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Under review

Oxygen Production Mechanism

Lillian Winter 5 months ago • updated by Mr. Fusion 5 months ago 3

    The use of chemistry in this game is one of its best aspects, but the management of the three vital elements, Carbon, Hydrogen, and Oxygen, can yet be improved.

    The current oxygenator functions by electrolizing water to produce hydrogen and oxygen. The Oxygen is saved, the Hydrogen is presumably released. This means that as Oxygen is consumed, Hydrogen is taken out of the system. This is inherently water-negative. As a result I would reccomend a different mechanism for oxygen production.

Instead of consuming our limited water supply, we should take in CO2 from the surrounding atmosphere. Put it through a co2 filter, and you get breathable oxygen. It's dependent on co2 filters, but they degrade rather slowly. 

    Instead of consuming the limited water supply, it enables a far more stable regulation of gasses.

Under review

You're not the first to point this out. I'll certainly look into it.

I gave a bit of thought to this a short while ago, and some of the alternate methods could actually work even without having to change gameplay or assets, except for the description of the systems involved, although there would be some unexplained/omitted parts of the process in this case.


It would also be possible to take this change to the next level, which would require the additon of a number of new assets and gameplay elements, however, would also extend ther range of player activities, and as a result game complexity and difficulty.


Let's consider the following factors:

  • As pointed out here and in also in a topic on the Steam Discussions for the game, CO2 is abundant in the atmosphere of Mars and thus being a potentially better candidate for harvesting O2 than finding and thawing only locally present and non-renewing water ice then splitting it into (discarded) H2 and O2.
  • In a closed system such as the habitat, only relatively low amounts of "new" consumables need to be introduced: a considerable amount of water can be recycled from the interior atmosphere (exhaled water vapor and perspiration) and by processing waste water, and Oxygen can be partially recovered by re-splitting CO2 exhaled back to the interior atmosphere (save for the amount that has been bonded into other, non-recoverable/inaccessible molecules by human metabolic processes).
  • The habitats were obviously placed on the surface by a powered landing process: they are equipped with a set of landing thrusters, and by extension, it's reasonable to assume that they have on board fuel reserves, not all of which was used up during landing (emergency margin). It is also reasonable to assume that this fuel may be hydrazine, which, by a catalytic process, can be split into N2 and H2, both of which being usable for maintaning a habitable environment in one way or another.

Using the above, life support system of the habitats could conceivably work as follows:

  1. Reoxygenator draws CO2 from external and internal atmosphere, receives N2 from Water Reclaimer (see below), recycles internal air through a process that removes physical/chemical/biological contaminants partialy by using replaceable active carbon filter cardridges and excess humidity (passed on to the Water Reclaimer for further processing). By splitting the collected and stored CO2, Reoxygenator produces O2 part of which is used locally and other part is passed on to the Water Reclaimer, and elemental Carbon in the form of activated/absorbent carbon which can be collected to be used for making carbon filter cardridges.
  2. Water Reclaimer primarily recycles waste water and the humidity excess received from the Reoxygenator, partially by way of using replaceable active carbon filter cardridges. To cover for unavoidable water losses (which should be reasonably small compared to the amount that can be recycled) due to various reasons, it is capable of producing water by drawing reserve hydrazine from the fuel tanks of the habitat's landing system, splitting it into N2 and H2, passing N2 to the Reoxygenator to be used as atmospheric filler to maintain internal pressure, and burning the H2 with the O2 received from the Reoxygenator to produce water. Recycled and produced water is then stored in tank until used.

The basic level of implementation would be just to update the description of the systems involved to roughly what's described above, without actually implementing the new elements of the process such as the hydrazine reserves and the Carbon production. The only change needed would be that instead of the current dependency (Water Reclaimer needs to be running to produce Oxygen), the systems can run independently to produce their respective resource, but only at 50% efficiency if only one is running, and 100% efficiency would only be achieved when both are online at a given time.


The complex implementation would require adding a number of new game obejcts and gameplay processes:

  • New resource types: Hydrazine, Nitrogen, Hydrogen, Absorbent Carbon
  • New crafting plans for making canisters filled with Hydrazne, Nitrogen and Hydrogen at different crafting stations.
  • Changed crafting plan: Carbon Filter now requires a certain amount of Absorbent Carbon in addition to the current materials.
  • New (one time?) crafting plan to craft "Hydrazine Splitter" tool.
  • New tool: Hydrazine Splitter, to enable crafting of Hydrazine Filled Canisters into 1x Nitrogen Filled Canister and 2x Hydrogen Filled Canister per job.
  • New storage capacity in the Reoxygenator for N2 and Absorbent Carbon, and in the Water Reclaimer for H2 (O2 is seamelssly exchanged between the two as needed, drawing from the O2 reserve tank).
  • New interaction point somewhere on the exterior of the habitats to "craft" Hydrazine Filled Canisters using empty canisters and interacting with this interaction point, from a finite amount of Hydrazine reserves in the habitat's propellant storage tanks.

Gameplay then would be as follows:

  • Reoxygenator, when powered, produces a certain amount of Oxygen and Absorbent Carbon over time, but with different efficiency levels. If the Nitrogen tank is empty, efficiency is only 50%, if it contains reserves, then efficiency is 100% until Nitrogen reserve is used up. Absorbent Carbon tank is non-blocking: excess over 100% capacity (if not emptied regularily) is simply lost.
  • Water Reclaimer, when powered, produces a certain amount of (recycled) water over time, but with different efficiency levels. If the Hydrogen tank is empty, efficiency is only 50%, if it contains reserves, then efficiency is 100% until Hydrogen reserve is used up. Compared to the simple implementation, the premise here is that the Water Reclaimer was NOT meant to be able to produce water by burning H2 and O2, this option is only present due to some addition/reconfiguration supposedly (but not being an active part of the gameplay) done by the player character at some point. (Actually, it also could be implemented by some interaction: use those large Storage Tanks and some other materials in a one time, per Reclaimer, interaction that adds the H2 storage capacity and converts it from the regular configuration to one that is capable of H2+O2 burning to produce water instead of just recycling.) (Another thing could be to somehow limit the "recycling only" water production over time: the more days have passed since the system was first brought online in any given hab, the water recycled per day would constantly diminish towards a minimal, very low value, unless upgraded to the water producing variant and supplied with H2.)
  • To improve production efficiency, the player needs to acquire a Hydrazine Splitter crafting plan by some means, and craft the tool.
  • Wth the tool available, the player will be able to "craft" Empty Canisters into Hydrazine Filled Canisters at an exterior interaction point at a 1:1 ratio per job requiring a reasonably short time.
  • With the tool available, the player can craft, at the interior crafing station, 1 Hydrazine Filled Canister and 3 Empy Canisters into 2 Hydrogen Filled Canisters, 1 Nitrogen Filled Canister and 1 Empty Canister.
  • The Hydrogen/Nitrogen Filled Canisters can be used to manually fill the respective tanks of the Water Reclaimer and Reoxygenator, potentially raising their effectiveness from halved to nominal.
  • The Absorbent Carbon collected from the Reoxygenator is needed to craft replacement Carbon Filters which are required by both the Reoxygenator and Water Reclaimer to function.

A somewhat simplified version could be not to require a Hydrazine Splitter and the processes associated with it, only a one time per unit reconfiguration of the Water Reclaimers from the regular version to the water producing version, which adds an internal Hydrazine tank, which needs to be filled manually, from time to time, with Hydrazine drawn from the habitat propellant reserves.

Having said all that, I think the current implementation is fine for serving the purpose it needs to. This was just something I had fun with to think about so I posted the result here, but I think actually implementing it would likely take more work and dev time than what it would add to the overall gameplay experience.