(2019 Archived) - ARGUMENT - II: The Low Martian Atmospheric Pressure vs. the Earth-Like Venusian Atmospheric Pressure.
Having written this in 2019, and originally published in 2021.. when I was 15 and 17, there would be inaccuracies that I would correct here. Having removed it, I'm publishing again, for sake of completion so that the efforts wouldn't have gone to vain: Most of this still stands true
Gravity isn’t the only gift of nature which we take for granted – the same could be said for the Earth’s atmospheric pressure. Although we don’t typically notice, our atmosphere constantly exerts a pressure of 1 bar (79mmHg) onto our heads. Having evolved to live by the circumstances of our blue home-world, we naturally tent to function most effectively at 1 bar. Still, that 1 bar is usually taken at sea-level and the human physiology doesn’t mind mild deviations from it – especially when it comes to living at higher or lower altitudes. But, how does the atmospheric pressures of Venus and Mars compare? Are they manageable or not?
As we’ve seen previously, the atmospheric pressure at the Venusian surface amounts to 92 bars, owing to the thickness of the large Venusian atmosphere. However, the Venusians wouldn’t have their habitats crushed like tin-cans or even have to deal with it at all; they’d be living above the Venusian cloud-tops. Nonetheless, how much does the atmospheric pressure amount to above the cloud-tops? How do I even know that the cloud-cities would float above the cloud-tops? Well, the cloud-cities would naturally be pressurized at 1 bar, so that the Venusians would be physiologically comfortable. Knowing the dynamics of a cloud-city, we know that it would float at an altitude where the pressure inside the city would be equivalent to the pressure outside; an altitude where the cloud-city would be at equilibrium.
The thin Martian atmosphere is disappointingly a near-vacuum, and only bears a meagre pressure of 0.0168 bars. To put this situation to a better perspective, the Martian atmospheric pressure is equivalent to merely 1.68% of that of the Earth. It is equivalent to the pressure 35km above the Earth’s surface [15]. That is quite dangerously low; no human – strong or weak – would be able to survive under the influence of such a low pressure. To put into a realistically deeper-but-hard perspective – The Martian atmosphere is merely a vacuum to the first decimal place – Mars is literally naked and thus vulnerable to the cosmic processes.
This would require the Martians to conduct all outdoor activities and EVA, inside the stereotypical pressurized spacesuits which we associate with space-travel. Is it bad? Well, no – it isn’t bad – Instead, it is quite very annoying: “spacesuits are amazingly clumsy... because of internal pressure. It’s been described as working with your fingers in a pressurized hose”[8].
Still, it isn’t only the internal pressure or clumsiness of a pressurized space-suitthat makes it quite annoying; It is also the sheer amount of time needed to put them on – Spacesuits take ages to put-on and take-off, and it’s often a long process; In the ISS (International Space Station), the process begins the previous day by decreasing the pressure of the entire space-station [8]! The Martians would have to deal with a similar procedure while putting-on their suits; most often with the same level of annoyance.
Then, if the Venusians don’t wear pressurized suits for outdoor activities and EVA, what would they? Well, an oxygen tank and breathing apparatus would still be required owing for the different composition of the Venusian atmosphere. Similarly, the suit would have to be acid resistant and potentially equipped with mild thermal protection. However, the most lucid fact regarding the suit is that it has no build-up of internal pressure. That is, it is quite convenient to use. It would have the comfort and convenience never-before associated with a space-suit, with its minimal resistance to its wearer’s free movement. It is unlike the Martians who still have to work as if their fingers were in a pressurized hose.
But, there is an argument that the atmospheric pressures are higher at the deeper places of Mars – there are the valleys and gorges, deep craters and Impact basins. It is true that the atmospheric pressures of those regions are higher, but they can never get to be satisfactorily high enough. To prove this point, there is this impact basin on Mars known as the Hellas; the 3rd-4th largest crater on Mars and one of the largest visible craters in the solar system [15]. At the Hellas are the lowest known altitudes on Mars, specifically at the Hellas Planitia which lies at an average of ~7,000 – 7,152m below the Martian sea-level. Yet, besides being so deep; the Hellas Planitia only receives an atmospheric pressure of 0.12 bars during the northern summer [18] – still a vacuum to the first integer. Also, such deep places for Martian civilization aren’t common too!
Another issue with regard to atmospheric pressure is the effects to habitat once serious compromised: Let’s take Mars as our first example – Due to the Martian atmospheric pressure being freakishly lower than the pressure inside Martian habitats, which again is 1 bar; the higher pressure inside the habitat, would always try to find a way outside, as a means of attaining an equilibrium of internal and external pressure. Once a Martian habitat is seriously compromised, with exposure to the external environment, the habitat could decompress as a means of attaining that equilibrium. Decompression of a habitat might turn out to be a violent process, which could take lives. And even if it were not much of a violent process, there won’t be much time to repair, which could mean certain doom to its residents, unless they find another habitat [1, 8].
On the other hand, since the pressure inside and outside the cloud-cities are equal; simply, “all that would happen after a large hole is that the outside atmosphere would slowly diffuse into the habitat. This would give plenty of time to repair any damage” [8].
I would like to put-forward a compilation of 12 favourable points which allude to the conclution that Venus is pressure-wise the winner, and more ideal for more ideal for colonization with floating cloud-cities: - (1) The cloud-city exterior has the ideal Earth-like pressure of 1 bar. (2) The exterior of the Martian bases have a freakishly low pressure of 0.0168 bars. (3) Pressurized suits are unnecessary for outdoor activities and EVA of the cloud-cities. (4) Pressurized suits are mandatory for outdoor activities and EVA of the Martian bases. (5) The EVA suits of the Venusians would be quite flexible, comfortable and convenient to use.
(6) The EVA suits of the Martians would be quite rigid, uncomfortable, clumsy and inconvenient to use. (7) The Venusian cloud-cities and habitats won’t explosively decompress when seriously compromised. (8) The Martian bases and habitats might violently decompress when seriously compromised. (9) There is ample time to repair a seriously compromised cloud-cities or Venusian habitats. (10) There is little-to-no time to repair a seriously compromised Martian base or habitat. (11) Dealing with the Earth-like cloud-top pressures is less expensive. (12) Dealing with the low Martian pressures bear a high price-tag.
Using the aforementioned twelve points, I would like to conclude this argument with the new-fangled understanding that Venus is pressure-wise more suitable for colonization with the assistance of floating cloud-cities.
[8] Walker, R. (2014, January 12). Will we build colonies that float over Venus like Buckminster Fuller’s “Cloud Nine?” Retrieved from (https://www.science20.com/robert_inventor/will_we_build_colonies_that_float_over_venus_like_ buckminster_fullers_cloud_nine-127573).
[15] Wikipedia (at 2019, February). Retrieved from (https://en.m.wikipedia.org/wiki/Mars).
[18] Wikipedia (at 2019, February). Retrieved from (https://en.m.wikipedia.org/wiki/Hellas_Planitia).
Achinthya Nanayakkara (30.03.2025)
Originally published - 2021 (now removed)
Originally written - 2019
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