OBJECTIVE 1: WHAT IS THE HISTORY OF ORGANICS IN OUR SOLAR SYSTEM?
We will investigate the link between interstellar and primitive solar system body material by tracing chemical functionality, molecular abundances, and isotopic compositions, as guided by studies of meteoritic samples in Projects 1.2, 1.3, and comet observations. The work will involve use of previous survey data, as well as new observations. From the meteoritic studies, as outlined in Projects 1.2 and 1.3, key functional groups and associated isotopic enrichment will be identified. Functional groups and isotope ratios will be identified in molecules found in dense clouds, based on our survey work of the giant molecular cloud Sgr B2(N) and in diffuse clouds. The same functional groups will be sought in species found in circumstellar shells and planetary nebulae. A set of interstellar “standards” pertaining to dense molecular clouds, diffuse clouds, planetary nebulae, and circumstellar (O- and C-rich) material will therefore be created from the data. Although this project is clearly exploratory, it has a potential for high yield as it could provide an estimate of the degree of processing of primitive interstellar material in the protostellar disk.
PROJECT 1.1: ORIGIN AND NATURE OF METEORITIC ORGANICS: FROM CIRCUMSTELLAR ENVELOPES TO COMETS
Lead: L. Ziurys (UA)
We will investigate the link between interstellar and primitive solar system body material by tracing chemical functionality, molecular abundances, and isotopic compositions, as guided by studies of meteoritic samples in Projects 1.2, 1.3 and comet observations. The work will involve use of previous survey data, as well as new observations.
PROJECT 1.2: THE DISTRIBUTION OF INSOLUBLE ORGANIC COMPOUNDS IN THE EARLY SOLAR SYSTEM
Lead: T. Zega (UA)
What were the nature of organic compounds delivered to the early solar system and Earth? What were their molecular forms? What were the diversities of compositions? In Project 1.2, we aim to understand the nature of that organic matter. We take a sample-based approach by studying the organic content of primitive carbonaceous meteorites, some of the most primitive relics from the time the solar system formed. Using sophisticated mass spectrometers and high-resolution electron- and X-ray microscopes, we can measure the chemical makeup of these organics and how they are distributed within meteorite samples. We will compare our measurements with the observations made in Project 1.1, which will examine organic compounds in molecular clouds in the interstellar medium, the circumstellar environments around nearby stars, and solar-system comets. We expect that these combined data sets will provide us with insight into what molecules were delivered to the early solar system, and by extension, the kind of organic compounds that could have also been delivered to other habitable planets.
PROJECT 1.3 THE DISTRIBUTION OF SOLUBLE ORGANIC COMPOUNDS IN THE EARLY SOLAR SYSTEM
Lead: S. Pizzarello (ASU)
In Project 1.3 we propose the following experimental undertakings.
Obtain a complete characterization of the soluble and insoluble organic composition of the known major classes of CC meteorites, choosing especially pristine meteorites from Antarctica to avoid interferences from terrestrial contamination.
To date, the non-racemic amino acids and amines of meteorites provide the only natural sample of molecular asymmetry measured outside the Biosphere and particular emphasis will be given to new searches for those compounds.
Recent analyses in our laboratory have shown a large presence of ammonia in the macromolecular material of meteorites. Since the molecule appears to be of solar origin, the finding open a new understanding of the prebiotic molecular inventory in our early planet and inform our estimates for the possible habitability of other planetary systems. The study will be extended to several Antarctic meteorites and within different classes.
The synthetic processes that lead to the formation of organic compounds in meteorites is still vague and leave open many uncertainties. Meteorites are rocky fragments of Asteroid, which are for at least 98% mineral phase, several of which are known catalysts. We will investigate any potential dependence between organic syntheses and mineral hosts in meteorites with model experiments in the laboratory.