Proton stimulated chemistry in the outer solar system

The outer solar system presents an amazing array of colors and features, easily observed with even small telescopes, that are somewhat surprising in light of the expected cold (less than 2000K) temperatures there. Included here are the recent detections of such gases as C2H6 and PH3, not expected from simple equilibrium cooling of a hot nebula (of solar composition). Thus non-equilibrium processes must be occurring in the solar system, as suggested by the above facts and by the temporal variations of the features (belts, zones, and spots) found on Jupiter. Such processes are probably stimulated by the interaction of energy from the sun (radiation) or the planetary interior (heat) with the gases in the atmospheres or on the surfaces. One possible source of this energy is the solar wind, in particular the protons therein. These particles can impinge upon the atmospheres or surfaces directly or from radiation belts (for Jupiter) and initiate chemical reactions. To investigate this concept, a number of laboratory simulations of the interactions of energetic protons with a variety of mixtures of CH4, C2H6, NH3, H2O, H2S, CO2, CO, N2, and PH3 have been carried out. It is possible that proton initiated chemistry may account for some of the phenomena observed in the outer solar system, and in conjunction with other chemical processes can produce the necessary chromophores. A more complete and definite understanding of such processes will hopefully be achieved with the use of planetary probes, planned for the near future (the end of this decade)