“Particles, Environments, and Possible Ecologies in the Jovian Atmosphere”, 1976-10-01 (; backlinks; similar):
The possible existence of indigenous Jovian organisms is investigated by characterizing the relevant physical environment of Jupiter, discussing the chromophores responsible for the observed coloration of the planet, and analyzing some permissible ecological niches of hypothetical organisms. Values of the eddy diffusion coefficient are estimated separately for the convective troposphere and the more stable mesosphere, and equilibrium condensation is studied for compounds containing Na, Cl, or both. The photoproduction of chromophores and nonequilibrium organic molecules is analyzed, and the motion of hypothetical organisms is examined along with the diffusion of metabolites and the consequent growth of organisms. Four kinds of organisms are considered: primary photosynthetic autotrophs (‘sinkers’), larger autotrophs or heterotrophs that actively maintain their pressure level (‘floaters’), organisms that seek out others (‘hunters’), and organisms that live at almost pyrolytic depths (‘scavengers’). It is concluded that ecological niches for sinkers, floaters, and hunters appear to exist in the Jovian atmosphere.
…The eddy diffusion coefficient is estimated as a function of altitude, separately for the Jovian troposphere and mesosphere. The growth-rate and motion of particles is estimated for various substances: the water clouds are probably nucleated by NH4Cl and sodium compounds are likely to be absent at and above the levels of the water clouds. Complex organic molecules produced by the Lα photolysis of methane may possibly be the absorbers in the lower mesosphere which account for the low reflectivity of Jupiter in the near-ultraviolet. The optical frequency chromophores are localized at or just below the Jovian tropopause. Candidate chromophore molecules must satisfy the condition that they are produced sufficiently rapidly that convective pyrolysis maintains the observed chromophore optical depth. Organic molecules and polymeric sulfur produced through H2S photolysis at λ>2300 Å probably fail this test, even if a slow, deep circulation pattern, driven by latent heat, is present. The condition may be satisfied if complex organic chromophores are produced with high quantum yield by NH3 photolysis at λ<2300 Å. However, Jovian photoautotrophs in the upper troposphere satisfy this condition well, even with fast circulation, only biochemical properties of comparable terrestrial organisms are assured. Unless buoyancy can be achieved, a hypothetical organism drifts downward and is pyrolyzed. An organism in the form of a thin, gas-filled balloon can grow fast enough to replicate if (i) it can survive at the low mesospheric temperatures, or if (ii) photosynthesis occurs in the troposphere. If hypothetical organisms are capable of slow, powered locomotion and coalescence, they can grow large enough to achieve buoyancy. Ecological niches for sinkers, floaters, and hunters appear to exist in the Jovian atmosphere.