How to cool Venusian atmosphere down?

Question

Carbon dioxide dominates the Venusian atmosphere. While I think it is possible to use the thermal energy in the atmosphere to split carbon dioxide to carbon and oxygen, the process may be too slow to cool down the planet. Also, the thermal energy needs to go somewhere.

Oxygen has three stable isotopes and other radioactive and unstable ones. After the oxygen is recovered from the splitting reaction above, oxygen-16 is going to be the dominant isotope as it is on Earth. My question is that is it possible to carry out a nuclear disproportionation reaction? Two Oxygen-16 atoms suck up huge amount of thermal energy to become one oxygen-18 and one oxygen-14. Oxygen-14 decays with a half life of over one minute to stable nitrogen-14. Creating nitrogen is the main goal.

If this transfer of neutron is possible, then transfer one more from oxygen-18 to oxygen-19. Here hydrogen can take part to become deuterium. Oxygen-19 decays with a half life of just under one minute to stable fluorine-19. Fluorine itself is then reacted with the carbon from the first reaction to create fluorocarbons. They are stored and shipped from Venus to Mars for the Martian global warming effort.

This whole question describes a hypothetical situation so I think only worldbuilding stackexchange site would accept this.

All the while, the Venusian atmospheric temperature cools. In the big picture, the huge amount of thermal energy in the atmosphere may be exploited but how? A way -- maybe foolish -- is to exploit the energy to make atoms in need, nitrogen and fluorine.

So after reading answers and comments, at this AD 2012 moment, it is possible to only use the thermal energy in the atmosphere to split carbon dioxide to carbon and oxygen. Then allotropes of carbon can be made. Oxygen is not a greenhouse gas and fixing the carbon removes carbon dioxide. So the bit by bit, the thermal energy is lost to space. As noted above this CO2-> C + O2 is too slow to ever cool down Venus significantly. But at least synthetic diamond and carbon nanotubes can be possible and help set up bases on other celestial bodies including the Moon and Mars.

Answer 1

Strong interaction

At the range of $10^{-15} m$ (slightly more than the radius of a nucleon), the strong force is approximately 137 times as strong as electromagnetism... the strong force binds these neutrons and protons to create atomic nuclei, where it is called the nuclear force

Give that the electron-nucleus distance is on the order of $10^{-10} m$ and that the electromagnetic force decays with the square of the distance, the force that bounds an electron to the nucleus is about $137\cdot(10^{-10}/10^{-15})^2 = 137\cdot10^{10}$ weaker than the nuclear force that bounds one neutron in its oxygen nucleus.

At this ratio, the energy to extract a single neutron from the oxygen is enough to strip all the electrons from the Carbon and the two Oxygen atoms in a carbon dioxide molecule and you'll still have enough to blow outta solar system the 3 nuclei, and do it at a significant fraction of the speed of light.

If you have that amount of energy available:

• build a shade between Mars and the Sun
• expend the rest of the energy to maintain the shade in position against the pressure of the solar radiation

Answer 2

The standard non-scifi answer does not involve exotic physics, but a solar shade. While technically a megastructure, it is structurally simple: basically a thin reflective foil (and presumably some structural support mass and a fair bit of reaction mass for attitude control, although you can decrease the latter considerably with clever designs, see statites)

Removing solar irradiation would cool the planet to the point where the atmosphere would condense on the ground and form ices on the surface. Dealer's choice from there. Hypothetically, nobody's stopping you from using the shades to generate power, and use the power to fuse-synthesize whatever elements you're need on the surface, or to ship unwanted extra material off-planet.

Answer 3

I'm not sure if I understand the physics here, either it is obscured in the question, or you are misunderstanding the principles of physics. You state:

My question is that is it possible to carry out a nuclear disproportionation reaction? Two Oxygen-16 atoms suck up huge amount of thermal energy to become one oxygen-18 and one oxygen-14. Oxygen-14 decays with a half life of over one minute to stable nitrogen-14. Creating nitrogen is the main goal.

To answer the question you must first answer the following questions

1.) What is meant by "Two Oxygen-16 atoms suck up huge amount of thermal energy to become one oxygen-18 and one oxygen-14"?

I'm not sure what this statement means. Nuclei don't suck up energy to decay into less stable configurations. Nuclei decay because it is energetically favorable to do so and allowed under selection rules. Nuclear decays are either spontaneous (exothermic) and release energy, or are endothermic and require an input of energy to decay. In either case, the unstable nuclei are unaffected by thermal excitations which are many orders of magnitude lower needed to induce change in the system.

To get O16 to change isotope you would need neutron bombardment, which can only occur from am appropriate radioactive source. Inducing O16 to change isotopes cannot occur by thermally extracting energy from the surrounding air.

2.) You state "If this transfer of neutron is possible, then transfer one more from oxygen-18 to oxygen-19".

Neutron bombardment will result in different capture rates (and immediate subsequent decays), however neutron bombardment is an energetically intensive process which requires the right set-up of radioactive elements. Again this does nothing to solve the problem of extracting energy from the atmosphere.

Energy moved out of the atmosphere must be moved into something else. The temperature of the atmosphere is characterized by the average kinetic energy of the air molecules. Quantum rules and the nature of the residual strong interaction forbid the transfer of energy on this scale (milli-micro electron volts) to and from the nucleus (energy scale of mega-electron volts).

Answer 4

Apart from the thermodynamic issues with the idea of using the atmospheric heat or the practical ones of adding neutrons to oxygen...Venus already has far more nitrogen than Mars needs. If it didn't, terraforming Mars still wouldn't get rid of more than a tiny fraction of the CO2. Also, you could run the same process with oxygen from Martian rock, without having to ship an atmosphere across the solar system.

However, you could in principle do something else that's actually both simpler and more effective. "Just" spall off protons and neutrons from oxygen nuclei, allowing the neutrons to decay. This is difficult and energy intensive, but far easier than sticking neutrons into other nuclei to produce stable products. Each proton stripped off will grab an electron to produce a hydrogen atom, each neutron that decays will produce both a proton and an electron. By doing this, you directly convert CO2 to solid carbon, and produce hydrogen that can be reacted with more CO2 to produce carbon and badly needed water.

However, this is not going to be an efficient process with any known mechanism. You have ~480 quintillion tons of atmosphere to process. I highly doubt you'll be able to do it on a scale that matters without actually making Venus hotter with waste heat.