Terraforming putative Proxima Planet

Tom Kalbfus · 2016-08-18 11:48:56

Lets say there is an "Earthlike" planet orbiting Proxima Centauri as advertised, let is say it is about the size of the Earth, has a magnetic field, has a rocky crust and would be 70% covered with water. the planet is tidally locked with its star, the Sun appears 3.7 times as large as our Sun does on Earth, and it glows a ruddy color.

Now the question is, given that Proxima is older than our Sun, does Proxima probably have life? would it be life we care about? Could we just move onto the planet's surface, or would we have to terraform it?

There are a number of things about this situation that humans might not find satisfying, how about that big bloated orb in the sky that does not seem to move, could human beings live with that? Could we grow crops under that. Could Earth life be adapted to that, or would you anticipate problems? The great thing is you could bask underneath that red sun, and not worry too much about getting a sunburn, unless there was a solar flare, and then maybe you would catch on fire!

Could we make this planet more Earthlike? One possibility is we could live on the farside of the planet and not worry about the bloated red orb?

RobertDyck · 2016-08-18 12:18:32

Depends on atmospheric conditions. Venus rotates backwards and so slowly that one "day" is longer than one orbital period. There doesn't appear to be significant surface differences between day and night sides. That's due to a very thick atmosphere (92 bar!), high velocity high altitude winds that exchange heat between day and nigh, and clouds that shade the the day and keep radiant heat in a night. Actually, it's believed primordial Earth had an atmosphere similar to Venus today, but then cooled just enough for an ocean. CO2 dissolved in the ocean forming carbonic acid, a very mild acid. Soda pop is carbonic acid, so it's obviously safe to drink. But the acid sped decomposition of rock, magnesium and calcium dissolved, then dissolved CO2 combined with magnesium and calcium to form dolomite and calcite. Those minerals precipitated out to form limestone. Venus never had an ocean, so it's think atmosphere is still there.

So, what will conditions be like on Proxima Prime? Will it be Venus-like? Or will it be hot enough to melt lead on the day side, and frozen on the night side? Or will it have a thick atmosphere with lots of clouds, and high velocity high altitude winds? Vigorous ocean currents between day and night? Perpetual arctic on the night side, tropical rain forest on the day side?

karov · 2016-08-18 13:19:34

https://arxiv.org/pdf/1405.1025.pdf

... and plenty of other materials available.

Literally thousands in the last few decades.

It seems quicker rotation is a habitable zone contraction factor, so ...

Tom Kalbfus · 2016-08-18 20:52:11

RobertDyck wrote:

Depends on atmospheric conditions. Venus rotates backwards and so slowly that one "day" is longer than one orbital period. There doesn't appear to be significant surface differences between day and night sides. That's due to a very thick atmosphere (92 bar!), high velocity high altitude winds that exchange heat between day and nigh, and clouds that shade the the day and keep radiant heat in a night. Actually, it's believed primordial Earth had an atmosphere similar to Venus today, but then cooled just enough for an ocean. CO2 dissolved in the ocean forming carbonic acid, a very mild acid. Soda pop is carbonic acid, so it's obviously safe to drink. But the acid sped decomposition of rock, magnesium and calcium dissolved, then dissolved CO2 combined with magnesium and calcium to form dolomite and calcite. Those minerals precipitated out to form limestone. Venus never had an ocean, so it's think atmosphere is still there.
So, what will conditions be like on Proxima Prime? Will it be Venus-like? Or will it be hot enough to melt lead on the day side, and frozen on the night side? Or will it have a thick atmosphere with lots of clouds, and high velocity high altitude winds? Vigorous ocean currents between day and night? Perpetual arctic on the night side, tropical rain forest on the day side?

Perpetual arctic might be a good thing for us. A planet that is too "Earthlike" is liable to have its own established ecosystem, and would that ecosystem be compatible with us? On the night side, you would have ice sheets, very little of the life on the day side would get to the night side, so we could establish out own ecosystem on the night side. One would place a mirror in a 24-hour orbit around the planet, that mirror would filter out the excess red light and concentrate the remaining blue, green, and yellow light to create an Earthlike day over part of the far side of the planet, leave some ice sheets at the rim to create a natural barrier between the alien ecosystem and the imported Earth life on the far side. We would probably want the far side because the planet would provide a natural barrier to stellar flares, the mirrors would have to adjust and not reflect so much light when Proxima is flaring.

karov · 2016-08-19 09:59:42

Tom,

Yeah. I like it.

A "Retina" habitat on the back of an "Eyeball" planet

http://3.bp.blogspot.com/-rMVXffb39tE/U … planet.jpg

RobertDyck · 2016-08-19 11:28:17

You're obsessed with colour of light? It doesn't have to be this exact colour. If the world is very red, that's Ok. If you want to live in another star system, expect light to be different. Examples from TV, the 1970s TV show Battlestar Galactics, episode "War of the Gods"...

Or the movie Star Trek Into Darkenss, a scene from the movie and a concept painting...

Antius · 2016-08-19 11:47:38

The existence of this planet is not confirmed and as of yet we know nothing about it. So talking of terraforming is premature. But a few thoughts.

One thing does stand out looking at the Kepler planets found to date. Most of them are larger and more massive than the Earth. The Earth's solar system is relatively unusual both in the small size of its terrestrial planets and their relatively discrete distance from their host star. Both discoveries are very bad news for interstellar colonisation and bad news also for the prospect of finding other space faring species.

Look at the difficulties we have trying to escape the Earth's gravitational pull using rockets. The amount of technology and effort that it takes. Would we really want to deliberately trap ourselves in a gravity well 10 times as deep? It would be a one way trip. Once human beings landed on such a planet, they would never leave it again.

RobertDyck · 2016-08-19 12:18:40

karov wrote:

A "Retina" habitat on the back of an "Eyeball" planet

That's a good image of a tide locked planet. Living on the terminator. Probably more realistic. However, the word "retina" reminds me...

Early single cell life on Earth first developed a photo-dye called retinal. It absorbs green light, reflects red and blue. Very efficient with the light that comes from our Sun. Then another single cell organism evolved. It had to make do with scraps left by the dominant species. This second organism evolved a photo-dye that absorbs red and blue, reflects green. So it used the light left over from the first organism. Here is our Sun's spectrum. Notice green is higher (more intense) than red or blue.

The photo-dye that absorbs green is called retinal. It was used by archaea, which are single cell organisms more primitive than bacteria. There are some archaea living on Earth today, they tend to live in extreme environments where more modern organisms can't live. Not because archaea prefer it, but simple because that's what's left. The photo-dye that absorbs red and blue is chlorophyll. It has to absorb two colours to gain enough energy for live to thrive efficiently. The first organism to evolve that was cyanobacteria, a true bacterium. Algae evolved from cyanobacteria, and eukaryotic cells enslaved cyanobacteria to become chloroplasts. Multi-cellular organisms with chloroplasts are called plants.

Cyanobacteria developed a further advantage: two photosystems. Double photosystem produced sugar to store energy, and oxygen as waste. Cyanobacteria had to develop ways to protect key parts of the cell from this toxic gas. But the double photosystem was far more efficient than a single photosystem, so more energy to the cell from the same amount of light. And oxygen was a toxin, poisoned the anaerobic archaea that had dominated before.

So ponds filled with living things were originally purple from the archaea using retinal. Today a pond with an algae bloom is green. One type of archaea today thrives in very salty water, too salty for algae or plants. It's called halobacteria.

So would life on another planet use retinal instead? Would the planet have purple plants? The detailed chemical process for photosynthesis using retinal is quite different than the chemical process using chlorophyll, but obviously living things can use either. In fact, the retina in human eyes use a variation of retinal. It's ever so slightly different than the retinal used by halobacteria.

We actually have cells in our retinal that absorb red light, other cells absorb green, and others absorb blue. That's how our colour vision works. We also have rods that have retinal that responds to any colour of light, and rods are very large so have a great deal of retinal. That large amount of photo-sensitive chemical makes them very sensitive to dim light. Actually, rods can see ultraviolet. Our lens filters out UV. Patients with cataract surgery who had their lens removed can see UV light for many months. The plastic lens implanted as a replacement doesn't filter UV. Eventually our eyes grow a film of material over the artificial lens, that material filters out UV so the patient can't see UV any more. For a while the military used patients with cataract surgery for navy signals. They would use lamps that only produce UV light. Signal men could see the flashing light, so translate the code. Any enemy ships in the area couldn't see the UV light, so this permitted ship-to-ship communication without revealing their presence to the enemy. The painter Claude Monet continued to paint after his cataract surgery.

With his lens removed, Monet continued to paint. Flowers remained one of his favorite subjects. Only now the flowers were different. When most people look at water lily flowers, they appear white. After his cataract surgery, Monet’s blue-tuned pigments could grab some of the UV light bouncing off of the petals. He started to paint the flowers a whitish-blue.

6a0162fff12125970d01630435136d970d-800wi

Last edited by RobertDyck (2016-08-19 12:19:23)

Void · 2016-08-19 15:18:29

I posted this yesterday in another place. (Science.....) You might want to open up your options for the apparent many cases where a red dwarf planet we expect will be tidally locked is not but has days of weeks and months, similar to Venus.

Noting all the very reasonable cautions against optimism for an Earth-Like planet around Proxima Centauri, I think I can turn to a degree of increased optimism for worlds around Red Dwarfs ("M") stars in general.

http://www.skyandtelescope.com/astronom … -01222015/
Do Atmospheres Spin Worlds to Habitability?
By: Shannon Hall | January 22, 2015

New research, however, suggests not all is lost for tightly orbiting planets. Jérémy Leconte (University of Toronto and Pierre Simon Laplace Institute, France) and his colleagues think that an atmosphere’s effect might be strong enough to break any tidal locking, allowing the planet to rotate freely and exhibit a day-night cycle similar to Earth’s.
Leconte and his colleagues created a three-dimensional climate model (similar to those used in analyzing climate change on Earth) to predict the effect of a given planet’s atmosphere on the speed of its rotation.
It all goes back to the amount of starlight able to penetrate the planet’s atmosphere and reach the surface. Any temperature differences at the surface — between day and night and between the equator and the poles — drive winds. Those winds constantly push against the planet by running into mountains or creating waves on the ocean. Such friction then influences the rotation rate of the planet, helping to speed it up or slow it down.
“While gravitational tides and their associated torques tend to tidally lock the planet, thermal tides, produced by the star heating the atmosphere of the planet, tend to oppose the gravitational tides, and prevent the planets from becoming tidally locked,” says coauthor Norm Murray (University of Toronto).
Astronomers have long seen this effect on the planet Venus, where the atmosphere’s influence is so powerful that it forces the planet out of synchronous rotation into a slow retrograde rotation: to a Venusian, the Sun rises in the west and sets in the east. But Venus’s large atmosphere weighs in about 90 times heavier than our own, and planetary scientists didn’t think thinner atmospheres like Earth’s could throw their weight around as effectively.
Leconte’s simulations show that thinner atmospheres actually have a larger rotational effect on their planets. With less scattered sunlight, extra heat reaches the deepest atmospheric layer and creates stronger winds. If Venus were to have an atmosphere like Earth’s, it would spin 10 times faster. This is radically different from previous research, which suggested that it would spin 50 times slower.
An unlocked planet should have strong atmospheric mixing and relatively stable temperatures. “This greatly increases the chances for atmospheric stability — and, hence, for life — on any of these bodies, provided they are Earth-like in terms of mass, water content, and maybe their atmospheres,” says exoplanet expert René Heller (McMaster University, Canada).
In addition, it avoids many problems created on tidally locked planets, Take the cold trap, for example. “Liquid water on the sunny side tends to evaporate, and is thence transported by winds (driven by the temperature gradient) to the dark side, where it precipitates as snow and forms large-scale ice sheets,” says Murray. “Since the back side never sees the light of the host star, the ice sheets may well be permanent.” Eventually all the liquid water would move to the dark side, making life impossible.
Although the researchers show that a large number of known terrestrial exoplanets should have a day-night cycle, potentially rendering them habitable, the duration of their days could last between a few weeks and a few months. So Heller cautions that these planets would still be far from Earth-like, with only a few days per year.
Hopefully the theoretical results don’t remain in the observational dark for too long. Astronomers can determine the temperature of exoplanets when they pass behind their host stars. But it won’t be easy to do this for Earth-size worlds. Leconte thinks it might be within reach of the James Webb Space Telescope (slated to launch in 2018) if there is a particularly favorable planet to observe. If not, astronomers might have to wait for the European Extremely Large Telescope, whose first light is tentatively scheduled for 2024.

Similar articles indicate that Venus rotates because of such an effect. Also, it is said that if Venus had a atmosphere as thin as Earths, it would rotate 10 times as fast as it does.

Rotation helps to provide magnetic field, and magnetic field helps to preserve atmosphere. (This is what I have been told).

So, if so, some planets presumed to be DOA, might not be. And it would also indicate that long periods of rain and snow on the dark side would be followed by melting and drying on the day side.

A land plant that might make it under those conditions might be grass. Even if there were a solar flair killing it's blades, perhaps the root system would remain alive to sprout again.

And if you had grass, perhaps grazing animals could eat it. How they might deal with solar flares, is a question. Perhaps some would only graze in the night time and would seek shelter during the day, like rabbits with a burrow. Perhaps they could graze in the daytime, if they stayed near their burrows, and had finely tuned senses that warned them of flares.

Maybe some animals would be amphibious, and would again only venture far into land to graze in the early hours (Days) of the evening?

Perhaps some amphibious animals would not come to land to feed, but to have young, to protect them from aquatic predators, maybe like a penguin, perhaps they would do that at night.

Perhaps flying birds would tend to be burrowing also. They might also need to be able to sense when a flare was about to occur.

Some plants might only perform reproduction in the nighttime under snow layers?

My understanding is that the spectrum of light from a Red Dwarf is better at melting ice than is ours, so, this variant factor would also affect habitability (Whatever that is).

As for humans, I guess they might have to emulate these imagined animals to make it on such a world.

Last edited by Void (2016-08-19 15:22:50)

RobertDyck · 2016-08-19 18:36:32

A technical note, karov put tags in his post for a URL. He could have put "IMG" tags so the image displays in his post.
That is [img]before, and[/img] after. This is his image...

Tom Kalbfus · 2016-08-19 23:36:19

Tidally locked planet. You know if the orbit is not circular, there will still be places on the planet where the Sun will rise and set. The planet orbits faster as it pulls closer to the star but orbits slower as it pulls farther away, but the rate at which the planet rotates remains constant, there will be places where the planet is rotating faster than its orbiting the sun, and other places where is it rotating at an angular speed that is slower. The Sun will appear to rise, and then set at the same place, so that way you can have a local day and night. The red sun will dip below the horizon and them pop up again, giving us about 4 days of night and 4 days of daylight. A star that is already red will give off a "bloody sunset." The sky will appear to be a very dark blue. Probably leaves in native plants if there are any will be black.

karov · 2016-08-20 03:06:29

Antius wrote:

The existence of this planet is not confirmed and as of yet we know nothing about it. So talking of terraforming is premature. But a few thoughts.
One thing does stand out looking at the Kepler planets found to date. Most of them are larger and more massive than the Earth. The Earth's solar system is relatively unusual both in the small size of its terrestrial planets and their relatively discrete distance from their host star. Both discoveries are very bad news for interstellar colonisation and bad news also for the prospect of finding other space faring species.
Look at the difficulties we have trying to escape the Earth's gravitational pull using rockets. The amount of technology and effort that it takes. Would we really want to deliberately trap ourselves in a gravity well 10 times as deep? It would be a one way trip. Once human beings landed on such a planet, they would never leave it again.

No.1 - observational bias due to tech limitations.

No.2 - gravity is the coolest. ( https://www.ocf.berkeley.edu/~fricke/dyson.html ). Rockets? - inefficient.
Visualize kinetic structures which work two way, dumping mass in to pull mass out.
Thus even the biggish planets are seamlessly interfaced with the flatter spaces.

karov · 2016-08-20 03:11:12

Tom Kalbfus wrote:

Tidally locked planet. You know if the orbit is not circular, there will still be places on the planet where the Sun will rise and set. The planet orbits faster as it pulls closer to the star but orbits slower as it pulls farther away, but the rate at which the planet rotates remains constant, there will be places where the planet is rotating faster than its orbiting the sun, and other places where is it rotating at an angular speed that is slower. The Sun will appear to rise, and then set at the same place, so that way you can have a local day and night. The red sun will dip below the horizon and them pop up again, giving us about 4 days of night and 4 days of daylight. A star that is already red will give off a "bloody sunset." The sky will appear to be a very dark blue. Probably leaves in native plants if there are any will be black.

or with axial tilt.

karov · 2016-08-20 03:16:28

RobertDyck wrote:

A technical note, karov put tags in his post for a URL. He could have put "IMG" tags so the image displays in his post.
That is [img]before, and[/img] after. This is his image...

thanks, Bob - i know but i just forgot to...

by optics, be it more primitive orbiting mirror or mark#2 weather machine each and every dot of the planetary surface can be provided with precisely managed 'illuministics' , but purely aesthetically, we should leave some wilderness, right? and as in the case with Earth, the 'terraformed' areas comprise very tiny percent of the total area.

so, a 'retina' spot of few thousands of km wide on the back side of an 'eyeball' planet would provide quite a sizeable LAND, to place lotsa 'countries' onto.

Void · 2016-08-20 12:35:06

The proposed planet if it exists may rotate like Venus, per a post I previously made here. That may make it more likely that it retained an atmosphere. Terrestrials further out of the habitable zone, may very well have denser atmospheres, and not be strictly tidal locked.

All of these factors make it more likely that the night side will be more moderate than is supposed, because of greater capacity of air circulation to moderate the night side, and greater greenhouse effect to hold heat in during a permanent night or a night of weeks or months.

I actually want to see terrestrials found outside of the habitable zone, as I think they will have better chances of being suitable. And surprisingly, they may not be as hostile as previously thought.

The scope of your descriptions indicate a well developed world, presumably modified by and obedient robot army. Not wrong.

What would your startup process look like with humans and robots?

I see the likelihood that at first the surface would be utilized, wind, geothermal hot spots. Unless you have uber robots which are able to find and use materials in solar orbit to provide your resources in a top down method.

Tom Kalbfus · 2016-08-20 17:28:29

It is much closer to its primary than Venus, a closer approximation would be to one of the larger moons of Jupiter, such as Ganymede for example. Ganymede is tidally locked to Jupiter. Ganymede has a very circular orbit, the only reason its not completely circular is that other moons tug on it.

Void · 2016-08-20 17:52:22

It may well be tidally locked, but if you read the article I posted, it also indicated that if Venus had an atmospheric density similar to Earth, it would likely spin 10 times as fast as it does. Anyway the planet is speculation and not demonstrated as real. If it is or is not real, I really want to think about another terrestrial planet further out, and also about red dwarf planets in general. But your thread is specific to Proxima Centauri, so sure, it might be locked. Proxima is a very small star, I believe.

Last edited by Void (2016-08-20 17:53:22)

karov · 2016-08-25 04:55:21

It is THERE!

We know orbit and size.

Lets dream on !

karov · 2016-08-25 15:39:44

http://nautil.us/blog/forget-earth_like … ll-planets

The light over the whole surface could be easily distributed in an ideal illuminosphere.

So red dwarfs literally trillions of 'eyeball' planets make really prime real estate.

Their habitats can live literally for trillions of years!

Using in-space statites or hall weather machine.

Void · 2016-08-25 23:29:43

Karov, Tom, and others.

I will try to add something complementary to what I think you and Tom may champion. My anticipation is you will lean towards the H.W.M. and Tom towards orbital solutions. My purpose will not be to impede such efforts, but to try to add something else.

I am working from recollections, without posted references.

I recall an article which indicated that terrestrial spinning planets appear to arrange themselves by a particular alignment, where the high mass side ends up at one pole, and the low mass at the other.

An example would be Mars, and I think Earth, in opposite ways. Mars has its highlands at the south pole, and the Earth by my reckoning has it's highlands at the north pole. That is there seems to be more continental mass in the northern hemisphere of Earth than the southern.

So, we may have two models to run by. The Earth has Tectonics, and Mars does not seem to. We could imagine sizing them up to the estimated size of Proxima b, and reason how they would operate.

Other alterations to the models:
-Tidal Locking, I think with the greater mass hemisphere pointing at Proxima Centauri.

*So, Earths Northern Hemisphere would be the day side, and the Mars Southern Hemisphere would be the Martian analog day side.

-Gravitation will > 1 g. So perhaps it is reasonable to expect that there would be less topographical altitude difference from the high to low elevations in both models.

-Water: Most articles I read seem to suspect that red dwarf worlds will be inclined to have less water than Earth by proportion.

But I will presume that both examples have a similar surface area covered by liquid water as Earth. That is if some of it is not tied up in ice. Of course, under those conditions, there would be a massive polar ice cap of ice on the dark side, so the liquid portion of water would be reduced.

For the Earth model, perhaps we could suppose that the ocean levels would be 100's or 1000's of feet lower. (Sorry for the units). But for the Earth model, the typical ocean floor is 10,000 feet deep. So there is a good chance that liquid water could be sufficient to overflow even into the north polar basin. So, all the way to the high noon position. I justify this presumption because as well as wind, water currents could be constantly eating away at the night side ice cap and ice shelves, even as water vapor would be often accumulating as snow in many places on the dark side.

The Mars model would be somewhat contrasting, as perhaps only the Mariner Rift Valley, and a fringe of ocean at various places would be exposed to sunlight, and that would likely all be near the terminator line.

The Mars model would resemble Pangea (One big continent on Earth).

*Which raises the question, "Would the suns pull tend to compress the separated land masses together on the sunward side, acting against the tectonic forces"?

Atmosphere: I think that Venus has managed to exhibit 3.5 bars of Nitrogen, and for a planet with photosynthesis we could suppose that some Oxygen could be added to that. So, lacking other information, I will speculate that it might be possible for a terrestrial planet to generate up to 4 bar of Nitrogen/Oxygen for an atmosphere. This is just a gestimate based on the evidence Venus provides. I am sure the value can be variable.

We think that "Our" Mars could have an Earth-Like average climate if it had 2 bars of Nitrogen/Oxygen, and that is because the luminosity at the orbit of Mars is approximately 1/2 that of Earth.

So, I presume that if we could have a 4 bar atmosphere, our model might have a Earth similar climate with a luminosity of about 1/4 that of "Our" Earth.

So, on that basis, I am going to violate the stated habitable zone and say that the outer limit is too restricted. For Proxima B, the atmosphere would likely only have to be a bit thicker than 1 bar, to have an Earth similar average temperature. (Leaving out other factors such as a possible cloud deck on the day side). My reading says that to limit an atmospheres volume you either have to have a limit on the gasses available, or you have to have running rivers to intern excess gasses, so I presume that often atmospheres will self regulate to provide the correct amount of rivers for a stable thermal system for the planet.

But I include that prior information because there is a suspicion of another planet in the system, and that might be a big one, and further out.

I could ramble on and on, but I will try to limit my further additions.

For my part, I would see no reason not to employ wind power on the surface of both models, where it was suitable. It would be particularly useful on the night side. As for the day side, for the day side, solar power of course, and perhaps pipelines and water pumped uphill, and cities which could still provide adequate shelter for the population even if the Ozone layer got destroyed during a flaring event.

So, as promised, I have left the H.W.M. and the orbital mechanisms for you and Tom (Karov). What would you want to do with those two models?

Last edited by Void (2016-08-26 00:25:29)

elderflower · 2016-08-26 05:29:01

Void said
"An example would be Mars, and I think Earth, in opposite ways. Mars has its highlands at the south pole, and the Earth by my reckoning has it's highlands at the north pole. That is there seems to be more continental mass in the northern hemisphere of Earth than the southern."
I don't know enough about Mars to comment on that planet's crust, but on Earth the continents are in approximate isostatic equilibrium, so no mass imbalance. The continents float on the more dense mantle rocks. There are lags such as adjustments following removal of the Northern ice sheets, but over a few thousand years these resolve themselves.
There may be some effect on rotational inertia due to the fact that the continental masses are carried higher than the ocean floors by reason of their lighter rocks, so moving some mass away from the axis of rotation. This would be reduced by the uplift of dense rocks at seafloor spreading axes and increased at subduction zones so there may be a residual effect from the continents.

Void · 2016-08-26 08:46:06

Hi Elderflower.

I guess you could be right. If what you say is true, then I can presume the north pole pointed at Proxima Centauri can be an arbitrary assignment I have designated.

My purpose was to make an "Earth" like model which would be in contrast to a presumed "Mars" like model. The Earth model presumes that ocean water might flow basin to basin to the high noon position, where the Mars model supposes that the oceans will be more restricted to a dark hemisphere, and possibly the margins of the terminator.

So then this provides different outcomes, and different terraforming treatments I would presume. These would after all be "Earth" and "Mars" similar planets, so exact replication of such information is worthy of mention, and perhaps the models should be modified, but I had to start somewhere.

I wanted to wind the clock, and see what we get.

Do you have modifications to suggest?

Last edited by Void (2016-08-26 11:07:04)

Tom Kalbfus · 2016-08-26 09:07:05

I calculate that if the orbital period is 11 days, then its distance from Proxima is 7,150,000 km or 0.048 AU. Luminoscity is 0.0017 Sol so the amount of radiation Proxima b receives fro Proxima is 0.0017 / 0.048^2 = 0.738 of what the Earth receives from its Sun, this might be good news. Proxima b it appears would be cooler than Earth but warmer than Mars before we add in the greenhouse effect. The nearside receives constant sunshine because the planet it tidally locked, the darkside has a frozen ice sheet, I'm assuming there is liquid water underneath even on the dark side, assuming the atmosphere isn't so thick as to completely distribute the heat from the dayside to the night side. There should never the less be a zone on the dayside which would have the maximum habitability for humans. It appears the updated the Wikipedia entry for Proxima Centauri
https://en.wikipedia.org/wiki/Proxima_Centauri
They have data for Proxima b, my estimate of its orbital radii is not far off.

Proxima Centauri b is an Earth-sized planet orbiting the star at a distance of roughly 0.05 AU (7,500,000 km) and an orbital period of approximately 11.2 Earth days. Its estimated mass is at least 1.3 times that of the Earth. Moreover, the equilibrium temperature of Proxima b is estimated to be within the range where water could exist as liquid on its surface; thus, placing it within the habitable zone of Proxima Centauri.[23][27][28]

Plant life may exist on the day side of the planet, one way it protects itself from solar flares would be if it is the alien equivalent to blue-green algae, it produces oxygen for the atmosphere and floats in the oceans, and then there is a flare, a lot of water evaporates, this produces a cloud layer on he day side that rains out when the Proxima flare ends. Aquatic life is thus prevented from burning, and the ocean depth prevents the water from boiling. Whether there is a huge ice cap on the darkside depends on whether there are any continents there, otherwise the ice cap will just be a frozen ocean surface with a liquid mantle underneath, much like Europa, but with an ice sheet that is likely thinner, water will flow under the ice sheet from the night side to the day side of the planet, and at a certain distance from the terminator, the ice sheet breaks up into ice bergs and then we have open ocean. It might be a good idea for humans to live near this ocean. The Ocean might offer some Solar Flare protection.

Void · 2016-08-26 11:11:12

I think the greatest danger of solar flares is that the worst ones are speculated to be damaging to any ozone layer, and after that, life on the day side would be at risk of U.V. So, if that is so, the danger would be after the flare. And that presumes that you would have a ozone layer in the first place. On the other hand it is supposed that Mars had Oxygen in it's atmosphere when it was younger, that from the splitting of water molecules by U.V. light. Oxygen in the atmosphere might promote the formation of an Ozone layer then. So, a flare might destroy ozone which would facilitate the formation of more Oxygen, and the more Oxygen would facilitate the formation of ozone, so, it's possibly a double edge sword. Maybe you could have a N2/O2 atmosphere without life.

...

Sectioning off the dark side ice cap, I then ponder the Katabatic winds.
https://en.wikipedia.org/wiki/Katabatic_wind
https://en.wikipedia.org/wiki/Katabatic … ind_hg.png

The Katabatic winds would be periodic, and could sweep very fine cold snow into lower areas, such as open water, and if the ice cap margins were grounded against a lowland area suitable it might even sweep the snow into those, and some of those might even be on the day side near the terminator. I suppose to a limited extent, snow might even travel uphill like sand dunes to the day side, provided the winds were fierce enough, and until the dunes reached a location where they would melt.

This and direct evaporation from open water or ice, and the possibility of an Earth model ocean spillage/circulation would provide moisture to the atmosphere, and in the case of snow pushed by winds, a direct source of melt water for rivers and streams.

...
Troposphere:
https://en.wikipedia.org/wiki/Troposphere

The average depths of the troposphere are 20 km (12 mi) in the tropics, 17 km (11 mi) in the mid latitudes, and 7 km (4.3 mi) in the polar regions in winter. The lowest part of the troposphere, where friction with the Earth's surface influences air flow, is the planetary boundary layer. This layer is typically a few hundred meters to 2 km (1.2 mi) deep depending on the landform and time of day.

So based on this, how high can an ice cap be on Proxima b?
The planet will have greater gravity, so the ice will flow more like a pancake, glaciers flowing faster I presume, if other conditions are similar to Earth. Total amount of water. For now I presume that the amount is proportionally similar to Earth. However many thinkers think that such planets will have a relatively reduced amount of water. I think that water may be conserved well on such planets if it were there in the first place.

So the next question is how high can water vapor go as a rule. For Earth we might think 7 km (4.3 mi) per the article linked to. So, the higher the ice cap, the more limited it is in receiving water vapor for snow on it's plateau.

And then there is the continental base. For the Earth model, Antarctica would help to isolate part of the ice cap from the presumed oceans.

For the Mars model, grounded ice would have no continent under it. It is possible that liquid water would exist under all portions of the ice cap, so it would be on banana peals so it really might pancake out over the ocean basin, and not be as high.

Last edited by Void (2016-08-26 11:38:00)

qraal01 · 2016-08-27 01:46:52

A 3/2 Day/Year cycle, like Mercury's, is another possible end state of tidal despinning. If so, then the Sol (sun-rise to sun-rise period) will be twice the Year - thus a 3 week diurnal cycle is a real possibility. Will make for very interesting effects on any life that might have evolved there, let alone what we might introduce (some day).

Of course there's also the additional radial velocity trend that might be a super-Earth further out. Long term orbital evolution of the system can be computed once we have harder figures.

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