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#26 2014-06-26 11:00:04

agent009
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From: a galaxy far away
Registered: 2014-06-16
Posts: 19

Re: Rogue super-Earths/mini-Neptunes...

JoshNH4H wrote:

Welcome to newmars, agent009!
Interesting post.

 
Thanks wink

JoshNH4H wrote:

I'd always written gas giant aerostats off as infeasible, myself, but I guess I was wrong to do so

Well, that mainly depends on pressure, temperature and exact atmospheric composition. Aerostats would certainly be very inefficient around cloud layers of Jupiter and Saturn, but "hot air balloon" principle could become more effective within the deeper layers (provided you can find appropriate temperature/pressure conditions where hydrogen would still be in gaseous phase). The outlooks on Uranus and Neptune are better, since there is some helium in the atmosphere, and buoyancy effect resulting even from minuscule mole mass difference between that mixture and pure hydrogen would be greatly amplified by high pressure and/or low temperature.

JoshNH4H wrote:

I always wonder about the possibility of hydrogen oceans on rogue planets.  According to some back of the envelope calculations, the radioactive decay energy produced in the earth's core is enough to heat a planet to an average temperature of about fifteen kelvins.  Under a helium atmosphere of appropriate pressure I see no reason why hydrogen oceans wouldn't form.

That would basically depend if you find temperature/pressure conditions somewhere inside those gas balls that would be compatible with the liquid phase of molecular hydrogen and gaseous phase of helium at the same time. Such conditions could, in principal, exist within temperature range 13-32 K and within pressure range 7-1290 kPa (triple and critical points of H₂).

Last edited by agent009 (2014-06-26 11:04:40)

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#27 2014-06-26 11:59:51

JoshNH4H
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Re: Rogue super-Earths/mini-Neptunes...

Regarding hot-hydrogen balloons, I'd think an aerogel balloon would be optimal, because of its light weight and good insulative properties.  Even if it is mostly Hydrogen, if the surrounding atmosphere is at 50 K, a 50 K differential is quite meaningful in terms of the density of the gas.  Assuming ideal behavior, Hydrogen at 50 K, 1 atmosphere has a density of .50 kg/m^3 (about 45% of air at STP) and at 100 K the density is of course half this, .25 kg/m^3.  This gives a lift of .25 kg/m^3, which is 1/4 of what a Hydrogen or Helium balloon on Earth gets.  This suggests that at the 4 atmosphere level the lift is equivalent, and if we go with a full 14 atmospheres, as you suggested for Heliox, it would give 3.5 times as much lift (approximately) as helium or hydrogen in Earth's atmosphere.

For the case of a Hydrogen ocean, if you allow for a cool enough gas or ice giant, it seems the natural result.  If the entire gas giant is at, let's say, 15 K (or simply doesn't exceed the critical temperature until you get into the metallic Hydrogen zone), Hydrogen will naturally rain out.  You might actually end up with quite a deep ocean, if the amount of helium is high enough.  Assuming Helium ice is heavier than Hydrogen ice, there will presumably be some equilibrium between atmospheric Helium and solid Helium, which would be buried beneath several kilometers or more of Hydrogen ice.

Anyway, my thoughts were oriented more towards a solid, rocky planet with Hydrogen oceans under a Helium atmosphere.  Rocky in a loose sense, of course; I don't really care all that much if it's stony or metallic or made of ices or really whatever.


-Josh

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#28 2014-06-26 13:10:48

agent009
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Re: Rogue super-Earths/mini-Neptunes...

JoshNH4H wrote:

If the entire gas giant is at, let's say, 15 K (or simply doesn't exceed the critical temperature until you get into the metallic Hydrogen zone), Hydrogen will naturally rain out.  You might actually end up with quite a deep ocean, if the amount of helium is high enough.

Don't forget that the substance phase is a function of both temperature and pressure. A substance can exist in a true liquid phase only if both temperature and pressure are between triple point and critical point values (though it could also exist in solid and gaseous phases depending on particular temperature/pressure values). If pressure is below triple point, the substance will transition directly between structured solid to gaseous phases and vice versa with temperature variations. At pressures above critical point, there will be no clear boundary between supercritical "gas" (which still behaves very much like any normal gas), "compressible fluid" (which would be as dense as liquid but retain some properties of gas) and amorphous (unstructured) "solid" - but there would still be a distinct boundary between compressible "liquid" / amorphous "solid" ans crystalline/metallic solid at some point of pressure/temperature curve. Helium, technically, becomes supercritical at pressure above 227 kPa (≈ 2.3 ATA), though we would never be able to tell it from a "normal" gas at temperatures compatible with human survival.

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#29 2014-06-26 14:03:09

JoshNH4H
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Re: Rogue super-Earths/mini-Neptunes...

Agent009, I am of course aware of that.  However, my assumption was that if the gas giant is in interstellar space, it would be heated from below*. and if the temperature were to be that low at the depth where the pressure was high enough that Hydrogen turns metallic, it would also presumably be quite low at the depths where the Hydrogen would be liquid.

By the way, as a matter of curiosity but little practical importance, why ATA and not atm?  I've never seen ATA used to represent one atmospheric pressure.

*I haven't done the calculations, but I am operating on the assumption that starlight is insufficient to heat an object above Hydrogen's boiling or sublimation temperature.  Doing some quick Back-of-the-Envelopes, I calculated here that the blackbody temperature of a flat blackbody object pointed at the Sun would be 394 K at 1 AU.  Because blackbody radiation is proportional to temperature to the fourth power, and insolation falls off with radius squared, the temperature will fall in proportion to the inverse of the square root of the radius.  This suggests that at 2 light years, the Sun will provide a blackbody illumination temperature of 1.1 K, less than the cosmic microwave background.  Because most stars are significantly farther than this, I don't think starlight will be able to provide more than (at a guess) 10 K [Recalling that this is the equivalent of about 10,000 sunlike stars from 2 AU], so the heat will still be coming up from the center of the planet.


-Josh

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#30 2014-06-26 14:05:11

Void
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Re: Rogue super-Earths/mini-Neptunes...

Under Ice Oceans:
http://www.wired.com/2011/02/steppenwolf-planet/

http://www.centauri-dreams.org/?p=16794


Thick Atmopheres:(Hydrogen and/or Helium on top, maybe Nitrogen below?) (Pressure at the bottom of atmosphere like the bottom of our oceans)

Based on initial estimates, approximately two free-flying planets exist for every "normal" star in our galaxy, but the results of the new study produced even more staggering findings: nomad planets may be up to 50,000 times more common than that.

Open water oceans?? (Under very very thick Hydrogen atmosphere:
http://abcnews.go.com/Technology/story?id=99236

Nice conversation you are doing on this one.


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#31 2014-06-26 14:43:26

JoshNH4H
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Re: Rogue super-Earths/mini-Neptunes...

50,000 times more common seems to be a bit excessive, but then what do I know...

Nitrogen oceans may be feasible also, under the right conditions.  It looks like, if you added some amount of some other gas to Titan, then moved it out to Neptune or so, they would form naturally.  Alternatively, you'd have nitrogen oceans under a nitrogen atmosphere, which would be interesting from a physical chemistry perspective because the equilibrium would be very sensitive to changes in pressure and temperature.


-Josh

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#32 2014-06-26 15:11:54

agent009
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Re: Rogue super-Earths/mini-Neptunes...

JoshNH4H wrote:

Agent009, I am of course aware of that.  However, my assumption was that if the gas giant is in interstellar space, it would be heated from below*. and if the temperature were to be that low at the depth where the pressure was high enough that Hydrogen turns metallic, it would also presumably be quite low at the depths where the Hydrogen would be liquid.

Ok, fair enough... I was basically theorizing about gas giants in general, not just nomad ones.

JoshNH4H wrote:

By the way, as a matter of curiosity but little practical importance, why ATA and not atm?  I've never seen ATA used to represent one atmospheric pressure.

ATA is "atmosphere absolute" which means you take into account the total pressure and express it in Earth "standard atmosphere" equivalent (101,325 Pa) - that is, if you go underwater, ATA means that you are counting both pressure of water and atmospheric pressure that is acting on it. Guess I've just spent too much time on divers' sites lately while doing my research on high pressure effects on humans wink 

JoshNH4H wrote:

Alternatively, you'd have nitrogen oceans under a nitrogen atmosphere, which would be interesting from a physical chemistry perspective because the equilibrium would be very sensitive to changes in pressure and temperature.

It would be even more interesting to have lots of same substance on a planet under temperature/pressure conditions near its triple point (or critical point, if you prefer). But then, conditions Earth (around the tropopause levels) are not that far off the triple point of water... would still be interesting to see such conditions on the surface though - boiling oceans covered with ice!

Void wrote:

Open water oceans?? (Under very very thick Hydrogen atmosphere

It would have to get pretty hot to have liquid water (well, at least around 0 °C) and, considering H₂ has no greenhouse effect to speak of, the planet would have to be pretty close to a star – it would need to have a damn strong magnetic field in order to prevent solar winds from blowing away the hydrogen.

Last edited by agent009 (2014-06-26 15:24:05)

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#33 2014-06-26 15:28:14

karov
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Re: Rogue super-Earths/mini-Neptunes...

Welcome on board, agent009

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#34 2014-06-26 15:32:01

Void
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Re: Rogue super-Earths/mini-Neptunes...

Josh,

I would defer to a lower number, myself, unless otherwise corrected.

However, there is the possibility that white dwarfs and neutron stars create a new set of planets, and some of those might get ejected.  Also without evidence, I speculate that nova and supernova events ejecting much complex matter, perhaps it does not all disperse evenly, but some might settle into swirls gravitationally bound, and perhaps some of those might eventually condense into "Planets".

The truthful honest answer is "I don't know" isn't it.

Agent009.  That was an older article.  If you dig, you will find reference to the atmosphere having to be thick enough for a pressure at the surface up to that of our ocean bottoms.  Also, there is a mention that any disturbance to the atmosphere, perhaps an impactor could cause it to disperse.  (But then it might collect a new hydrogen atmosphere.  Anyway the article indicates that such a pressurized and very thick Hydrogen atmosphere has a very very good green house effect).

Although the articles do not mention it, I would argue a "Best Case" (From a human view) would be enough Hydrogen to greenhouse a nitrogen layer below it, so that the top of the nitrogen layer was at 70 degrees K.  A substantial layer of Helium below the Hydrogen and above the Nitrogen is unlikely, but there would be some.  Then within the Nitrogen atmosphere could be supported Methane perhaps, and if the lower layers were warmer, CO2.  From that perhaps liquid water could exist ideally with less of a total atmospheric pressure.

But in reality even better for humans would be that case with the modification of no open water, but a more long lasting ocean with a layer of ice over it.

Such a world might not have a atmospheric pressure that was such a challenge.  It also could be hoped that it had mountains with lower pressure where cities could be built.

I have serious reservations on the thought that H2 could provide enough greenhouse effect to warm the Nitrogen to 70 K + on it's own without pushing the pressure too high for a human habitat.

The only possible "Out" I could speculate on is if H2 at a substantial density could have a super greenhouse gas disolved into it.  Such gases are too heavy to stay with the Hydrogen otherwise.  Further, I don't know if there could be a super greenhouse gas that could remain disolved in an H2 column of say 0-3 bars at 60 K.  I might wish for one.



All speculation though.

Last edited by Void (2014-06-26 16:30:42)


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#35 2014-06-26 15:37:50

JoshNH4H
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Re: Rogue super-Earths/mini-Neptunes...

Agent009-

Makes sense smile  I normally assume that all pressures are absolute pressures, especially when it comes to space and terraforming, unless I have reason to think otherwise. 

Triple point would be interesting indeed.  I would think that that would be where you might expect to see some kind of crystalline life forms.

Going in the opposite direction, I've always wondered about tidally locked lava worlds.  If Mercury were tidally locked, its hottest temperature would be about 650 K, which is not hot enough for most kinds of rock to melt.  The orbital radius would have to be approximately .1 AU before rock started to melt, which is just 20 solar radii.    This will be farther for hotter stars, because they have a higher ratio of output power to radius.


-Josh

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#36 2014-06-27 02:41:08

Terraformer
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Re: Rogue super-Earths/mini-Neptunes...

Then there's gas dwarfs, worlds where the atmosphere dwarfs the central body in size (but not mass). Think of a body with 1% the surface gravity of Terra, but a nitrogen atmosphere that is ~1atm at the surface. A few thousand kilometres of atmosphere to play around in (gravitationally bound 'Virga'), most of which will be at substantially lower gravity. No place for aerostats, it pains me to say, since powered flight would be trivial to achieve, and terminal velocities so low that a failure would not be catastrophic. You'd probably have such even where the world is 4% of Terran surface gravity, actually. But, it gets you fighter craft that *are* atmospheric, and Giant Battleships, and Islands In The Darkness...


"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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#37 2014-06-27 03:16:20

agent009
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Re: Rogue super-Earths/mini-Neptunes...

Terraformer-

Well, aerostats based on "light gas balloon" principle have their merits since they require no power input for lift... How about you replace part of N₂ in the atmosphere with, say, SF₆ (sulfur hexafluoride) - which has more then 5 times the mole mass of nitrogen and lots of greenhouse effect, but is still completely inert and much less narcotic than CO₂ (it is still about 6 times more narcotic then N₂, but you could have up to 25% of it under 1 atm without getting narced - even more, if you replace the rest of N₂ with non-narcotic neon). An atmosphere consisting of 44% Ne, 33% SF₆, 21% O₂, 2% N₂ and some trace amounts of CO₂ would still be perfectly breathable for humans and capable of sustaining Earth-like biosphere under 1 atm pressure, but you would have 64.36 g/mol mole mass (which would give you more then twice the density of Earth atmosphere under the same pressure and temperature) and lots of greenhouse effect.

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#38 2014-06-27 05:52:13

karov
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Re: Rogue super-Earths/mini-Neptunes...

F is expensive.

How about atmosphere with a stuff which has enormous molar mass, but lesser density ... topped with nanobubbles foam.

Last edited by karov (2014-06-27 05:53:36)

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#39 2014-06-27 07:21:40

Terraformer
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Re: Rogue super-Earths/mini-Neptunes...

Well, actually what I have in mind is worlds that could either form naturally, or be produced by adding in trace greenhouse gases and heating. A lot of the Plutoids appear to be coated with thick layers of frozen nitrogen that may be 1km thick. If such a layer was on a world with a 0.01g surface, it would result in a 1bar surface pressure, but an atmosphere that would stretch for over a thousand kilometres without thinning much, dwarfing the central body. Though it would perhaps be much denser and smaller, if only heated to ~100K.

For a given density, aerostats are the same size regardless of gravity. But the required power for powered flight is dependent on gravity, so if gravity goes low enough, powered flight becomes more attractive. If you can fly with short wings by moving through the air at a few miles an hour...

The lower the gravity gets, the more it becomes like Space With An Atmosphere, a.k.a Virga. Of course, if you have gravity, you have a plausible reason why your ships are laid out like planes.


"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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#40 2014-06-27 08:10:59

agent009
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Re: Rogue super-Earths/mini-Neptunes...

karov wrote:

F is expensive.

F is expensive on Earth, and Ne is even more so, since we've got relatively few of that stuff down here. Doesn't mean such would be the case on some other world as both elements are relatively abundant throughout the universe. There is no particular reason why there cannot be a planet with natural Ne/SF₆/O₂ atmosphere (may be with just a little bit N₂ and CO₂ to support plant life). I don't get why people are so transfixed on N₂ as major atmospheric gas when thinking of "habitable" worlds - it's not actually required for life (not in the amounts it is present in the Earth atmosphere at any rate). All it does for humans and other animals is diluting O₂, which would otherwise be poisonous at partial pressure above 0.48 atm - but any inert gas could do that.

If tomorrow, through some bizarre magic or highly advanced alien technology, all N₂ in Earth atmosphere was replaced by Ne or Ar for instance, most humans wouldn't even notice. First people to notice would likely be the pilots, since both air density and speed of sound would change. SCUBA divers would notice pretty quickly too, since Ar is about twice as narcotic as N₂ while Ne is at least 12 times less narcotic. Finally (after a while), farmers would likely notice as well, since plants need ammonia which is produced by special bacteria form atmospheric N₂ - but, considering how little CO₂ it actually takes to sustain the carbon cycle, nitrogen cycle likely wouldn't suffer if even as little as 1% of N₂ was left.

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#41 2014-06-27 09:28:11

JoshNH4H
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Re: Rogue super-Earths/mini-Neptunes...

Agent009, While the abundance of various elements varies somewhat, at least within the solar system it seems to be fairly constant for rocky bodies.  I grant that a planet with a neon or argon or SF6 atmosphere is possible, but Earth should have held onto these elements as well as anywhere else and we certainly don't have one.


-Josh

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#42 2014-06-27 11:17:49

agent009
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Re: Rogue super-Earths/mini-Neptunes...

Josh, abundance of elements other then H, He, C and O (which are, by far, more abundant then anything else) in the Sol System is a purely circumstantial. For instance, we have anomalously high abundance of N and anomalously low abundance of Fe here judging by the estimated relative abundance of those elements in the Milky Way. There is nothing to say that there would be no similar anomalies in other places - thus there could be unusually high abundance of F and S, which would readily react with each other and produce SF₆ (which is one of the most stable compounds of F). Again, especially if we consider nomad planets, they would not be subject to stellar winds as much as planets closer to a star, so they would be able to better hold on to lighter inert elements and chances are, there would be much more Ne in the atmosphere then N₂ (since as Ne is estimated to be nearly twice more abundant in this galaxy). There could also be other factors that would allow rocky planets to hold on noble gases better then Earth, Mars, Venus and Titan managed. Again, as I said, there seems to be anomalously high abundance of N in the Sol System - but, even then, Earth and Titan seem to have gotten the most of it since you haven't got much of it on Mars and Venus (not to mention other rocky bodies). I really do not think we should regard all patterns we observe in a single stellar system as universally applicable.

Last edited by agent009 (2014-06-27 11:21:15)

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#43 2014-06-27 11:47:49

Terraformer
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Re: Rogue super-Earths/mini-Neptunes...

Hmmm. Perhaps the reason is that the Nitrogen was delivered later by comets (as NH3?), whereas Neon and Argon would not have become trapped as much? That would suggest that they will be a lot more common in the outer solar system, then, since they would have been able to freeze out and accumulate around bodies.

Argon is quite common on Earth. Maybe it will be a major component of any Plutoid atmospheres.


"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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#44 2014-06-27 12:19:17

agent009
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Re: Rogue super-Earths/mini-Neptunes...

Terraformer wrote:

Argon is quite common on Earth. Maybe it will be a major component of any Plutoid atmospheres.

Argon is common on Earth for a completely different reason, actually. Most of Ar we've got here is Ar[40] - which is a product of radioactive decay of unstable K[40], of which there seems to be quite a bit in the Sol System (another anomaly?). Most of Ar produced through stellar nucleosynthesis is Ar[36], of which we've got nearly as little as we've got of Ne (which is actually believed to be the 5th most common element in the universe after O, btw).

You should take this into account when speculating about planetary atmospheres in other systems that contain argon, btw... because argon you would most likely have there would be mostly Ar[36], which is about 4 g/mol "lighter" than "common Earth argon" (that's about the mole mass of He and may make quite a bit of difference when estimating air density, buoyancy and speed of sound).

Last edited by agent009 (2014-06-27 12:47:43)

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#45 2014-06-27 13:43:58

Void
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Re: Rogue super-Earths/mini-Neptunes...

I will be happy for corrections, but;

On a Rogue planet far away from an external heat source, with potential major gasses Hydrogen, Helium, Neon, Nitrogen, Methane, Carbon Dioxide.

Mixing will be reduced because of reduced wind.  Even so perhaps although somewhat layered some mixing will occur.

I think the primary laying forces are gravitation on heavier and lighter gasses, and condensation.

Frankly I am trying to beg, borrow, steal a reason why it would behave the way I want it to.  Which will very possibly leave me open to attack, but so what.

I am thinking I want a Neon Layer under a Helium Layer, under a Hydrogen layer, and under the Neon, Nitrogen, and under that Argon.

Although the Neon is heavier than Nitrogen (Apparently), I am counting on condensation to contribute to what I want.  I am supposing that the Hydrogen and Helium will never condense, because the universe is too warm.

The Neon will mix with Helium and Hydrogen to some extent and form a mixed layer that is just possibly lighter than Nitrogen.  The reason I think this is that some of the Neon would perhaps condense into a supercooled state, or an ice fog, and begin to drift downward slowly, making sure that the Neon part of that layer of atmosphere never gets above a certain percentage.  I am looking for fog/cloud cover to hold in geothermal heat.

Lower down, I am hoping for another such fog/cloud layer at the boundry of the Nitrogen/Hydrogen-Helium-Neon mix where the mix is too warm to condense Neon, but Nitrogen mixed in can condense into a heat trapping fog.

Finally below that I am hoping for a Nitrogen/Argon interface where Argon condenses into a heat trapping fog.

From there, if all the above were to work, it might be hoped that Methane as a greenhouse gas would hold in heat somewhere in the Nitrogen/Argon column.

And then just possibly below that CO2,

and then incredibly optimistically a layer of water vapor.

However I just included that for fun.  I think more likely a frozen surface with the possiblity of under ice oceans, and just maybe geothermal hot springs.

You guys started this thing with Neon.  I can see it is heavy, but it also is vapor down to ~25 K.  So I tried to find a way it could help, and just maybe I did.

I didn't mention Hydrocarbon Fogs to hold in heat either.


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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#46 2014-06-27 14:08:37

JoshNH4H
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Re: Rogue super-Earths/mini-Neptunes...

It's my understanding that diffusion is strong enough to make the above scenario unlikely.

Regarding Nitrogen, it does remain to be seen whether Mara had a significant amount of primordial Nitrogen.  The MAVEN probe, due to arrive at Mars in September, will tell us about the loss rate of gases from Mars.

Venus, also, has a huge amount of Nitrogen, more actually than Earth.  Mercury has none, of course.  Depending on the MAVEN results, we may be looking at a situation where we are asking ourselves why the Jovian system has so little Nitrogen, rather than looking at Earth and Titan as anomalies.

It seems very possible that a combination of low mass and Jupiter's radiation belts could be responsible for the absence of Nitrogen, or really any gas, around the Jovians. 

Having said that, Terraformer's explanation for the ratio of Nitrogen to Neon in planetary atmospheres makes sense to me, and is not in any way contrary to the observed quantities of Nitrogen on nearly every rocky body with an atmosphere.

If you wanted to posit a planet with more Neon than Nitrogen, you would in effect be saying that somehow gases did not boil off of the tiny rocks, asteroids, and eventually planetoids that the planets are made from.  This seems improbable.  Look at the Moon, after all.  We can guess that most of each body's volatiles, especially the most volatile ones like Neon and Helium were lost long before they became planets, and that they were brought back by collision with bodies from the outer system on elliptical orbits. This would have brought in Water, ammonia, and some carbon dioxide, and less methane.  A Neon atmosphere would necessitate a large solar system around a cold star, which while not impossible seems unlikely.


-Josh

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#47 2014-06-27 15:07:15

agent009
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Re: Rogue super-Earths/mini-Neptunes...

Void wrote:

Although the Neon is heavier than Nitrogen (Apparently)

Not so. Atomic neon has mole mass of 20.18 g/mol. Molecular nitrogen - 28.01 g/mol. Neon, as "noble gas", does not form diatomic molecules as nitrogen does.

JoshNH4H wrote:

A Neon atmosphere would necessitate a large solar system around a cold star, which while not impossible seems unlikely.

Ok, I'm more of a sci-fi writer then an actual scientists - though I do like to write hard sci-fi rather then rely on suspension of disbelief wink For me, "not impossible" means "possible". And since Ne/SF₆ atmosphere certainly makes a more interesting setting then N₂, I assume it is possible until I have a conclusive prove of the opposite.

Last edited by agent009 (2014-06-27 15:41:35)

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#48 2014-06-27 16:56:22

JoshNH4H
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Re: Rogue super-Earths/mini-Neptunes...

Sure.  In discussions of geology and planetary science, pretty much any state, be it transitory in the short or long term, is possible.  And I'm not a geologist or a planetary scientist, but to me it's all reverse engineering-- knowing the basic equations of gravitation and a few other laws, you can look back and see how the universe made itself. 

I am a lover of hard sci-fi, myself.  And I try to refrain from being excessively proscriptive in general.  Having said that, I do wonder about an SF6 atmosphere.  We've already seen, for example on Io, a place where Sulfur has gotten concentrated on the surface in elemental form instead of bonded as sulfides.  The issue is finding a mechanism to concentrate Fluorine, which is not common at all in the universe.  In general, it will become more common as the universe gets older because stars  are converting Helium and especially Hydrogen into heavier elements.  So I would expect to see more of it closer to the center of the galaxy and in globular clusters.   

From a chemical perspective, it's tough to imagine fluorine concentrating on the surface of a planet because it's so reactive and is perfectly happy forming solids.  Perhaps there could be a world covered in Water (or ammonia? Some polar solvent anyway) with a lot of volcanism.  If the oceans are full to their solubility with fluoride and there was a volcanic vent on the floor spewing sulfur at high temperature, some of the fluorides might react to SF6.

Alternatively, there's the biological explanation: perhaps as part of their metabolism, some creature turns metal fluorides and sulfur into sulfur fluorides and metal. 

That's all I've got.  But if I were to read an SF6 world, I'd probably accept it on authorial fiat.

Are you published, by the way?


-Josh

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#49 2014-06-27 18:26:41

Void
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Registered: 2011-12-29
Posts: 3,884

Re: Rogue super-Earths/mini-Neptunes...

Agent009 supplied:

Void wrote:

    Although the Neon is heavier than Nitrogen (Apparently)

Not so. Atomic neon has mole mass of 20.18 g/mol. Molecular nitrogen - 28.01 g/mol. Neon, as "noble gas", does not form diatomic molecules as nitrogen does.

Giving some additional support I did not realize.

Josh argued that Diffusion would act against what I suggested.

I think you are both correct.

I will start by arguing that whatever Hydrogen and Helium could diffuse into the other layers would.  But upon being saturated with them any remaining balance of them would float to the top of the atmosphere and pool there.

Nitrogen, Neon, and Argon would be below that in some arrangement.  They would indeed have some Hydrogen and Helium mixed with them.

For my continuation I will speculate that water does on Earth what I expect to happen in the Rogue planet for Nitrogen, Neon, and Argon.

Water vapor cannot get into the Stratosphere very much because of a precipitation height.  So, stays below that level until large precipitation brings it down.  Snow, Rain, Hail.

I don't expect enormous amounts of Neon.  Just a little might do.

Because as Agent009 informed me it is lighter than Nitrogen as a Molecule, at the area where the atmosphere transitions into Hydrogen and Helium, I would expect Nitrogen to precipitate out more aggressively than Neon.  This would then leave behind a reduced content of Nitrogen in the Mix, and an enhanced content of Neon, Hydrogen, and Helium.  This would be a continuing replenishing process I believe, that might resemble air on Earth being dryer after the clouds release their rain.

However I might hope that the Neon would also condense to a degree at about ~25 K, into a fog either droplets or ice fog.  Why I care, is Nitrogen needs ~70 K to maintain pressure (Unless at very low pressures).  So, the cloud tops for a Neon enhanced layer would only radiate ~25 K to the universe through the Hydrogen and Helium.  It is an improvement over radiating ~70 K.

Further, if the Nitrogen then is kept warmer by a Neon cloud deck and the Neon vapors (Don't know if Neon has much greenhouse value, then  below that could be a Nitrogen cloud fog. 

Maybe also somewhere an Argon cloud fog.

Since the source of heat that matters is geothermal, 3 cloud decks would help a lot.

Then there might be Hydrocarbon fogs somewhere like on Titan.

Particulates in the atmosphere would have a lot to do with the atmospheric behaviors.

To Teraform such a world injecting particulates might be a tool, and of course fusion reactors. 

Since such worlds are said to have a heat source of 1/5000th of that of our sun, it is not that far fetched to imaging adding another 1/5000 to the environment from waste heat.

For my part, I would disperse the waste heat into any oceans, and let it move into the atmosphere through the ice, getting double use from it.

With a cold atmosphere, I do not think it would be that far fetched to have domes made of flexible materials, which would be inflated by heated air inside, and which might have a Breathable atmosphere inside.

Some worlds would be better than others.

I hope there's lots of them.

True, 1/5000th might not be enough to keep Neon, Nitrogen, and Argon from freezing, but maybe 1/2500th would or with more aggressive heating that that, such an atmospheric process could be manufactured.

I am just saying that prospects for at least creating a terraformed Rogue planet are improved by what I think can be done.

With enough fusion power on the surface and super greenhouse gasses added perhaps it could eventually host open water, and lighted gardens.

Last edited by Void (2014-06-27 18:32:36)


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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#50 2014-06-27 19:51:24

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Rogue super-Earths/mini-Neptunes...

I see what you're going for, and I agree with the conclusion you've come to only because of the low temperatures we're talking about.


-Josh

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