Why Colonize Venus Instead of Mars

Venus offers unique advantages and disadvantages to space colonizers, which are different from Mars.

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Hell Planet

Yet there is a very good reason why Venus is left out in the cold in these discussions. Venus is unofficially labeled the hell planet of the solar system. The surface temperature of Venus is 460° Celsius, which is so hot that lead melts. The pressure is 96 bar. You got to go 1 km below water on earth to reach that sort of pressure. To put that in perspective:

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Venus is covered by a lot of volcanoes. This is just an artistic rendition as we got almost no pictures from Venus.
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Artistic rendition of lightning on Venus. On the surface there is a permanent yellowish haze, which prevents you from seeing the sky.

Venus Cloud tops

If we go about 50 km above the Venus surface, we reach the Venus cloud tops, and there the conditions change dramatically.

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Change in temperature and pressure at different altitudes on Venus
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An artist’s imagination of an airship on Venus
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Illustration of early soviet ideas for colonization of Venus using geodesic domes

Aerostat Habitats

Air with the same composition as on earth, roughly 80% nitrogen and 20% oxygen, would be a lifting gas on Venus because CO₂ has 50% more density.

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How NASA imagines the HAVOC concept’s ariship will enter the Venus athmosphere from outer space
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Sci-fi illustration of floating cities

Possible Raw Materials

Any colonization of course relies on being as self sufficient as possible. You don’t want to rely on massively expensive supplies from the earth being shipped on a regular basis. When you can’t have easy access to the surface, that might seem overly limiting. Landis does it in fact discuss contraptions for accessing raw materials from the surface of Venus in Colonization of Venus, but say we assume that is limited there are still more possibilities with an atmosphere than might first meet the eye.

  • Oxygen — 45
  • Hydrogen — 6
  • Nitrogen — 1.5
  • Potassium — 1.0
  • Calcium — 0.5
  • Magnesium — 0.2
  • Phosphorous — 0.2
  • Sulfur — 0.1
  • Trace elements: Chlorine, Iron, Boron, Manganese, Zinc, Copper, Molybdenum
45 + 45 + 6 + 1.5 = 97.5
1000 * (1 - 0.95) * (1 - 0.97.5) = 1.25
  • 3.5% Nitrogen
  • Venus clouds contains sulfuric acid H₂SO₄ and hydrogen sulphide H₂S
  • Various gasses in trace amounts
  • Oxygen
  • Hydrogen
  • Nitrogen
  • Sulfur

Carbon Fibre and Carbon Nanotubes

Just with carbon you can make carbon fibre, which can be woven into clothes and carbon nano tubes can be used as excellent electrical conductors, avoiding the need for metals like copper to make electrical wires.

Plastics (synthetic resin)

With carbon and hydrogen you can make all sort of hydrocarbon gasses like methane and ethylene. These are chained together in a chemical process called polymerization to create various forms of common plastics like polypropylene and polyethylene. With just carbon, you can make carbon fibre, which can be used with thermoset resins (a synthetic resin which sets when heated, e.g. epoxy).

Rocket Fuels

Methane (CH₄) is already being used by SpaceX for their new Raptor rocket engine, and so is Blue Origin with their BE-4 engine. Then there are rocket fuels for more specialized usage.

How to Obtain Useful Chemical Compounds

CO₂ is easy as 96% of the Venus atmosphere is made of it, so you can pretty much just suck it in. Together with water and nutrients brought from earth, you can grow plants, which gives you food and oxygen for breathing.

Water

The challenge then is, how to we get water? Since it doesn’t exist in pure form it has to be extracted from sulfuric acid H₂SO₄. There are several ways of doing that.

Water using Bateria

Sulphur-eating bacteria or more correctly Sulfate-reducing bacteria could be used to convert sulfuric acid to water.

Fe₂O₃(s) + H₂O(l) + 3 H₂S(g) → Fe₂S₃(s) + 4 H₂O(l)
2 Fe₂S₃(s) + 3 O₂(g) + 2 H₂O(l) → 2 Fe₂O₃(s) + H2O(l) + 6 S(s)

Water from Heating

Although according to Karen Rei at space stackexchange it is considerably easier to create water from sulphuric acid:

Hydrogen

Hydrogen has many uses. We can used with carbon dioxide to create methane gas or other hydrocarbons.

2 H₂SO₄ → 2 SO₂ + 2 H₂O + O₂ (830 °C)
I₂ + SO₂ + 2 H₂O → 2 HI + H₂SO₄ (120 °C)
2 HI → I₂ + H₂ (450 °C)
2 H₂O(l) → 2 H₂(g) + O₂(g)
2 H₂SO₄ → 2 SO₂ + 2 H₂O + O₂ (830 °C)
SO₂ + 2 H₂O(l) → H₂SO₄ + H₂(g) (electrochemical, T = 80-120 °C)
2 H₂O(l) → 2 H₂(g) + O₂(g)

Oxygen

Oxygen is of course needed for astronauts and oxidizer for rocket fuels. We could make it with the processes above for creating hydrogen, or get it as a byproduct of growing plants.

Manufacturing

So manufacturing on Venus would be quite different from Mars, in that it will be centered on chemical processing plants and processes.

Small Chemical Processing Plants

When trying to research this, the problem is that of course most chemical processing plants on earth are huge because there is a benefit of scale. But we are of course more interested in knowing how small a versatile processing plant can be made.

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Example of a pilot plan. Essentially a full chemical processing plant at smaller scale and with more flexibility.

Building Structures

Constructing new habitats or modules will be much harder than on Mars as there is no ground to stand on.

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Small electrical motors with cycloidal propellers used for model ships.

Summary

Advantages of a Venus cloud top colonization over Mars could be summed up as:

  • Same temperature and pressure as on earth. Which means no need for complicated heating and cooling systems, or pressurized habitats and airlocks.
  • Same gravity as on earth. The lower gravity on Mars has potential for a lot of long term health problems for humans.
  • Same protection against solar radiation as on the Earth. No need to build extensive protective layers or burrow under ground.
  • 4x as much sun, which means much better conditions for energy production and plant growth.

Geek dad, living in Oslo, Norway with passion for UX, Julia programming, science, teaching, reading and writing.

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