A Colony on Venus

It’s not as far-fetched as you might think.

A lovely picture of Venus from the Japanese Akatsuki spacecraft.

Why Venus?

Every space colonization enthusiast is quick to bring up the possibilities of settling on Mars. It has an Earth-like rotational period, somewhat Earth-like temperatures, and possibly even a very Earth-like history. Mars is also appealing due to its large abundance of subsurface water-ice, both for human consumption as well as the potential of splitting it into oxygen and hydrogen to use as a fuel source. Mars also provides plenty of CO2 for plant life, as well as surface craters for elemental protection for Martian bases.

When we cast our gaze to Earth’s evil twin, Venus appears to be the last place that humanity should consider for a permanent outpost. It’s atmosphere is toxic and dense, it’s surface is molten and arid, and it’s lack of magnetosphere does no help against the deadly shower of charged particles and UV light careening from the sun. Temperatures on Venus claim the blue ribbon for highest in the Solar System due to the planet’s rampant runaway greenhouse effect, and the atmospheric pressure on the surface is equivalent to being a kilometer underwater on Earth.

An actual image of Venus’ surface taken by the Russian Venera 13 lander, its broken lens cap in the foreground. Fun fact: the Venusian atmosphere is so dense that it actually bends incoming light akin to looking through a tank of water, which is why all of the images of Venus’ surface look “curved”.

But Venus receives a vital resource that Mars is short of: sunlight. Powering an interplanetary colony requires enormous amounts of power. Fission RTGs are bulky and dangerous for manned space applications, and fusion power may turn out to be impractical or impossible to maintain on an interplanetary scale, but solar power has proven to be cheap and reliable for a vast array of space applications. What’s more is that solar power increases with proximity to the sun, making Venusian colonization even more practical.

Venus also boasts other colonization benefits which Mars cannot claim. Venus’ gravity is 90% that of Earth’s, which is strong enough to combat the effects of bone and muscle degeneration which would be faced by Martian colonists. Furthermore the transit time to get to Venus is nearly two times shorter than the transit time to Mars, and Venus has two times as many launch windows to get there. Finally, Venus’ highly CO2 saturated atmosphere and high levels of solar intensity are ideal for setting up plant-filled bio-domes for the production of food and oxygen for colonists.

The Concept

Venus’ surface may be impossible to settle with near-future technology, but there may be another way to erect a permanent settlement on Venus without setting foot on the molten hell below. In the same way that a dirigible stays aloft in the atmosphere of Earth, a Venusian colony may be able to operate on similar principles, drifting along atmospheric currents high above the surface where the conditions are more Earth-like. Such a colony would have access to the power-providing solar flux from above while avoiding the immense temperatures and pressures far below.

Artist’s conception of a floating, solar powered Venusian settlement.

A floating interplanetary colony offers some intriguing benefits that a fixed base may not offer. While a fixed settlement is tied to a specific set of coordinates, a floating settlement’s movement would be governed by the motion of the atmosphere. This means that even with no thrust input, a hovering colony would cover more land area for research than a fixed settlement given a certain time frame. A hovering settlement would also have the ability to maneuver readily to various locations, both for scientific research purposes as well as hazard avoidance. Finally, a hovering settlement would not only have the ability to explore the ‘X’ and ‘Y’ axes of its surroundings, but would also maintain the option to change its altitude in the ‘Z’ direction. A colony on Mars would have no such luxuries.

The Design

The first step in designing a floating colony on Venus is deciding where in the atmosphere to put it. We want to be high enough to receive proper sunlight through the atmosphere, but still low enough that the external pressures and temperatures are manageable for our craft’s hull and subsystems to withstand. At 50 kilometers, the Venusian atmosphere has strikingly Earth-like conditions, with pressures and temperatures around 1 atmosphere and 70⁰ C (158⁰ F) respectively. Though still shrouded in atmospheric haze, a floating colony at this altitude would receive about 500 Watts/m², comparable to the solar intensity imparted on Earth on a mostly sunny day.

Temperatures and pressures in Venus’ atmosphere. The black line denotes the temperature and pressure at a given altitude.

For an object to remain aloft in a fluid without changing altitude, its average density must be the same as the fluid which it is submerged in. For example, a submarine which wishes to dive underwater on Earth must achieve an average density of 1 g/cm³; the density of ocean water. Submarines are designed with average densities lower than that of ocean water when surfaced and full of air. However, using chambers designed to take in water, these vessels have the ability to gain mass without changing their volumes effectively raising their densities enough to dive below the surface.

Though fairly dense, the Venusian atmosphere is far more tenuous than ocean water. It would take a very large structure full of Earth air to remain aloft in the clouds of Venus, which would be difficult to transport there and construct. Instead, we can design our colony ship more like a dirigible, with a separate inflatable component filled with hydrogen. Unlike on Earth, Venus’ atmosphere contains no oxygen, so a hydrogen-filled structure poses little threat for fires or explosions. Furthermore, hydrogen is readily available in Venus’ atmosphere. This hydrogen filled structure would add a huge volume to the craft with very little mass, lowering the overall density to match that of Venus’ atmosphere at 50 km.

A hypothetical Venusian colony held aloft by a hydrogen-filled torus.

A Venusian settlement of 100 people will require a slew of resources to keep its inhabitants alive. Such a colony must be self-sufficient, having the ability to provide its inhabitants with water, oxygen, food, power, and living space without relying on Earth for support. Venus’ clouds are composed of sulfuric acid, comprised of hydrogen, oxygen, and sulfur. By performing electrolysis on this toxic molecule, we can split it into these less harmful components. The oxygen and hydrogen atoms could be recombined to form water, while the waste sulfur would be returned to the atmosphere.

Oxygen and food can both be provided by plants, which could survive off of sunlight, human waste products, and our manufactured water. In one of my previous articles, “Our First Martian Plants”, I discussed what it would take to support a colony of 100 people on Mars with plants. By modifying these equations to account for Venus’ sunlight intensity, I arrived at the conclusion that it would take a transparent dome 50 meters in diameter to supply 100 Venusian colonists with enough plants to meet all of their oxygen and food needs.

Now the colonists require power. The average person in the US today siphons 897 kilowatt-hours per month to meet their power needs. For a base dependent on solar power, our panels will need to be collecting a minimum average of 307 Watts per colonist, or about 31 kilowatts, to meet this need. The base will actually require more power than this for both regular vessel operations as well as scientific research, but as long as the craft reaches this power requirement the base can sustain itself. For solar panels which are 40% efficient receiving sunlight through Venus’ atmosphere, our base will require at least 241 m² of solar panels; slightly larger than the dimensions of a tennis court.

A Fraunhofer ISE solar cell; the first of its kind to break 40% efficiency. Though still expensive, these solar cells show great potential for the near future.

For living quarters, each colonist could reside in small rooms with about 25 m² (270 ft²) of floor area; the size of a modest studio apartment. These rooms would exist in a separate crew module, designed as a cylinder and installed below the plant bio-dome to keep the vessel bottom heavy to ensure it doesn’t flip over in the turbulent Venusian atmosphere.

My (very preliminary) designs. The habitation module is shown from the ‘front’ and ‘top’ views respectively.

Above is my design for a 100 person, solar powered, floating Venusian colony. The hydrogen torus, if composed of carbon fiber, has the structural integrity to travel between the altitudes of 46 km and 54 km before imploding or exploding due to pressure differences. The two gimballing propellers offer the dexterity to maneuver the craft in any direction along the ‘X-Y’ plane, traveling into the ‘Z’ direction by inhaling or exhaling the dense Venusian atmosphere into specialized chambers. The vessel pulls in a maximum of 160 kilowatts, exceeding our minimum power requirement by nearly 6 times. This may be necessary, however, considering that the planet’s atmosphere rotates around the surface once every 8 days, causing 4-day periods of night for a floating colony. Proper battery storage would need to be outfitted into the colony to maintain power through these periods.

Potential Issues

Strong winds plague the upper Venusian atmosphere. These winds could be minimized by flying strategically along the equatorial region where the planet’s two Hadley cells meet. However, other phenomena such as gusts and storms aren’t as predictable. Weather predictive technology such as radar will be necessary to warn the colony of encroaching weather events so that it can maneuver itself accordingly.

Cutaway of Venus’ atmosphere, highlighting the planet’s atmospheric circulation. The equator has substantially less atmospheric activity than the rest of the planet, akin to the atmospheric “doldroms” on Earth.

Another potential issue is Venus’ toxic sulfuric acid clouds. Though useful for extracting water from, sulfuric acid is highly corrosive and would pose a stark threat to external components of a Venusian colony. Special acid-resistant coatings, such as polytetrafluoroethylene (PTFE), could be used to protect these components from corrosion.

Raw materials like metals would be extremely difficult to come by in Venus’ atmosphere. Though the surface is known to contain certain useful raw minerals, the extraction and refining of these materials would be difficult to undertake in Venus’ environment. The colony may be self-sustaining when in working operation, but it may require shipments from Earth for spare parts when large subsystems are damaged.

Finally, Venus’ lack of magnetosphere poses the small issue of increased solar wind, which could be overcome by strategic shielding of the living quarters and computer components. If this proves to be ineffective, an artificial magnetosphere could be constructed in high-Venus orbit.

Conclusion

A hundred million kilometers away, a planet not so different from Earth orbits the same star that we open the blinds to each morning. Though Venus’ surface is scalding and hellish, its atmosphere provides a suitable location to establish a permanent human presence, independent of the resources of Earth. Such a settlement could offer a limitless access to the scientific study of our nearest planetary neighbor, a body we currently know so little about. These floating colonies have the potential to be expanded into enormous cities to aid in spreading our population about the solar system to avoid our species’ annihilation. In many respects, Venus’ atmosphere may be even more suitable for colonization than the cold deserts of Mars.

Only time will tell where our species will propagate to in the ensuing decades. We may end up in the clouds of Venus, the canyons of Mars, the ice plains of Europa, or the geysers of Enceladus. But one thing is certain; we are upward bound, and Venus’ atmosphere is about as high up as we could get!