Is Venus the Better Option?
January 17th, 2025
Current initiatives all point toward establishing human presence on the Moon (permanently) and Mars (for the first time) within the next 25 years. But after society has accomplished both these challenging but massive feats, where would humans go next? While a couple moons might be attractive destinations, the closest and largest astronomical home for humanity would probably be Venus.
At first, Venus isn’t the most attractive location. The planet’s atmosphere is much thicker than Earth’s atmosphere, and is incredibly dense; because of this, heat is trapped under the atmosphere and temperatures can be incredibly high near the surface–over 464 degrees Celsius according to NASA. Similarly to Mars, however, Venus has a CO2-rich atmosphere (96%). But unlike Mars and Earth, the atmosphere of Venus has an immense amount of pressure which makes human exploration at the surface an automatic death sentence (even when disregarding all other factors). Venus’s atmosphere even has clouds composed of sulfuric acid droplets that are responsible for sulfuric acid rain.
I don’t think humans would enjoy living on the surface of Venus. But in 2015, “HAVOC: High Altitude Venus Operational Concept - An Exploration Strategy for Venus” was presented at NASA. The HAVOC mission detailed multiple stages of execution that would lead to human colonization of Venus’s atmosphere.
The first few stages detail how one would go about establishing a “cloud city” on Venus. The initiative proposed sending small robotics down to the atmosphere first to both collect more information on Venus’s atmospheric conditions, as well as prove the possibility for floating objects in the atmosphere. The proposed floatation technology, known as an aeroshell, would utilize a helium-filled envelope/balloon to act as a buoyant force against gravity; concept designs of this floating spacecraft are similar to large blimps. Phase 2 would mirror the Apollo Program’s preparation by sending orbit missions–with and without humans–around Venus. The following stage of the plan would send humans down into the atmosphere in a small spacecraft equipped with the helium-filled aeroshell, which would span over 129 meters long and 34 meters deep, and hold over thousands of kilograms worth of helium tanks. However, as human habitats grow larger, these aeroshells would need to continue expanding in size, making it extremely difficult for non-astronaut, research-specific missions. One of the major flaws is transporting the astronauts back to orbit from the atmosphere, as it would require a significantly powerful rocket due to the gravitational force of Venus, which is similar to Earth. Derived from this mission proposal are several different iterations of Venus colonization designs and methods, including massive floating cities that give Star Wars vibes.
While NASA chose not to pursue this proposal for now, it is something to keep in mind for later. Once humans have established a stable colony on Mars, the needed technology (aside from an aeroshell and spacecraft) will definitely be feasible. The paper “Settling Venus: A City in the Clouds?” by Geoffrey A. Landis proposes Venus’s atmosphere to be a habitable place to live due to its relatively similar pressure and temperatures to Earth; because of this, unlike Martian bases, technology on Venus would not need to account for as dramatic changes in pressure or temperature. Additionally, Venus’s surface gravity is 8.87m/s^2 according to NASA–90% that of Earth’s 9.82 m/s^2. Mars has a much lower surface gravity, which would affect quality of life and convenience (and also anatomy, as discussed in a previous article). The potential habitat would still need to protect against radiation, yet Venus’s thick atmosphere would help deal with a majority of the radiation exposure.
On the contrary, Mars requires much more equipment: exercising machines to help with the decreased gravitational force, pressurization methods to deal with lower atmospheric pressure, astronaut suits for the cold temperatures and radiation protection, and much more. However, with a Mars mission, establishing a ground-level base would be quite familiar, as humans have done it before with the Apollo landing (and it's similar to Earth). With Venus, getting down into the correct atmospheric level and inflating an aeroshell will require testing, experimentation, and failure of new technology. Unpredictable and deadly winds in the atmosphere can also make Venus a tricky venue.
And while it might be easier to obtain surface resources on Mars, Landis’s paper, also briefly mentions a remedy to the lack of resources in Venus’s atmosphere: the human habitats can send down a heat-resistant tether to bring up surface material, which would be aided by moving the spacecraft and aeroshell with the atmospheric wind. It’s challenging to move closer to the surface due to the increase in temperature. However, the atmosphere already provided some of the fundamental resources needed, such as nitrogen, hydrogen and CO2.
But what does Venus have to offer? While Mars holds promising evidence for a potential discovery of past life, there’s been a lot of debate surrounding Venus’s past habitability.
Published in 2016, “Was Venus the first habitable world of our solar system?” by Michael Way and his colleagues, their research with 3D climate simulations of Venus billions of years ago suggested that life could’ve been given the opportunities, as well as time, to grow. While many unknowns about Venus’s early life placed limitations on the accuracy of the simulations, such as specific topography and solar luminosity, their results indicated that the surface temperatures could’ve been manageable for life to survive. When “comparing Sims A and B, where the solar flux increases from 77% to 94% of modern, one sees that the global mean surface air temperature increases only 4°C,” meaning that any large bodies of water or oceans on Venus stayed present for some time. The surface temperatures of some of their simulations weren’t that far off from current Earth temperatures, with “Sim A [giving] a global mean surface air temperature of 11°C…and a maximum of 36°C…the simulation with Earth topography (Sim C) produces habitable surface temperatures but is 12°C warmer” A couple of their simulations allowed for a few centimeters of snow to form as well, and/or surfaces to stay wet.
However, a more recent study published in 2023 by Alexandra O. Warren and Edwin S. Kite, “Narrow range of early habitable Venus scenarios permitted by modeling of oxygen loss and radiogenic argon degassing,” claims that there wasn’t a long-enough period of time during Venus having surface water and adequate temperatures for life to grow and sustain itself. Running a variety of simulations themselves, the duo believed that due to the lack of oxygen in the planet’s current atmosphere (and difficulty for a majority of the substance to be completely removed), water on Venus was never plentiful to begin with. Their simulations also faced limitations due to lack of knowledge of Venus’s early conditions, such as its volcanism history, or lack of data for the planet’s entire geological evolution. Their findings suggest that “although these results reconcile a potential early habitable era on Venus with the paucity of O2 in Venus’s modern atmosphere, only 2.6% of parameter combinations in our models lead to post-habitable era outcomes that satisfy atmospheric abundance data for modern Venusy.” When the researchers added additional criteria to their simulations so their data would more closely reflect Venus’s current atmospheric composition (which could be concluded as the most accurate match of Venus’s past and evolution), the success rate lowered to less than 1%. From this, they concluded it was improbable for Venus to have sustained habitability for long in its history.
Ultimately, it is undetermined whether Venus was able to successfully harbor life in its past. Yet, there are mysteries with every planet, and they deserve to be investigated; while discovery of life might seem more promising elsewhere, no one knows for sure where in the solar system new life could exist, if it does. After humans tackle Mars and the Moon, Venus should be next. From technological challenges, to new discoveries about its past evolution, the planet has much to offer.