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Julian Chela-Flores

Julian Chela-Flores The Abdus Salam ICTP, Trieste, Italia and Instituto de Estudios Avanzados, Caracas, Republica Bolivariana de Venezuela. Can a future mission detect a habitable ecosystem on Europa, or Ganymede?. The Europa Jupiter System Mission (EJSM). Io. EJSM (JEO). Europa. EJSM (JGO).

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Julian Chela-Flores

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  1. Julian Chela-Flores • The Abdus Salam ICTP, Trieste, Italia and Instituto de Estudios Avanzados, Caracas, Republica Bolivariana de Venezuela Can a future mission detect a habitable ecosystem on Europa, or Ganymede?

  2. The Europa Jupiter System Mission (EJSM) Io EJSM (JEO) Europa EJSM (JGO) Callisto Ganymede

  3. Top questions: The search for habitable ecosystems (a question in geochemistry, 1970s, Vikings). The search for the origin of life itself (a question in chemical evolution, 1920).

  4. Top questions: • The search for habitable ecosystems • (a question in geochemistry, 1970s, Vikings). The search for the origin of life itself (a question in chemical evolution, 1920).

  5. Can we identify reliable biomarkers on Europa with EJSM?

  6. Oceans in contact with silicate cores in the Solar System Ice-core interface • Working hypothesis: The ocean-core interface can provide a variety of chemical elements for sustaining life. Ocean-core interface Europa Earth

  7. The geochemistry of Europa: 1. Stained icy surface ______________________________ There is a unique opportunity to focus on another Earth-like world with EJSM by probing 1 and confirming 2: ________________________________ 2. Liquid ocean in contact with its silicate core

  8. Plan of the talk Analysis: • 1. The stained icy surface of Europa. • 2. The liquid Europan ocean in contact with its silicate core. Conclusions: • Instrumentation for identifying reliable biomarkers. • An EJSM test for a habitable ecosystem on Europa.

  9. 1. The stained icy surface of Europa International Journal of Astrobiology (April, 2010) (Cambridge University Press).

  10. There are alternative views on the effect of space weather on the surficial patches. But S is common to both interpretations of the radiation-induced S-cycles produced on the surface. Galileo Mission, 1995-2003

  11. To get insights into the significance of the sulfur patches on the icy surface of Europa, we should look at the sulfur patches on icy terrestrial surfaces.

  12. What do we know about sulfur icy patches on Earth? Antarctica

  13. C: Canada Glacier F: Lake Fryxell H: Lake Hoare Taylor Valley

  14. Underneath the surface of these lakes Algal mat pieces

  15. The icy surface of Lake Hoare (Taylor Valley) Algal mat pieces Algal mat pieces on the surface of Lake Hoare (Parker et al, Phycologia, 1982) Algal mat pieces

  16. Biogenic sulfur on the icy surfaces of Taylor valley lakes [Annual escape of biogenic sulfur (kg)] The larger Taylor Valley lakes ( ) (1.8 sq. km) (5.4 sq.km)

  17. 2. Implications of Europa’s ocean in contact with its silicate core. • External Jovian magnetosphere source, is excluded due to the patchy nature of the stains. • Internal source: Cryovolcanism, or biogenic. • Geochemistry allows to select between these two possibilities.

  18. The biogenic hypothesis

  19. Sulfate-reducing bacteria 4H2 + H2SO4 –» H2S + 4H2O + 39 kilocalories • The H2S then combines with Fe in sediments to form grains of the biogenic mineral pyrite. • Unite H with S atoms from dissolved sulfate ( SO4-2 ) of seawater to form hydrogen sulfide H2S : Iron sulfide, FeS2

  20. Processing sulfur in the Solar System Microbial single-step large sulfur fractionation • Dissolved sulfate: on evaporation sulfate minerals are depleted of 32S by 20 per mil. • The H2S given off by S-hungry bacteria is enriched in 32S by 20 per mil. Large depletion:

  21. Biogenic S on icy surfaces • Large, and even extreme depletion of sulfur takes place on terrestrial ecosystems. The delta34S-parameter Terrestrial Modern sulfate coexisting with ocean water (21 per mill) • 70 per mill • (extreme fractionation) • The Integrated Ocean-Drilling Program (IODP) while exploring terrestrial structure has identified extreme fractionation on the Australian seafloor. Meteoritic Lunar (per mill) (per mill)

  22. Instrumentation required for identifying reliable biomarkers Credit: British Consortium

  23. Penetrators for probing Europa’s icy surface Credit: British Consortium

  24. Penetrators should be inserted in the EJSM orbital probes: JEO and JGO. Gowen et al., 2009

  25. To answer what is the meaning of the Europan icy patches we should go beyond measurements from JEO alone for detection of biomarkers.

  26. Both JEO and JGO can test biogenicity with two sets of penetrators lower values of 34S. JGO +penetrator JEO +penetrator Europa, NASA Ganymede, ESA

  27. An EJSM test for a habitable ecosystem on Europa • We expect diverging results from mass spectrometry: — large minus d34S for Europa, and — small minus d34S for Ganymede. • Such data would provide a test of a habitable ecosystem on Europa.

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