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... Gerald Nordley style.
Just add 7 bars atmospheres onto Io, Europa, Ganymede, Calisto and somehow tweak the Jovian mag-field to not be excentric and to not sweep the atmospheres, but to keep them on-moon via gas toruses as Saturns does for Titan...
https://www.google.com/url?sa=t&rct=j&q … 3778,d.Yms
5. Io - 41 mln.km2 ( 0,081 Earth surface - 0.28 Earth's land ) -- 0.1847 gees
6. Europa - 31 mln. km2 ( 0.061 Earth surface - 0.21 Earth's land ) -- 0.1347 gees
7. Ganymede - 87 mln. km2 ( 0.171 Earth surface - 0.58 Earth's land ) -- 0.1449 gees
8. Calisto - 72 mln. km2 ( 0,141 Earth surface - 0.48 Earth's land ) -- 0.1265 gees
The Galilleans ( Io, Europa, Ganymede, Calisto ) offer combined 1/2nd of the Earth's surface or 1.55 of the Earth's land or if we choose for their surfaces 2:1 land-water surface then entire 1 Earth's land surface or 2 if we make it without ice or hot deserts.
Envision the Galilleans as 4 massive continents - Io comparable with Eurasia, Europa with Africa, Ganymede with 2+ Eurasias, Calisto - Eurasia + North America + Australia...
Their father-planet Jupiter has on 7 bars level depth a 300 Celvins temperature!
The illumination / insolation of these moons - they get 1/25th ( 4% ) of the Earth's level, which is enough even for photosyntheisis!
7 bars breathable atmosphere would have to have lower then 3 bars N2 and lower then 0.25 bars of oxygen. The balast gases should be heavy and non-toxic - argon which is abundant in Jupiter and the Sun ( and universally ), etc.
A "bark" or foamy silicate and carbon crust to keep the icy mantle solid or semi-solid
...
?
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Why would you want more than 1 bar of atmosphere?
Come on to the Future
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That chart is the structure of Jupiter's atmosphere. Why would you want to duplicate it on the moons?
I have suggested building an atmosphere on Ganymede and Calisto of oxygen / sulphur hexafluoride (SF6). That gas is very heavy, inert, clear and colourless, odourless, and very dense. The idea is to provide pressure in the moon's weak gravity. But you would need weather to "stir" the atmosphere, ensure oxygen doesn't settle to the stratosphere. SF6 is also a very powerful greenhouse gas. But I'm not just saying trace amounts; I'm saying a dominant gas, equivalent to nitrogen on Earth.
Io? Sulphur volcanoes cannot be easily stopped. I don't know how to stop them at all. Tides in gravity from Jupiter causes stress on Io, heating its interior. The only way to stop that is to move the moon to a higher orbit. Yea right! Terraforming is a big enough task, you can't move a moon. Just accept Io as an airless industrial world. Lots of geothermal power, and plenty of sulphur for industrial uses.
Last edited by RobertDyck (2013-06-16 11:23:01)
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RobertDyck,
I believe for atmospheric greenhousing the mass, but not the composition is dominant.
http://www.gdnordley.com/_files/Gravity.pdf
<<<4.4 The Case of Titan
The adiabatic lapse rate varies inversely with scale height,
which means it varies directly with local gravity. For a given kind
of atmosphere, the higher the gravity, the faster things get
warmer as you go deeper into the atmosphere. Compare Jupiter
and Saturn, or Earth and Titan.
This creates the interesting situation wherein, if there is any
internal or external source of energy at all, and the atmosphere is
deep enough, one will eventually reach a temperature at which
liquid water can exist--almost regardless of how cold the top is.
What if Titan's atmosphere extended further down? If it went
down another eighty kilometers, the solid surface would have a
radius of 2495 kilometers. (If the mass remained the same, its
mean density would have to increase slightly, the surface gravity
would be somewhat higher surface gravity the scale height less,
but we'll ignore that for now.) An adiabatic curve would lead to a
new surface temperature of about 300 kelvins–room
temperature, but at a pressure of some 87 atmospheres.
This is about the same that a diver would experience at some
eight hundred meters–well beyond the limit of what divers can do
with even the most risky gas mixtures. The level of illumination
would be very low, of course--perhaps a tenth of one percent of
of what we get on a sunny day. But that is still much brighter than
a full moon at night--unlike in our ocean depths, one would have
no problem reading. It is noteworthy that Jupiter's atmosphere
reaches liquid water temperatures at a tolerable seven
atmospheres (NASA 1996).
>>>
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Io? Sulphur volcanoes cannot be easily stopped. I don't know how to stop them at all. Tides in gravity from Jupiter causes stress on Io, heating its interior. The only way to stop that is to move the moon to a higher orbit. Yea right! Terraforming is a big enough task, you can't move a moon. Just accept Io as an airless industrial world. Lots of geothermal power, and plenty of sulphur for industrial uses.
Yes, Io.
Sulphur volcanoes - why stop them at all. Most of all ( only ) 400-500 Io's volcanoes form distinct volcanic DEPRESSIONS. Hence they'll remain underwater which gives good conditions for various type of biota to eat away / utilize the surphur.
Tidal flexing - nowadays Io is in state of excessive volcanism, temporary condition, usually the energy injected in tidal way is far less.
<<< Models of its orbit suggest that the amount of tidal heating within Io changes with time, and that the current heat flow is not representative of the long-term average.[20] The observed release of heat from Io's interior is greater than estimates for the amount presently generated from tidal heating, suggesting that Io is cooling after a period of greater flexing.[21] >>>
from: http://en.wikipedia.org/wiki/Volcanolog … eat_source
Moving the moon - it IS possible via momentum-exchange loops ( Paul Birch style ), which need several years, but indeed not necessary at all. Highly volcanic and habitable world is not an oximoron , indeedd pretty useful feature volcanism on habitable world shall be - lots of fertilizing, chemicals and energy flow...
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I have suggested building an atmosphere on Ganymede and Calisto of oxygen / sulphur hexafluoride (SH6). That gas is very heavy, inert, clear and colourless, odourless, and very dense. The idea is to provide pressure in the moon's weak gravity. But you would need weather to "stir" the atmosphere, ensure oxygen doesn't settle to the stratosphere. SH6 is also a very powerful greenhouse gas. But I'm not just saying trace amounts; I'm saying a dominant gas, equivalent to nitrogen on Earth.
Yes, I remember this. SF6 is good for smaller bodies. No need of it for 2+ km/s escape velocity worlds. Also F is quite rare = expensive.
There are plenty of techs using cheap chemicals to achieve the same results.
My design here is 7 bars 300K @surface Galilleans.
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Yes, Io.
Sulphur volcanoes - why stop them at all. Most of all ( only ) 400-500 Io's volcanoes form distinct volcanic DEPRESSIONS. Hence they'll remain underwater which gives good conditions for various type of biota to eat away / utilize the surphur.
...Highly volcanic and habitable world is not an oximoron , indeedd pretty useful feature volcanism on habitable world shall be - lots of fertilizing, chemicals and energy flow...
Ok, you intrigued me. But where does the water come from?
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Ok, you intrigued me. But where does the water come from?
From the outer Galileans and smaller Jovian moons.
Downloading ( siphoning ) mass ( via orbital ring systems - http://archive.is/5in9 ) in-system gives gain of energy & momentum, which could be utilized for mining helium, ammonia, nitrogen, neon, argon, other noble gases ... ... etc. from Jupiter itself. The excess energy could be used for reverse separation of the outer Galileans extracting and layering insulation-cover of foamy (?) silicates and carbon ON-TOP the ice. Dozens of miles thick bark... These orbital rings could also utilize the violent mag-sphere of Jupiter as source of energy and as mechanical support medium ( momentum "sink" ), thus also taming it and tweaking the giant magnetosphere into shape and state to dynamically support ( re-replenish with escapees ) then rather to sweep / strip the Galilean atmospheres. Flux-tubes amplified and harnessed.
Guys please help me.
1. apparently it would kind of polimix atmosphere - up to 3ish bars N2, higher partial oxygen but under the O2 toxicity level, higher CO2 but under the toxicity level, He + Ne + other noble gases for ballast but under the narcosis levels ... ... Lets play out breathable mixtures' distros...
2. At 7 bars @surface :
2.1. water freezing and boiling point?
2.2. air-mixture density at 7 bars pressure and 300K temperature?
2.3. sky and sun colors?
2.4. transparency and illumination intensity?
...
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Strong gravity from Jupiter produces rings of radiation. Van Allen belts on steroids. Galilean moons are within these radiation belts. Strong radiation can break up atmosphere molecules, and excite light elements to escape velocity. On Earth, water does break up and hydrogen escapes. Our magnetosphere deflects most of that radiation. What hydrogen does escape gets trapped in the "tail" of the magnetosphere, and drawn back. It re-enters the atmosphere where magnetic field lines intersect the Earth: the poles. As hydrogen and other plasma from solar wind is drawn down, the magnetic field accelerates it. When it hits the atmosphere it does so at extreme speed, causing interaction with Earth's atmosphere producing light. This is the aurora. But no magnetic field means no magnetosphere. No magnetosphere means hydrogen will escape into space. This is believed to be what happened to Venus. It has 90% of Earth's surface area, and 90% surface gravity. It's close enough that small meteoroids with ice fall on that planet, just like Earth. But without a magnetosphere, solar wind eroded its water. Specifically the hydrogen portion of water blew into space. Pioneer Venus measured hydrogen flow off the back of Venus even to this day. Without liquid water oceans, CO2 did not combine with calcium and magnesium to form limestone. Primordial Earth had a thick CO2 atmosphere like Venus, but it was sequestered as limestone. Venus still has it. Clouds of Venus are water clouds, but since the surface temperature is +450°C, those clouds are all the water for the planet. Even if all that water rained out, Venus would still be dryer than the Sahara.
So how are you going to prevent that on Galilean moons? How do you prevent intense radiation from Jupiter's Van Allen belts from quickly eroding all the water? And all hydrogen from any other atmospheric gasses? If you build an ammonia or hydrocarbon atmosphere, you have the same problem with hydrogen. These moons have much lower gravity, and radiation around Jupiter is far more intense than solar wind that reaches Earth or Venus. So you may have the same problem with other elements of atmospheric gasses, such as carbon or even oxygen. I suggested an artificial magnetosphere around each moon. How would you solve the problem?
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I don't quite see what the justification for terraforming is. By the time we had finished I would expect that technology would have advanced to the point where the means used to terraform would have become obsolete.
-Josh
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So how are you going to prevent that on Galilean moons? How do you prevent intense radiation from Jupiter's Van Allen belts from quickly eroding all the water? And all hydrogen from any other atmospheric gasses? If you build an ammonia or hydrocarbon atmosphere, you have the same problem with hydrogen. These moons have much lower gravity, and radiation around Jupiter is far more intense than solar wind that reaches Earth or Venus. So you may have the same problem with other elements of atmospheric gasses, such as carbon or even oxygen. I suggested an artificial magnetosphere around each moon. How would you solve the problem?
RobertDyck,
Firstly, thank you for the alphabetical truths. not all of them pretty exact, but so be it.
On the "artificial magnetosphere" - why create artificial for the each moon , when we have enormous natural for the whole jovian system.
"JUST" make it to rotate around the same axis as the planetary diurnal rotation, and you get not simply global, but pan-systemic atmo-shield.
Ref.: gas torus.
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Any magnetosphere captures charged plasma. It orbits, and forms belts. Galilean moons are right in those belts. Jupiter's magnetosphere protects Jupiter itself, not its moons. In fact the moons experience increased, highly concentrated radiation. Much greater than interplanetary.
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RobertDyck,
We DO know this. We know the mechanism, and it works so because Jupiter's mag-field is off-axis / excentric.
Pls, see the G Nordley material about this.
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Gents,
C'mon. Lets play out this...
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https://www.google.com/search?q=magneti … e&ie=UTF-8
There must be way to make the Jovian magfield to become co-axial?
Ideas?
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The blunt answer is to focus on Callisto first, which is the only moon outside Jupiter's radiation belts. Until a better solution to the radiation is thought of, the other moons could only be colonized at most.
I used to think Ganymede could be a very interesting terraformed world but that moon receives 0.08 Sv per day. For perspective, Earth receives 0.024 Sv in a year. Ganymede's magnetic field is too weak to stop the incoming radiation. Living on the surface would be like getting two chest x-rays a day. The radiation is so much worse on Europa and Io that any talk of living on those is basically preposterous. 5.4 Sv on the surface of Europa. That's like standing right next to Chernobyl as it was exploding.
I will say I didn't realize just how high it was on Europa until I looked it up for this post, and I'm still trying to wrap my head around that number.
http://www.space.com/22207-jupiter-moon … aphic.html
Check it for yourself. Is that wrong?
Last edited by Spatula (2014-04-19 02:31:34)
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I recall a proposal to scatter dust in the radiation belts to dispose of them...
If you have an atmosphere, the radiation isn't a problem. Your problem is more to stop the atmosphere from escaping.
Use what is abundant and build to last
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For human habitation, most of the benefits of terraforming would appear to derive simply from increasing atmospheric pressure (and to a lesser extent, temperature). The air itself need not be breathable.
If a Jovian moon is provided with a surface pressure of 0.3 bar, it would permit human beings to live on the surface in ordinary non-pressurised buildings containing 50-50 mix of O2 and N2, with perhaps a pascal of overpressure to prevent external air from seeping in. Buildings could be produced from icy surface materials with an internal insulated lining. Entire cities could be built under non-pressurised glass or plastic domes. Victorian technology. Food crops can be grown within simple polytunnels. Human beings could venture outside wearing oxygen masks, but otherwise ordinary clothing.
In other words, simply by increasing atmospheric pressure and raising external temperature to perhaps -50C, we get 90% of the benefits we would get from a fully terraformed planet. This might be accomplished relatively easily, simply by delivering a hundred million tonnes of assorted CFCs to the surface. The global warming effect would then sublimate surface water ices, CO2, ammonia and any trapped oxygen produced by aeons of cosmic ray bombardment of ice.
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An interesting paper on super-greenhouse gases.
http://www.pnas.org/content/98/5/2154.full.pdf
Presumably, the quantity of gases needed is sufficiently small (~100million tonne?) that they could be manufactured in Earth (or Mars) orbit and delivered to the Jovian moons using mass-driver propulsion and direct impact. Only after the process is well under way would any human presence be needed.
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Guys please help me.
1. apparently it would kind of polimix atmosphere - up to 3ish bars N2, higher partial oxygen but under the O2 toxicity level, higher CO2 but under the toxicity level, He + Ne + other noble gases for ballast but under the narcosis levels ... ... Lets play out breathable mixtures' distros...
2. At 7 bars @surface :
2.1. water freezing and boiling point?
2.2. air-mixture density at 7 bars pressure and 300K temperature?
2.3. sky and sun colors?
2.4. transparency and illumination intensity?
...
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ooops!
7 bars??
Isn't it the overlying MASS of atmosphere which matters for heat retention / greenhousing, but not the pressure?
Liquid water temperatures at 7 bars level down into the atmosphere of Jupiter, but under 2+ gees!
It must be 3.5 bars on this distance needed for livable surface temperatures under 1 gee.
Or 0.7 bars for 0.2 gees as average for the Galileans?
---
Am I right? Or I have error in my considerations?
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7 bars breathable atmosphere would have to have lower then 3 bars N2 and lower then 0.25 bars of oxygen. The balast gases should be heavy and non-toxic - argon which is abundant in Jupiter and the Sun ( and universally ), etc.
Argon won't work as dill under 7 bars since it has two times greater narc factor then N₂. You'd want to use Ne or He (Ne would be better, but He is easier to come by). H₂ would work too under 7 bars since you've got lots of it on Jupiter - hydrox is perfectly safe and breathable for humans as long as your O₂/H₂ ratio does not exceed 4:96 and as long as ppH₂ stays below 8 bars. Methane is a good greenhouse gas and it would not be a fire hazard as long as you keep ppO₂ low enough. SF₆ is the best greenhouse gas you can think of and it is completely inert (almost as inert as noble gases) - but it might be bit harder to come by here in Sol System.
Last edited by agent009 (2014-06-27 13:11:33)
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agent009,
thank you for the comment.
Indeed the Gerald Nordley's 7 bars design is about shear atmospheric mass, not chemical content.
Pls, see my question about "whether 7 bars OR adjusted acc. to surface gravity - 0.7-0.8 bars for Galileans"?
IF you have knowledge ( and it seems you DO ), pls. see my questions above...
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karov, chemical composition is very important for both human survivability and greenhouse effect. It is not the sheer pressure of density of the atmosphere that would matter for the latter, but partial pressures of the relevant greenhouse gases - most potent ones (among those that would be breathable for humans to greater or lesser extent) being SF₆, CF₄, H₂O and various hydrocarbons - see GWP values in the table I've posted here for reference (GWP index for H₂O has never been calculated, but it's greenhouse effect is estimated to be, at least, by several orders of magnitude higher than that of CH₄). You get very little greenhouse effect (by several orders of magnitude less then CO₂) from diatomic gases (i.e. O₂, N₂, H₂) and no greenhouse effect to speak of from monoatomic noble gases (i.e. He, Ne, Ar, Kr, Xe). So, if you're looking for greenhouse effect, you would be better of pumping some potent greenhouse gases into your atmosphere rather then increasing sheer pressure of diatomic gases (of which you cannot have too much without bumping narc factor or ppO2 beyond limits that are safe for humans anyway).
However, when speculating about various greenhouse gases, you should also keep in mind their narc factors, toxicity and flammability (the latter two may be estimated from NFPA 704 index values in "H" and "F" columns of my table). CO₂ is a very bad choice since it only has very moderate greenhouse effect, but is extremely narcotic and mildly toxic. CH₄ has better greenhouse effect and is non-toxic - but it is still relatively narcotic and highly flammable (which means, you wouldn't want to mix it with oxygen at any great ratios). N₂O (nitrous oxide, aka "laughing gas") is actually quite a bit better then CO₂ - despite its notorious reputation as potent drug (which it certainly is, but much less so than our good old carbon dioxide) it is much more effective as GHG. CF₄ is an even more potent GHG and has narc factor almost as low as N₂ - but it is mildly toxic, so you wouldn't want too much of that stuff in the air you breath either. SF₆ is about as narcotic as CH₄, but it is completely inert and non-toxic - and it has greenhouse potency by several orders of magnitude greater then anything else that may be safely inhaled by humans in more then trace amounts. Downside - SF₆ is quite a bit harder to come by then CH₄, CO₂ or N₂O.
EDIT: According to my simulations, the most effective greenhouse atmosphere that would be still safely breathable for humans would consist of 64% SF₆ and 36% O₂ pumped under 0.5 bar pressure. You might also want to add about 1-2% of N₂ and about 0.02% CO₂ to that in order to have a self-sustaining Earth-like biosphere.
Your second best option would be 68% O₂, 28% N₂O, 3.97% N₂ and 0.03% CO₂ under 0.3 bar. You would only have a fraction of the greenhouse effect you'd get out of the previous option, but this much nitrous oxide would be much easier to obtain. Do not mind the high NFPA "health hazard" index - it is greatly overrated mainly because of its reputedly high narcotic potency and its oxidizing qualities. In fact, N₂O is no more toxic than O₂ and not really that narcotic compared to CO₂ or Xenon, for instance.
Finally, your third best option is probably hydrox (H₂/O₂) pumped under 8 bar pressure. You would have about 1% O₂ in that mix and some trace amounts of N₂ and CO₂ - the rest being H₂. While hydrogen is not a very potent greenhouse gas, this much of it would probably still have considerable effect and it won't be any fire hazard with so small O₂ fraction (you cannot increase pressure above 8 bar, because H₂ would start having narc effect at point). Advantage - plenty of H₂ on Jupiter!
Last edited by agent009 (2014-06-28 06:03:14)
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