From all planetary models, probably the hardest to terraform is a planet similar to Venus. Such a celestial body is scourged by a runaway greenhouse effect. Building a Terraforming Plant on its surface is impossible, since almost all buildings and devices will meltdown, exposed to the high pressures, temperatures and corrosion effects. A different approach is needed.
A planet similar to Venus can exist around many stars. A runaway greenhouse effect, leading to temperatures above water boiling point, can exist beyond the orbit of Earth and even around the orbit of Mars, if the atmosphere has enough carbon dioxide for this. Basically, any Habitable Zone Planet can, with the needed atmospheric ingredients, be like Venus. Also, closer to its sun, as long as the solar wind is not too strong and assuming the planet has enough gravity, large atmospheres can exist.
If we take Venus to the orbit of Mars, it will still have an average temperature above 100 degrees C. However, if we put it where Mercury is, we could expect surface temperatures to rise dramatically above 1000 C, while the atmosphere will still be relatively safe.
Given the high temperatures, all water will be found in the atmosphere. UV radiation will break water molecules into oxygen and hydrogen. Hydrogen will be lost into space, while oxygen, since it is a highly reactive gas, will interact with other compounds. Many rocks will change structure at high temperatures. First, they will lose all water and other volatiles that are bond in their structures and crystals. Also, metals will change oxidation stages. The result is that many substances will move from the rocks into the atmosphere. Many chemical compounds, which are stable at Earth's temperature, break apart in high temperatures, like those found on Venus.
Another factor is that the lower Venusian atmosphere is in fact not a gas, but a hyperfluid. It penetrates through the smallest pores and separation of impurities becomes impossible. This is the way water behaves in high-pressure thermal plants, the only places on Earth's surface where we have similar conditions with Venus.
Terraforming such a planet is probably the most difficult of any known or theoretical planet. Before even terraforming starts, scientists must make sure that the result is worth the investment. A planetary-scale feasibility study is needed.
In the first phase, we need to know exactly what we are dealing with. We must know exactly what is the planet made of, what is the atmosphere made of and what is the way to terraform.
- The first step should be building an orbital research station. Scientists will stay there and guide their research.
- Much of the research can be done from outer space, including close measurements of wind and weather patterns, a global temperature map, radar mapping of the surface and measuring the interaction between the atmosphere and solar wind.
- The third step will require sending atmospheric probes, balloons that will fly at various altitudes for a long time. Their goal is to precisely measure the amount of all atmospheric compounds.
- During the fourth step, space probes will land on the surface and take samples. It is very important to know what the rocks are made of.
- Next, we have to drill and take deeper samples. Ground water will infiltrate and will interact with deeper ground layers.
- The final phase of the research would involve complex research and the use of manned missions. These missions would test how rocks react when cooled, exposed to lower pressure, to oxygen or water.
Scientists will analyze rocks on the planet surface. There is a high chance that these rocks will change structure when exposed to lower temperatures. If this is the case, then naturally occurring rocks could, when temperature drops, ameliorate the atmosphere. Only then, when we will precisely know what are we dealing with, we can move forward.
Many theoretical solutions have been proposed for cooling Venus (and similar planets). I come with one solution that is much cheaper: the use of Micro Helium Balloons. These balloons are filled with helium (or hydrogen, if the risks of an explosion are not too high). They are small (about 1 cm diameter) and fly at a specified height. They are coated with a material that reflects light, preventing both visible light and heat from reaching the planet.
Building balloons on the surface will be impossible, so we have to build them elsewhere. The best way would be to make a factory on a nearby asteroid. We can bring helium from a gas giant (if technology will make this possible) or we can extract hydrogen from water, from an outer planet. Balloons will be carried to the planet and dropped into the atmosphere.
Venus has a strong greenhouse effect. In fact, it reflects far more light then Earth does, but the light that remains is well trapped. It will also take a lot of time for all that heat to escape from the planet. During day, the layer of balloons will reflect 90% of the incoming light, while during night, vertical currents will move them at various altitudes, allowing heat to escape into cosmos.
Atmosphere cleansing Edit
Once temperatures drop below 100 C, what little water exists, together with many volatiles, will condense on the surface. For Venus, there will be more sulfuric acid then water. Rocks will interact fast and will absorb the fluids. Also, the sulfuric acid will interact with these rocks and create complex molecules that are unstable at high temperatures.
It is very important that we create an ocean, or at least a swamp. However, Venus has very low amounts of water in its atmosphere. All that water will be saturated with sulfuric acid and with salts. Only extremophiles could survive there, if at all.
Once temperatures on the surface reach an acceptable value, scientists can build a terraforming plant on the surface. However, at this point, they will focus on different problems. They will have to create genetically modified algae or bacteria, that will have to do some important tasks:
Carbon algae will use photosynthesis to transform carbon dioxide into organic matter and then into atomic carbon (a powder made of carbon atoms). This way, we will create oxygen and this oxygen will interact, will burn many of the naturally occurring toxins found in Venus's atmosphere.
Sulfur bacteria will work on the sulfuric acid. If we can bond the sulfur to existing minerals, we can get rid of it. Also, if we can break the sulfuric acid molecule, we get solid sulfur, oxygen and water.
Building the seas Edit
It is not known how much water has Venus left and how much we can produce from sulfuric acid. What is to be said is that, with the huge amounts of sulfuric acid and salts and given the fact that water will be fast absorbed in the dry rocks, it is questionable if we would be able to create at least a brine swamp.
If the planet has enough water for a sea, that sea will be populated with genetically modified algae and bacteria, to help us clean the atmosphere. However, as these microorganisms will transform the air, atomic carbon and sulfur will accumulate on the seabed as fine deposits, that also absorb water in their structure in a similar way fine granulated sand absorbs water. This means that, after some time, there will be no liquid water at all.
In order to further terraform these worlds, we need water. We can bring water by diverting comets. However, comets don't have the same composition. They also contain salt, methane, carbon dioxide and their water is not the same. It might be scarce or wit excess of Deuterium. Choosing the right comet to divert is important.
In theory, planets with huge atmospheres and massive winds, like Venus, don't have large mountains, they had been eroded by wind force. Also, they lack of craters. A plain surface can be flooded more easily.
Further temperature changes Edit
At first, ground temperature will fall down, but underground, the rocks will still be very hot and will need a lot of time to cool down. We will see a lot of geysers powered up by subsurface heat. Underground water will boil and will form many thermal springs. However, in a few decades, this process will stop. The atmosphere will receive the excess of heat. What is worse, this is moisture heat and will create a greenhouse effect. On the other hand, as the amount of carbon dioxide decreases, the greenhouse effect will also decrease. In the first step, we might need to increase the amount of micro helium balloons, but later, we will have to reduce it, to protect the planet from a global freeze. This will not be difficult, since water (liquid and ice) will condense on the balloons. At the poles, where ice caps might start forming, balloons, made heavier by water ice, will reach the surface, where they can be collected and destroyed. If the balloons use hydrogen, they can be burned when lightning occurs, producing more water.
Until the atmosphere is made breathable, we will have to keep an eye on the amount of balloons floating.
Chemical adjustments Edit
As on any terraformed planet, there will be many naturally occurring toxins in the ground, in the water and in the air. The terraforming plant will have to counter them through chemical reactions and sequestration.
Of great interest is the risk involved from atomic carbon powder, excess salts and sulfur. It is good if both carbon and sulfur are trapped beneath the oceans, where they cannot ignite. Excess salts will have to be covered with impermeable ground.
Adding life Edit
The final step in terraforming is the addition of life. Plants can be inserted in certain areas, then left alone, to multiply. Plants will conquer the new land and oceans. Then, animals can also be inserted. We have to bring anything: bacteria, algae, fungi, insects, worms, protozoa, vertebrates, inferior and superior plants.
After terraforming Edit
Finally, after terraforming, humans will settle too. Colonies will appear all over the planet.
However, a terraformed Venus will not be like a new Earth, it will be a new Venus. There will be a few differences:
- Oceans might cover a significant surface of the planet, but they will be shallow. If we suppose Venus has the same amount of salts as Earth does, then these oceans, having less volume to dissolve, will be more salty then the ones on Earth. Also, for a long time, they will be heated by heat radiated from underground.
- Underground will be hotter. Building a tunnel or a mine will be more difficult. In addition, water from a well will be hot. Springs will be hot, too. Hotter water dissolves more salts and therefore might not be good for health.
- These planets are usually closer to their sun then Earth is. With stronger gravitational forces, they will be tidal locked or low - spinning. This will result in very long (or eternal) days, with extremely high temperature variations.
- Settlers will have to always keep an eye on deposits of atomic carbon. If they are exposed and ignite, all carbon will be sent back into the atmosphere, into another runaway greenhouse effect. Also, the amount of micro helium balloons must be kept under control.
Terraforming a Venus - class planet would be difficult, but creating a new place for settlers to live could be a reward enough.