Our primary goal is to understand how the Solar System and Earth formed and evolved, and how life began and developed. This presents a major unsolved chemical, physics, and astronomical problem that will yield to a focused attack given the timely combination of emerging laboratory techniques, theory, and observations. Here, chemistry - defined as the change of matter – must be considered as the major driving force to control the chemical evolution of matter on the microscopic level (elementary mechanisms of chemical reaction) and also on the macroscopic scale (planets, moons, asteroids, comets, and Kuiper Belt Objects (KBOs)). Since the present composition of each Solar System body reflects the matter from which it was formed and the processes which have changed the chemical nature since the origin, a detailed investigation of the reaction mechanisms altering the chemical composition of the pristine environment is of paramount importance to rationalize the contemporary chemical make-up. Here, laboratory experiments simulating the interaction of ionizing radiation (electrons, nuclei, photons) from the solar wind, cosmic radiation field, and planetary magnetospheres with low temperature solids in our Solar System (ices, minerals, carbonaceous matter) offer extraordinary opportunities for understanding the origin and chemical evolution of the Solar System and how life emerged and developed for several reasons:
1. Due to activation energies (entrance barriers) of chemical reactions and diffusion barriers of atoms, radicals, and molecules on the surfaces and inside Solar System ices, classical chemical reactions are effectively eliminated at low temperature. Therefore, the interaction of ionizing radiation with icy surfaces and bulk ices like water, methane, ammonia, carbon monoxide, carbon dioxide, nitrogen, hydrogen sulfide, sulfur dioxide is imperative to couple the energy of the radiation inside the ices and to synthesize new molecules via non-thermal, non-equilibrium chemistry. |
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2. Utilizing Solar System bodies like planets, their moons, comets, and Kuiper Belt Objects (KBOs) as ‘natural laboratories’ at the frozen stage, we can compare the chemical nature of the newly formed molecules in laboratory experiments with the contemporary chemical composition of the diverse Solar System bodies as obtained from astronomical observations and space missions. Once these underlying chemical processes and reaction mechanisms have been unraveled, we can identify those molecules which belonged to the nascent Solar System body distinguish molecular species synthesized in a later stage, and predict the imminent chemical evolution of our Solar System. This also yields valuable clues how proto-Earth may have developed chemically billions of years ago. By selecting distinct ice mixtures, temperatures, and radiation sources, we can mimic for the first time in history the chemical processing of any body in our Solar System. |
3. Since molecules in simple, low temperature ices can also act as precursors to biologically important species like sugars, amino acids, and phosphates, the laboratory experiments can also be utilized to develop key-concepts how and where in our Solar System astrobiologically important molecules might have been formed. Most importantly, the studies will also provide crucial information how these astrobiologically important molecules might have ‘survived’ the strong ionizing radiation from the solar wind and planetary magnetospheres. Recall that due to the absence of ozone, one of the crucial requirements for the evolution of life as we know it, biologically important molecules can be destroyed easily by the strong UV radiation field. However, embedded inside ices, the bulk ice matrix will protect these biologically important molecules from the destructive UV radiation field. Further, our experiments can also assist to rationalize how and to what extent ozone can be formed via abiotic processes inside Solar System ices. |
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4. Chemists have known for a long time that chemical processes produce isotopic fractionations in hydrogen, carbon, nitrogen, oxygen via chemical reactions predominantly to differences in zero-point energies of the products and in some cases to a shift from an exo- to an endoergic reaction once the heavier isotopes are placed in the reactant molecules. Therefore, by investigating the radiation-induced isotopic enrichment in Solar System ices containing oxygen, carbon, nitrogen, and hydrogen, these studies will also shed light on isotope enrichment processes of H/D,14N/15N,12C/13C, and16O/17O/18O at an early stage of our Solar System. Similar processes will be studied to simulate the radiation-induced isotopic fractionation in minerals (Mars, asteroids). These studies can be compared directly with samples returned in future space missions, for instance, from Mars. |
5. By investigating the effects of charged particles and photons on the chemical composition and spectroscopic properties (infrared, optical) of minerals (silicates, carbonates, sulfates) and carbonaceous compounds, the new laboratory can also provide valuable data on space weathering effects. By comparing the laboratory spectra with those data obtained from observations on Mauna Kea (Keck I/II), we can ultimately determine the exposure age of asteroids since their formation. These studies can be also expanded to Solar System ices. By obtaining data on the amorphization rate of crystalline ices, such as of crystalline water observed on KBOs, by ionizing radiation in our Solar System, we can provide quantitative data on the exposure ages of distinct ice surfaces. |
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In our surface scattering machine, we investigate the interaction of energetic particles (electrons, atomic and molecular ions, photons, neutral atoms) with low temperature ice surfaces. These ‘ices’ are either neat like water, methane, ammonia, carbon monoxide, carbon dioxide, nitrogen, oxygen or complex mixtures. By inducing non-equilibrium chemistry, we can follow the reaction in real time via infrared spectroscopy and mass spectrometry. The information obtained are data on reaction products, their formation rates, and information on the kinetics and dynamics. These findings can be utilized to better understand the chemistry of interstellar grains and the astrobiological evolution of our Solar System.
1. Surfaces of Kuiper Belt Objects
3. Formation of Astrobiologically Important Molecules in Extraterrestrial Ices
