In the setting of my projects there is a gas giant (with a mass of about 3 jupiters) that migrated within the habitable zone, as such it's outer atmosphere would feature plenty of water wapor and have conditions that would be favorable to organic compounds and even life forms.

Essentially it would be a class 2 water cloud gas giant.

What if an advanced space faring civilization (at the solar system level) engineered life forms, akin to phytoplankton/zooplankton but maybe also more complex life forms such as algae, capable of thriving in the gas giant's conditions and essentially turned the whole celestial body into a huge aeroponic farm to produce food for the entire solar system.

Would something akin to this be feasible, especially compared to other concepts like orbital farms in space?

For additional background, the civilization would have access to fusion energy and also already exploit the gas giant for helium 3.

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    $\begingroup$ It strikes me there'd be a paucity of micro-nutrients - are you "fertilising" the atmos with ground-up space-rubble or something? $\endgroup$ Mar 17, 2023 at 14:20
  • $\begingroup$ @AngryMuppet a fine suggestion, yeah the atmosphere would be fertilized through inorganic and organic means. $\endgroup$ Mar 17, 2023 at 14:22

1 Answer 1


Most of the mass exported from the gas giant would be water, or hydrogen and oxygen within the organic materials of the food produced. Much of the remainder would be carbon. Hydrogen, oxygen, and carbon are the three most common reactive elements in the universe, exporting them from the gravity well of a gas giant is rather silly.

Worse, growing them suspended in the open atmosphere with nutrients supplied from off-world would be incredibly lossy. It would take huge amounts of energy to deliver the nutrients, and a large fraction of them would sink into the core of the gas giant. The portion you successfully import and use to grow harvestable plant biomass then simply gets exported out of the gravity well again.

Collecting helium-3 from a gas giant only makes sense due to its extreme energy density and scarcity outside of that gravity well. Exporting a usable amount of food would involve far more mass and volume...the US consumes energy equivalent to a few dozen tons of helium-3, but it produces over 300 million metric tons of corn a year.

Everyone not actually living on the gas giant would be far, far better off growing their food in orbital agricultural stations, positioned close to where they actually live so they can make use of the organic wastes produced by the consumers of that food.


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