From interstellar space to planetary atmospheres

Time is in fact the hero of the plot. The time with which we have to deal is of the order of two billion years. Given so much time the impossible becomes possible, the possible probable, the probable virtually certain. One has only to wait, time itself 

Bioinorganic Photochemistry Grazyna Stochel, Malgorzata Brindell, Wojciech Macyk, Zofia Stasicka, Konrad Szacilowski 

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Homogeneous Systems From Interstellar Space to Planetary Atmospheres and Primitive Soup Models... 

The similarities in products and pathways between interstellar molecules and terrestrial laboratory experiments imply a unity of physical and chemical laws in the universe. Given certain conditions and appropriate energy sources, the same chemical pathways will be followed to create certain products from the elements. That is not to say that life, even in primitive form, could be supported in interstellar space. The significant precursor molecules found in interstellar space are at extremely low concentrations, but if they were transported to planetary atmospheres, perhaps by comets, they might then react in the proper environment and evolve into self-replicating systems. 

The present work is only the very first step towards a comprehensive and systematic understanding of the fundamental elementary processes involved in the chemistry of hydrocarbon-rich planetary atmospheres and interstellar medium. Our experiments explicitly identified synthetic routes to nitriles — the alleged precursor molecules to amino acids. The experimental data can be employed to set up a systematic database of reaction products and can predict the formation of hitherto unobserved gas phase molecules. The applications of the crossed beam method to astrochemical problems have just begun. Many interesting problems remain to be studied. In the coming century, laboratory experiments of the kind we have presented here combined with observations and planetary-space missions will undoubtedly unravel the complex chemical processes which extend from atoms and simple molecules to large molecules and aggregates. 

In this chapter, we describe the current status of theoretical kinetics for chemical reactions at low temperature, i.e., from 1 to 200K. The desire to understand the chemistry of interstellar space and of low temperature planetary atmospheres provides the general motivation for studying chemical kinetics at such temperatures. For example, the chemistry of Titan s atmosphere is currently a topic of considerable interest. This motivation led to the development of novel experimental techniques, such as the CRESU (cinetique de reaction en ecoulement supersonique uniforme) method, which allows for the measurement of rate coefficients at temperatures as low as lOK (see Chapter 2 by Canosa et ai). Such measurements provide important tests for theory and have sparked a renewed interest in theoretical analyses for this temperature range. ... 

In the discussion above there are indications that ammonia is a common substance in space, distributed from grains (interstellar dust) over asteroids to satellites. Hence it is logical to assume that during the formation of the planet (icy) ammonia (and water and likely other substances) was carried to earth. The survival of ammonia would be extremely limited, first because the planetary bodies were soon molten after aggregation and will lose all volatiles (see Chapter 2.2.1) and form a primitive atmosphere. Secondly, most icy matter falling to the earth s surface would afterwards evaporate (by frictional heating) in that atmosphere, but it would input the volatile matter, e. g., ammonia and other substances (water, methane), which easily explains the first atmosphere (cf Table 2.7). 

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