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So why write about it?
The history of Jovian biological speculation is a fascinating case study that demonstrates how science works. Dealing with the unknown, it illustrates creativity, curiosity, and ultimately, the restraining virtue of rationality; it is a perfect example of how developing astrobiological models are formed. Without further adieu, let us begin our fun foray into antiquated territory:
The connection between science fiction and science dynamic. As science leads, science fiction inspires. And this special bond can go both ways. The first roots of the idea of Jovian life went back to the experiments of Stanley Miller and Harold Urey in the 1950s. They sought to validate the earlier hypothesis that conditions on primitive Earth, so in far as those conditions may be replicated in a modern laboratory, could yield organic products from their inorganic precursors. The components involved in the experiment were methane, water, ammonia, and hydrogen, inlet with a continuous electrical stream (which was to replicate the intense lighting conditions of primordial Earth). In triumph, amino acids, the building blocks of protein and life, were found. Yet, we need not visit a chemistry laboratory for an example of this Frankensteinian quirk of chemistry and biology; the planet Jupiter itself may represent a planetary version of his experiment.
The jovian atmosphere contains hydrogen, methane, ammonia, and water, and is tempered by turbulent weather and lighting. The possibility of biota, at least in the upper-atmosphere, was hypothetically proposed by Carl Sagan and Edwin Salpeter three years after the Pioneer 10 flyby of Jupiter, in 1976. He compared the Jovian ecology to our terrestrial oceans. Ammonia-based life, was not terribly out of the question. Experiments done by Siegal and Giumarro showed that certain microorganisms could survive in ammonia-rich atmospheres. It would do the reader injustice not be informed of this marvelous video, narrated by Sagan himself, in which he describes life in a gas-planet. It is called ''Carl Sagan's Cosmos: Life on Jupiter", from his Cosmos. It may be found in a web search. In it, the ecology of floating, jellyfish-like ''floaters'', are described, and massive creatures of intelligence are pictured swimming along in the upper atmosphere, staying aloat by pumping helium out of its interior, conveniently leaving the lighter gases, such as hydrogen, within. In this way it may be reminiscent of a hot-air balloon. These floaters are imagined to be terrible in scope-many kilometers across. They would eat organic molecules found in the atmosphere, or create their own from air and sunlight, in the same way plants do. The reader is highly encouraged to view the visual.
However, the likelihood of this, shown by later experiments, was diminished. It seems that the forces of convection, powerful gusts in the Jovian atmosphere, would probably blow any promising molecules into the lower atmosphere. There, the rigid pressures and intense temperatures would do away with them. Jupiter is a far cry from the tranquil orb that it appears in the night sky. And, most importantly, there has yet to emerge any form of evidence of Jovian biology. Carl Sagan, a cautious skeptic himself, noted the hypothetical nature of this in his introduction that 1976 paper by restating that the plausibility of life in a gaseous giant does necessarily correlate to its likelihood.
Yet Isaac Asimov's words do have an appeal to the imagination:
"If there are seas on Jupiter, think of the fishing".
For further reading:
1. Heppenheimer, T. Colonies in Space. 2007.
2. Sagan, C, et al. Particles, environments, and possible ecologies in the Jovian atmosphere. Astrophysical Journal Supplement Series. 32, 737-755. 1976.
