Organic Materials in Space

The polycyclic aromatic hydrocarbons (PAHs) have been inferred to exist in the interstellar dust by the correlation of their general infrared spectral characteristics with observed celestial infrared emission bands [13-15]. 

Interstellar clouds, the birthplace of stars and planetary systems, are rich in simple organic materials and radicals in the gas phase and may contain more complex molecules and even macromolecular organic matter on grains. Although these complicated molecules have not been observed in interstellar 

To account for these compositional features of comets, Bar-Nun et al. [23] experimentally showed a relation of the relative abundances of CO, Ar, N2, and CH4 trapped in ice, versus temperatures, and inferred that the abundances of N2 and CO in comets were inherent from the gases trapped during ice forming in the Uranus-Neptune regions [24]. Notesco et al. [25] have performed a similar analysis for CH4 and C2H6, successfully accounting for the proportions of these two gases observed in comet Hyakutake by Mumma et al. [22]. 

6 ji emission band is observed with moderate spectral resolution in some comets. This band is the signature of both aliphatic and aromatic unsaturated carbonaceous compounds. In particular, the 3.28 p band is characterized by aromatics. Moreels et al. [26] identified phenanthrene in the recorded visible spectrum of comet Halley. 

Most of interplanetary dust particles (IDPs) contain 2-10 % carbon by weight in a variety of physical forms, including amorphous materials with a minor amount of oxygen and nitrogen. Allamandola et al. [27] reported that both IDPs and meteorites might contain materials similar to PAHs. Clemett et al. [28] identified many PAHs and their alkylated derivatives in IDPs. 

---

Shock waves and carbon-bearing materials occur ubiquitously in tl>e universe and the interaction between them is a common phenomenon. In tlie interaction, wliich we call shock reaction, Uie shock wave compresses and heats the caibon-hearing materials, producing organic materials witli compositions differing from those of the initial materials. We believe that the shock reaction is one of the most important reactions for the chemical evolution of organic materials in space. 

Carbon monoxide is found in varying concentrations in unventilated and confined spaces resulting from partial oxidation of carbonaceous matter. Burning wood, paper, kerosene, or other organic materials in inadequate air can produce this gas. It also is found in automobile exhaust and tobacco smoke emissions. 

Refractory dust particles not only serve as condensation nuclei for ices (see above), but are also necessary for energy dissipation during gas phase reaction between energetic atoms and molecules. Furthermore, solid inorganic particles (mostly oxides and sulphides) may play a role of photocatalysts in transformations of organic materials in both space and the primitive soup [5, 31]. 

Oxygen is driven toward saturation on contact with the atmosphere, produced by biological fixation in the upper ocean, and consumed by bacterial degradation of organic material in the water column and sediments below. These processes are clearly variable in both space and... 

Duce RA, Mohnen, VA, Zimmerman PR, et al. 1983. Organic material in the global troposphere. Reviews of Geophysics and Space Physics 21 921. 

As with the previous examples, exposed nanocomposite samples showed enrichment of the silicate near the exposed surface. Figure 9 shows the FT-IR spectrum for a thin 7.5 wt% nanocomposite before and after the simulated space exposure. As seen in the post exposure FT-IR spectra (spectra 2), the relative intensity of the peak centered around 1000 cm indicative of silicate absorption, is much larger after than before UV exposure, indicating enhancement of silicate species in the exposed sample with regard to selective removal of organic material. In corroboration, sample mass decreased with exposure. 

Evaluation, Proc. Int. Symp. on Spacecraft Material in Space Environment, Toulouse, France, jointly organized by CNES, ESA CERT (June 8-12, 1982)... 

The main advantage of wholesale climate control Hes in easy access to the objects, and the absence of differences in conditions between various spaces within the institution, eg, storage areas, conservation laboratories, and exhibition galleries. The actual values set for the rh are a matter of compromise metals, stone, and ceramics are best served by humidities as low as possible, but organic materials generally require higher values. An accepted... 

The product is considered nonhazardous for international transport purposes. However, it is an oxidizing agent sensitive to decomposition by water, direct sources of heat, catalysts, etc. Decomposition is accompanied by the Hberation of oxygen and heat which can support combustion and cause pressure bursts in confined spaces. Decomposition in the presence of organic material is rapid and highly exothermic. 

---