as well use the materials to build lots of space colonies, which can be lit with solar energy...
Magnetic fields only work on ions, so almost the entire atmosphere would have to be ionised. Besides, I wouldn't want to make it rotate, since that would cause it to escape into space...

Why not do both? No laws against it.

Let me attempt to in a better way communicate what I intended with the Magnetic field.

It is about frame of reference. I would not want the lower layers ionized. I would want it to rotate with the surface.

The magnetic field is intended to counter rotate the highest ionized layer, so that relative to the solar wind it would not rotate, but relative to the surface of Ceres it would rotate in opposition to the surface, causing approximately and on a average a zero speed. This if possible would remove the centrifuge effect which you fear would contribute to atmospheric loss.

And since a magnetic field is in use, then why not use it to oppose the solar wind?

Ceres if it is to have an atmosphere would need every trick.

I have little to offer for the effect of solar heat overheating molecules to escape velocity however.

I might offer, that I am trying to figure out if somehow with the shape of the field, you could have one magnetic field always behind Ceres, and hope to catch some otherwise lost molecules and funnel them back down to the atmosphere through magnetic lines of force.

But if that worked, you are left trying to figure out how you spin the upper atmosphere in the solar plain.

An alternating field might funnel some particles down from the dark side, using two different polarities, north and south in alternating fashion. Perhaps a rotating spin followed by a South on the dark side, then another spin, and then a north on the dark side?

It might also be hoped that if the molecules can be directed to the dark side, and then funneled down the magnetic pole, they might cool to a degree? But I believe that plasma holds heat by electrons spinning around a magnetic line of force, and I don't know if exposure to cold alone will cool them. However if they contact cooler atmosphere, then I believe that plasma will
then quench into it.

It is also worth speculating that such an alternating field would also warm a salt water body of ice, might cause very cold brine to develop and eventually an ice covered ocean. Eventually warming even the rocky core, but this would take time.

We have had these conversations before. I want habitats in hollows in the ice above the ocean, and chemosynthesis and artificial induced photosynthesis in the ocean, with mining of the core, you want orbital habitats, but why can't I/You/We have all of it?

Ideally a magnetic field would be induced by the solar wind which would require orbital machines to capture it's energy and convert it to a world field. I don't have a master plan for that but I have intentions to think about it.

The colder than Mars temperatures are a plus for an ice covered ocean. Some mechanical assistance such as domes, and other protective coverings required. As for the thickness of the ice layer, I would want it generally thick enough to place hollowed out habitats into, as a trial balloon 1 mile or 1 Kilometer thick? However where domes are on the surface no problem with having pressurized ponds, lakes and swimming pools.

Last edited by Void (2013-04-16 21:23:16)

StarDreamer · 2013-04-17 06:14:37

Terraformer wrote:

Mars at it's warmest point is above the melting point of water...

Sorry -- I was thinking of dry ice! CO2

robertwalker · 2014-01-04 12:40:54

For the oceans idea why not live under the ice? The ice would insulate and also warm up somewhat by the solid state greenhouse effect. Is amazingly insulating I remember figures for Mars someone calculated that after a major impact on the polar regions you'd get melted subsurface lakes that last for millennia before they freeze through completely again.

I think that long term it is likely to make more sense to use the material from Ceres to construct free-floating habitats. That's because there is enough material in Ceres to create material for several hundred times the surface area of Earth by way of adequate cosmic radiation shielding in Stanford Torus type habitats - a calculation from the 1970s.

See my article here: http://www.science20.com/robert_invento … ths-116541

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#107 2012-01-02 00:25:58

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#110 2012-02-08 04:46:06

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#118 2013-04-15 18:52:59

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