By Matt Williams | 11 October 2020
Welcome back to our series on “Going Interplanetary!” Today, we take a look at “Earth’s Sister Planet,” the “Morning Star,” the “Evening Star,” and the Goddes of Love and Fertility – Venus! Much like Mars, this planet is our next-door neighbor and even orbits closer to Earth than Mars does. It’s also more Earth-like in terms of its basic physical characteristics.
But due to the hellish nature of the planet’s atmosphere and surface, it tends to get second-billing as far as exploration or colonization is concerned. Still, with the right know-how and a little elbow-grease, Venus could become another “second home” for humanity. With some long-term investment, it could be made into a planet that’s even more habitable than Mars.
“Earth’s Sister Planet”
Due to its association with the Greco-Roman goddess of fertility and its similarities to Earth, Venus is often referred to as “Earth’s Sister Planet.” Like Earth, it is terrestrial (rocky) in nature, composed of silicate minerals and metals that are differentiated between a silicate mantle and crust and a metallic core.
Venus also has similar dimensions and about as much surface area as Earth. Its mean radius is roughly 6,052 km compared to Earth’s 6,371 km (or 0.9 Earth radii), and its surface area is about 4.6 x 108 km (again, 0.9 that of Earth). In terms of mass, Venus weighs in at 4.8675 x 1024 kg (0.815 Earths) and has a density of 5.243 g/cm³, or 95% that of Earth’s.
Because of all this, the gravity on Venus is also pretty close to what it is on Earth. On Venus, objects fall towards the surface at a velocity of 8.87 m/s² compared to 9.8 m/s² on Earth – which works out to about 90% of Earth’s gravity (0.9 g). Beyond that, Earth and Venus could not be more different!
“Abandon All Hope, Ye Who Enter Here!” According to Dante, this inscription marked the entrance to Hell. With all due respect to Dante, Hell has nothing on Venus! On this planet, the average temperature is 737 Kevlin (464 °C; 867 °F), which is hot enough to melt lead, by the way!
Venus also rotates very slowly and in the opposite direction of the other planets (retrograde rotation). All told, it takes Venus about 243 days to complete a single rotation on its axis (a sidereal day). In addition, it takes Venus 224.7 days to complete a single orbit around the Sun. Combined with its slow and retrograde rotation, this means that a single solar day on Venus lasts 116.75 Earth days!
Because of this, surface temperatures are isothermal, meaning that there is very little difference between day and night or with the seasons. The atmosphere is also poisonous to humans and other terrestrial lifeforms. Whereas Earth’s atmosphere is a lovely mix of 21% oxygen, 78% nitrogen, and trace gases, Venus’ is a toxic plume consisting of more than 96% carbon dioxide, 3.5% nitrogen, and trace gases.
Also, the atmospheric pressure is estimated at 9200 kilopascals (92 bar), which is the equivalent of about 92 Earth atmospheres. That makes Venus’ atmosphere the densest in the Solar System, and enough to crush the bones of even the most robust human being! And need we even mention that it rains sulfuric acid on Venus?
A City in the Clouds
However, Venus still presents options for the creative and adventurous. Above the dense cloud canopy, at an altitude of 50 km (31 mi) above the surface, the atmospheric pressure is approximately 100,000 Pa – which is slightly less than Earth’s at sea level (101,325 Pa) and offers protection against cosmic radiation that is equal to the shielding mass of Earth’s.
Temperatures at this altitude also range from 273 to 323 K (0 to 50 °C; 32 to 122 °F), which is actually better than the temperature regime here on Earth, which ranges from -89.2 to 56.7 °C (-128.5 to 134.0 °F). In other words, above the cloud layer on Venus is the most Earth-like environment beyond Earth in the Solar System.
For these reasons, scientists have been proposing that we could colonize Venus’ atmosphere (rather than on its surface) since the 1970s. In 2003, NASA scientist Geoffrey A. Landis wrote a paper titled “Colonization of Venus,” where he proposed that floating cities could be built above Venus’ clouds.
These habitats, according to Landis, would initially consist of lighter-than-air aircraft (aerostats) filled with a 21:79 oxygen-nitrogen mix. In Venus’ dense CO² atmosphere, this air would provide lift, possessing over 60% of the lifting power that helium has on Earth.
These would provide initial living spaces for colonists and could even be used to slowly convert Venus’ atmosphere into something livable so the colonists could migrate to the surface. This could be done by building these same aerostats out of low-albedo or reflective materials, which would prevent some of the Sun’s radiation from reaching the surface.
Locally-sourced carbon could also be used to create reflective sheets of carbon nanotubes or graphene. Once deployed, these would act as solar shades, which would gradually lower the temperature of Venus’ atmosphere. This brings us to how we could make Venus livable in the long-term.
Looking to the long-term, it might even be possible to transform Venus from the hellscape it is today to a liveable planet that is covered in oceans and endless archipelago’s. Interestingly enough, the process is the exact opposite of what would be needed to terraform Mars. In theory, the process is simple and comes down to three things:
- Cool the planet’s atmosphere down
- Reduce the atmospheric pressure
- Convert the air to something breathable
As with Mars, these three items are all complimentary and progress in one will inevitably lead to progress with the other two. Done properly, it could even create a world that is very Earth-like, has a mild climate, and large oceans intercut by vast networks of archipelagos and small continents (see the artist’s rendition below).
And there’s no shortage of possible methods. One way would be to pump hydrogen gas and iron aerosol into Venus’ atmosphere, which would convert the carbon dioxide into crystallized carbon (graphite) and water. This would trigger the “Big Rain,” a torrential downpour that would cover up to 80% of the surface in oceans.
However, the graphite would need to be sequestered to prevent it from chemically combining with water molecules to produce CO² and hydrogen gas, which would cause the planet to revert to its former state. The remaining atmosphere would be composed of nitrogen, while oxygen gas could be harvested from atmospheric CO² captured beforehand.
Another idea is to bombard Venus with refined magnesium and calcium, which would chemically interact with CO² to create calcium and magnesium carbonates. It’s been ventured that Venus’ may have sufficient deposits of calcium and magnesium oxides on its surface that could be mined and used as carbon sinks.
Solar shades, as noted, could be deployed from a series of floating aerostats, small spacecraft, or a single solar shade could be deployed at the Sun-Venus L1 Lagrange Point. This would not only cool the atmosphere but also shield Venus from incoming radiation. The resulting cooling would cause the atmospheric CO² to liquefy or freeze, which would then fall to the surface as dry ice.
It’s also been suggested that Venus’ rotational velocity could be spun-up to the point where its day-night cycle is the same as Earth’s. This could be done by hitting it with impactors (comets or asteroids), conducting close flybys with massive bodies, or using mass drivers or dynamic compression to generate rotational force.
Lastly, there’s the possibility of ejecting some of Venus’ atmosphere into space, which would reduce the air pressure and the amount of heat retained by it. Again, this could be done by hitting it with impactors or gradually scooping it up with space elevators or mass accelerators.
And there you have it! As far as colonization goes, people hoping to colonize Venus will have to be satisfied with living in cities in the clouds, at least in the short term. In the long-run, and with a massive commitment in time, energy, and resources, humans could live on the surface in conditions that are amenable and the gravity is close to what we experience here on Earth.
Such a planet could be a paradise, provided we’re patient and up to the (admittedly) herculean challenge!
Reprinted with permission from the author.
Matt Williams is a professional writer, lecturer, and science fiction author whose articles appear in Universe Today, Interesting Engineering, HeroX, Popular Mechanics, and other publications. His first collection of novels is available through Amazon, Audible, and Castrum Press. He lives in Esquimalt, BC, Canada. For more info, check out: https://storiesbywilliams.com, https://www.universetoday.com/author/mwill/ and https://interestingengineering.com/author/matthew-s-williams. Follow him at Twitter.
Finished “The Jovian Manifesto,” an absolute treasure trove of space science. https://t.co/fDYGDr89rJ It’s second in the #books series I recommended last year, so if you’re in the market for well-researched & believable-not-kitschy #SciFi #novels, check these out!
— Heather Archuletta (@Pillownaut) July 19, 2019
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