When you hear the word “terraforming”, the planet that most likely springs to mind is the planet Mars. In recent decades, Mars has captured the public imagination, and the red planet is considered to be the most likely target for any terraforming efforts within our Solar System. But it wasn’t so long ago that scientists and science fiction writers alike considered Venus to be the most agreeable subject for our terraforming ambitions.
Venus has long been considered to be Earth’s twin, and it is thought to have once had an atmosphere comparable to our own (before runaway global warming turned it into one of the hottest places known to man). So, instead of trying to heat Mars, should we really be trying to cool Venus?
The following information on the terraforming of Venus was provided by Dmitriy Ivashchenko and was first published on the Mars Terraforming Corporation Facebook page…
The terraforming of Venus is the hypothetical process of engineering the global environment of the planet Venus in such a way as to make it suitable for human habitation.
Why Terraform Venus?
Venus after terraforming:
Ideally, terraformed Venus could be a planet with a warm and humid climate. It’s estimated that if the Venusian atmosphere had composition identical to the atmosphere of Earth, its average temperature would be about +26 ° C (on the Earth it’s +15 ° C)
Current conditions on Venus:
The average temperature on Venus is currently + 467 ° C (Venus is the hottest planet in the solar system), the atmospheric pressure is about 93 atmospheres (bar), the composition of the atmosphere is carbon dioxide – 96 % , nitrogen – 3.5% , carbon monoxide and sulfur dioxide – 0 3%, oxygen and steam – 0.12%.
The attractiveness of colonization:
Venus is the twin sister of our planet: the diameter of Venus 12104 km (95 % of the diameter of the Earth), the mass is 4.87.1000000000000 billion tons (81.5 % of the mass of the Earth), the acceleration of gravity 8.9 m / s ² (91 % of the earth gravity).
Venus is the nearest planet to us in solar system.
Venus gets a lot of solar energy, which potentially could be used for terraforming.
Difficulties of colonization and terraforming:
- Venus is very hot; the average temperature on the surface of +467 ° C (hotter than Mercury).
- Pressure on the surface of Venus is 93 atmospheres.
- The atmosphere of Venus is 97% composed of CO2.
- Venus has virtually no water, so it must be delivered there by artificial means. For example, by means of comets or asteroids, or by synthesizing water (e.g. from atmospheric CO2 and hydrogen).
- Venus rotates in the opposite direction to the Earth and the other planets of the solar system, the axis of rotation is nearly perpendicular to the plane of the orbit (176°). Because of this unusual combination of directions and periods of rotation and revolution around the Sun, a single day – 24 hours here on our planet – lasts 117 Earth days on Venus.
- The magnetosphere of Venus is much weaker than the Earth’s. In addition, Venus is closer to the Sun than the Earth. As a result, during the terraforming (by decreasing the mass of the atmosphere), the level of radiation on the surface of the planet will likely be higher in comparison with the Earth.
How to Terraform Venus
The methods of Venus terraforming:
1. Solar screens between the Sun and Venus
Screens should be installed in the Lagrange point between Venus and the Sun. However, it should be remembered that this equilibrium is unstable, and to hold it in the Lagrange point, we will need to correct its position regularly.
It is assumed that such “umbrellas” can dramatically reduce the flow of solar energy reaching Venus and, as a result, reduce the temperature of the planet to an acceptable level. Moreover, by sufficient shielding from the sun the temperature can be decreased to such extent that the atmosphere of Venus will freeze and substantial part of it will fall on the surface in the form of dry ice (solid CO2). The result will be a significant drop in pressure and additional (by increasing of albedo) cooling of the planet.
One of the options for such project could be the installation of ultralight reflective mirrors, the light from which can be used for simultaneous heating of the colder planets (for example Mars). The screen could also be used as gigantic photo cell for mega-powerful solar power station.
2. Bombardment by comets or water-ammonia asteroids.
The amount of water that would need to be delivered to Venus is enormous. For example, to provide a suitable hydrosphere on Venus requires at least 100,000,000 billion tons of water, which is about one hundred thousand times more that the mass of Halley’s Comet. The required icy asteroid should have a diameter of 600 km (6 times smaller than the diameter of the Moon).
Aside from icy comets and asteroids, a large amount of water can be delivered from some moons of Jupiter and Saturn, as well as from Saturn’s rings.
Delivery of water to Venus by means of asteroid bombardment solves one problem but creates new ones. Here are some of the problems this could create:
- First, a large asteroid strike could lead to the destruction of the planet’s crust and create even more life-threatening conditions, so we should probably use a lot of weaker strikes.
- Second, the rocks of Venus have an enormous heat capacity and relatively low thermal conductivity, so the process of cooling in any case will last for many years.
- Third , the current temperature of the surface layers of the atmosphere is far above the boiling point of water. Consequently, without substantial cooling below +300 ° C (at 90 Earth atmospheres) free water could not exist on the surface of the planet. Water will be present in the atmosphere as water vapor, which is also a greenhouse gas. However, the clouds of dust, raised by strikes, will contribute to decreasing of the temperature, creating the effect of a “nuclear winter”.
3. Delivery of terrestrial algae or other organisms to Venus
In 1961, Carl Sagan suggested introducing chlorella to the upper atmosphere of Venus. It was assumed that with no natural enemies, the algae would start multiplying exponentially and break down a lot of carbon dioxide relatively quickly. As a result, the Venusian atmosphere would be enriched by oxygen. This in turn would reduce the greenhouse effect and decrease the surface temperature.
4. Neutralization of the acidic atmosphere
Article by Dmitriy Ivashchenko of the Mars Terraforming Corporation
Shock spraying of metal meteor in the atmosphere can bind sulfuric acid into salt with liberation of water or hydrogen (depending on the exact composition of a meteor). Asteroids like (216) Kleopatra could be used for this process. Perhaps the plutonic rocks of Venus also have suitable composition. In such a case it is sufficient to use a hydrogen bomb with sufficient power to simultaneously cause the “nuclear winter” effect and to bind acid by means of dust.
Edited by Mark Ball