Depending on where each planet is in its orbit, Venus is often the closest planet to Earth. Transit times to Venus with current technology are around 4-5 months, with launch windows every 584 days. This would facilitate travel to and from the planet more frequently and quickly than Mars or other targets. The round trip communication delay is also shorter, although still too long for live communication, making potential colonists far less removed from Earth society than many locations.
Depending on where each planet is in its orbit, Venus is often the closest planet to Earth. Transit times to Venus with current technology are around 4-5 months, with launch windows every 584 days. This would facilitate travel to and from the planet more frequently and quickly than Mars or other targets. The round trip communication delay is also shorter, although still too long for live communication, making potential colonists far less removed from Earth society than many locations.
The surface of Venus is completely unlivable due to the heavy atmosphere of carbon dioxide. A runaway greenhouse effect has resulted in temperatures above 450 C planet-wide, hot enough to melt lead. Pressures are over 90 times that of Earth, similar to being a kilometer under water. Conditions make even robotic missions difficult, with most so far lasting only minutes on the surface. Volcanoes and pyroclastic flows also present dangers near the surface, and the clouds of sulfuric acid the cover the planet are extremely corrosive. Colonists on Venus would be restricted completely to the upper troposphere.
The surface of Venus is completely unlivable due to the heavy atmosphere of carbon dioxide. A runaway greenhouse effect has resulted in temperatures above 450 C planet-wide, hot enough to melt lead. Pressures are over 90 times that of Earth, similar to being a kilometer under water. Conditions make even robotic missions difficult, with most so far lasting only minutes on the surface. Volcanoes and pyroclastic flows also present dangers near the surface, and the clouds of sulfuric acid the cover the planet are extremely corrosive. Colonists on Venus would be restricted completely to the upper troposphere.
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[[File:Surface.jpg|left|thumb|689x689px|Surface of Venus from the Venera 13 probe.]]
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=== [[File:Surface.jpg|left|thumb|689x689px|Surface of Venus from the Venera 13 probe.]] ===
The hellish surface environment of Venus makes exploration difficult, and living directly on the surface would be impossible. However, around 50 km above the surface the atmospheric pressure is approximately 1 atm, and temperatures in this band are a very reasonable 20 C to 37 C. An aerostat habitat or 'floating city' at this altitude would find possibly the most Earth-like environment in the solar system outside of our own planet.
The hellish surface environment of Venus makes exploration difficult, and living directly on the surface would be impossible. However, around 50 km above the surface the atmospheric pressure is approximately 1 atm, and temperatures in this band are a very reasonable 20 C to 37 C. An aerostat habitat or 'floating city' at this altitude would find possibly the most Earth-like environment in the solar system outside of our own planet.
[[File:Aerostat_Habitat.jpg|thumb|left|688x688px|NASA High Altitude Venus Operational Concept]]
[[File:Aerostat_Habitat.jpg|thumb|left|688x688px|NASA High Altitude Venus Operational Concept]]
The surface of Venus is always hidden from view by thick cloud coverage. To the naked eye, it appears white and almost featureless.
"In many ways Venus is the hell planet...However, viewed in a different way, the problem with Venus is merely that the ground level is too far below the one atmosphere level. At cloud-top level, Venus is the paradise planet."
-Geoffrey A. Landis
Venus is the second planet from the Sun and the second largest terrestrial planet in the solar system. It is very similar to Earth in size and mass, but due to a number of significant differences the conditions on Venus are some of the most extreme in the solar system.
Venus has a thick atmosphere composed of mainly carbon dioxide, which has led to a runaway greenhouse effect. The result is extreme surface temperatures and atmospheric pressures ninety times that of Earth at sea level. Clouds of sulfuric acid are also present in large quantities, pushed by winds of up to 100 m/s in the higher levels of the atmosphere. In addition, Venus rotates extremely slowly and in the opposite direction of the other planets, resulting in a solar day lasting close to 117 Earth days. All of these present significant obstacles to colonization.
Proximity to Earth
Depending on where each planet is in its orbit, Venus is often the closest planet to Earth. Transit times to Venus with current technology are around 4-5 months, with launch windows every 584 days. This would facilitate travel to and from the planet more frequently and quickly than Mars or other targets. The round trip communication delay is also shorter, although still too long for live communication, making potential colonists far less removed from Earth society than many locations.
Surface Gravity
Venus is the only terrestrial body to offer gravitational conditions nearing Earth's, at 0.904 g. This is a major concern for other colonization targets, since it is unknown whether partial gravity is enough to keep humans healthy and there is currently no way to provide artificial gravity on a planets surface.
Thick Atmosphere
Although the thick carbon dioxide atmosphere makes the surface of Venus unlivable, it has benefits as well. It provides near complete protection from harmful radiation, a major concern elsewhere in the solar system. There is a band in the troposphere where the pressure and temperature are very close to Earth's, and because nitrogen and oxygen are lighter than carbon dioxide, a breathable air mix functions as a lifting gas. The carbon dioxide and in the atmosphere can be used to grow plants, and sulfuric acid could be broken down to produce water.
Conditions at Various Altitudes
Height [km]
Temperature [C]
Pressure [atm]
0
462
92
45
110
1.98
50
75
1.07
55
27
0.53
60
-10
0.24
65
-30
0.10
Difficulties
Extreme Surface Conditions
The surface of Venus is completely unlivable due to the heavy atmosphere of carbon dioxide. A runaway greenhouse effect has resulted in temperatures above 450 C planet-wide, hot enough to melt lead. Pressures are over 90 times that of Earth, similar to being a kilometer under water. Conditions make even robotic missions difficult, with most so far lasting only minutes on the surface. Volcanoes and pyroclastic flows also present dangers near the surface, and the clouds of sulfuric acid the cover the planet are extremely corrosive. Colonists on Venus would be restricted completely to the upper troposphere.
Surface of Venus from the Venera 13 probe.
Poor Resources
Water, oxygen, and hydrogen are rare on Venus, and the lack of magnetosphere means they are constantly stripped away from the atmosphere. Sulfuric acid and sulfur dioxide vapors blanket the air, corroding unprotected surfaces. Any mineral resources on the surface are nearly inaccessible except by hardened robotic excursions.
Deep Gravity Well
The gravity on Venus may be good for human health, but with an escape velocity only slightly lower than Earth at 10.4 km/s, leaving the planet can be difficult. This means unless fuel can be processed on Venus, spacecraft would need to carry much more propellant with lower useful payload. Airfoils could potentially be used to lessen these difficulties as the atmosphere extends much higher than Earth's, meaning aerodynamic lift can assist spacecraft up to great altitude. However, drag is also a factor even far above the surface.
Locations
Floating Habitats
The hellish surface environment of Venus makes exploration difficult, and living directly on the surface would be impossible. However, around 50 km above the surface the atmospheric pressure is approximately 1 atm, and temperatures in this band are a very reasonable 20 C to 37 C. An aerostat habitat or 'floating city' at this altitude would find possibly the most Earth-like environment in the solar system outside of our own planet.
NASA High Altitude Venus Operational Concept
Due to the density of the Venusian atmosphere, the breathable air mix in the habitat would actually provide buoyancy, perhaps supplemented by light gas balloons to increase lift. There would be no need for pressure suits or extensive heat shielding outside, and any gas leaks would cause slow diffusion rather than explosive decompression. The thick atmosphere above would provide adequate radiation protection, and surface coatings could protect against the corrosive effects of sulfuric acid.
The structure would be untethered and allowed to move with the air, riding high speed winds around the planet every four or five days, producing a day/ night cycle much closer to Earth's and removing structural requirements for resisting the powerful winds. Incoming spaceships could make use of extensive aerobraking and either launch airships or use a final powered descent to access the colony.
Solar power could be harnessed at this altitude, and the high winds would also be an excellent source of energy. Filtration of the atmosphere would provide carbon dioxide for plants, producing oxygen and food. Reactions could produce water from sulfuric acid for consumption and agriculture.
Venus has been the subject of a number of terraforming proposals. The proposals seek to remove or convert the dense carbon dioxide atmosphere, reduce Venus's 500 °C (770 K) surface temperature, and establish a day/night light cycle closer to that of Earth's.
Most proposals involve deployment of a solar shade and/or a system of orbital mirrors, for the purpose of reducing insolation and providing light to the dark side of Venus. Another common thread in most proposals involves some introduction of large quantities hydrogen or water. Proposals also involve either freezing most of Venus's atmospheric CO2, or converting it to carbonates, urea or other forms.
