I'm currently working on a science fiction comic about humans marooned on an alien world for generations.

This world is slightly larger and more metallic than earth with greater gravity a higher percentage of oxygen (I was thinking similar levels to the Carboniferous period here on earth 35-40%) and 3-4 earth atmospheres of pressure at sea level and a more comfortable level higher up where most humans live in domed habitats and can move around outside for limited periods with some protection. Though I'm really flexible on all those numbers if they don't work or aren't actually possible.

My question is related to the people moving between higher and lower levels of pressure to scavenge materials and war with the locals. How much pressure is too much? how quickly could they move between these levels? how long could they survive in the lowlands with and without equipment? and what other unforeseen issues could I have missed?

Mainly I want to know if these issues could be resolved with cybernetic modification (particularly modifications that make them repugnant to the unmodified) to allow for a lower level of protective equipment at all pressures. I remember reading peter watts Rifters trilogy in which the deep sea divers were modified to remove all their internal pockets of gas at will and store them in a canister, presumably so nothing could rupture under the pressure.

Would something that extreme be viable or necessary? and more important would switching it on while shirtless be unsettling and cool looking?

Thanks for taking the time to read this and sorry for any errors or faux pas on my part I'm not good with words.

Please be gentle, its my first time.


2 Answers 2


The bends.

Decompression sickness (DCS; also known as divers' disease, the bends...) describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurisation. DCS most commonly refers to problems arising from underwater diving decompression (i.e., during ascent), but may be experienced in other depressurisation events such as emerging from a caisson, flying in an unpressurised aircraft at altitude, and extravehicular activity from spacecraft. DCS and arterial gas embolism are collectively referred to as decompression illness. Since bubbles can form in or migrate to any part of the body, DCS can produce many symptoms, and its effects may vary from joint pain and rashes to paralysis and death.

Going into a high pressure atmosphere drives gas under pressure into solution within our blood. Then when a diver returns to normal atmospheric pressure the gas comes out of solution. Bubbles form in tissues and cause trouble where they do - stroke is the worst thing but these bubbles can cause holes in bones, tissue damage, etc. This is why divers must decompress slowly on ascent. The pressure changes your human experience on this world put them at risk for the bends.

I propose your cybernetic humans are modified such that an ascent they can outgas pressured bubbles quickly and in a controlled manner, through the lungs. This outgassing of pressurized gas is the same thing that happens if a bottle of soda is shaken and then opened. This is how it would look for a human too - gouts of pinkish foam spurting from nose and mouth.


With greater gravity and no artificial gravity available, some extra oxygen in the atmosphere will surely help since they will be living in a constant state of greater strain. This will also cause them to be less focused, sweat more -thus losing minerals and getting cramps more frequently. They will be needing mineral sources for their bodies and to increase their diet -especially in sweets and proteins- to make up for this continuous extra exertion. Very high probability of heartstrokes and ictus.

If by 'cybernetic adaption' you mean a single or two helpful body replacement, our heroes can replace their hearts with an artificial one, stronger, to keep the blood flowing to a normal rate

  • $\begingroup$ never heard of oxygen toxicity, I assume ( en.wikipedia.org/wiki/Oxygen_toxicity ). At 6-8 times the Oxygen pressure we have on Earth, the OP is right in that region. $\endgroup$
    – L.Dutch
    Jun 16, 2018 at 6:38
  • $\begingroup$ right!! OK, we can throw in that, given their tech level, they could use masks to filter the excess oxygen until they improve their pulmonary AND circolatory sistem. But in the meantime, they will also be needing a bit more oxygen for their condition $\endgroup$ Jun 16, 2018 at 6:42
  • $\begingroup$ I have taken oxygen toxicity into consideration with everyone making use of masks or helmets to ease the pressure on the sinus and brain as well as mix nitrogen, hydrogen or argon with oxygen drawn from the surrounding air. $\endgroup$ Jun 16, 2018 at 15:00
  • $\begingroup$ Note if they are living higher up above sea level the air is thinner there so there might not be as much oxygen as down by sea level it is why oxygen tanks are needed on mount Everest $\endgroup$ Jun 17, 2018 at 2:25

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