The colonization of Venus has been a subject of many works of science fiction since before the dawn of spaceflight, and is still discussed from both a fictional and a scientific standpoint. However, with the discovery of Venus's extremely hostile surface environment, attention has largely shifted towards the colonization of the Moon and Mars instead, with proposals for Venus focused on habitats floating in the upper-middle atmosphere [1] and on terraforming.
Space colonization is a step beyond space exploration, and implies the permanent or long-term presence of humans in an environment outside Earth. Colonization of space was claimed by Stephen Hawking to be the best way to ensure the survival of humans as a species. [2] Other reasons for colonizing space include economic interests, long-term scientific research best carried out by humans as opposed to robotic probes, and sheer curiosity. Venus is the second largest terrestrial planet and Earth's closest neighbor, which makes it a potential target.
Venus has certain similarities to Earth which, if not for the hostile conditions, might make colonization easier in many respects in comparison with other possible destinations. These similarities, and its proximity, have led Venus to be called Earth's "sister planet".
At present it has not been established whether the gravity of Mars, 0.38 times that of the Earth, would be sufficient to avoid bone decalcification and loss of muscle tone experienced by astronauts living in a micro-g environment. In contrast, Venus is close in size and mass to the Earth, resulting in a similar surface gravity (0.904 g) that would likely be sufficient to prevent the health problems associated with weightlessness. Most other space exploration and colonization plans face concerns about the damaging effect of long-term exposure to fractional g or zero gravity on the human musculoskeletal system.
Venus's relative proximity makes transportation and communications easier than for most other locations in the Solar System. With current propulsion systems, launch windows to Venus occur every 584 days, [3] compared to the 780 days for Mars. [4] Flight time is also somewhat shorter; the Venus Express probe that arrived at Venus in April 2006 spent slightly over five months en route, compared to nearly six months for Mars Express. This is because at closest approach, Venus is 40 million km (25 million mi) from Earth (approximated by perihelion of Earth minus aphelion of Venus) compared to 55 million km (34 million mi) for Mars (approximated by perihelion of Mars minus aphelion of Earth) making Venus the closest planet to Earth.
Venus's atmosphere consists mostly of carbon dioxide. Because nitrogen and oxygen are lighter than carbon-dioxide, breathable-air-filled balloons will float at a height of about 50 km (31 mi). At this height, the temperature is a manageable 75 °C (348 K; 167 °F). At 5 km (3.1 mi) higher, it is a temperate 27 °C (300 K; 81 °F) (see Atmosphere of Venus § Troposphere).
The atmosphere also provides the various elements required for human life and agriculture: carbon, hydrogen, oxygen, nitrogen, and sulfur. [5]
Additionally, the upper atmosphere could provide protection from harmful solar radiation comparable to the protection provided by Earth's atmosphere. The atmosphere of Mars, as well as the Moon provide little such protection. [6] [7] [8]
Venus also presents several significant challenges to human colonization. Surface conditions on Venus are difficult to deal with: the temperature averages around 464 °C (737 K; 867 °F), [9] higher than the melting point of lead, which is 327 °C. The atmospheric pressure on the surface is also at least ninety times greater than on Earth, which is equivalent to the pressure experienced under a kilometer of water. These conditions have caused missions to the surface to be extremely brief: the Soviet Venera 5 and Venera 6 probes were crushed by high pressure while still 18 km above the surface. Following landers such as Venera 7 and Venera 8 succeeded in transmitting data after reaching the surface, but these missions were brief as well, surviving no more than a single hour on the surface.
Furthermore, water, in any form, is almost entirely absent from Venus. The atmosphere is devoid of molecular oxygen and is primarily carbon dioxide. In addition, the visible clouds are composed of corrosive sulfuric acid and sulfur dioxide vapor.
Over 20 successful space missions have visited Venus since 1962. The last European probe was ESA's Venus Express, which was in polar orbit around the planet from 2006 to 2014. A Japanese probe, Akatsuki, failed in its first attempt to orbit Venus, but successfully reinserted itself into orbit on 7 December 2015. Other low-cost missions have been proposed to further explore the planet's atmosphere, as the area 50 km (31 mi) above the surface where gas pressure is at the same level as Earth has not yet been thoroughly explored.
At least as early as 1971 [10] Soviet scientists had suggested that rather than attempting to settle Venus' hostile surface, humans might attempt to settle the Venusian atmosphere. Geoffrey A. Landis of NASA's Glenn Research Center has summarized the perceived difficulties in colonizing Venus as being merely from the assumption that a colony would need to be based on the surface of a 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.
Landis has proposed aerostat habitats followed by floating cities, based on the concept that breathable air (21:79 oxygen/nitrogen mixture) is a lifting gas in the dense carbon dioxide atmosphere, with over 60% of the lifting power that helium has on Earth. [11] In effect, a balloon full of human-breathable air would sustain itself and extra weight (such as a colony) in midair. At an altitude of 50 kilometres (31 mi) above the Venusian surface, the environment is the most Earth-like in the Solar System beyond Earth itself – a pressure of approximately 1 atm or 1000 hPa and temperatures in the 0 to 50 °C (273 to 323 K; 32 to 122 °F) range. Protection against cosmic radiation would be provided by the atmosphere above, with shielding mass equivalent to Earth's. [12]
At the top of the clouds, the wind speed on Venus reaches up to 95 m/s (340 km/h; 210 mph), circling the planet approximately every four Earth days in a phenomenon known as "super-rotation". [13] Compared to the Venusian solar day of 118 Earth days, colonies freely floating in this region could therefore have a much shorter day-night cycle. Allowing a colony to move freely would also reduce structural stress from the wind that they would experience if tethered to the ground.
At its most extreme, the entirety of Venus could be covered in aerostats, forming an artificial planetary surface. This would be supported by the atmosphere compressed beneath it. [14]
Because there is not a significant pressure difference between the inside and the outside of the breathable-air balloon, any rips or tears would cause gases to diffuse at normal atmospheric mixing rates rather than an explosive decompression, giving time to repair any such damages. [11] In addition, humans would not require pressurized suits when outside, merely air to breathe, protection from the acidic rain and on some occasions low level protection against heat. Alternatively, two-part domes could contain a lifting gas like hydrogen or helium (extractable from the atmosphere) to allow a higher mass density. [15] Therefore, putting on or taking off suits for working outside would be easier. Working outside the vehicle in non-pressurized suits would also be easier. [16]
Structural and industrial materials would be hard to retrieve from the surface and expensive to bring from Earth/asteroids. The sulfuric acid itself poses a further challenge in that the colony would need to be constructed of or coated in materials resistant to corrosion by the acid, such as PTFE (a compound consisting wholly of carbon and fluorine).
In 2015, NASA developed the High Altitude Venus Operational Concept (HAVOC) for exploring the possibility of setting up an atmospheric crewed mission. [17] Also planning a hypothetical float sky station with key supplies and communication. [18]
Venus has been the subject of a number of terraforming proposals. [19] [5] The proposals seek to remove or convert the dense carbon dioxide atmosphere, reduce Venus's 450 °C (723 K; 842 °F) surface temperature, and establish a day/night light cycle closer to that of Earth.
Many proposals involve deployment of a solar shade 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 of hydrogen or water. Proposals also involve either freezing most of Venus's atmospheric CO2, or converting it to carbonates, [20] urea [ citation needed ] or other forms.[ citation needed ]
Terraforming or terraformation ("Earth-shaping") is the hypothetical process of deliberately modifying the atmosphere, temperature, surface topography or ecology of a planet, moon, or other body to be similar to the environment of Earth to make it habitable for humans to live on.
Venus is the second planet from the Sun. It is a terrestrial planet and is the closest in mass and size to its orbital neighbour Earth. Venus is notable for having the densest atmosphere of the terrestrial planets, composed mostly of carbon dioxide with a thick, global sulfuric acid cloud cover. At the surface it has a mean temperature of 737 K and a pressure of 92 times that of Earth's at sea level. These conditions are extreme enough to compress carbon dioxide into a supercritical state close to Venus's surface.
An aerobot is an aerial robot, usually used in the context of an unmanned space probe or unmanned aerial vehicle.
The Venera program was the name given to a series of space probes developed by the Soviet Union between 1961 and 1984 to gather information about the planet Venus.
Planetary engineering is the development and application of technology for the purpose of influencing the environment of a planet. Planetary engineering encompasses a variety of methods such as terraforming, seeding, and geoengineering.
Venera 7 was a Soviet spacecraft, part of the Venera series of probes to Venus. When it landed on the Venusian surface on 15 December 1970, it became the first spacecraft to soft land on another planet and the first to transmit data from there back to Earth.
Venera 4, also designated 4V-1 No.310, was a probe in the Soviet Venera program for the exploration of Venus. The probe comprised a lander, designed to enter the Venusian atmosphere and parachute to the surface, and a carrier/flyby spacecraft, which carried the lander to Venus and served as a communications relay for it.
The planet Venus has been used as a setting in fiction since before the 19th century. Its opaque cloud cover gave science fiction writers free rein to speculate on conditions at its surface—a "cosmic Rorschach test", in the words of science fiction author Stephen L. Gillett. The planet was often depicted as warmer than Earth but still habitable by humans. Depictions of Venus as a lush, verdant paradise, an oceanic planet, or fetid swampland, often inhabited by dinosaur-like beasts or other monsters, became common in early pulp science fiction, particularly between the 1930s and 1950s. Some other stories portrayed it as a desert, or invented more exotic settings. The absence of a common vision resulted in Venus not developing a coherent fictional mythology, in contrast to the image of Mars in fiction.
Observations of the planet Venus include those in antiquity, telescopic observations, and from visiting spacecraft. Spacecraft have performed various flybys, orbits, and landings on Venus, including balloon probes that floated in the atmosphere of Venus. Study of the planet is aided by its relatively close proximity to the Earth, compared to other planets, but the surface of Venus is obscured by an atmosphere opaque to visible light.
The terraforming of Mars or the terraformation of Mars is a hypothetical procedure that would consist of a planetary engineering project or concurrent projects aspiring to transform Mars from a planet hostile to terrestrial life to one that could sustainably host humans and other lifeforms free of protection or mediation. The process would involve the modification of the planet's extant climate, atmosphere, and surface through a variety of resource-intensive initiatives, as well as the installation of a novel ecological system or systems.
The terraforming of Venus or the terraformation of Venus is the hypothetical process of engineering the global environment of the planet Venus in order to make it suitable for human habitation. Adjustments to the existing environment of Venus to support human life would require at least three major changes to the planet's atmosphere:
The atmosphere of Venus is the very dense layer of gasses surrounding the planet Venus. Venus's atmosphere is composed of 96.5% carbon dioxide and 3.5% nitrogen, with other chemical compounds present only in trace amounts. It is much denser and hotter than that of Earth; the temperature at the surface is 740 K, and the pressure is 93 bar (1,350 psi), roughly the pressure found 900 m (3,000 ft) under water on Earth. The atmosphere of Venus supports decks of opaque clouds of sulfuric acid that cover the entire planet, making optical Earth-based and orbital observation of the surface impossible. Information about surface topography has been obtained exclusively by radar imaging.
Venera-D is a proposed Russian space mission to Venus that would include an orbiter and a lander to be launched in 2029. The orbiter's prime objective is to perform observations with the use of a radar. The lander, based on the Venera design, would be capable of operating for a long duration on the planet's surface. The "D" in Venera-D stands for "dolgozhivuschaya," which means "long lasting" in Russian.
The possibility of life on Venus is a subject of interest in astrobiology due to Venus' proximity and similarities to Earth. To date, no definitive evidence has been found of past or present life there. In the early 1960s, studies conducted via spacecraft demonstrated that the current Venusian environment is extreme compared to Earth's. Studies continue to question whether life could have existed on the planet's surface before a runaway greenhouse effect took hold, and whether a relict biosphere could persist high in the modern Venusian atmosphere.
A planetary surface is where the solid or liquid material of certain types of astronomical objects contacts the atmosphere or outer space. Planetary surfaces are found on solid objects of planetary mass, including terrestrial planets, dwarf planets, natural satellites, planetesimals and many other small Solar System bodies (SSSBs). The study of planetary surfaces is a field of planetary geology known as surface geology, but also a focus on a number of fields including planetary cartography, topography, geomorphology, atmospheric sciences, and astronomy. Land is the term given to non-liquid planetary surfaces. The term landing is used to describe the collision of an object with a planetary surface and is usually at a velocity in which the object can remain intact and remain attached.
High Altitude Venus Operational Concept (HAVOC) is a set of crewed NASA mission concepts to the planet Venus. All human portions of the missions would be conducted from lighter-than-air craft or from orbit. A similar concept, the "Floating Islands of Venus", was proposed by Soviet engineer and sci-fi writer Sergei Zhitomirsky in 1971.
DAVINCI is a planned mission for an orbiter and atmospheric probe to the planet Venus. Together with the separate VERITAS mission, which will also study Venus, it was selected by NASA on 2 June 2021 to be part of their Discovery Program. Its acronym is inspired by Leonardo da Vinci in honor of his scientific innovations, aerial sketches and constructions.
The following outline is provided as an overview of and topical guide to Venus:
Venus Atmospheric Maneuverable Platform (VAMP) is a mission concept by the aerospace companies Northrop Grumman and LGarde for a powered, long endurance, semi-buoyant inflatable aircraft that would explore the upper atmosphere of planet Venus for biosignatures as well as perform atmospheric measurements. The inflatable aircraft has a trapezoidal shape that is sometimes called delta wing or flying wing, and would have dual electric-driven propellers that would be stowed during atmospheric entry.
Zephyr is a concept of a robotic Venus rover for a mission called Venus Landsailing Rover. This mission concept would place a rover on the surface of Venus that would be propelled by the force of the wind. The rover would be launched together with a Venus orbiter that would perform both communications relay and remote atmospheric studies.
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