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Having no solid surface, Jupiter seems to be an unsuitable
place to live. In any case, this concerns the earth-like life. However, fundamentally
different conditions could give rise to “slightly” different creatures. That
is, ones exactly the same as on Earth, but slightly differently adapted. This,
of course, is a separate, rich topic, but attempts to construct a life significantly
different from the one we observe inevitably lead to a result that will not
But for the case of Jupiter, something special does not need to be invented. The habitable environment on giant planets can be the atmosphere only. And on the Earth, bacteria have learned to live in clouds. For example, the gas ocean of Jupiter includes a layer covered in clouds of water vapor, in which, at a pressure of only three to seven atmospheres, the temperature is +30 degrees Celsius. Like on the young Earth, there is enough ammonia, methane, hydrogen sulfide and carbon dioxide. Similar “comfort” zones, where there is nothing that even terrestrial bacteria could not cope with, are present in the clouds of Saturn, Uranus and Neptune.
However, there are also some problems. Firstly, despite the fact that the ideas about the mechanism of the appearance of life are incomplete at the moment, it is clear that it happened not in clouds, but in solution. For the bacteria that have already mastered the technique of synthesizing the necessary substances the droplet moisture is sufficient – and, maybe, even the droplets of sulfuric acid, which make up the clouds on Venus, would be just as good. However, the emergence of life is more difficult problem. These droplets are not durable enough to accumulate chemicals in them, forming the “primordial soup” necessary for life at an early stage.
The second problem is gravity, which is characteristically high for giant planets. And then an additional aggravating circumstance pops up. Giant planets are giants because they are able to hold hydrogen in their atmospheres. Archimedes’ law forbids anything to float in hydrogen gas. A balloon filled with hydrogen floats in the Earth’s atmosphere consisting of heavier nitrogen. But in an atmosphere of hydrogen, it will sink under the weight of its shell.
Both active and aerostatic flights are actually impossible on a heavy planet. The first one will require too much energy consumption, because gravity is very large. The second one is hampered by the extremely low density of the medium. Although, it is only difficult, but not excluded. After all, the atmosphere of Jupiter consists of hydrogen with 20% admixture of helium. Then, if helium is removed from a certain volume, the lifting force, albeit negligible, will still arise.
The most obvious lifeform in such conditions will be atmospheric phytoplankton – microorganisms engaged in synthesis in the “comfortable” layers of the atmosphere, where, among other benefits, the light is also present, which no longer penetrates into the lower layers of Jupiter’s atmosphere. Bacteria will have to become like fluff, relying on the volatility provided by the body outgrowths and ascending gas flows. It will prolong their stay in a habitable zone, giving them time to multiply.
But they will fall all the same, dying and dissolving in the hydrogen ocean. Survival in sizzling hot liquid hydrogen, which is extremely chemically active and capable of penetrating even through crystalline grid, is out of the question, regardless of the principles on which life is built. It means that the cycling of matter will be unclosed. The substances necessary for synthesis will be withdrawn from the atmosphere, returning back only due to abiogenic processes. That is, a rampant “blossoming” of clouds of Jupiter cannot be expected in any case… By the way, it is not observed, although it would be noticed by modern means.
However, an alternative to microscopic fauna can also be giant creatures whose size will be calculated in kilometers – living balloons using a slight difference in density between pure hydrogen inside and hydrogen with an admixture of helium outside their bodies to maintain volatility. This difference is really small, and only a grand scale will allow the balloon to compensate for the weight of the shell with lifting force. Such a creature is more likely to be a plant that assimilates carbon dioxide, water vapor and light with its surface than an animal. But the latter is also not excluded, in the case of symbiosis with synthesizing microorganisms.
Theoretically, mobile creatures are also possible, keeping at the proper height due to gliding. Colossal vortices, and hence updrafts that have existed for centuries, technically allow an animal capable of maneuvering to stay at the proper height in the atmosphere of Jupiter with virtually no energy expenditure. However, this way of life involves a relatively complex organization. It is unlikely that there will be a place for such creatures in the “unclosed” and therefore extremely resource-poor biosphere.
Translated by Pavel Volkov, 2021
The original Russian article is here