In the future, humans build massive factories on the moon Titan, components of which drill tunnels down to the water ocean beneath the ice surface. Assuming the ocean is there, and that it's similar to a cold Earth ocean, the factories use electrolysis (or some future handwave tech) to turn the water into oxygen.

There are enough of these factories throughout Titan that they are able to pump massive amounts of oxygen into Titan's skies, displacing enough of the nitrogen and methane in its atmosphere to make it breathable to humans.

Is this feasible, and if not, what am I missing?

EDIT: Could the gasses already there in abundance, nitrogen and methane, and the hydrogen produced by the factories processes be used, dissipated, burned up, sucked away, gotten rid of somehow? Maybe used as fuel in the processs?

Current composition Titan's lower atmosphere is primarily composed of nitrogen (94.2%), methane (5.65%), and hydrogen (0.099%). Pressure 1.5 bar. Temperature 93.7 K (−179.5 °C) (wiki)

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    $\begingroup$ Methan, oxygen, what am I missing - missing a disaster I guess, of epic proportions. Where hydrogen goes also a thing to be adressed, stones could be a better oxygen source by electrolysis or 2 processes combines with net result as if stones one was used directly, and hydrogen/water is recyclible catalyst $\endgroup$
    – MolbOrg
    May 27, 2021 at 19:41
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    $\begingroup$ What does the word "displacing" mean? Gases do not displace each other, they mix freely. (And methane mixing with oxygen is a great way of obtaining water and carbon dioxide plus a great deal of heat.) $\endgroup$
    – AlexP
    May 27, 2021 at 19:42
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    $\begingroup$ Titan's atmosphere is also four times denser than Earth's, so the partial pressure of oxygen might also be a problem. $\endgroup$
    – jdunlop
    May 27, 2021 at 21:26
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    $\begingroup$ Use rocks, electrolysis of magma/stones is a thing, it can be done in a direct electrolysis, or trough reduction with hydrogen and later water electrolysis. Results and energy used is about the same, but instead of fluffy hydrogen u have metals and semiconductor materials which can be used elswhere. In any way storing is easier. Use oxygen to burn any flamable components in atmosphere, in fuel rich way, to get solid carbon dust and water. All that not so big problems, getting energy for all that and intensity of process to finish it in reasonable time those are challenges. $\endgroup$
    – MolbOrg
    May 27, 2021 at 22:43
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    $\begingroup$ @Len, suggestion if you really, really, really, really, really want a moon of a gas giant with a breathable atmosphere as a result of electrolysis factories, just choose one WITHOUT an external atmosphere. $\endgroup$ May 28, 2021 at 2:27

4 Answers 4


Task at hands

To make Titan hospitable for people, you have to alter both the temperature and the makeup of the atmosphere. Your idea for electrolysis can solve both of these problems. To make an impact on an atmosphere, a massive amount of infrastructure has to be built, likely hundreds or thousands of large reactors to generate energy and gas, and large support teams or robots to ensure they run smoothly.

Way to go

First, you convert water into Oxygen and Hydrogen gas. You store the Hydrogen gas and release the Oxygen into the atmosphere. When enough Oxygen starts to accumulate, you set the atmosphere on fire, converting the Oxygen and Methane into Water and Carbon Dioxide. Eventually, the Methane runs out, and the Oxygen begins to accumulate until enough has been produced to be a breathable level, but humans still can't live here.

The firestorm heated the atmosphere up a respectable amount, but you may have to continue the heating process. That's alright, remember the Hydrogen you collected? That's the perfect fuel for fusion reactors to run on(if you're lucky, Titan's oceans have an abundance of heavy water, otherwise you need energy from another source). By making numerous fusion reactors on the surface, you can power more electrolysis and dump excess heat into the atmosphere until it reaches a comfortable temperature.

At some point, you may want some native biology that help scrub the air of CO2.

In conclusion, you make oxygen to get rid of the methane and make the air breathable, then you heat the air up until it's warm enough for humans, and you power it all with fusion energy on the hydrogen by-product of electrolysis.

Energy, holy fusion

On a final note, ITER is trying to use deuterium and tritium for fusion, which are both rarer forms of hydrogen. Deuterium is naturally occurring in the earth's ocean, so one could suppose that it also occurs in Titan's. It's also possible that fusion with other isotopes of Hydrogen will be developed by the time Titan is ready to be terraformed.

1kg of hydrogen in a fusion reaction can generate around 80 million MJ(Wikipedia). Electrolysis of water uses around 180MJ per kg(Wikipedia). Thus, 1kg of fusion of the hydrogen by-products can convert 444,444kg of water into gas. In earth, about 1 in 6,400 hydrogen atoms are deuterium(Wikipedia), which is suitable for fusion, though not necessarily ideal. 444,444kg of water means 49,382 kg of hydrogen, of which around 7.5kg should be deuterium. Essentially, fusion and electrolysis can form a closed energy-generating ecosystem, so once the fusion plants are established they should be able to run in perpetuity as long as they have a constant supply of water.

Infrastructure size in NYC's

New York City uses around 3.5 billion liters of water every day, or 12.775 trillion kg of water every ten years. The atmosphere of Titan has around 5.94E18 kg of gas, most of which is nitrogen. We only need to convert enough oxygen to equal around 15% of the atmosphere(5% to eliminate the nitrogen, 10% to supply air to breathe). This means we have to make 8.91E17kg of oxygen. If we assume each powerplant can consume as much water as NYC, then we need 87,181 terraforming stations (87,181 = 8.91E+17/((12.775E+12)*8/10).


With current technology, these terraforming stations are obviously out of reach, but the only significant technological requirement they have is very effective fusion. Once you have energy, you can make oxygen easily, and humans already have lots of experience moving large amounts of water around.

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    $\begingroup$ "hundreds or thousands of large reactors to generate energy" u underestimate that by a mile $\endgroup$
    – MolbOrg
    May 28, 2021 at 11:02
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    $\begingroup$ The only other isotope of hydrogen is protium, the most common, and p-p fusion is far too slow to be used in a power reactor. $\endgroup$ May 28, 2021 at 15:17
  • $\begingroup$ @MolbOrg Made some edits $\endgroup$ May 28, 2021 at 21:34
  • $\begingroup$ Yep, abundance of energy is a key to situaton, measuring equipment it NYC's also not bad. It just that the number I got is like 90 million 1GW blocks for 10y plan was the reason to say a 1000 stations is low, as typically it few GW max per station(not that they can't be bigger, but if we use similar sized measuring sticks for both places) There is a mistake in number u have, "444,444kg of water means 88,888 kg of hydrogen", hydrogen is 1/9 of mass, it not moles. Nice edit overall. $\endgroup$
    – MolbOrg
    May 28, 2021 at 23:17
  • $\begingroup$ Made formatng edit feel free reject or adjust the way u like $\endgroup$
    – MolbOrg
    May 28, 2021 at 23:27

When that happened on Earth it turned out to be the great oxidation event, and was caused by all the algae busy photosynthesizing in the oceans.

The Great Oxidation Event (GOE), sometimes also called the Great Oxygenation Event, Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust, or Oxygen Revolution, was a time period when the Earth's atmosphere and the shallow ocean first experienced a rise in oxygen, approximately 2.4–2.0 Ga (billion years ago) during the Paleoproterozoic era. Geological, isotopic, and chemical evidence suggest that biologically-produced molecular oxygen (dioxygen, O2) started to accumulate in Earth's atmosphere and changed it from a weakly reducing atmosphere to an oxidizing atmosphere, causing many existing species on Earth to die out. The cyanobacteria producing the oxygen caused the event, which enabled the subsequent development of multicellular life forms.

Now, mixing oxygen and methane together is not as dangerous as mixing hydrogen and oxygen, but it will still raise the hair on the head of any engineer worth their degree.

Anything that is oxidable in the atmosphere and on the surface will react with that oxygen, meaning that before you will notice a significant increase in the atmospheric concentration of oxygen you will need to consume all those substances.

The oxidation of methane will fill your atmosphere with water vapor and CO2, which are both greenhouse gases, which will probably contribute to raising the temperatures of the moon. From there you will be starting a feedback loop which is beyond me to estimate.

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    $\begingroup$ The oxygen exhaust from the generators is almost certain to get ignited at some point (so will likely be done intentionally for safety) and resemble the gas flares from cat cracking plants and oil refineries (before the gas became too valuable and environmental rules stopped this practice). So, how long does it take to burn all the methane in a methane atmosphere? On Earth, with all the oceans feeding oxygen, it took millions of years, I gather... $\endgroup$
    – Zeiss Ikon
    May 27, 2021 at 18:20
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    $\begingroup$ @Len They combine explosively, to create the relatively harmless greenhouse gas H20... reversing the effect of the electrolysis you're working so hard on. $\endgroup$
    – jdunlop
    May 27, 2021 at 21:27
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    $\begingroup$ Water is H2O, and electrolysis effectively reassembles (2 H2O molecules) into (2 H2 molecules and and O2 molecule). Burning hydrogen has the precise opposite effect: burning reassembles (2 H2 molecules and and O2 molecule) into (2 H2O molecules). What you could do with the hydrogen is run it through a fusion reactor to make ludicrous amounts of heat, some of which can be converted to usable energy. However, you have too much hydrogen to dispose of this way, due to waste heat. You can send it offworld, and treat it as an export. $\endgroup$
    – Anon
    May 28, 2021 at 2:05
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    $\begingroup$ Water vapor and CO2 are only greenhouse gases when they're gases. They're both quite solid at Titan temperatures and pressures. And the methane you're burning is an even stronger greenhouse gas. Titan with an oxynitro atmosphere will be even colder, since all the stuff that produces its current hothouse environment will be converted to solid ices. $\endgroup$ May 28, 2021 at 15:01
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    $\begingroup$ @Len: No, because the energy you get from recombining the H2 and O2 to make H2O is exactly the same (assuming perfect efficiency) as you spend splitting the H2O apart in the first place. $\endgroup$
    – jamesqf
    May 28, 2021 at 15:45

I don't think Titan has rocks. Its all ice.

I'll expand my comment a little bit to adress some hurdles, as it seems there is a necessity for general picture here.

"Based on its bulk density of 1.88 g/cm3, Titan's composition is half water ice and half rocky material." "Titan is probably partially differentiated into distinct layers with a 3,400-kilometer (2,100 mi) rocky center" (wiki)

Yes there is some depth to reach it, but hey aren't you looking for epic challenges to overcome, lol. It part of that titanic endeavor. You need to turn the thing inside out to do what you describe.

Indeed 900km down to reach basalt and stuff, seems a but too much, even if it is "just" ice on top of it which one can melt, and lower gravity on that body.

But a problem is that any global changes on a scale like this one, even if it just a moon, even if it looks not so significant like just adding 20 percent something of oxygen, and removing 5 percent methane, it still quite a big task, not something which can be done with a fortpost in a reasonable time.

How much efforts or something it requires, I do not know at the moment, but let us see, some measurable things we can deduce, just a portion of required activity.

Observations from the Voyager space probes have shown that Titan's atmosphere is denser than Earth's, with a surface pressure about 1.45 atm. It is also about 1.19 times as massive as Earth's overall

That already speaks volume, but what it means in practical reality, in things we can have a more palpatable subjective percepton.

Total mass of Titan atmosphere is about 6e18 kg, and for 20 percent oxygen we need to add around 1/5 of that but let's go with 1.3e18 kg

  • not try to be precise with numbers and there are hidden assumptions and maybe some mistakes as well, just wish calculus to be easier on me in this case, as I interested in order of magnitudes of those results.

Assuming your installations blow out somwhat warm air, for whatever reason there is enough of those, then it means the process has to release about 1e18 cubic meters of oxygen, or about 1e9 cubic km of oxygen.

Assuming you have 1 square km crossection pipe to blow that oxygen out, at speed of 100 m/s, it will take about 317 years to finish the job.

Sooo, 317 such installations can do that in a year, and if speed of expelling air is 10 m/s which seems less demanding and more realistic, then it is 3170 such installations.

  • Okay, I have to admit it way much better than I have expected.

If each of those installations takes 10x10km square, for other equipment and such, then overal it just 0.5 percent of surface of Titan, to have the result in a year.

what order of energy it takes

According to wiki industrial processes take about 50 kWh per kg of hydrogen, which means 8 kg of oxygen, so about 6kWh per kg of oxygen.

According to our number 1.3e18kg oxygen required, we need about 8e18 kWh to finish the job, and with our 1 year timeframe it requires about 913,242,009 GW power for electricity production.

For comparison, industrial countries as of today here on earth produce electricity in hundreds of GW numbers, 50 to 300 something like that, per country. (Total energy production and consumption per country is about 6 times of that, if I recall it correctly)

  • Sooo energy requirement are quite good, as expected, satisfied to guess at least something right.

So even if we extend time frame to 10 or a 100 years, it still, beats the total energy production consumption on that planet, like in a hundred or thousand times.

That is just one energy consumption activity, but it needs more, scrubbing air for methane, extracting amonia from water so it won't be released in your freshly created athmosphere. And I have to stress it, solution of water and NH3 is half of the planet, and seen it 8 percent of mass(or something, won't reread those wikis) and that we talking up to 1e22kg of material to process(total mass of Titan is 1.34e23 kg), at least some portion of it which is on top of the new waterworld, it may be a fraction of total but it still humongous. Maybe even not in a sense of energy required to extract, but in a sense how much movement of mass you have to create, to be able to extract stuff.


Waste hydrogen can be converted in to ammonia, at the same time removing some nitrogen from athmospnere to decrease pressure (maaan the whole moon will start to bubble, will be epic), and then it can be stored at some depths of the ocean thing, it does not require that much pressure to convert it to a liquid.

Electrolysing rocks - waste products will be metals and Si, they are easier to store and can be useful in constructions, but yeah it may be quite deep, to get a free access to it, if there aren't some sticking out mountains at bottom of ocean. Option which depends on technologies available and situation on the grounds.

better options, alternatives

In comments there was a siggestion to use some moons which do not have athmosphere, it may be a better choice indeed, from a perspective for things to remain more clean and controlable. There are no poisonous gases to mix with your newly created athmosphere.

I understand the desire to paint a grand picture, express idea, but it not always goes along with what makes sense to do.

Those dome like constructìns in Expanse series, they are actually not a bad alternative for a full conversion.(on ganimede if I recall correctly)

Probably one of the things which you may miss importance and implicatiins of it, is that sun as light energy source there is basically non existant at that place. Meaning just making air does not give that much benefits for Titane moon without that free sun energy which we are so used to. You have to create artificial sun for the whole moon to take advantage of that atmosphere, or no plant life will grow and athmosphere will be near to be pointless.

Build space habitats in orbit, do what you need that Titan for, do it remotley, via machines and satelite network like StarLink, enjoy full gravity, grenery of plants fresh air and other good working conditions, and let robots to suffer for their ai overlord to come.

Do it for all the moons, conver them all in to space habitats and battleships or whatever. The stuff you try to have fantasy about is outdated and direct hello from 70's - not cool, not epic. Or if things are just backdrop, then just handwave and make a good story instead. If activity in space is one of the bones for the story or main line then take a red pill and convert to space habs which is the way to make good environment in any place you go. And welcome remote operated equipment and robots, which are a thing of today, in mining(mature enough) and other places(maturity varies).


You have several problems to deal with.

Abundant free oxygen and methane can be an explosive mixture. But it is concentration dependent. In earth's atmosphere, the lower and upper limits for flammability is 5% and 17% (by volume), so for safety, you will want to reduce the volume of methane in the atmosphere before you get too far in release free oxygen. Hydrogen limits are 4% to 75%

Fortunately, the atmosphere is already so cold that fractional distillation to remove methane is fairly easy. This methane could be stored long-term easily given the frigid conditions, but if you plan on terraforming, it would be easier to store after cracking the methane into something easily stored at higher temperatures such as methanol (which would require oxygen too).

Long term hydrogen storage is even more difficult. It is such a small molecule, it leaks through materials, and the hydrogen embrittlement of metals is a definite problem. However, converting hydrogen into ammonia is straightforward and you have all the nitrogen you need in your atmosphere.

In the context of terraforming, long-term storage is not in terms of years, or decades, but millennia or even longer. You don't want methane or hydrogen leaking back into your environment unless you plan to continuously use active removal of these components from your atmosphere. And when you consider scale, you really don't have a choice to do that either.

Finally, the issue of scale. Total mass of Titans atmosphere is about 19% greater than Earth's atmosphere, so it's close enough to ignore the difference in ballpark scale requirements. So, lets just assume you need to generate enough oxygen to match the oxygen in Earth's atmosphere. So you need about 1E18 kg of free O2. Using round numbers, you will need at least 9 MJ per kg of O2 produced, so lets just call it 10 for our estimate. 10 MJ time 1E18 kg of O2 means you will need about 1E25 KJ of energy. A 1 GW powerplant running for 1 year gives you 3E16 Joules. So you need roughly 300,000 Powerplants running for 1000 years.

I do not even try to guess how much additional free oxygen you are going to need to counteract that which will be used up in oxidizing the minerals on Titan's surface.

For comparison, total earth annual electric generating capacity is about 20,000 TWH or about 6.3E14 J. meaning that you need about 16 billion years worth of the entire world's electric output just to make free O2.

I made a very generous assumption that your electrolysis process is 100% efficient because it would clearly be in your interest to perfect this process. You better invent Mr. Fusion too.

Get your O2 from someplace else if you can, making your own on Titan will be extremely challenging. I suggest the Sun. The oxygen is a trace element in the sun, I did the math once and discovered that the mass of oxygen in the sun outmasses that of the total earth (not its oxygen, but everything) by about 10:1. Stellar uplifting should given you a nice mass stream, and solar panels are rather effective when located near the sun.

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    $\begingroup$ Lifting oxygen requires plus minus an order of magnitude 1e28J sooo it not cheaper energy wise. Yeah energy source is next to the job site, but there are other challenges as well requering a better tech level in the first place. Yeah Mr. Fusion is probably minimal prerequisite for all that, but then shuttling matter between moons and gas giant itself isn't a big deal with fusion engines. Was it u digging for sun mining q recently? Lol $\endgroup$
    – MolbOrg
    May 28, 2021 at 18:58

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