Colonization of Venus
The colonization of the planet Venus , Earth's closest planetary neighbor , has been widely discussed. After the discovery and research of the hostile surface conditions (extremely dense CO 2 atmosphere, almost 500 ° C), however, the discussion about colonies outside the earth mainly focused on the moon and Mars . There are no plans for manned Venus missions or even a settlement of humans on Venus.
Arguments for and against a Venus colonization
Advantages and reasons
Venus has many similarities with the earth that could make colonization easier when compared to other celestial bodies. Because of these similarities, it is also called the "sister planet" of the earth.
- Of all the planets in the solar system, Venus is most similar to Earth in terms of mass and size. Their surface gravity is 0.904 g and is thus comparable to the earth. In the case of a Venus colonization, the health impairments caused by weightlessness or low gravity could be avoided.
- The upper Venusian atmosphere is similar in terms of temperature and air pressure at an altitude of about 50 kilometers (1 bar, at 0–50 degrees Celsius); At this height, sufficient solar energy can also be obtained, since about 2610 watts of solar radiation fall on every square meter , 1.9 times the amount of solar radiation on earth. The clouds reflect a large part of it, so that solar panels could be pointed towards the sun as well as towards the surface of the planets to generate electricity.
- Furthermore, the upper areas of the atmosphere rotate around the planet in 100 hours or less, which would allow approximately a day-and-night rhythm (in contrast to the surface, which requires 243 earth days for one orbit)
- Apart from the moon, Venus is the closest celestial body to earth, which would make communication with the colony and transportation easier. Assuming current spacecraft propulsion, a launch window opens between Earth and Venus every 584 days , compared to 780 days for Earth-Mars. At closest approximation, Earth and Venus are 38 million kilometers apart, Earth and Mars 56 million kilometers.
Counter-argument
- The surface conditions of Venus are extremely hostile to life. Due to the greenhouse effect , temperatures are around 500 degrees Celsius near the equator, enough to melt lead . The atmospheric pressure on the ground is 90 bar , equivalent to the pressure in one kilometer of water. These conditions resulted in the Venera 5 and Venera 6 space probes being crushed 18 and 10 kilometers above the ground, respectively. Venera 7 and 8 that followed them made it to the surface but both worked for less than an hour. As a result, it would be difficult to transport materials from the surface, for example raw materials.
- There is almost no water on the planet. The atmosphere has no molecular oxygen, but consists of toxic concentrations of carbon dioxide and clouds of sulfuric acid and sulfur dioxide vapors.
- The biggest problem is likely to be the extremely slow rotation of Venus. A sunny day is 117 earthly days on Venus. If the atmosphere was thinned out after terraforming, the day side would heat up strongly and the night side would cool down considerably. Large amounts of the water would evaporate on the day side and the clouds would be driven by gigantic hurricanes to the night side and rain down there. The rotational acceleration required as a result would require enormous amounts of energy.
Methods of colonization
In view of the hostile conditions on Venus, colonization of the planet with current technological means is not possible. Therefore, it is usually suggested to make Venus habitable (more) habitable first by means of terraforming . The amounts of energy required for this are gigantic, and thousands of years can pass before results become visible. However, there are also approaches that can be implemented in the near future; two approaches are given below.
Floating cities
Geoffrey A. Landis suggested avoiding the surface difficulties by allowing the colonies to float in the atmosphere , much like hot air balloons or zeppelins . The starting point here is that the air you breathe (78% nitrogen, 21% oxygen) is lighter than the Venusian atmosphere. Breathing air would have about half the buoyancy of helium in the earth's atmosphere. Alternatively, additional balloons filled with helium or hydrogen, which could be obtained from the environment, could provide additional buoyancy.
Colonies in orbit
Another promising approach is the use of Venus to keep comets and asteroids in orbit. Although Venus does not currently have any moons, the orbits of smaller bodies can be manipulated to be captured by the planet's gravity. Venus is so well suited for this because it causes high atmospheric braking. It is better suited than the earth for such projects, since a wrong course and the impact of the body on the planet would be harmless to humans. The freely available solar energy in the vicinity of Venus could promote future industrial development.
Terraforming Venus
This section deals with the individual proposals for making Venus habitable for humans. For information on the process and requirements of terraforming in general, see Terraforming .
In 1961, Carl Sagan suggested sprinkling algae into the atmosphere in order to extract oxygen from the existing carbon dioxide. However, we now know that the abundance of water on the planet is so small that photosynthesis would only produce negligible amounts of oxygen.
Following the study by Paul Birch from 1991, Robert Zubrin proposed that a solar shield, which, simply explained, casts a shadow and thereby cools the planet, is stretched in front of Venus, initially to 304.18 Kelvin (31 , 03 ° C) and air pressure of 73.8 bar (the critical point of carbon dioxide), and then further to 216.85 Kelvin (−56.30 ° C) and 5.185 bar (the triple point of carbon dioxide). From this point resublimated the CO 2 and sets itself as dry ice on the surface down. This dry ice would either be disposed of or transported to Mars (to accelerate its terraforming there). This would solve the problems of heat, the greenhouse effect and air pressure, but Zubrin also has to admit that the lack of water is still a serious problem that even comet bombardment could not solve satisfactorily. Birch suggests throwing one of Saturn's moons out of orbit and bombarding Venus with its fragments, which would result in an amount of 100 liters of water per square meter.
Landis also suggested combining floating city colonization and building a solar shield so that direct colonization in the near future and terraforming of Venus later would go hand in hand. These solar shields could even consist of carbon nanotubes whose raw material carbon could be obtained directly from the air.
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- ↑ Geoffrey A. Landis: Colonization of Venus . In: Conference on Human Space Exploration, Space Technology & Applications International Forum, Albuquerque NM . .
- ↑ a b Paul Birch: Terraforming Venus Quickly . In: Journal of the British Interplanetary Society . 1991.
- ^ Robert Zubrin: Entering Space: Creating a Spacefaring Civilization . 1999.
