Type V worlds in other locations?

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Re: Type V worlds in other locations?

Postby Crucis on Fri 11 Jan 2013 23:44

AlexeiTimoshenko wrote:The problem is that most of the potential planet types that we come up with will be little more than scenery other then their moons. Planets with atmospheres other than O-N based will most likely be uninhabitable for sentient life as we know it.


Exactly, Alexei. For example, there's a theoretical type of planet called the "Carbon planet".

http://en.wikipedia.org/wiki/Carbon_planet

I doubt that this type of planet would be habitable for any type of T/ST life. It might be possible that some alternative lifeform might like it. From what I've read, it doesn't seem to present the dangers of a Type V planet, and yet, it sounds like it could be a very hostile place. I've avoided including Carbon planets because I just don't know how to fit them into the mix, given that they're so ... different.
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Re: Type V worlds in other locations?

Postby procyon on Sat 12 Jan 2013 01:28

Crucis wrote:BTW, if Venus had had a significant moon, like Earth has Luna, would it be a different place today?


This has been debated for a number of years.

The general consensus is no.
In fact, the current belief is that Venus has 'consumed' two moons already.

As long as you have an atmosphere that dense around a planet that is nearly tidelocked to its star, the tidal drag of the dense atmosphere will eat away the momentum of any moon until it is pulled into the planet.

Whether it had moons at one time, I don't know. The science to back it up isn't particularly convincing to me.

But the math to show that if Venus - as we see it now - were to have a moon, that said moon would be pulled into the planet over time...that math is solid and nearly undisputable.
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Cralis wrote:I would point out that the "what was" which is different from "here and now" can easily change in the "future then."
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Re: Type V worlds in other locations?

Postby Crucis on Sat 12 Jan 2013 01:45

procyon wrote:
Crucis wrote:BTW, if Venus had had a significant moon, like Earth has Luna, would it be a different place today?


This has been debated for a number of years.

The general consensus is no.
In fact, the current belief is that Venus has 'consumed' two moons already.

As long as you have an atmosphere that dense around a planet that is nearly tidelocked to its star, the tidal drag of the dense atmosphere will eat away the momentum of any moon until it is pulled into the planet.

Whether it had moons at one time, I don't know. The science to back it up isn't particularly convincing to me.

But the math to show that if Venus - as we see it now - were to have a moon, that said moon would be pulled into the planet over time...that math is solid and nearly undisputable.


Procyon, I was thinking a little more along the lines of if Venus had had a moon much earlier before its atmosphere had become so dense. Would such a moon have helped prevent the loss (if one existed beforehand) of its magnetosphere, and prevented the planet from becoming what it is today?
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Re: Type V worlds in other locations?

Postby procyon on Sat 12 Jan 2013 03:48

Crucis wrote:Procyon, I was thinking a little more along the lines of if Venus had had a moon much earlier before its atmosphere had become so dense. Would such a moon have helped prevent the loss (if one existed beforehand) of its magnetosphere, and prevented the planet from becoming what it is today?


If I had that answer...

Oh well, here is my take on it.

As it stands, Venus has only a negligible (compared to Earth) magnetic field. Likely created by interaction in its high atmosphere with stellar particles/ionizing radiation.
But it should have the ability to generate a dynamo and create a sizable magnetic field.. Why it doesn't is completely unknown. And without knowledge of why it doesn't - it is impossible to say whether a moon would affect the system or not.

If sulfur is too abundant in the core/mantle of Venus - it may already by solid due to the high melting temp of many of those compounds. A moon won't fix that.

If it is due to lack of thermal conduction (Venus' liquid layer) isn't cooling adequately - again, a moon wouldn't help.

Now it does appear that Venus surface does undergo remodeling every so often -apparently as the mantle overheats and sheds heat by massive subduction over millions of years. Essentially it overheats, the surface melts down, and then it starts over.
DURING those periods of subduction - Venus could exhibit a magnetic field. Some folks have looked for evidence of transient magnetic field evidence on Venus. But Venus is a hard nut to get a look at. If it can be shown that Venus occasionally has a magnetic field - then we would have a better handle on what it looked like inside.

But if it does occasionally have one, we have pretty good proof that a magnetic field won't protect you if your atmospheric composition is wrong.

In a few cases, a moon may help a planet keep a magnetic field. In most cases we are looking at for Venus - it really wouldn't have mattered. Venus simply rotates to slowly for a moon to save it.

I am also not sold on the theory that Venus once had an Earth like atmosphere. Everything we can see shows that Earth started with a more 'Venus like' atmosphere and became more Earth like with time. It is likely that Venus started with and even 'more Venus like' environment and has lost some of it due to cooling over time. Although I will admit this is only my opinion.
...and I will show you fear in a handful of dust....

Cralis wrote:I would point out that the "what was" which is different from "here and now" can easily change in the "future then."
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Re: Type V worlds in other locations?

Postby AlexeiTimoshenko on Sat 12 Jan 2013 06:42

I think that part of the issue with Venus is a lack of Hydrogen. If early in it's history, water was present and the molecules were split due to solar radiation, the resulting free Hydrogen would have escaped into space. The resulting Oxygen would then have been free to bond with both Carbon and Sulfur to create the atmosphere as we see it today.
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Re: Type V worlds in other locations?

Postby procyon on Sat 12 Jan 2013 21:26

That is pretty much the posited pathway, although the lack of hydrogen is a 'result' and not a cause.

Minimal magnetic field results in water vapor in high atmoshere being ionized to H2(x2) and O2. Free oxygen ends up oxidizing other compounds that contribute to greenhouse gases -as does the small amount of H2 that doesn't escape to space (as in CH4 for methane, another greenhouse gas...).

Gases heat up atmosphere resulting in increased evaporation of H2O, with increased ionization. And this leads to the upward spiral of temps.

Now sulfur is actually the element that stops the progression, as opposed to aiding it. The increased temps liberate sulfur from compounds that would otherwise remain stable at lower temps. The sulfer oxidizes and creates the clouds that reduce the amount of ambient light reaching the surface - slowing the greenhouse effect. When enough sulfur has been liberated - an equilibrium can be reached and the temp stabilizes. As Venus is now.

Should Venus undergo another subduction - it will likely cool down some as the surface melts due to increased deposition of sulfur into the atmosphere. Then as the surface cools the extra sulfur will settle as more stable compounds that will 'precipitate' out of the atmosphere. That is what the 'snow' that we see on Venus' higher mountains is believed to be. Sulfur compounds that have settled out of the atmosphere at altitudes where it is cool enough for them to be stable.

But I agree with the experts that V. heard. Given adequate atmosphere density and composition - you could have a 'Venus' a fairly long way from a primary. And if it was positioned around a gas giant that could deposit enough energy - you might see one quite a long way out.
...and I will show you fear in a handful of dust....

Cralis wrote:I would point out that the "what was" which is different from "here and now" can easily change in the "future then."
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Re: Type V worlds in other locations?

Postby AlexeiTimoshenko on Sat 12 Jan 2013 23:29

How far out would depend upon the solar radiation being able to ionize the water vapor.
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Re: Type V worlds in other locations?

Postby aramis on Sun 10 Feb 2013 21:01

AlexeiTimoshenko wrote:How far out would depend upon the solar radiation being able to ionize the water vapor.

Quite likely, it's part of the reason for Mars' low water and high CO2...
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Re: Type V worlds in other locations?

Postby procyon on Mon 11 Feb 2013 22:12

AlexeiTimoshenko wrote:How far out would depend upon the solar radiation being able to ionize the water vapor.


That would be a LONG way out. (Particularly with Ice XI's triple point posited at nearly 72K. And the fact that non vapor water is also susceptible if in direct exposure.)
But they aren't necessarily dependant on one another.
Water can be 'ionized' (not the actual term, but close enough for this) at energies as low as 50-100 eV. So if you have a surface exposed to gamma radiation for long enough - you will eventually see all the water decay to H2 and residuals (O2, OH-, etc).

aramis wrote:Quite likely, it's part of the reason for Mars' low water and high CO2...


I agree.
Solar radiation turned Mars surface water to H2 and residuals long ago, in all likelihood.
Which is why you find so many hydroxides on Mars' surface. It is the 'corpse' of the long gone water.

But it wasn't because Mars was a 'V' type planet (and I am sure aramis wasn't implying that was the case).
It was just because it couldn't keep direct solar radiation from reaching the water.

Particle radiation is much more effective at breaking down the H-O-H bond in water, and why the lack of a magnetic field is so damaging to a planet's water retention. This is what happened at Venus. Not the simple proximity to the sun. Earth is close enough to have its water broken down. It is just that most ways solar radiation would do this on Earth are VERY ineffective due to our magnetic field and atmospheric composition.
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Cralis wrote:I would point out that the "what was" which is different from "here and now" can easily change in the "future then."
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