RuBisCO

That an the superconductor has virtually no resistance, all you need to do is energy-wise is keep it cool. Also I would like to point out I disagree about the time it would take the build orbital mirrors. First of we can build them off the asteroids and sail them to mars, they are just solar sails that hold their position in psudo-L2 halo-orbits via mars and sun gravity and light pressure, so they could be built just about anywhere and sailed to mars. Second lets assume a technologically reasonable 3 g/m^2 and a total surface area equal to a circle as wide as mars, that would be ~10^8 tons (~100 million tons), for comparison that would be equal to about 3 years our present world wide aluminum production. So a reasonably size asteroid mining industry could make that in a few centuries, and mind you that is for enough orbital mirrors to double Mars's solar flux and increase its surface temperature several dozens of degrees (at the sacrifice of a "night" replaced with a "day" of many many tiny "suns", which would truly be an alien sight to behold) Also again I disagree with CFCs, they aren't as stable or as powerful as a greenhouse gas as SF6. SF6 is so dam perfect for mars I can't stop talking about it, it density and mass, its stability to UV (thus the ozone depleting Florine levels are lower), it's relative ease of production, for CFCs we are going to need Florine, we are going to need to mine salts for Florine, sulfates will be a by-product, might as well make SF6 from it. If we use *Aqua* 400 million tons of CFCs need, and SF6 has at least double the greenhouse gas potential of the best CFC (in the 100 year span, at the 1000 year span it 6 times better then any CFC!), then we would need ~200 mt of SF6.

I would put a guess that it would require a fraction of that energy to jut build a superconducting ring around mars and charge it up... heck why are we doing this?, a magnetic field is superfluous.

No heat differentials matter, if not it would be possible violate thermodynamics. As such if the outside is hot your going to have heat coming in and your going to have to spend energy just to pump heat out. So that expelling heat received and produced is going to be very expensive energetically. That is just a guess, for all we know winds on venus are not consistant and there is much up and down drafting, the vega aerobots showed this to be the case. Worse would be traveling droping a line several kilometers down to generate energy on different wind layers, this would put drag on the whole habitat causing it to experience apparent wind. But we are talking about a surface area of thousands if not millions of m^2, low heat capacity and heat conductance of CO2 gas are completely made up for by that. Also we have not considered the possibility of sulfuric acid condensation on the surface what what they will do, beside add weight it would also likely add to heat transfer. That water not gas, for the case of gas you need height deferential of hundreds of meters. http://es.wikipedia.org/wiki/Torre_solar “La máxima potencia eléctrica que puede desarrollar el diseño es de hasta 200 MW. La chimenea solar propuesta inicialmente debía medir 1 kilómetro de alto, y la base 7 kilómetros de diámetro, con una superficie de 38 km². La chimenea solar extraería así cerca del 0.5% de la energía solar (1 de kW/m²) que fuese irradiada en el área cubierta.†You guaranteedly by the laws of thermaldynamics must, MUST spend more energy cooling your city then you would get back from this scheme. You need to bring all that extra weight of insulators, of heat pumps, of radiators to the outside, of power plants to power it to venus... or we could just float higher for 2-3 times the gas (made from venus) and NOT have to carry all those extras. Which costs more: gas or insulated balloons, heat pumps, radiators, and power plants? I would guess gas is the cheaper option, single layer balloon surface can be cheap and light, even transparent or translucent for plant growth, the weight savings in NOT having to lift AC, radiators, power plants, may make up for the higher altitude. Great, no plant growth for food. Oh sure your just exchanged AC for insulators, lots of insulators, and again low heat conductivity of are is completely made up for and then some by the incredible surface areas your working with as I showed. Your going to need many, heavy insulating layers, your going to need AC, your going to need power plants and your going to need radiators. You must spend more energy cooling your city then your get back as electricity, or else thermodynamics are violated. Your violating thermaldynamics if your get more energy back then you put in, to maintain a temperature difference, you must MUST spend energy, not receive energy. So to cool the city will by the laws to thermodynamics cost more energy then you can get back by any scheme. So? This system spends energy, and costs weights and money, any system will spend energy, and weight and cost money. Well that going to add weight too, lots of it, just to move a structure of this size as several kmh is going to be costly. Kerbin... I was talking about Venus, Venus has nearly the same diameter as earth. Again thermal equilibrium would push for everything being the same temperatures as the surroundings, maintaining a temperature other then the surroundings costs energy, maintaining a cooler temperature will require insulators, heat pumps, power plants, maintaining a higher temperature will require only a lower albedo nothing more, no insulators, not heat pumps not power plants for those heat pumps, no radiators. As for this romantics notion of going “outsideâ€Â, to do what exactly, look over a rails at a sky of completely white bright blankness? A venus city would spend most of its time floating a haze of completely white blankness (inexpresividad blanco) if their lucky maybe there are openings in the haze now to a small clearing in the clouds, but it likely not even fluffy clouds would ever by visible, just endless whiteness. It would be a completely dreary existence suited for a penal colony with no escape but to fall into hell. Well over times the balloon skin is going to degrade from UV light, from sulfuric acid, from what ever other chemical corrosion there is, from lightning perhaps, still inconclusive if that exist on Venus, I was not meaning wildlife would perforate it.

It is best to start off with the worse values not hope the best ones are true. And again 37°C would still require a heat pump as most people don't like living in that kind of heat and the habitat will invariably be hotter. No contention there. What ever, all that matters is the habitat has to be warmer then the surroundings, not colder, by enough to allow passive cooling. No conduction is what is occurring, it just without convection the layers of air will insulate each other, if we assume a layer of air several meters thick and not 0.1 mm heat conduction drops by orders of magnitude, this of course is impossible as any heat gradients will induce some level of convection allowing different layers to air to conduct as one. With bodies the size of zeppelins convection along it skin is assured. The height difference within the balloon it self will create currents that move air around transferring heat from low to high, the same will occur on the outside skin. As for winds, we know nothing of wind dynamics at those altitudes, for all we know there are none... or there are crosswinds blasting around like a hurricane. In short attempting to insulate something of that size against a hotter outside is going to weigh so much in insulation, heat pumps and power source to to negate the lifting advantage. The same as how heat transfers from any atom to any other atom: atoms touch or hit a each other transferring energy (conduction), atoms give of EM radiation that are absorbed by other atoms (radiative), but because we have a fluid we have an added mechanism in which heat is motion and heat can transfer (via conduction) in groups of atoms to a surface rather then just random individual interactions. How? Don't we need heights of kilometers to get that difference? How much energy? Thermal towers on earth need to be a kilometer tall and have many kilometers of base heating in order to get up 100 MW, with the distance your talking about I would think only a few hundred kilowatts at best with the added noise of having all these fan generators in the habitat. Worse if your achieving this because the habitat is cooler then your only making back a small amount of energy that you have to put in to maintain coolness. Thermal equilibrium means being at the the SAME temperature as the surroundings, that means living at 55°C! It would violate the laws of physics to maintain a lower temperature without a heat pump that requires workable energy. Again you can't violate physics, even "heat diodes" require electrical energy in order to pump heat in one direction. And again to live at that altitude will require all the extra weight of insulation, heat pumps and power plants. What is more expensive: more gas volume or magical hyper-insulators, heat pumps and powerplants? We can make water form H2SO4 as well so that not really a big concern. Sure why not, but where are they going? It is for attitude control, is it for changing latitude or is it for actually holding position because the amount of "control" needed for each increases exponentially. The reduction is minor, Venus's gravity is 90% earths so the reduction in delta v is going to be ~10% that over earth. That not a bad idea now all you need is ammonia factory floating +50 km above Venus and high thrust to weight nuclear thermal rockets in a reusable space-plane-o-zeppelin. Aside for having to deal with the torsion and strain to the city, oh about winds, once you do that your city is now going to be moving against winds, lots and lots of convection. Actually it was earth that got it rotation from a world colliding impact (that made the moon) not the other way around, where venus got its rotation is unknown. What is theorized for Venus is that it did not get that impact, solar winds stripped off all its hydrogen from its water, without water its geosphere lacked the "lubricant" to from tectonic activity. But all this is frankly supposition based on what very little we do know about Venus. The very first space probes we should send should be aerobots, just a few days spent in the clouds with a GC-MS and some other instruments for determining what the clouds are really made of, surface to core of the particles, would really go a long way. Longer term operation may be possible in the clouds in fact this discussion has brought up ideas for how to sustain not manned but also unmanned outposts in the clouds. A little solar power hydrogen ballooned aerobot with a small electrolysis kit could remain operation until something punctures it balloon such it can't make up the losses with electrolysis hydrogen (lightning perhaps, there is some evidence for it on venus)

The fusion option is completely unnecessary, it would produce very little helium, it would likely weigh ALOT!, hydrogen is already a better lifting gas and power is all plentiful in the clouds of Venus as solar power. Again in the clouds of Venus light levels during the day will generally be so high that you could face the panels any direction and get peak earth levels of sunlight. As long as they have enough battery/fuel cell power, to make it through the super-rotary night of 72 hours tops they are golden. Well yes of course lunching from height is way better then from the surface of venus, cooling the fuel is not as 'problematic', you reduce the amount of air you need to cut through, and your already at good height, but you still have like 7-8 km/s of delta-V to go! By the way ever used hooligans balloon mod to lift a rocket off of Eve and lunch it at altitude, it is fun as heck. Nuclear thermal would need to run off of CO2, which is a poor ISP propellant and also highly oxidizing and coke forming, it would be very technically challenging. It would make for a great rocket on mars though, you can land, pump up the fuel tanks with rarefied martian air and fly back to orbit, on Venus it may even be possible to make it self-compressing at least at lower altitude, a kind of nuclear jet engine, yes it most defiantly would need wings, but if it is reusable it would also need to have a thrust to weight ratio above 1 and be able to hoover to dock with the colony.

This chart you posted it says at 50 km that the temp is 350 K, that is 76.85°C or 170.33°F. Again I'm talking about 58-57 km, try to keep up. And again room temp is a few degrees above ambient we can maintain temp passively by having a lower albedo, which solar panels and plants will incur. So we want the surrounding air to be COLDER by like 5-20 K. We would need no insulation. Thermal energy from the sun or from the clouds themselves will be absorbed to keep the habitat warmer than the ambient air. Lets calculate heat conduction shalt we. Now we won't include radiative heating and convection, convection most certainly though would be a factor with a body the size of a Zepplin moving around in the winds of Venus's upper atmosphere CO2 has a thermal conductivity of 0.0146 W/(m*K), lets say the balloon is a sphere and is 80 m wide (that would lift 100 tons at that altitude) it has a surface area of 20,126 m^2 lets assume the balloon is 0.1 mm thick and has a thermal conductivity equal to CO2 (less then a 1/12 PVC plastic, or a really good conductivity insulated material, it makes the calculation easier) the temperature difference is 55 K then the balloon is losing 1.6 GW per hour! And that not including convection! Again we are talking about conduction with the air alone, not radiative heating, even if you could reflect all the IR radiation, ALL OF IT, the surface area with the air is so great that the heat conducted directly by thermal contact with the air is phenomenal! How are you going to release heat if the air around you is so dam hot? It can only be passive if your outside air is a little colder then the inside air. It a matter of logic here you can't be colder then outside air because of THERMAL CONTACT with it, the only way to be colder is a heat pump, there is no passive way to be colder than ambient! There absolutely no passive radiative way to do it or that would break thermal dynamics! You will have heat coming it, lot of it from thermal contact alone, you MUST have a heat pump to pump it out. If the outside is colder though that a different story: now you can passively use the IR heat of the sun or the planet its self to heat your habitat, thermal dynamics are in your favor. No one is going to want to go outside over there for any amount of time without protection, regardless if their face will melt off or not. I would say a lot of hydrogen made from the sulfuric acid would be very helpful, the reaction would be 2 H2SO4 → 2 H2 + O2 + 2 SO3. The energy required is very low, less then 1/3 what is required to water lysis. The SO3 would be dumped and the O2 would be breathing air and the hydrogen would be pumped into another balloon. At 57 km hydrogen has a lifting force of 660 g/m^3, nearly twice your air at 50 km. So this means for every m^3 of oxygen there will be ~2 m^3 of hydrogen in a separate purely lifting balloon. Of coursed that oxygen is cut with nitrogen so the ratio would be closer to 1:1 More so we can recycled oxygen with plants, hydrogen we would keep losing, so we would have to start dumping oxygen made to make up loss hydrogen. Anyways I would figure a cloud city would be made of many balloons only some of them would be filled with breathable air for habitation, the rest would be hydrogen or even a few backup pure oxygen and breathing air balloons. I would imagine a structure somewhat like a zeppelin, long cylinder with floor space at the bottom, attach above would be many more balloons filled with hydrogen, back up air, oxygen, during altitude changes from day to night air would be pumped in/out the back-ups to keep the pressure in the habitat 'zeppelin' stable. Of course this zeppelin does not need motors, assuming venus's winds do not move it about it latitude much. As for rocket launches back to earth... fat chance!

So how could I make it darker, or at least less transparent, the alpha value appears maxed.

Is it possible to make the clouds of Duna darker and lower? I've been playing around with the settings, besides radius and color what do the offsets x and y do for the texture?

I really recommend the book "Venus Revealed" by David Harry Grinspoon. 50 km puts us right in the middle of the clouds, even 60 km is just barely in the upper cloud layers. The clouds usually reach their thickest at ~50 km at least from the readings of the Venera and Pioneer Venus Probes. There some good to that, first off it reduces Venus's very bright sunlight (more then twice our solar flux), it also make solar panel aiming unnecessary for we could aim the panels straight down and still get power off the panels like we are on earth aiming straight at the sun! The probes also detected transients clearings here and there between cloud layers, so it is not like floating in the clouds would be boring scenery, now and then you would enter a clearing and be surrounded by extremely bright white fluff, it would be very romantic, aside for the whole 'acid melting off your face' factor. Anyways there is alot still unknown about venus's clouds, we know only that sulfuic acid is a major component but we also know there other things in there, exactly what is still a mystery. We have a unknown UV absorber, we have Venera fantastic chlorine readings (only probes to directly capture cloud particles and try to decifer their composition), heck there could be life in those clouds, feeding off UV via an exotic photosythetic pathway, the point is the nucleus if the cloud particles is mystery. There also mysteries about venus surface, for example all venus's highlands are coated in something radar reflective that literally sure as hell is not snow (because even on the mountain tops conditions are as horrify as hell) All of these mysteries should be answered, especially ones in the clouds, before manned missions that float up there. Here a good reason why: http://www.wired.com/wiredscience/2013/04/vega-venus-rain/

Yes but what is the cost of maintaining a -55 K temperature difference? Heck with surface area of a balloon no less! Heat is transferring physically from the outside air to the balloon skin to the inside air, you need to add insulated layers to prevent this. All the extra weight in insulation and power plant and cooling system may make it worth it be a little higher! You can't radiate heat away either as the air around is emitting more IR radiation! The density of Venus air at 50 km is 1.612 kg/m^3 at 350 K, the density of breathing air (79% nitrogen, 21% oxygen) at the same pressure but at room temp of 295 is 1.253 kg/m^3, so the lifting force is 358.4 g/m^3. If we go to an altitude of 57 km where the temperature is 285 K or 10 K below room temp which should still be in the range of passive temperature control, the breathing air would be 43% N2 and 57% O2 at 0.37 bar, the breathing air would weigh 457 g/m^3 while the outside air weighs 688 g/m^3, that is a lifting force of 231 g/m^3 or 64% of the low altitude. If we go to equal temp altitude lifting power is 284 g/m^3 or 79% the lower altitude. As for making O2, that easy enough, a carbonate fuel cell can make O2 out of CO2 (actually it makes O2 on one side and CO on the other) the carbon monoxide we can dump or use in a *separate* balloon as lifting as gas, as good as nitrogen in lifting force. Nitrogen would need to be separated from venus atmosphere, a multiple stage CO2 scrubber could remove all the CO2 and nitrogen would be all that is left, plus trace gases, or we could go with good old fashion Liquefaction, but that may be more energy intensive.

To caculate lift you need only caculate the mass of your ballon gas per volume, via re-arranging the ideal gas law equation: ((P*V)/(R*T))*M = m, P = pressure in bar*100,000 = pascals, V = 1 m^3, R= 8.3145 m3 Pa mol-1 K-1, T= Temperature Kelvin, M = molar mass, oxygen = 32, nitrogen = 28, CO2 = 44, m = mass of gas in grams. Then divide this by mass by venus's air at the same temp, pressure, volume. So For lift I get at 60 km = 134 g/m^3, 55 km = 305 g/m^3, 50 km = 557 g/m^3. Lets go with altitude of 60 so as to aviod any active cooling system, we can maintain temperture passively because the air inside will be hotter than the air outside because of thermal aborption of light and IR radiation. So lets say we have room temp air of 295 k inside and outside air is 20 K lower at 275 k, this is an altitude on venus of of 58.4 km, pressure of .3 bar, a nominal breathing atmosphere inside the ballon would consist of 31% nitrogen 79% oxygen, 30.8 g/mol, 379.9 g/m^3 verse an outside air of 582.7 g/m^3 and thus a total lifting force of 202.7 g/m^3. Thus to lift say a 100 ton habitate would require a spherical ballon 79 m wide. A titanic 1 km^3 ballon could lift over ~200,000 tons (the mass of two of the largest curise liners). Of course spherical ballons are not nessassary, the mass of ballon fabric is negliable (At thick mylar is 10 g/m^2 that only ~0.2% the mass) So we could go with many smaller ballons of varying shape (ice-cream cone shape would probably be ideal). We could also fill the ballons with hydrogen, the lift advantage would 2.75 times the breathable air, but the change in radius of the ballon would not be much, from 79 meters to 56 meter and of course it would not be breathable and would require a litte more complex extraction for sulfuric acid, verse breathable air made for CO2 via photosnythesis or carbonate fuel cell and nitrogen extract from venusian air via membrane pumps.

Found this: www.lpi.usra.edu/meetings/lpsc2013/eposter/2648.pdf Basically present theories suggest mars lost most of its nitrogen and that at best it has 3 m depth worth of nitrates across the planet, that ~17 m less than needed to give mars ~200 mbar of nitrogen (that only enough for ~30 mbars). So to make the atmosphere breathable to present day humans will require importing alot of nitrogen to mars. Of course the alternative is to engineer organisms to live in CO2 primed atmosphere, heck we still don't know if human's can adapt to such an atmosphere physicologically without genetic enhancement: http://newmars.wikispaces.com/Minimally+Terraformed+Martian+Atmosphere

That was a nice read. That certianly solves the problems of radiation and sheilding all in one, mining out an asteriod and fill it with a habitate.

If you can't sustain life breathing it, then yes it is not "breathable"... i don't see why that is so hard to understand? This is a matter of semantics here started by you not I. The point was to begin with is that habitable pressure, temperature and *snicker* gravity on venus is not worth as much as being able to live outside without respirator or your skin “melting offâ€Â, I would take lower gravity, lower air pressure and low temperatures for the ability to live in open air continuously without a respirator... now if “breathable air†is not the term you want to describe that by all means give it what ever name you want, but the term is not the point, the concept is. The point was that in venus's clouds we will still need a closed habitat with a completely different atmosphere made of [insert your name for the air]. Maintaining a closed habitat in the vacuum of space in solar orbit near an asteroid ~1AU from the sun would be easier then maintain a habitat on venus, for the advantages of lower delta-v, easily minable resources (as opposed multi-stationed robotics mines working in conditions of a literal hell) make up for the disadvantages of having to build pressure vessels and shield them from radiation and micro-meteors with asteroid mined waste, and spin them to produce what ever desired gravity one wants. Appeal to authority... by the way I am a biochemist, does that count? Sure why not, lets make it a choice between air you can continue living on breathing, or air with the same pressure and temperature but can't continue living on breathing, which one do you want? And what do you mean by Gas Mixture exactly, venus's air is certainly not a gas mixture viable for breathing. No I mean elements, not minerals. What specifically do you want a source for? Well that a personal belief, just like the belief that dental plaque is merely a figment of the liberal media and the dental industry to con people into buying toothpaste. Look believe what ever you want but if your not willing to test your beliefs and argue about them with the ability to change your mind, then don't waste everyone time by posting. Ok where did I say 2.5 km/s, if I did I was a in error. The point was and remains that we would need a round trip delta-v greater then 16 km/s to make Venus a competitive option for a space colony, frankly that covers ALL the asteroids in the asteroid belt! I don't know about this 2 km/s part, now its 2 km/s that I supposedly said? Anyways the 16 km/s is the 3.5 km/s required to get from LEO to Venus and the 12.7 km/s required to get off of venus and back to an earth transfer orbit, not including the cost of enter back into LEO (or landing) I believe the calculation is call “addition†The source is the cute delta-v cartoon everyone cites: http://clowder.net/hop/railroad/deltaveemap.html If you have multiple automated based on the surface of Venus able to extract and separate different ores and produce different products all while operating at 500 C and 92 atmospheres... frankly mining several asteroids at once would cost less then developing the technology to mine Venus and sending it all to Venus. “less destructive†same to me, what exactly is it less destructive to? Is not the point the shockwave? I'm really failing to see what your getting at here, blasting a “nozzle†into a KBO or a moon of Saturn is going to require an obscene amount of energy either as fissionable, fusionable or anti-matter material, and getting it to provide enough force to move said body rapidly will risk the structural integrity of that body regardless if the blasting agent is anti-matter or not, its all about the redunkulus amount of energy being released in such a short time to provide the desired propulsive action, any kind of mechanism for distributing that energy will also reduce its effectiveness as a propulsive agent. And worse sending it inwards towards Saturn or Titan to get gravity assistance will risk its integrity more from gravitation strain... you know what the roche limit is correct? This thread is not about such an idea, this thread is about Terraforming Venus, if you want to talk about cloud cities on Venus make a thread for that. I already covered those effects, we would need to impact many small masses that we can dissipate most of the impacting energy into the atmosphere rather then the surface, we would need to build sun shade first so that impactors were all the energy input on Venus.

Again breathable air means the minimum pressure and temperature to sustain human life, 0.6% is not enough pressure to make the air "breathable" I already stated this before, stop playing semantic games. The vacuum of space is a pretty good insulator, at 1 AU temperature control can be achieve passively or with very minimal energy input. Its doubtful it will be a serious problem, at least for people that never in their lives will set foot under earth gravity... more so if 100% earth gravity is what is needed then an orbital space colony in a gigantic centrifuge is the way to go. No all your premises are invalid, breathable air is the most important factor. Let me put this way, someone gives you a choice on how to live, you can only have one: breathable air, earth gravity, earth pressure or earth temperature, any of the other beside breathable air means your dead in under a minute. Well first off because our rocks are differentiated and have much poor generally concentrations of minerals, and second of because without the power-plant mass to power advantages of zero gravity at 1 AU, it would not be energy efficient. On earth we need to burn fuels, complex power plants, we cant just aim a mirror at the sun and get continues heat and power 24/7. On earth 100 Kw per kg only makes sense for the most rare of elements, in space that would not be a concern because power is plentiful. Again I have explained how 2D thermal-electrocution process can separate every element, you can't make a vague statements as a counter argument, you need to actually explain how in detail my process can't separate every element. The machine is not fundamental complected, 20 cold traps with 5 electrodes per trap could separate ~100 elements. A lot easier to build an asteroid colony then one on Venus. Want to talk about construction difficulty: try build stuff on a balloon, now that has not even been tried. Try mining and extracting and even constructing at 500 C and 92 atm, that too has never been tried, and yet you just assume it will be easy? Not really, at 1 AU the average temperature is at freezing, most hydrates are stable in that, even in a vacuum, as long as the first few meters average out 'day' and 'night' time temperatures. No I posted that source before, there are already over 100 known requiring less then 4.5 km/s. Why 2km/s? I never said 2 km/s! Lets consider the round trip cost two and from Venus, even with aerobraking that is going to be a delta-v of over 16 km/s, with an asteroid colony we could do it in 8 km/s for hundreds of asteroids. Then I advice reading up on chondrites. Again this assertion of yours has been countered in multiple ways: a break down of the most common elements and quantities that could be extracted per ton of C-type material has been given to you. The argument that for what the asteroid colony can't make right way they can trade for in what they can mine, which can't be done on Venus without having to get things off of Venus. Heck even a stellar asteriod mining network would require less delta-v to get from each other then to get off of Venus! What you said did not make sense. Well lets just assume you hitting anti-protons with protons and forming pure energy and that your saying these gamma rays will harmlessly leak out (harmless to what?) then would not most of the yield be lost to space? Anti-matter against regular multi-proton atoms though will be quite messy and form lots of high speed charged particles. Well sure, even with the near term ones like fission and fusion it would take obscene space infrastuture to do it, but I don't think technology is the limitation here: energy is! The amount of energy required to move that much matter is not going to change, and no new technology is going to reduce the energy needed, not even antimatter, which requires an unbelievable amount of energy to make. I know that, but usually a common complaint is no magnetic field, that one is put to rest. hydrogen will react with co2 thermochemically (by heat alone) to form water and carbon monoxide and methane at venus's temperatures and pressure (or by the temperatures of impact), no biology is required for that process. Also the process of reducing CO2 with hydrogen to make water and biomass is biologically common among certain primitive bacteria, mind you without needing light. Venus under sunshade would need to be kept warm by the impacts alone. I and others have repeatedly ask her for that to no avail.

Where exactly do you plan to put the CO2? To convert the CO2 into biomass, water or solid carbon we are going to need hydrogen, as you already know we can only turn a tiny fraction of it into oxygen. So we are going to have to deliver a ridiculous amount of hydrogen, and that going to have to be bombarded one way or another into Venus, unless there are wormholes and/or teleporters in the future.

Well everything you said has been covered before in detail, by my self, with basic calculations no less. Some of what you said though is in error though, for one Venus does not suffer for temperature swings, it atmosphere super rotates and keeps the whole surface at about the same temperature day and night. Second Venus is very nitrogen rich, 3 times as much nitrogen as earth, at least in gas form. Anyways mining hydrogen and water form the Kepler belt is ideal, a minimum of ~1x10^21 kg of water is needed. The Kepler belt provides high concentrations of water with a delta-v of 4-6 km/s. Even cracking water into hydrogen from the Kepler belt makes sense because trying to extract it from gas giants would consume even more energy in delta-v (making 1 kg of hydrogen is equal to pushing 1 kg of matter to 6.3 km/s) plus the waste oxygen could be used as propellent mass. Venus already has 4.6x10^21 kg of CO2, add 4.1x10^19 kg of hydrogen, have the heat convert it and the CO2 to water and methane and have engineering cloud flora covert the methane back to hydrogen and carbon soot and you got 3.7x10^20 kg of water, that a quarter of the needed amount of water for 1/11 the input mass. The other 75% of water though will have to be mined and shiped directly. Titanic ships in a continues convoy would need to move 5.3X10^16 kg per year for 20,000 years to get the job done. That equal to over 50,000 km^3 of water pear year! Or you can think of it at 50,000 ships moving 1 km^3 of water weighing over 1 billion tons EACH, with 500 years to complete a round trip from the Kepler belt and back that would be 25 million titanic cargo ships in continues use, dumping 1 trillion kg of water (and hydrogen) every 10.5 minutes into Venus, for 20,000 years! Just a fraction of the kenetic energy from smacking that much mass into Venus at 40-50 km's (the speed gained from free-falling for the Kepler belt) would be enough to spin up Venus to an earth long day, this would also likely give Venus a magnetic field. Heat from the impacts would be a problem, impacts would need to be small enough and spread out enough that they can be dissipate in Venus's thick atmosphere, combined with a gigantic solar shade 4 times the width of Venus in Venus-Sun L1 that blocks out all light and thus all thermal input on Venus. Once the water is deliver, and the planet has cooled down enough, can the sun shade be partially opened to provide earth like levels of sunlight. Terraformed Venus would still have 3-4 times the atmospheric pressure of the earth, almost all of that nitrogen.

I think I and AngelLestat, we have yet to make ad hominems of insult at each other and have kept high on the argument pyramid, sure there has been a repeated inability to acknowledge specific points but that nothing. Also why is the Mars Terraforming thread not a sticky? That would be order of magnitude easier to terraform than Venus, so I would think it slightly more viable and discussable.

Then make a new thread about cloud cities on Venus. If we are going to be impacting 10^21-10^22 kg of matter at 40-50 km/s that energy is simply a bi-product of which we can make use off in giving Venus and Earth like day (and magnetic field). I was talking about terraformed mars. Earth-ish Gravity, temperature and pressure are not all of equal value, especially not against breathable air. Earth-ish gravity is the least necessary characteristic, we suspect people will be able to live just fine on Mars gravity for example. Habitable temperature and pressure are certainly much valuable, but on Venus that would come with a in-breathable acidic atmosphere. Breathable air is the most necessary characteristic, that alone requires a minimal pressure and temperature to sustain human life. Even on your cloud cities, your colonist would spend all their time in a habitat with BREATHABLE AIR, we could maintain such an environment on a moon colony, asteroid colony, mars colony for much cheaper then in the clouds of Venus. You can have oxigen, but if you dont have a similar pressure and temperature, you dont gain nothing. And I explained repeatedly that is untrue and that its possible to mine ALL the elements even if they are in concentrations as low as 1 ppm. The method I describe is actually several methods, thermal-evaporation separation under hydrogen atmosphere followed by chloride or fluoridation and elector-winning or direct electrolysis (for water, SH2, ClH, etc) . The first process produces metals and hydride that evaporate off at different temperatures and are collected by cold traps at different temperatures, the second process separates elements via their voltage of formation. That is two dimensions of separation. The build up on the electrodes can be from hours to months depending on the concentration of a specific element it is selecting for, so it will allow collection of even very rare elements like platinum. There not a problem to get all elements for 1 asteroid either. As I explained repeatedly now this would be on an asteroid in Near Earth Space, not an asteroid in the asteroid belt. Such asteroids regularly cross even into Venus space. These include C-type asteroids. Originally these asteroids were in orbits and formed in the asteroid belt (with water and hydrates) then got knocked into earth crossing orbits by rare circumstances, their water content would remain for they entered into these orbits recently (last few million years) and their surface layers provide thermal protection. I'm not sure what you saying here, there are plenty of NEO to choose from, many more yet to be discovered. If you have a problem with my calculations please point out where specifically. Well now I'm talking about the Kepler belt, please keep up. So? what are you saying exactly? That they don't have those compounds in high concentrations? What evidence do you have? None of them weigh as much as the moon, even Eris, are all much smaller in size and mass then the moon, and I'm talking about specifically moving them or removing large chunks of them at a time. What do you mean by "Common sense" I present numbers of how it is double to move 10^21 - 10^22 kg from the keplar belt with near term technologies in a several thousand year spanned to show that terraform Venus is doable, if you find that beyond the bounds of "common sense" then you should not be talking on this thread: because the very topic of terraforming Venus would be beyond "common sense". And that would be? A laser from where, how much power output would that laser need to have, millions of terrawatts? And don't think for a moment you can beam it from across the solar system for a the beam will divergence. Also how are you going to produce the antimatter? Do you understand that antimatter explosions release huge amounts of gamma rays? You can look up how the moon and earth formed for one. Good for you, good bye then.

Is there a way to turn off citylights and just have clouds?

Not really it all depends on how effective its atmosphere is at retaining heat and how much solar flux we have on it. With titanic orbital mirrors doubling if not more Mars's solar flux and/or massively enhanced greenhouse effect it would be possible to have t-shirt summer time temperatures at the equator at the very least. Its just a matter of how much flux and heat retention is induced. I honestly don't think a coat is as inconvenient as a breathing apparatus. 10^15 kg tops. This is based on the assumption that Mars would need ~2 atm of CO2 to have an earth like climate, divided by 22,000, the partial pressure of SF6 would be ~0.1 mbars. For Methane though the partial pressure would need to be 67 mbars, out of a 500 mbar atmosphere puts it at 13.4% and its explosive limit is between 4.4-17% so that atmosphere would be burst into flames at the smallest spark. That is because its only in parts per million. On Mars we would be talking about several percent methane, because its greenhouse gas effectiveness is only 20-40 times CO2 and it halflife (on earth) is only 10 years. Sulfur hexafloride on the other had is the most powerful greenhouse gas known with over 22,000 times the greenhouse gas effectiveness of CO2 and a half-life of over 1000 years. We would need

because be able to breath is not really that useful? Wll sure and we could potentially acheive that in just a century from starting out. Methane will not last long if we ever want the atmosphere to be breathable. Methane also has a very poor half-life on mars, because of the UV and because of unknown methane sequestration mechanism.There is plenty of sulfur and flouride salts on mars nad sulfur hexaflouride is incredibly stable. Another way of keeping Mars warm without need so much greenhouse gases would be orbital mirrors, lots of them, big ones at that, We coud have low CO2 and a breathable atmosphere that won't explode because of all the methane, the only sacrifice would be no more nighttime. Imagine when the sun sets a ring of "suns" rises.

Oh no I'm not asking to stop it rotation, I'm asking to speed it up! With the mass and speed of body bashed into the Venus it should be more then enough to give Venus's a rate of rotation under 100 hours! The Math is clear on that, 1*10^22 kg traveling at 40-50 km/s is 1*10^31 J, the rotational energy of the earth is 2.6*10^29 J for comparesion. If only 2% of that energy were transfered to rotating venus by impact some of the comets at an slant to the equator venus would have a 26 hr day! There a big diffrence between living and breathing open air on terraformed mars verse, living in a cloud city on venus. Lets limit terraforming to open air that is breathable and climate like that of earth's such that people could live at least some of the year in t-shirts. Yeah but you don't get open breathable air, that is the biggest criteria of terraforming! All you have done is make habitates afloat on venus, for which the advantages of pressure and temperature and 1g are little compare to the costs of having to maintain a enclosed breathable atmosphere. Take the moon for example, the Lava caves of the moon could provide hundred meter wide kilometer long encloses with constant tempertures, radiation proofing, meteror proofing, potentially all we need to do is silica plate the caves and pump in oxygen and nitrogen gas and we have untold cubic kilometers of living space, with the advantages of dozens of meters of rock over a flimsy ballon skin and lower distance and Delta-v to and from the Earth. Technically we could build habitate enclosures anywhere in the solar system including as a use of material by-product of asteriod mining and afloat in solar orbit. Venus provides little advantage and grand detriments in comparision. Yes, we do. Some of the C-type asteroids have the same elemental composition of the sun (with exception of hydrogen and the noble gases) so Oxygen. Carbon, nitrogen, silicon, magnesium, Iron Sulfur are at several dozen parts per thousand! All the way down to elements like Platinum which even on a C-Type asteroid is over 1 ppm! Not really because most of those elements would be 50 kilometers below at 450 C hotter and 92 atmosphere of pressure higher. Much of your industrial processing would need to be up in the clouds as well because of the inability to do advance chemist at 500 C and 92 atmospheres. Every kg needing to be supported by balloon fabric and balloon gas. Efficiency is irrelevant! At a obscene 100 Kwh/kg we would need only 154 m^2 of solar concentrators (assuming 50% efficiency) or 770 m^2 of solar panels assuming an overall horrible 10% efficiency and 1 AU from the sun, to process 1 kg per hour, 8.7 tons per year. That an array area underr 30x30 m per kg processed, of which we could be talking about 100-1000 g/m^2 of powerplant mass! A minning complex capable of processing 10 tons per day would have a powerplant mass of 32 – 320 tons. Of which it would produce roughly ~5.2 tons of oxygen, ~2.1 tons of carbon, ~500 kg of nitrogen, ~500 kg of silicon, ~400 kg of Mg, ~75 kg of iron and ~200 kg of sulfur, and >1000 kg of everything else, per day. In a year it would produce 365 tons of miscellaneous elements of which important stuff like phosphorous, copper, aluminum would make up major percentages, but even the rare stuff like platinum would come out at ~4 kg per year. And that just 10 tons per day, out of a minning facilities with a power plant mass of under 160 tons and a total mass likely under 1000 tons. Assuming ~10% of those products goes into build more mining capacity, (carbon fiber, magnesium metal, steel being most of the structural mass) the asteroid colony could double it capacity every 3 years, in 10 years it would exceed 100 tons per year, 20 years 1000 tons per years and in 30 years 10000 tons per year. All of that an inefficient 100 kwh/kg or 6 times the energy cost of making aluminum from bauxite. With thermal separation and electrowinning you can do just that, slowly grow the really rare stuff on the electroplates at the same time you separate out the really common stuff rapidly. The Kepler belt is between 30-50 AU and already is noted for having many times the mass of the asteroid belt and a total of ~1/30 the mass of the earth or 20 to 200 times more matter than we are looking for, so the Kepler belt will do, so no need further into the oort cloud unless somehow that very low delta-v is worth the extreme wait. Again we don't need to go to the oort cloud. But as for its composition based on all the oort cloud bodies that come down (comets) I can give it a very good estimate. As well as again sending probes to these bodies beforehand is a negligible cost compared to the trillions of tons fusion or fission tug ships needed. No again we know enough about their compositions already. Let me put it a different way: we know they are mostly ice, water, ammonia, co2, methane in that order. For the Keplar belt object to be unsuitable for venus terraforming they would need to be made out of something we have not yet seen, something truly radical, so far from what we have seen from just the bodies we have found they are already suitable. We already found enough Kepler belt objects so what ever your saying now is irrelevant. Again you completely ignored the fact we can't do anything but circular orbits because we don't have the thrust for “maneuversâ€Â, try to fly by a world for a gravity assist would be very difficult and again if it flies top close to Saturn we run the risk of ripping it apart. Just calculate how much delta-v is needed to enlarge it orbit until it leaves the Saturn system. I highly doubt your claims about once reaching Titan we can magically get tens of km's in delta-v, that not possible, delta-v a gravity assist can do is proportional to the mass of the world your going around, hence why the moon can't proved more then 2 km/s of delta-v in a gravity assist maneuver, likewise there is no way of flying around titan and then Saturn from Saturn orbit and magically gaining nearly 9 km/s in velocity, gravity slinging is not magic! And blow up the moon while your at it. Or we could just take it in a million pieces. Blowing it up would not really help in that, we could just mine Iapetus directly, its escape velocity is minor enough. No it is not the same, for one titanic impact that liquifies the whole surface will create convection which will allow all the energy in Venus's mantel to circulate, multiplying the energy required to be released many fold. Many many small impacts can avoid that. No please present calculations on that.

Again people Zubin has already done the calculations for you. Assuming a certain amount of CO2 and water is sequestered in the Martian soil all that is needed is to bring up Mars's temperature a few degrees to start a global warming chain reaction, he's numbers show that it should be possible to bring Mar's surface to habitable pressures and temperatures in UNDER A CENTURY! Making enough oxygen would take a few centuries to a millennium longer. So we are talking roughly 1000 years to terraform mars with minimal energy imputs of a few GW a year. Also maybe we can do it all without having the slam in comets if there is enough CO2 and Water on Mars already, which is a big if, alot more science is needed to be done on Mars to answer the questions of how much water ice, permafrost and geological deposit still exist and how much CO2 is soaked up by the very cold-dry soil, the answers to this will determine if mars can be terraformed without need of outside sources of water, CO2 and nitrogen. That last one is one Zubin barely talks about but is rather important. Human's may not be able to live in a majority CO2 atmosphere or >250 mbar, water there would have the pH of soda water (actually it would be soda water, it just would not bubble) Blood pH would also be shifted, I don't know if humans could adapt to that without significant genetic engineering. http://www.globalunderwaterexplorers.org/carbon-dioxide-narcosis-and-diving So the atmosphere is going to have to be made out of mostly nitrogen in the end, at most 50 mbar CO2 (if we can't adapt to higher physiologically) 150-200 mbar oxygen and then at least 150-200 mbar more nitrogen, total air-pressure of at least 40% earths or >350 mbar total. That is going to be alot of nitrogen at least 10^18 kg of nitrogen. If that was to be found as sodium or potassium nitrate deposits it would be ~2.7 million km^3 of nitrate salts, or equal to a cube of salt ~140 km wide! Or a layer of nitrate salts 20 meter deep across all of mars. Alternatively if this amount of nitrates can't be found on mars, we could mine ammonia from comets, and outer solar system bodies. Base on what little we know of KBO and comets we know they have an ammonia content of 7-19% that of their water content So a comet that is 80% water is also roughly 9% ammonia. So we can say we need to go through roughly 10^19 kg of comets to get enough ammonia, we could either mine the ammonia directly or smack comets into mars. By the way from my calculations on Venus terraforming this is 1/100 to 1/1000 less matter needed for terraforming Mars then Venus. I would forgo bashing Mars with comets, at least not directly. Mars's low gravity would mean a lot of atmosphere loss from the impact plums. Comets would at best need to be detonated somehow into snow to spread out their impact over a whole hemisphere of the planet. Forgoing that we would need to mine ammonia directly from a comet, ship it to Mars and dump it in smaller manageable amounts. ~10^18 kg of ammonia would also provide a lot of hydrogen (24% of that ammonia is hydrogen) that hydrogen would react with all the oxides and superoxides to form water. Adding a little more water to Mars, not much though that is between 1/10,000 to 1/100,000 the amount of water on earth. If Mars needs more water we can just take chucks out of comets and deliver them to mars without processing out the ammonia. Still 10^19 kg of water-ammonia is still 1/100 less water then on earth, so hopeful Mars already has lot of water stored in it poles and under its soil to make up the diffrence. Terraformed Mars's atmosphere should be stable for millions of years, despite the lack of a magnetosphere and the loses from solar striping and low gravity. 50 mbar of CO2 though will not be enough to keep it very warm. We would need another greenhouse gas, like my favorite sulfur hexafluoride: that one we would need much less then a mbar of as it has a green house potential 22,000 times that of CO2!

Just providing an example. Well we already have many Keplar Belt Objects cataloged even ones less then 1 km accross, spectra can tell us what their surface is made of at least, as well as a probe to one can give us rough figures on a whole class of others with matching spectra. Last but not least sending a probe to each one before sending the tug ship is cents compared to the tugs ships price tags. Not really worthwhile considering it weighs less then one millionth the thing it is moving, in short even if it cost 10 times as much delta-v to move tugs up there that would still be negliable compared to the cost in energy and fuel to move the Keplar Belt Objects down here. I don't think you can get much gravity assist off of Rhea, maybe Titan, but pass too close to saturn would likely tear Lapetus apart. Just figure out the raw Delta-V needed to get it out of Saturn space first. Since we would likely only be able to change it delta-v by a few meters a year at most slowly enlarging its orbit outwards is the only option, for going inwards will likely result in hitting one of the other moons because we can't make it orbit parabolic enough to not miss them. Lastly: once it is out of the Saturn system its going to cost almost 9.5 km/s to get it down to venus space. Yeah sure, the problem though is that it would be one world colliding impact, it might end up completely melting the surface of venus and that is going to slow down terraforming and even lead to that ocean world problem: where we have to wait millions of years for land masses to form. The question of this thread is: can we terraform venus and how? not "should we" or "why not be more pratical and do..." or "what problems will it solve?"