1. CHARACTERIZATION OF EXOGENOUS ORGANIC MATTER ON THE GANYMEDE SURFACE. M. A. Zaitsev 1, M. V. Gerasimov 1, E. N. Safonova 1, M. A. Ivanova 2, C. A. Lorenz 2, A. V. Korochantsev 2, Yu. P. Dikov 3,1 1 Space Research Institute (IKI), 2 Vernadsky Institute of Geochemistry and Analytical Chemistry (GEOKHI) 3 Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry (IGEM) International Colloquium and Workshop "Ganymede Lander: scientific goals and experiments“ IKI, Moscow, 06.03.2013

2. ocean icy crust stony and metallic core What is the Habitability of the Ganymede Ocean? What is the Habitability of the Ganymede Ocean? What Organic Compounds (OC) and Biomarkers are Present in the Ocean? What Organic Compounds (OC) and Biomarkers are Present in the Ocean? What is the Signature of the Ocean Organics in the Surface Ice? What is the Signature of the Ocean Organics in the Surface Ice?

3. Cratered terrain of the Ganymede

4. OC OC T, P (synthesis) rocky core ice OC UV, X-ray, γ OC OC OC Impacts of meteorites and comets Dynamics of exogenous (OC) and endogenous (OC) organic compounds OC crack

5. Important questions to answer: What is the proportion between endogenous and exogenous OC in the upper ~1 m layer of surface ice (available for analysis by a lander)? How to discriminate endogenous OC from exogenous?

6. Given the different isomers for organic molecules with the same composition Murchison should contain several million different carbon-, hydrogen-, nitrogen-, oxygen-, and sulfur-based organic chemicals (Philippe Schmitt- Kopplin et al. (PNAS, 2010, 107, no. 7, 2763–2768). What is the fate of OC during impact processing? Delivery of biologically important OC by meteorites. Numerous studies of Murchison by different researches had revealed a complex mixture of large and small organic chemicals, including amino acids, sugar related compounds, carboxylic acids and nucleobases (Botta & Bada, 2002).

7. Composition of endogenous OC is unknown Composition of OC in falling bodies can be characterized by OC in meteorites of different classes Hypervelocity impact-induced modification of OC can be simulated in laboratory The aim of the work: Characterization of OC in carbonaceous chondrites of different types and to investigate modification trends of these OC during simulated impact- induced high-temperature processing.

8. Experiment Samples: o carbonaceous chondrites – Murchison (CM2) and Kainsaz (CO3) o starting meteorites - selection of fresh pieces (~20 mg) and their powdering o condensed material (~20 mg) collected after simulated impact- induced evaporation by means of a pulse laser Extraction of OC: o thermodesorption at 460°С/pyrolysis at 900°С Analysis of OC: o collection of OC in a cold trap at liquid nitrogen temperature, then pulse heating to ~250-300°С and transfer of volatile species to GC- MS

9. Typical chromatogram of thermodesorption products of Murchison at 460°С and mass-spectra of some OC 1 12 2 3 3 4 4 5 56 6 (1) - CO 2, (2)-isobutene, (3)-benzene, (4) – thiophene, (5) – toluene, (6)-methyl thiophene, (7) – n-dodecane, (8) – n-tridecane 7 7 8 8

10. OC in the products of thermodesorption of Murchison Results of identification Abun- dance, % Classes of OC Subclasses of OC Groups of compounds and individual substances Hydro- carbons Alkanes > C 10 N-dodecane (C 12 H 26 ), n-tridecane (C 13 H 28 ),, n-tetradecane (C 14 H 230 ),, н- pentadecane (C 15 H 32 ), structural isomers of С 11 -С 19 alkanes. Main components are n-alkanes С 11 -С 18 56,5 Unsaturated hydrocarbons Isobutene (C 4 H 8 ), isomers of С 6 -С 10 alkenes, С 4 -С 7 alkadyenes, alkynes 3,3 Alicyclic hydrocarbons Isomerides of alkylcyclopropanes, cyclopentene (C 5 H 8 ), alkylcyclopentenes, alkylcyclohexanes, decahydronaphthalene derivatives 1,2 Benzene and aklylbenzenes Benzene (С 6 H 6 ), toluene (С 7 H 8 ), xylene (С 8 H 10 ), styrene (С 8 H 8 ), cumene (С 9 H 12 ), cymenes (С 10 H 14 ), trimethylbenzenes (С 9 H 12 ), alkylbenzenes containig С 4 ÷<С 7 side chains 20,4 Naphthalene, its derivatives and other aromatics Naphthalene (С 10 H 8 ), methylnaphthalenes (С 11 H 10 ), dimethylnaphthalenes (С 12 H 12 ) 9,1 O- containing compounds Carbonyl compounds Aldehydes: acetaldehyde (CH 3 CHO) and others, cetones: acetone (С 3 H 6 O) and others. 2,2 Other O-containing compounds Alcohols, furan (С 4 H 4 O) and its derivatives 2,4 S- containing compounds - Thiophene (С 4 H 4 S) and alkylthiophenes with С 2 ÷>C 4 side chains, benzothiophene, dimethyldisulfide CH 3 S-SCH 3 4,0 N- containing compounds - Nitriles (acetonitrile CH 3 CN, benzonitrile C 6 H 5 CN), pyridine (C 5 H 5 N) and its derivatives 0,9 Total: Total:100

11. Comparison of abundances of different subclasses of OC in products of thermodesorption at 460°С of Murchison and Kainsaz

12. Comparison of products which are produced during pyrolysis (at 900°С) of Murchison and Kainsaz meteorites Components and groups of components MurchisonKainsaz CO 2 ++ SO 2 +- Methylmercaptane CH 3 SH +- Isoprene (С 5 H 8 ) +- Acetonitrile (CH 3 CN) +- Benzene (С 6 H 6 ) ++ Toluene (C 7 H 8 ) ++ Xylenes and other alkylbenzenes ++ Naphthalene (С 10 H 8 ) ++ Alkanes >C 10 ++

13. Summary: We have measured ~200 organic compounds in products of thermodesorption (460ºС) of Murchison (CM2) and Kainsaz (CO3) carbonaceous chondrites. Some biochemically important compounds (e.g. amino acids) were not targeted in this step of investigation. OC are qualitatively similar in composition for both Murchison and Kainsaz, though Murchison has higher abundance and diversity of OC rather than Kainsaz. This is consistent with the higher metamorphic temperatures of the Kainsaz (453±29ºC) compared to the Murchison (96±65 ºС) which resulted in depletion of volatile organics. Organic sulfides (methylmercaptane and dimethylsulfide) were measured in the Murchison thermodesorption products but were absent for Kainsaz. This observation may indicate the absence of sulfide and disulfide bridges in the Kainsaz OC, which bounds fragments of high-molecular OC (result of high metamorphic temperatures). Such OC as acetonitrile and isoprene were also absent in the Kainsaz pyrolysis products contrary to that of the Murchison and are probably lost due to defragmentation of kerogen during thermal metamorphism. Based on the pyrolysis results, high-molecular polymerized OC (kerogen) of the carbonaceous chondrites can be characterized as blocks of high-condensed aromatic structures with functional groups, which are bound by hydrocarbon- and sulfur-containing bridges.

14. Comparison of abundances of different subclasses of OC in products of thermodesorption at 460°С of Kainsaz and the condensate from its impact-simulated high-temperature vaporization

15. Main characteristics of high-temperature products of impact- simulated vaporization of Murchison and Kainsaz: high qualitative similarity of OC in starting meteorites and in their experimentally produced condensates; high qualitative similarity of OC in starting meteorites and in their experimentally produced condensates; high abundance of CO 2 and SO 2 ; high abundance of CO 2 and SO 2 ; higher concentration of acetonitrile, furan group compounds, various thiophene derivatives, compared to starting meteorites thermodesorption products; higher concentration of acetonitrile, furan group compounds, various thiophene derivatives, compared to starting meteorites thermodesorption products;

16. Conclusions: endogenous OC delivered to the Ganymede surface by falling meteorites can be represented by a wide diversity of hydrocarbons, O-, S-, and N- containing compounds; endogenous OC delivered to the Ganymede surface by falling meteorites can be represented by a wide diversity of hydrocarbons, O-, S-, and N- containing compounds; being fragmented from a high-condensed kerogen-like material, OC can be presented by a sufficiently complex molecules; being fragmented from a high-condensed kerogen-like material, OC can be presented by a sufficiently complex molecules; biologically important molecules like amino acids and nucleobases can be also delivered by carbonaceous chondrites/comets; biologically important molecules like amino acids and nucleobases can be also delivered by carbonaceous chondrites/comets; impact-induced high-temperature processing of meteoritic material does not change qualitatively the pattern of delivered OC; impact-induced high-temperature processing of meteoritic material does not change qualitatively the pattern of delivered OC; we need to elaborate composition- and isotope- based criteria to discriminate between endogenous and exogenous OC; we need to elaborate composition- and isotope- based criteria to discriminate between endogenous and exogenous OC; try to find fresh ices to avoid exogenous contamination. try to find fresh ices to avoid exogenous contamination.