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#76 2013-04-24 07:22:49

StarDreamer
Member
From: Ontario, Canada
Registered: 2007-04-28
Posts: 92

Re: Venus

Atmospheric circulation is an interesting topic. I dont know who is studying comparative atmospherics across planets. But here is my take on it: the bands of clouds on the Jovian worlds and my knowledge of hadron convection cells on Earth (I think this is the correct term) suggests to me some mathematical relationship between atmospheric viscosity, rotation/tilt and climate zones. Earth has five zones: 2 frigid, 2 temperate and 1 tropical. The zones are kept separate by winds at the doldrums and horse latitudes known to sailors, where winds blow out in opposite directions and those caught in the gap must drift until they emerge from one side or the other. On Mars, I believe there are three zones -- 2 hyperfrigid and 1 frigid. Perhaps there are gradients there as well? But certainly threee zones -- it is a small planet and the atmosphere is thin. A thin atmosphere on a large planet would break into more zones. On the Jovian worlds, we see that the size of the planet overwhelms the viscosity of its atmospheric gasses and we get a great number of zones and gradients. Now consider Venus: on Venus, the viscosity of the atmosphere overwhelms the size and spin of the planet, so you get just one big zone, all hypertropical. The images I have seen of the cloud cover of Venus, showing mixing in the clouds, shows one pole-to-pole hadron cell at work there, with no bands.


~~Bryan

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#77 2013-04-24 16:42:50

Void
Member
Registered: 2011-12-29
Posts: 4,681

Re: Venus

I like that information as well.

I think that I am done on this thread for a while.  I think it was worthwhile for me.  I have a better understanding now.


Done.

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#78 2013-07-10 07:27:45

Zo0tie
Member
Registered: 2013-07-05
Posts: 5

Re: Venus

I realize I've arrived late to this party but the idea of terrforming our neighboring planets has always fascinated me.  Clearly Mars will likely be far easier to terraform than Venus.  But I've always had a soft spot for our little hot headed sister world and feel that she could be a valuable asset to human expansion to space if handled correctly.  Two major problems that need to be addressed are her slow rotation and suffocating thick atmosphere. If those two issues are addressed then the other problems (no magnetic field, hot surface, toxic atmosphere) may be easier to deal with and may solve themselves naturally in time.

Unfortunately the crash bang methods (comet/asteroid collisions, nuclear explosions) usually suggested sound too much like planetary rape.  Also I don't think they'll work. Anyone who has seen an animation of two earth sized objects colliding understands that at a planetary scale a rocky crust behaves more like a fluid rather than a solid.  Kinetic energy is absorbed chaotically and a great deal is dissipated as randomized heat energy. The Boltzmann distribution of nuked or impacted atmosphere molecules means only a tiny fraction of the air will achieve the escape velocity necessary to leave the Venusian gravity field permanently. The rest will just fall back with all the heat and radioactive fallout that may take millenia to dissipate. There has to be a better way.

I did some back of envelope calculations to clarify minimum mass and energy needs for terraforming Venus and came up with some interesting results. I'm sticking to the basic joule-second-kg-meter system and scientific notation because using impressive sounding terms like TerraWatt and PettaJoule does not help in allowing others to compare numbers or participate in the conversation. And I’d really like feedback.

Mass of Venus = 4.87*10^24 kg
Mass of Venusian Atmosphere = 4.7*10^20 kg
Escape Velocity of Venus = 10,360 m/sec
Energy to expel all of the Venusian Atmosphere at Escape Velocity = 2.5*10^28 joules

Current Kinetic Energy of Rotation of Venus = 3*10^25 joules
Current Kinetic Energy of Rotation of Earth = 2*10^29 joules

The NASA site says the moments of inertia of Earth and Venus are nearly equal.

Therefore since rotational energy is one half the moment of inertia times angular velocity squared the energy needed to spin up Venus to one day per Earth day is approximately  2*10^29 joules.

Some have suggested that the air could be expelled from Venus along the equator at escape velocity thus not only reducing the total mass of the atmosphere but also speeding up the planetary rotation like Heron's steam turbine.  Inspection of the above data shows that even if we can expel every atom of air we just can't get to a Venusian 24 hour day.  However since rotational kinetic energy is proportional to the square of the angular velocity we CAN get to a longer day.  I estimate that 2.5*10^28 joules can get us to an airless Venus with a SQRT(2*10^29/ 2.5*10^28) * 24 = 67.8 hour day.  Obviously we want some of the Venusian atmosphere left for final terraforming.  I'm assuming one tenth or 9.2 atmospheres (bar). The energy budget drops to  2.5*10^28 * 0.9 = 2.25*10^28 joules.  Plugging into the rotational energy formula above gives approximately = 72 hours or 3 Earth days/per Venus day.

That's a pretty decent spin and could not only help stabilize temperature through atmospheric convection but may also help activate a magnetic field. If the rotational acceleration is applied gently tidal stresses may delicately crack the crust into sections allowing built up heat to release along the fissures and the beginning of a true continental plate tectonics system. This may allow for volcanic release of fresh water vapor into the atmosphere. For the Planet of Love a slow seduction is far better than a brutal assault. 

Otherwise water can be added by means of comet impacts or a small outer solar system object. I've considered Phoebe, Saturn's outermost major moon (approximately 200 km diameter, est. 50% ice) but there may be others. There may be a way of slowly introducing the water to avoid disrupting the crust.  Creating a 1000 year magma ocean is not good for colonization.

So how to do this megaproject? The construction of a massive tower sticking 100 km out of the atmosphere with a powerful blower nozzle has been suggested but as I've said rock behaves like a fluid at planetary scales. Such a device would likely sink into the ground before completion and if not it would topple over once you turned on the blower nozzle. I'm not even going to discuss the challenges of building such a monster in the hot corrosive atmosphere and deep gravity well of Venus.

An elegant solution may be possible. Build a huge solar powered ion cannon and use it to convert Venus into a homopolar motor!  It's easier to build big machines in space rather than on the Venusian surface. And there are many M-class Venus orbit crossing asteroids that could serve as construction material.  The idea goes like this:

1-Place a gigantic solar powered ion beam cannon so that it is always above one pole of Venus. Alternatively place it at the L1 point.  Since an ion cannon is also an ion thruster it could stay there as long as you had fuel to compensate for gravitational attraction and solar pressure. Just don't get too close.
2-Divert a comet or larger water rich object to make an atmospheric grazing encounter with Venus. The fragmentation would make a spinning ring of ionized dust and gas going all the way down to the ionosphere.  The angle of the strike will determine the angle of the ring.
3-Turn on the ion cannon aiming at the perimeter of the ring.  A compensating electron beam will fire where we want the pole to be.
4-As electric charge builds up in the spinning ring a magnetic field will form per the right hand rule.  Electricity flowing outward will accelerate the particles in the ring all the way down to the ionosphere of Venus at right angles to the electric flow and induced magnetic field. In theory the electric flux will reinforce the magnetic field and the ring particle orbital kinetic energies will increase.
5-The particles in the ring perimeter will ultimately reach escape velocity and be dissipated to be replaced by more of the atmosphere.  Ultimately more of the air would be ionized as it spun around the planet with increasing speed.
6-Superhurricane winds are induced from the spinning ionosphere through angular momentum exchange down to the surface causing a slow increase of the planetary spin at the angle of the ring and opposite the direction of the ring.  The ring will be self replenishing as more of the air and some the surface is sucked up ionized and accelerated outward through the electromagnetic homopolar effect.
7-The ring will significantly expand the surface of the Venusian atmosphere, accelerating cooling. However resistive heating from electric flow will have to be factored in.
8- When enough of the air is gone and Venus is spun up enough turn off the ion cannon. If the original comet or moonlet has enough volatiles rain will begin to fall cooling the surface.  The residual ring if formed at a sufficient angle will add to the cooling effect.  Forming rain clouds during the shortened day and dispersing them at night perhaps by using the ion cannon at lower power will also cool things off.
9-If done right the planetary magnetic field and crustal tectonics may be induced from all this activity. Management of the remaining artificial ring and cloud formation will continue to maintain the environment. Then comes atmosphere modification using microbes. Nevertheless the surface will be rather inhospitable until things settle down.

So where to get the energy to do this and how long will it take? Solar energy falling on a solar cell the diameter of Venus at Venus orbit assuming 100% conversion efficiency will produce 2.58*10^22 joules per day.  2.25*10^28 joules/2.58*10^22 joules per day = 872093 days or 2,389 years. This is clearly too long for most civilizations. However if we increase the size of the solar cell by a factor of 5 diameters then the time is reduced to 2389/5^2 = 95.57 years or about 1 century.

The final Venus should be suitable for bioengineered life and modified humans who can handle high CO2 levels. CO2 greenhouse effect will be an issue but an artificially maintained daylight cloud cover can reduce the problem and evening rain will gradually strip it out of the atmosphere to form carbonates.  Solar shading from the residual ring will also help.  And if not a laser cooling effect suggested by karov perhaps using the ion cannon could keep temperatures down. Also the huge solar power cell could be used as a solar shield besides providing virtually unlimited beamed power to the inhabitants of Venus. A true paradise.

Unresolved questions relate to the creation of a self sustaining magnetic field in the spinning ionized ring of electrified air.  Can it be sustained with enough intensity and directional stability to do the work required?  I don't have enough understanding of plasma electrodynamics and ring particle orbital mechanics to answer that question. Perhaps someone out there has access to the requisite knowledge and a powerful computer. smile

Also the ions fired from the cannon will have to come from somewhere.  Just about any element can be ionized under the right conditions. What to use? Obviously it has to be accessible in sufficient quantities. Hydrogen, oxygen, carbon, even nickel/iron are possibilities.  I’ll leave that for future speculation.

2.25*10^28 joules is obviously well beyond the capacity of a Type 0 civilization like ours.  But that's only 2.25*10^28/3.8*10^26 = 59.21 seconds or about one minute of total solar output.  So a Type I civilization on the Kardashev scale that is trending to a Type II could do it without much problem.

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#79 2013-07-11 20:43:30

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

Re: Venus

Hey Zo0tie!  Welcome to Newmars!

You've made an interesting analysis.  However, as I see it, there are a couple of flaws and logical issues.  Please don't be intimidated!  You raise a lot of good points, and if you think you're right after you've read my post don't be dissuaded just because I happen to disagree :D

First:

You seem to have no issue with building an ion thruster with a power of 6.5e23 W (What kind of specific mass are you getting?  Even at the currently grossly unattainable 1000 W/kg, this will mass as much as the atmosphere you're trying to eliminate...), but shy away from building a tower that is 500 km tall.  This seems unreasonable to me.  Surely the issues involved in building an ion thruster with power consumption equal to that of a Kardashev Type I (Really more like 1.3 or so) are much larger than those associated with building a tower tall enough to hold it up?  Keep in mind that the difficulty is not equivalent to building a 200 km tall skyscraper, because there will be nothing on any of the floors: It's all structure, 100%.  No offices or windows or anything else.  The base can be coated in cement or whatever is needed to protect against the H2SO4.  A layer of Aluminium might be enough, and a layer of glass definitely would be.

Second:

You're neglecting the fact that the CO2 doesn't go away once it leaves the Sphere of Influence of Venus.  What it's going to do initially is probably to stick around Venus, and later under the influence of light pressure drift out into the inner solar system.  "No big deal!", you say.  But it is.  CO2 levels in the Earth's atmosphere currently stand at 400 ppm, up from 280 ppm before the Industrial Revolution.  These 120 ppm have already had significant climate effects.  1000 additional ppm in the Earth's atmosphere represents .00001% of Venus' atmosphere.  Keep in mind that Earth's gravity will affect anything within millions or even tens of millions of kilometers or more (If it's in the plane of Earth's orbit at approximately the same distance most any material will be affected).  It seems likely that expelling the gas in this manner would have catastrophic effects. 

That's not to speak of Venus itself, of course.  50 millibars of CO2 is the limit for breathability.  Once you have a nice breathable atmosphere, you don't want the CO2 coming back and poisoning it.  But it just 0.5% of the CO2 comes back eventually, this is just what will happen.  You can remove it again, I guess, but continuous maintenance isn't the point of terraforming.  The only safe option is to eject the CO2 at solar escape velocity, or point it at the Sun.  Both actually require similar velocities, and of course manyfold increases in energy expenditure.

Third (Somewhat related):

If you would like to spin Venus up to one full Earth day, you can simply eject the material faster.  It's at a higher energy cost, but we already seem to have shaded off into self-replicating machinery.  What's another couple trillion terawatts?

Fourth:

You still haven't addressed the issue of temperature.  Even with no CO2, Venus is still subject to about twice the insolation as Earth.  Holding all else equal, this will result in a final mean planetary temperature of 71 C (relative to 16 C on Earth).  The longer day will only exacerbate this.

Fifth:

Other methods would seem easier.  For example, importing hydrogen and allowing organisms in the clouds to convert the CO2 to oxalic acid.  Or, as more commonly proposed, turning the CO2 into an ocean, + carbon.  Or putting a sunshade in front of the planet and allowing the CO2 to condense out, and then shoving it down a volcano into the planet's interior.  Or any of a million other things.

Sixth:

What exactly are the benefits of terraforming?  How do you justify the cost of this multi-multi trillion dollar project?  Do you expect that it will ever pay off that much?  Why do we need to live on Venus when there are so many other places in the Solar System?  Terraforming always seems to be a form of planetary chauvanism to me; It's got to be easier to develop better spacesuits and robotic resource extraction than to totally change a planet.  If you need somewhere to live, build a habitat.  If you want the feeling of open space, build a bigger habitat.

Will we even have physical bodies a hundred years from now?

I could understand the benefits of turning Venus' atmosphere into a CO2 ocean when it comes to resource extraction; The cooler temperatures make things much easier.  But in terms of actually making it livable, I don't see the need.  Colony-aerostats should suffice where needed.  If there's a CO2 ocean they can float on top of it and send robots and machines down to extract resources, if that is necessary. 

Seventh:

Is a shorter day really necessary?  Right now, Venus' siderial day is 116 days long, 58 days (2 earth months) of continuous light.  I would expect that plants would be able to grow to maturity in that time.  They do on Earth, after all.

I think this is a good sampling of objections.  I hope to be arguing with you on this and other matters for quite some time; You seem to be quite intelligent :)


-Josh

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#80 2013-07-12 01:52:46

Zo0tie
Member
Registered: 2013-07-05
Posts: 5

Re: Venus

Hi Josh! Thanks for the welcome.  Sorry your site went kablooey! It seems I've always been a dollor short and a day late to have a conversation like this with technically savvy people. It seems that patience has paid off.

You've asked so many good questions. I'll try to address them as best I can. I'm an engineer not a space scientist or plasma physicist so my answers will have to be considered within that constraint. Also my personal philosiphical/political/social opionions will leak in occasionally. wink

The specific mass of a thruster with a power of 6.5*10^23 W. (your quote)
W = Joules/sec
My energy budget for 24 hours or 8.64*10^4 sec is estimated as  5^2 *2.25*10^22 Joules
5^2 *2.25*10^22 Joules / 8.64*10^4 sec = 6.5*10^18 W - a smaller value by a factor of 10^4
Unless I made a mistake your conversion is off.  That's why I like to stick with Joules. It minimizes errors and makes comparison so much easier. I'd really appreciate if you show me calculations  where you're getting your numbers.  Otherwise I have to puzzle it out which wastes time. Nevertheless it's still a big honking number. I'm assuming you're talking about the power of an ion stream that is powerful enough to blast away the atmosphere like hydraulic miner blasting away at a hill side. If that was the approach I'd agree with you. But using a homopolar effect is different.  Electric current flows through an ionized fluid within a magnetic field causing the ions to accelerate at right angles to both electric current flow and the magnetic field. Continue this and they finally leave at escape velocity.  Voltage and Current flow are the big issues, not the total mass of ions. The mass requirements will likely be far smaller.  The tricky thing with my system is the fact that the magnetic field will have to be artificially provided by the system itself since Venus currently has no magnetic field. That's the BIG question about the utility of my method. I know the interaction of ionized plasmas, current flows and magnetic fields, in high energy physics labs and tokamak reactors can do amazing things. Astrophysicsal journals are full of reasearch about natural plasma interactions.  Add the orbital mechanics of an artificial ring of ionized air molecules around a planet an a couple of ion beams and things could get interesting. I just don't have the physics expertise to say if this method would work without an externally applied magnetic field but I can't say it won't either. That's what some expensive simulation program might tell us.

The problem with a tower is scaleup.  Ionic bonds in metals and concrete appear strong at our scale, but as objects increase in size they remain fixed while volume related values such as mass/weight go up according to the cube root.  That's why a dinosaur the size of Godzilla would collapse into a pile of goo from his own weight as his cellular structure ruptured from the stress. A 100 km tower will have the same problem. Then you add the heat and corrosivity of the venusian atmosphere to contend with.  Momentum exchange will be localized on pillars sunk into the surface rather than distributed over the entire atmosphere as in my system. Space based systems can be lightweight and spidery except for the heavy duty components.  High tension components like carbon nanotubes would hold room temperature superconductors with minimal reflective shielding from the suns energy.  I estimated that the solar electric cell might mass only 1.13*10^13 kg well within the mass of several Venus crossing asteroids.  I agree it's going to be a big project, certainly beyond our puny little Type 0 civilization.

Actually I'm counting on the CO2 sticking around.  A thin donut of gas will form around orbit of venus, gradually dissipating from the solar wind. I wouldn't worry about contaminating our atmosphere. The fact that the disk of venus has to be seen through a telescope tells you how much space there is between us and Venus. In 1910 people panicked when they learned that we'd be passing through the cyanogen laden tail of Halley's Comet. No one died and scientists couldn't detect the gas.  Frankly If we can't solve our carbon footprint problem with wise conservation and planning then we won't make it to Type 1.3 and terraforming mars and venus will be a moot point.

I'm trying to attach a picture of the planetary engineering system I have in mind. As you can see
(I hope) there is besides a solar power cell and a dual ion beam cannon, there is a ion stream collector. I cribbed the design from a schematic of a the ion scoop of a Bussard ramjet starship. It's purpose will be similar but far less severe, to capture some of the ejected atmosphere to ionize and use it to fuel the ion cannon. I think after an initial expendature of fuel for 1 Venusian year, the scoop will be able to collect enough ions to make the system self sustaining.

As far as throwing out the air faster, the energy goes up according to the square of the velocity which extends the terraforming time frame. Also my system can't hold the ring ions once they reach escape velocity so that's pretty much the limit.

As you've seen in my diagram my system is on the anti-sunward side of Venus. I realized it was pointless to shield the atmosphere of Venus from the sun when we are blowing 90% of it away. The planetary engineering system will be a statetite, hovering a fixed distance from Venus balanced between light pressure and gravititional attraction. After the project is complete we might move the solar cell to the other side for shielding. Or the residual ring can be used to deflect some of the solar energy. Or we can form clouds on the day side and dissipate them at night allowing heat to escape.  Maybe the laser cooling effect proposed by karov.  qraal01 linked to a paper that proposed that under the right conditions Venus may be inside the edge of the habitable zone. 1.9 insolation shouldn't be that serious a problem to a Type 1 civilization.  CO2 will gradually be absorbed into the new lakes and oceans to form carbonates but that may take thousands of years. In the meantime we'll just have to wear breathers or bioengineer ourseves to handle it.  Humans not wishing to 'go native' would live in aerostats with earth normal air floating above everything.

Yes I've heard of many other methods. Problem is they never discuss WHERE the material that will be used will come from. Where are you gonna get the stuff and how much will it cost in joules. And what kind of giant mechanical hand are you going to use to shove stuff down a volcano and where will it come from. There aren't any hardware stores in space. Every generation comes up with some new 'magic wand' to solve a problem and it never works out as planned. X-rays, electricity, atomic energy, lasers, computers, nanotechnology.  Chemical manufacture requires the presumption of factories, energy producers, raw materials, storage, transportation costs that are never considered. If such an idea is proposed I'd like to see energy and mass requirements. Otherwise it's just hand waving.  I want to see a real energy and mass budget.  And real time frames.

I think reasonably short day will be minimim necessary to maintain psychological health if nothing more.  We are not robots, and I really see no reason to become robots. 3 billion years of a day night cycle is part of our nature. So is living on a planetary surface under an open sky.  No one wants to learn the REAL lesson of Biosphere II.

As far as cost and justification. I'm taking off my engineer hat and putting on my political/social hat I realize we're hierarchichal hunter gatherer hominid primates. It's in our nature to claw and scratch for 'stuff', for mates, for power.  That may be the epitaph on our grave stone.  I really don't think we'll make it to Type 1.3 at our current rate. There's an iceberg on the horizon and the crew has barricated themselves in the wheel house with all the booze and babes and telling us to trust them and shut up.  If we do survive the impending crisis our culture will experience a fundamental change.  I personally think we're fooling ourselves about our own adaptibility.  Where are all the clean futuristic city skylines, the domed underwater metropolises, the arctic luxury hotels?  If we survive it will be because our minds have changed not our bodies.  A type 1 civilization will see the terraforming of Venus as an art project. A way to extend and expand the beautiful variety of life beyond the earth. Of course if we trash the Earth there won't much beauty to extend and expand. As I've said elsewhere we will not be able to reach for the stars while the earth rots away under our feet.

I think i got all the major questions. I'm sure you'll remind me if I didn't. smile


  th_615012623_PLANETARY_ENGINEERING_MACHINE02_122_367lo.jpg

th_466673127_T_Venus00a_122_517lo.jpg

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#81 2013-07-12 02:22:11

Zo0tie
Member
Registered: 2013-07-05
Posts: 5

Re: Venus

Oops I made a slight error myself on the 24 hour energy budget. It should be 2.58*10^22 joules not 2.25*10^22 Joules. Watts goes to 7.45*10^18 W.

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#82 2013-11-01 18:55:14

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: Venus

zhar2 wrote:

A space shield infront of the planet still seems the best bet to decrease the venusian temperature.

I got a better idea a solletta around Venus in orbit around it that both shields Venus from light and reflects light around the planet.

http://groups.yahoo.com/neo/groups/theh … /410928091

This is a diagram of a solletta around Venus, it is composed of mirrors, the mirrors as the diagrams show are in orbit around the planet as a distance of 39,000 km from the planet's center, this gives the solletta an orbital period of about 24 hours, it can be adjusted to give an image of the Sun rising in the west and setting in the east directly over the planet's equator. One part of the solletta is an array of open aperatures letting in sunlight, in most cases the sunlight goes past the planet to reflect off another mirror array surface, and perhaps off of a third mirror array to illuminate half of Venus for day leaving the other half in darkness for night. The reflectivity of the mirrors is adjustable so that the final reflection towards the planet delivers Earth normal sunshine, although the disk of the Sun may appear larger in the Venusian sky than it does in the skies of Earth. One point of this solletta is always the one where the final reflection towards the planet occurs or where sunlight is let in to shine on the planet directly, in which case the light passes through a transparent filter to reduce sunlight to Earth normal intensity.

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#83 2014-01-04 14:56:36

robertwalker
Banned
Registered: 2012-06-03
Posts: 31

Re: Venus

A few links that might be of interest:

Venus society, at Linkedn discusses issues of terraforming Venus
http://www.linkedin.com/groups/Venus-Society-4897138

Many posts on Venus ideas by Jon Goff at Selenium Boondocks blog
http://selenianboondocks.com/category/venus/

I've got a section on Venus cloud colonies in my article "Trouble with Terraforming Mars".
http://www.science20.com/robert_invento … ars-126407

First suggested by the Russians in the 1970s, and more recently by Geoffrey Landis, the idea that just ordinary Earth atmosphere is a lifting gas in CO2 and if you work it out then apparently a normal Earth habitat with Earth normal atmosphere would be bouyant enough to float naturally at the right level in Venus to be at the cloud tops, and would be internally and externally in equilibrium at about Earth normal atmospheric pressure and protected from cosmic and solar radiation by the upper atmosphere and also coincidentally at just the right level for tolerable temperatures or humans too in range 0C upwards. Plus most of the resources humans need can be extracted from the atmosphere. In many ways is actually more habitable than just about anywhere in the solar system apart from Earth if you can figure out how to deal with the acid droplets and how to travel there and back. For getting back it might help that rocket stages also would float in the Venus atmosphere if you left a bit of fuel inside to use as lifting gas to keep them floating in the Venus atmosphere.

One idea there is the idea to use rail guns to fire the atmosphere of Venus as dry ice to Mars and terraform both planets in one go - that is assuming we try to terraform Mars also.

If you just blow the atmosphere of Venus into space in same orbit as Venus, there is so much of it that it just gathers it back up again over geological time.

However one issue with this is the global resurfacing of Venus every few hundred million years (instead of steady continental drift). Perhaps you would do better to leave a fair bit of the atmosphere there which would also help to insulate your colonies from present day eruptions also as Venus is probably geologically active.

Paper on the global resurfacing
http://onlinelibrary.wiley.com/doi/10.1 … 8/abstract

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#84 2014-01-04 20:21:46

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 25,992

Re: Venus

We have talked about the cloud cities but until we are brave enough to put up the cash then we might as well be quite about or dreams as that is all that they will be unless we can find away to make them real.

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#85 2014-01-04 21:20:18

robertwalker
Banned
Registered: 2012-06-03
Posts: 31

Re: Venus

Yes well I think we shouldn't do them anyway until first we investigate the - perhaps remote chance - that there is life already in the clouds. Because if there is life in the Venusian clouds already - then it must be biologically unique.

It's hardly likely that present day Venus could be seeded by meteorites from Earth - anything on them would soon be destroyed on the surface, and meteorites small enough to disintegrate in the upper atmosphere would not be big enough to shelter microbes from solar radiation except in very fast transits from Earth. At least can't say for sure but I'd think a bit unlikely it has a more recent common ancestor than at least a few billion years - and might be the only remnant of an early Venusian ecosphere actually independently origins.

So, I think we need to study the atmosphere first remotely - and if there is any risk of Earth life spreading to the clouds - treat it as a Category III location so sterilize the balloons etc as for Viking on Mars - at least until we have a much better understanding of the upper atmosphere of Venus, it's habitability for Earth life, possibilities of impact of Earth life on it, and whether there is any Venusian life or not.

But - certainly can send balloons to the Venus atmosphere as that's already been done, so can do more of that, longer lived balloons. That's not such a vastly expensive mission and can do more ambitious things also at not too much expense as launch costs come down.

It might well turn out to have no life there.

Article suggesting possibility of life in the cloud tops
http://www.newscientist.com/article/dn2 … sjTz9JdXh4

Detailed model that found the observed levels of OCS without life
http://www.issibern.ch/teams/venusso2/m … sky_12.pdf

Discussion here about planetary protection issues for the Venus cloud tops - back in 2006 the study group decided is no chance of Earth microbes contaminating the Venus atmosphere or any Venus microbes if they exist contaminating Earth.
http://www.space.com/2065-planetary-pro … venus.html

But was one dissenting astrobiologist not part of the group who was not so sure of their conclusions. I wonder if a present day re-examination would come to the same conclusion - as ideas do develop and we discover microbes on Earth with increasingly surprising extremophile capabilities.

For cloud cities and terraforming of anywhere I think surely you are talking about at least a few decades into the future and I think that is how it should be as we simply don't know enough to make such irreversible decisions about any location in the solar system right now, and why hurry to start a process that will take centuries to complete?

But, keeping an open mind, once we know enough about Venus - and meanwhile can be a fine basis for sci fii. stories, films, and scientific studies. These are long term projects anyway if feasible, only our descendants a few centuries from now will really get the fruit of them, if they work, and I think myself that's one of the great things about them, chance for more long range thinking than the short term decade or even few years approach to much of space policy. Whether we eventually do them or not.

Last edited by robertwalker (2014-01-04 21:46:29)

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#86 2014-01-06 14:15:39

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: Venus

SpaceNut wrote:

We have talked about the cloud cities but until we are brave enough to put up the cash then we might as well be quite about or dreams as that is all that they will be unless we can find away to make them real.

the same could be said about Mars as well, both Mars and Venus are in the same boat right now. I didn't even know there was a Venus Society, very interesting bythe way. Right now we're both in the pipe dream business until someone does something to put the money up to make it happen. The main difference between Mars and Venus is that Mars has an accessible surface and Venus mostly does not. Some extreme form of technology could allow surface habitation, so I wouldn't completely rule it out. Whatever we put on Venus' surface has to support the weight of almost 100 Earth atmospheres and pump out heat at a tremendous rate to keep the interior cool enough for habitation. On venus the larger the dome on the surface the stronge the dome has to be to support the weight of all those atmospheres, but also the larger the dome the easier it is to keep cool, as the surface area increases to the square of the radius but the volume increases to its cube. It is easier to keep a large object cool than a small one. Perhaps the best place to live on the surface of Venus would be inside a mountain.

We'd first have to insulate the mountain from its surroundings including the ground and atmosphere, a good location for this would be the Maxwell Mountain range near the north pole of Venus. We cover the mountain with an insulating foam, and dig under the mountain and insulate the mountain from the ground with similar material, then we erect giant radiators, power it with a nuclear power plant to pump heat away from the interior of the mountain, and place a small cavity in the center where humans can live. A narrow tunnel can lead to the surface where an airship docking port is located.

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#87 2014-01-06 14:21:21

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: Venus

robertwalker wrote:

Yes well I think we shouldn't do them anyway until first we investigate the - perhaps remote chance - that there is life already in the clouds. Because if there is life in the Venusian clouds already - then it must be biologically unique.

It's hardly likely that present day Venus could be seeded by meteorites from Earth - anything on them would soon be destroyed on the surface, and meteorites small enough to disintegrate in the upper atmosphere would not be big enough to shelter microbes from solar radiation except in very fast transits from Earth. At least can't say for sure but I'd think a bit unlikely it has a more recent common ancestor than at least a few billion years - and might be the only remnant of an early Venusian ecosphere actually independently origins.

So, I think we need to study the atmosphere first remotely - and if there is any risk of Earth life spreading to the clouds - treat it as a Category III location so sterilize the balloons etc as for Viking on Mars - at least until we have a much better understanding of the upper atmosphere of Venus, it's habitability for Earth life, possibilities of impact of Earth life on it, and whether there is any Venusian life or not.

But - certainly can send balloons to the Venus atmosphere as that's already been done, so can do more of that, longer lived balloons. That's not such a vastly expensive mission and can do more ambitious things also at not too much expense as launch costs come down.

It might well turn out to have no life there.

Article suggesting possibility of life in the cloud tops
http://www.newscientist.com/article/dn2 … sjTz9JdXh4

Detailed model that found the observed levels of OCS without life
http://www.issibern.ch/teams/venusso2/m … sky_12.pdf

Discussion here about planetary protection issues for the Venus cloud tops - back in 2006 the study group decided is no chance of Earth microbes contaminating the Venus atmosphere or any Venus microbes if they exist contaminating Earth.
http://www.space.com/2065-planetary-pro … venus.html

But was one dissenting astrobiologist not part of the group who was not so sure of their conclusions. I wonder if a present day re-examination would come to the same conclusion - as ideas do develop and we discover microbes on Earth with increasingly surprising extremophile capabilities.

For cloud cities and terraforming of anywhere I think surely you are talking about at least a few decades into the future and I think that is how it should be as we simply don't know enough to make such irreversible decisions about any location in the solar system right now, and why hurry to start a process that will take centuries to complete?

But, keeping an open mind, once we know enough about Venus - and meanwhile can be a fine basis for sci fii. stories, films, and scientific studies. These are long term projects anyway if feasible, only our descendants a few centuries from now will really get the fruit of them, if they work, and I think myself that's one of the great things about them, chance for more long range thinking than the short term decade or even few years approach to much of space policy. Whether we eventually do them or not.

the chance of life on Venus is much less than on Mars, so it a way this makes Venus more suitable for terraforming. if there is life in the clouds, so what? I think life on Earth especially our own, is more valuable than life on Venus, the more complex life forms take precedence over the simpler variety. if there is life on Venus, there is probably life in many other places as well, we shouldn't let that fact prevent us from settling the cosmos. Now if there was intelligent life on Venus, that would be a different story, but I don't think there is, and there is no evidence for any.

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#88 2014-01-06 14:48:20

robertwalker
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Re: Venus

the chance of life on Venus is much less than on Mars, so it a way this makes Venus more suitable for terraforming. if there is life in the clouds, so what? I think life on Earth especially our own, is more valuable than life on Venus, the more complex life forms take precedence over the simpler variety. if there is life on Venus, there is probably life in many other places as well, we shouldn't let that fact prevent us from settling the cosmos. Now if there was intelligent life on Venus, that would be a different story, but I don't think there is, and there is no evidence for any.

I totally agree that the chance of life on Venus is far less than for Mars, and life on Mars seems on the face of it likely to be more interesting, and especially, it would have a long past history which we could trace through all the sediments on Mars, pristine sediments preserved in a deep freeze for hundreds of millions or billions of years.

But - Venus life if it did exist might turn out to be more interesting than expected. For one thing, would be surviving in an environment unlike anything on Earth. Might have special adapatations - e.g. microbes with "wings" to help keep them aloft in the dense atmosphere, or even colonies that form bladders full of hydrogen or oxygen to keep them aloft - or ways of working with the sulfuric acid, or whatever maybe things we haven't thought of. Not saying this is likely. But we don't know yet if there is anything there of interest and there just might be.

More interestingly also, it could have evolved independently of Earth life. Aren't that many places in the solar system where there were early oceans (probably) and also a big influx of energy from solar energy (or radiation from Jupiter in case of Europa).

Just Europa, Mars, and Venus. I leave out Encladus etc because it is a habitat that probably doesn't have so much by way of energy input though life there may also be fascinating if it does exist.

If life is abundant, they may all have life and if life evolves independently easily may each have its own version of XNA. But that's just three big chances of independently evolved XNA, and it might be that only one of them succeeded, and who knows, might be that just by chance, the one with the interesting XNA is Venus. (Could equally be Mars or Europa and could be somewhere unexpected that we haven't thought through properly yet).

With Venus, wouldn't have evolved originally in the cloud tops of course, but retreated to the clouds when the surface became uninhabitable. And because of the difficulty of transfer of life from clouds of Venus back to Earth or from Earth to the cloud tops of Venus at least in present solar system - you could put a case for Venus as quite a good chance for XNA.

Europa perhaps most likely to have XNA, though it also could be related to Earth life DNA as some study showed that in the late heavy bombardment period especially, material from Earth could easily get as far as Europa, big chunks large enough to protect microbes inside from the radiation.

Other way out places like Titan, Triton, or life forms that survive at extremely low temperatures, I remember sci fi story where they used superfluid hydrogen smile. Who knows, very way out but can you really say it is impossible?

But I think Venus is one of the top places where we just possibly might find XNA not related to DNA. If so certainly want to study in pristine state. And if there is life, highly unlikely to be just a single species, surely lots of species of different types in an ecosphere - if only of microbes, still may be complex - and concievably might also be fragile in response to introduction of extremophles if there are any Earth extremophiles that could survive there. A planetary protection work shop a year or two back looked at it and concluded that it was unlikely that Venus cloud top life could live on Earth or vice versa. But it was not conclusive, pending future research - and as we continue to find more and more extra-ordinary extremophiles on Earth, I wonder if they would come to the same conclusion again today.

Now if it was an either or - that the only way Earth life could continue to survive was by colonizing the Venus cloud tops - then it would be reasonable I think, at least on what we know so far, to say that the Earth life is more valuable than some Venusian life form we don't even know if it exists - especially if there were some emergency meaning we have to vacate Earth say.

But we are not in that situation. No imminent danger. Even a nearby gamma ray blast would only damage one side of the Earth and leave it far more habitable than anywhere else in the solar system and with many survivors. Similarly a giant meteorite impact or huge comet suddenly appearing from the Oort cloud headed straight for Earth with not enough time to deflect it - still after either of those disasters, Earth would remain far more habitable than Venus or Mars or anywhere else in the present day solar system.

Then longer term - there are materials in the asteroid belt to make habitats with cosmic radiation shielding with area of a thousand Earths (- as far as I know first worked out in a book by T. A Heppenheimer in the 1970s) and see my Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths). Much more material also further out in the solar system. And a lot of work needed even in Venus cloud tops to make it a second home that can work independently of Earth.

So, though working out ideas and ways of doing it is fine and great, I think no need to hurry things along if there is any chance of finding interesting new things about biology and evolution by a delay of a few decades. It would take centuries anyway for it to make a significant difference, and by then we may mostly be living in free flying space colonies and the idea of colonizing planetary surfaces may have become archaic. And in the remote chance that Venus is much more interesting for xenobiology than it seems, then our descendents may want to keep it in its current pristine state or transform it in some other way we can't currently imagine.

I agree though - that on the face of it anyway - Venus seems an unlikely place for life even in the cloud tops. Compared with Mars and Europa - is a place likely to have minimal planetary protection implications. Just think, though that seems likely, yet we shouldn't conclude definitely that it is okay until we have got some ground truth from more direct studies of the Venus atmosphere e.g. with floating probes equipped with biosignature detectors, miniaturized DNA sequencers (in case it is related to Earth life), advanced label release, electron microscopes etc - all things we can now miniaturize enough to put onto a spaceship in the very near future. some of these instruments especially the sensitive biodetectors for Mars are going to fly as soon as 2018, and perhaps could be adapted to Venus cloud tops?

It would be so amazingly interesting, and the best result for humanity and understanding of biology and evolution, if Venus cloud tops or Mars or Europa or all of them were host to interestingly different XNA, or other life forms unlike Earth life to be worth extended study - easily offsetting the inconvenience that you need to delay ideas for colonization and terraforming, in my view.

Last edited by robertwalker (2014-01-06 15:06:29)

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#89 2014-01-06 15:36:43

SpaceNut
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Posts: 25,992

Re: Venus

Tom Kalbfus wrote:

the chance of life on Venus is much less than on Mars, so it a way this makes Venus more suitable for terraforming. if there is life in the clouds, so what? I think life on Earth especially our own, is more valuable than life on Venus, the more complex life forms take precedence over the simpler variety. if there is life on Venus, there is probably life in many other places as well, we shouldn't let that fact prevent us from settling the cosmos. Now if there was intelligent life on Venus, that would be a different story, but I don't think there is, and there is no evidence for any.

Then capture a sample test it and lets move on as life that we know will look alot like what we already know.

I feel the same way for Mars. There is no reason to save touching a planet in chances of life that will be like our own.

Last edited by SpaceNut (2014-01-06 15:39:07)

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#90 2014-01-06 15:49:05

robertwalker
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Posts: 31

Re: Venus

SpaceNut wrote:
Tom Kalbfus wrote:

the chance of life on Venus is much less than on Mars, so it a way this makes Venus more suitable for terraforming. if there is life in the clouds, so what? I think life on Earth especially our own, is more valuable than life on Venus, the more complex life forms take precedence over the simpler variety. if there is life on Venus, there is probably life in many other places as well, we shouldn't let that fact prevent us from settling the cosmos. Now if there was intelligent life on Venus, that would be a different story, but I don't think there is, and there is no evidence for any.

Then capture a sample test it and lets move on as life that we know will look alot like what we already know.

It's not so easy as that. First are different layers in the atmosphere, life may not be everywhere so may be some searching needed. Then - our tests may not detect it at first. If it is DNA based we can find it easily - just a tiny fragment of DNA and we can find it by DNA sequencing. But if it is XNA then not so easy to find. (XNA is like DNA but with a different backbone and so XNA microbes probably can't exchange genetic material with DNA based microbes or be detected by DNA sequencers).

Some tests work for both DNA and XNA such as searching for chirality - probably most forms of life will prefer one isomer rather than another - e.g. the XNA probably always (or almost always) spirals the same way so that the transcription machinery can work more easily.

Another good test for XNA is the labelled release where you try to cultivate the life and see if it takes up nutrients and  has chirality preferences again.

But - only 1% of species are cultivable on Earth with us knowing a lot about how to try to cultivate it. And though it is likely that XNA would have chirality preferences, we can't really say it has to. The thing about alien life is that the more different it is from DNA, the more interesting it is, but also the more possibilities that our tests miss it.

So - I think - more than just doing some simple tests such as you might do if searching for life here on Earth. Same also for Mars. You are talking about a scientific process and these typically take months, years, sometimes decades, and sometimes can't be rushed. I think we shouldn't rush the scientists who want to study life on Mars or Venus. There is no deadline and no need for hurry. Instead give them the resources they need, to find out what they want in as much detail as possible - and bear in mind the possibility that they might find interesting life different from Earth life - and that that is the most interesting possibility that we should celebrate. So, give them a chance to find this.

That is I think the view of xenobiologists generally, for instance eight of them wrote a paper for the last decadal review strongly urging against a Mars sample return for these reasons saying we don't have enough understanding of Mars to know what samples are likely to be biologically interesting enough to return, but need to study it in situ, and surface deposits down to a depth of a few meters are sure to be severely degraded by cosmic radiation as well as other processes that seem to remove organics from the surface as an on-going process - and hard to interpret biologically. Their paper was ignored in the Decadal review summing up as far as I can see.

Planetary geologists I think tend to be a little impatient with the exobiologists at times, you can see all the geology plain to view on Mars and Venus, maybe at times a bit hard to appreciate that the situation is not the same for exobiology, where we can't see XNA or microbes from orbit or even have a clue about whether there is any there at all from those wonderful orbital images the planetary geologists use. And is not enough to just take a few samples - until you know where to look, then samples you return to Earth are likely to be uninformative, and they also pose a planetary protection issues as well for Earth, because although they are unlikely to have life in them when we don't know where to look, on the chance that they do ahve life, biological samples of course can reproduce, which purely geological samples can't do. Have written quite a lot about this also on my science20 column.

XNA particularly, if it exists, could present a particularly tough challenge for planetary protection, because of the possibility that either XNA or DNA may be superior to the other - e.g. XNA microbes are hardier, better at metabolizing - or vice versa. If XNA is better then it could wipe out DNA on Earth in the very worst case, or most of it. If DNA is better, it could wipe out most of the XNA on the target planet we want to study - and if both coexist - then still, the microbes based on XNA may behave differently from the previous DNA based microbes in the same ecological niche and so disturb the balance of nature, as well as lead to extinctions, also the microbes based on DNA could lead some of the interesting XNA species to extinction before we have a chance to study them and disturb the cycles again so we can't study the target planet in its pristine state - and also means of course that it is hard to tell what came from Earth in our probes and what was indigenous.

Lots of other contamination issues both ways - needs a fair bit of thought and there have been several studies which all conclude that great care is needed just in case. I think at least not going to sort this out with a simple sample return as the geologists seem to think, but is a long term at least several decades project - which would go more quickly if we have more resources available to study Mars e.g. by telerobotics from orbit around Mars. And if also the instruments developed by the exobiologists and the interesting missions presented to NASA and other space agencies by exobiologists were given higher priority than they are now.

Last edited by robertwalker (2014-01-06 16:07:33)

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#91 2014-01-06 20:03:18

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: Venus

If Venus can't kill it, I would think it would have little to fear from us. Any life there is is likely to be very simple, little more than a complex chemical reaction really, I don't think it will evolve into anything. Venus' best chance for having complex life forms again, if it ever had them, is us! When the Solar System was young, perhaps one billion years old Venus might have once had oceans, it was likely within the habitable zone then, and since it condensed from the same solar nebula that Earth did, it would likely have had all the chemical ingredients for life. Complex life was a relatively recent phenomenon on Earth, having evolved only within the last one billion years. Perhaps complex life on Venus got an earlier start. If there ever was life on Venus, its days are about numbered, if there are single celled life forms in the cloud droplets of Venus, that is likely all they'll ever be without our interference. I think there are probably a lot of Venus-like planets in the Universe, if they are, the sort of life  forms which might evolve in the cloud tops are probably not unique. Uniqueness comes from complexity. We can study them, but that's no reason not to Terraform Venus, I believe terraforming Venus will take a long time, and if we wipe them out, which seems unlikely of they can survive an environment as tough as Venus, we would be replacing them with something better, we would be an agent of intelligent directed panspermia in terraforming Venus. I think we could make the Universe a more interesting place than it already is.

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#92 2014-01-06 20:15:24

SpaceNut
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Registered: 2004-07-22
Posts: 25,992

Re: Venus

In the past life question have lead to flame wars so we need to tread lightly.

We do know that the essential elements are available but what are the catylists. First are protiens but then, What is the next key event that will cause a radom RNA strand to form is it as simple as a stirred pot that is left to simmer causing a slow mixing and fragment forming. At what point do we call it life?

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#93 2014-01-06 21:02:31

robertwalker
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Posts: 31

Re: Venus

Tom Kalbfus wrote:

If Venus can't kill it, I would think it would have little to fear from us. Any life there is is likely to be very simple, little more than a complex chemical reaction really, I don't think it will evolve into anything. Venus' best chance for having complex life forms again, if it ever had them, is us! When the Solar System was young, perhaps one billion years old Venus might have once had oceans, it was likely within the habitable zone then, and since it condensed from the same solar nebula that Earth did, it would likely have had all the chemical ingredients for life. Complex life was a relatively recent phenomenon on Earth, having evolved only within the last one billion years. Perhaps complex life on Venus got an earlier start. If there ever was life on Venus, its days are about numbered, if there are single celled life forms in the cloud droplets of Venus, that is likely all they'll ever be without our interference. I think there are probably a lot of Venus-like planets in the Universe, if they are, the sort of life  forms which might evolve in the cloud tops are probably not unique. Uniqueness comes from complexity. We can study them, but that's no reason not to Terraform Venus, I believe terraforming Venus will take a long time, and if we wipe them out, which seems unlikely of they can survive an environment as tough as Venus, we would be replacing them with something better, we would be an agent of intelligent directed panspermia in terraforming Venus. I think we could make the Universe a more interesting place than it already is.

Yes, just to say, I'm not arguing for the intrinsic merit of the lifeforms on Venus. I have seen that argument, some think we should keep the solar system just as it is in its present state. I think it is an interesting idea, we could do that if we want to, but am not saying we should do that.

Yes especially if they evolved independently then they may be examples of a form of life that is very common in our galaxy (or there again they might not, who knows at this stage).

However - common in our galaxy still means for us, that we would need to travel for thousands of years at sub light speeds to find an example to study. I think we are amazingly lucky to have Mars, and Venus both in our own solar system which were very much like Earth in its early years.

I don't know if either have life, just feel it would be really interesting if they did. In my view make them much more interesting than for their terraforming potential. Just because then they are exoplanets that are interestingly different IN  OUR OWN SOLAR SYSTEM (that emphasis isn't me shouting by the way just to emphasize what for me is the most amazing thing about it if they do happen to have XNA or other independently evolved life).

Yes if there is life there, then it would be highly unlikely to have evolved there as I understand it. We have surprisingly many micro-organisms in the upper atmosphere of Earth. Nothing unique that only lives up there - probably most just gets lifted up there in hurricanes and if the surface of Earth could somehow become inhospitable to life maybe they could no longer survive. But in case of Venus - they take months to float down rather than the days for Earth - enough time perhaps to spread around and reproduce so a tiny percentage but enough get into updrafts again - so microbes that got up into the upper atmosphere of early Venus could possibly still be there. At least some exobiologists have entertained it as a possibility. So, am just saying, is no hurry to colonize Venus cloud cities, and we don't know enough about our solar system.

I think myself that we should explore at present in an open ended way, doing nothing yet that is irreversible like introducing new life to a planet or colliding comets with Mars or building giant mirrors or whatever - but first see what the solar system is like in its pristine state. Though fine to build up lots of future ideas in ones imagination and work out all the details theoretically, and do experiments as far as one can in a safe and reversible way to try to get an idea to see if they would work. But to be prepared to be surprised by things we never expected and to give the scientists plenty of time to find out things and do their work - and be ready to change our plans based on what we find.

Last edited by robertwalker (2014-01-06 21:06:18)

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#94 2014-01-06 21:15:30

robertwalker
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Registered: 2012-06-03
Posts: 31

Re: Venus

SpaceNut wrote:

In the past life question have lead to flame wars so we need to tread lightly.

We do know that the essential elements are available but what are the catylists. First are protiens but then, What is the next key event that will cause a radom RNA strand to form is it as simple as a stirred pot that is left to simmer causing a slow mixing and fragment forming. At what point do we call it life?

Yes I've come across flame wars on this topic in other forums, and will tread lightly - if there are signs of a flame war developing I'll shut up. I got in one truly horrid one early last year actually - didn't realise what was happening until I was right in the middle of it. Learnt from that!

One rule I use now is that if I find myself repeating myself, then that normally means both sides have had their say in an argument and there is probably not that much more to be said at this stage. And the other rule I use is - that in an online conversation - it is okay to just drop out of it when things get heated - and you don't need to keep answering back - can be good to let the other person have the last word smile. And if you have said something that challenges their ideas they need time to think it through anyway, is good to give them some space if there are signs that their views are being challenged in a major way by what you say.

Yes that is a great mystery about abiogenesis. If Venus is the place with XNA then there would probably be very little evidence of how it evolved, much less so than for Earth. I think Mars is by far the most likely planet to have extensive past deposits showing all the details of whatever evolution did happen on Mars. And even if there is no life on Mars and never has been - it had global oceans almost certainly - so will show what happens to a planet with global oceans and organics and the ingredients of life left for a few hundred million years. Should have e.g. protobionts which form easily in the laboratory - things that look like cells but can't reproduce. May have chemical mixtures that are almost life, but not quite, reproduce a bit but imperfectly, or whatever. Anything like that would be fascinating and maybe shed a light on the very distant past.

There is one other source of information though - that could give us insight into not just early Mars but also early Venus and early Earth. That's the debris from the late heavy bombardment. After a big meteorite impact on Earth (say) - then most of the material ends up in the sun, Venus, Mars, also the Moon within a few tens of millions of years. The interesting thing is there - the Moon - this means there should be debris of impacts on early Earth on the Moon. Also there should be debris of impacts on Venus also on the Moon (obviously much less but still should be some). For Mars the best place to look for it is the surface of Phobos. So - may be meteorites, recognizable meteorites or meteorite debris from Earth or Venus on the Moon and especially if buried deep, so not too much damaged by cosmic radiation, then we might find reasonably intact organics, maybe even reasonably intact XNA and DNA in it. Might even find things such as fragments of fossil ammonites on the Moon smile as someone said in one of the news stories on this subject. But unlike on Earth - would be unaltered by anything since then, any organics for instance might still be there - if buried deep enough so also in conditions of extreme cold.

Is a nice idea anyway and a good motivation for sending rovers and astronauts to the Moon along with other reasons for going back there.

Last edited by robertwalker (2014-01-06 21:19:23)

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#95 2014-01-06 21:15:39

SpaceNut
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Registered: 2004-07-22
Posts: 25,992

Re: Venus

New Study Brings Scientists Closer to the Origin of RNA

Chemists at the Georgia Institute of Technology have shown how molecules that may have been present on early Earth can self-assemble into structures that could represent a starting point of RNA. The spontaneous formation of RNA building blocks is seen as a crucial step in the origin of life, but one that scientists have struggled with for decades.

RNA is perfect for the roles it plays in life today, Hud said, but chemically it's extraordinarily difficult to make. This suggests that RNA evolved from simpler chemical couplings. As life became more chemically complex and enzymes were born, evolutionary pressures would have driven pre-RNA into the more refined modern RNA.

RNA is made of three chemical components: the sugar ribose, the bases and phosphate. A ribose-base-phosphate unit links together with other ribose-base-phosphate units to form an RNA polymer. Figuring out how the bond between the bases and ribose first formed has been a difficult problem to address in the origins of life field, Hud said.

They homed in on a molecule called triaminopyrimidine (TAP).

The researchers mixed TAP with ribose under conditions meant to mimic a drying pond on early Earth. TAP and ribose reacted together in high yield, with up to 80 percent of TAP being converted into nucleosides, which is the name for the ribose-base unit of RNA. Previous attempts to form a ribose-base bond with the current RNA bases in similar reactions had either failed or produced nucleosides in very low yields.

So the soup thickened...

The study demonstrated one possible way that the building blocks for an ancestor of RNA could have come together on early Earth

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#96 2014-01-06 21:25:55

robertwalker
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Re: Venus

That's interesting smile. Yes I've also heard that RNA is astonishingly hard to derive from early conditions and that some sort of intermediary step is probably needed. Is one of many hypotheses, starting with RNA world of some form, if you've seen the wikipedia article on abiogenesis, gives a good overview of some of the possibilities that have been suggested.

But the intriguing thing is - that if you measure by the number of on redundant nucleotides, log plot - then what we know about life as we trace it back goes only half way back to the origin of life. Also another way of looking at it, the smallest cells we know at about 0.2 microns are far far too complex to have evolved by chance just as they are. So must have been much smaller precursors that presumably were in some sense alive, maybe not reproducing quite as perfectly as present day life, but - some way to get the whole complex machinery of cell reproduction underway simpler than the smallest cells that we know. I saw one estimate that they were probably about 40 nanometers across, the very earliest protocells. Just one idea.

This is the wikipedia article on Abiogenesis if any of you haven't seen it, gives a good idea of the complexity of the subject of the origins of life and how little we know and how many and varied are the ideas about how life might have got started.

Last edited by robertwalker (2014-01-06 21:26:29)

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#97 2014-01-06 21:27:37

SpaceNut
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Registered: 2004-07-22
Posts: 25,992

Re: Venus

organics have been seen in meteors but it will take one fresh one the sceene of mars to help say that we did not contaminate it once it arrived on earth.

The evidence has been trapped in glass for the most part.
Meteor impact trapped ancient swamp plants in glass

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#98 2014-01-06 22:00:11

SpaceNut
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From: New Hampshire
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Posts: 25,992

Re: Venus

Here is the geological clock

http://campus.udayton.edu/~INSS/ThemeEv … dchunk.htm

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

So what was earth 3.5 billion years ago how was the land arranged.

Now was the soup fresh water or salted?

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#99 2014-01-07 09:59:15

robertwalker
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Re: Venus

SpaceNut wrote:

organics have been seen in meteors but it will take one fresh one the sceene of mars to help say that we did not contaminate it once it arrived on earth.

The evidence has been trapped in glass for the most part.
Meteor impact trapped ancient swamp plants in glass

Yes that's exactly one way that organics from ancient Earth or Venus could end up on the Moon. Yes if you return a sample from Mars to Earth is a big issue to make sure you didn't contaminate it. It's a bit of an issue if you don't return the sample but study it on Mars also, studying for traces of life in situ.

The rover that examines the sample must itself be very clean so as not to contaminate the readings. Clean not just of dormant life, but - especially if you are going to send the miniaturized DNA sequencer, also of dead life as well. That's quite a challenge. The normal ways of sterilizing a spacecraft would leave dead microbes on the surface, even heat sterilized like Viking. There's a technique for Mars using supercritical CO2 snow - CO2 in a semi-liquid state  which can get rid of the organics as well and is rather neat as it uses the CO2 in the Mars atmosphere, you'd do that when the spaceship gets to Mars on top of all the other sterilization procedures.

Last edited by robertwalker (2014-01-07 10:05:59)

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#100 2014-01-07 10:26:11

robertwalker
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Registered: 2012-06-03
Posts: 31

Re: Venus

SpaceNut wrote:

Here is the geological clock

http://campus.udayton.edu/~INSS/ThemeEv … dchunk.htm

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

So what was earth 3.5 billion years ago how was the land arranged.

Now was the soup fresh water or salted?

Rather unlike today, hot ocean well above present day boiling point for water, huge tides, probably some small proto continents.

Started off with liquid rock and hundreds of bars pressure of CO2

Then later, very hot oceans over 200C, but also high pressure CO2 atmosphere so kept the water liquid though well above boiling point at present day atmospheric pressure. See Hadean (Wikipedia).

The water was probably more salty than today because a lot of the salt now is in salt deposits result of evaporating oceans - in early Earth not enough continents to make places for the sea to evaporate and deposit salt as rock salt. Probably 1.5 to 2 times as salty as today. See The Hadean-Archaean Environment

Huge tides from the Moon which was much closer than today and shorter day, shorter month.

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