Abstract
Jupiter’s moon Europa, which is thought to possess a large liquid water ocean beneath its icy crust, is one of the most compelling targets in the search for life beyond Earth. Its geologically young surface, along with a number of surface features, indicate that material from Europa’s interior may be emplaced on the surface. However, the surface is affected by the harsh radiation environment of Jupiter’s magnetosphere, which over time may lead to chemical alteration and destruction of potential biosignatures. We show that radiation dose rates are highly dependent on surface location. Radiation processing and destruction of potential biosignatures is found to be significant down to depths of ~1 cm in mid- to high-latitude regions, and to depths of 10–20 cm within ‘radiation lenses’ centred on the leading and trailing hemispheres. These results indicate that future missions to Europa’s surface do not need to excavate material to great depths to investigate the composition of endogenic material and search for potential biosignatures.
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References
Chyba, C. F. Energy for microbial life on Europa. Nature 403, 381–382 (2000).
Chyba, C. F. & Hand, K. P. Life without photosynthesis. Science 292, 2026–2027 (2001).
Hand, K. P., Carlson, R. W. & Chyba, C. F. Energy, chemical disequilibrium, and geological constraints on Europa. Astrobiology 7, 1006–1022 (2007).
Carr, M. H. et al. Evidence for a subsurface ocean on Europa. Nature 391, 363–365 (1998).
Pappalardo, R., Belton, M. & Breneman, H. Does Europa have a subsurface ocean? Evaluation of the geological evidence. J. Geophys. Res. 104, 15–24 (1999).
Squyres, S. W., Reynolds, R. T., Cassen, P. M. & Peale, S. J. Liquid water and active resurfacing on Europa. Nature 301, 225–226 (1983).
Bierhaus, E. B., Zahnle, K. & Chapman, C. R. in Europa (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K. K.) 161–180 (Univ. Arizona Press, Tucson, 2009).
Zahnle, K., Schenk, P., Levison, H. & Dones, L. Cratering rates in the outer solar system. Icarus 163, 263–289 (2003).
Greenberg, R. et al. Chaos on Europa. Icarus 141, 263–286 (1999).
O’Brien, D., Geissler, P. & Greenberg, R. A melt-through model for chaos formation on Europa. Icarus 156, 152–161 (2002).
Schmidt, B. E., Blankenship, D. D., Patterson, G. W. & Schenk, P. M. Active formation of ‘chaos terrain’ over shallow subsurface water on Europa. Nature 479, 502–505 (2011).
Roth, L. et al. Transient water vapor at Europa’s south pole. Science 343, 171–174 (2014).
Sparks, W. B. et al. Active cryovolcanism on Europa? Astrophys. J. 839, L18 (2017).
Sparks, W. B. et al. Probing for evidence of plumes on Europa with HST/STIS. Astrophys. J. 829, 121 (2016).
Pappalardo, R. T. et al. Science potential from a Europa lander. Astrobiology 13, 740–773 (2013).
Hand, K. P., Murray, A. E. & Garvin, J. B. Europa Lander Study 2016 Report (NASA, 2017).
Paranicas, C., Carlson, R. W. & Johnson, R. E. Electron bombardment of Europa. Geophys. Res. Lett. 28, 673–676 (2001).
Cooper, J. F., Johnson, R. E., Mauk, B. H., Garrett, H. B. & Gehrels, N. Energetic ion and electron irradiation of the icy Galilean satellites. Icarus 149, 133–159 (2001).
Patterson, G. W., Paranicas, C. & Prockter, L. M. Characterizing electron bombardment of Europa’s surface by location and depth. Icarus 220, 286–290 (2012).
Paranicas, C., Cooper, J. F., Garrett, H. B., Johnson, R. E. & Sturner, S. J. in Europa (eds Pappalardo, R. T., Mckinnon, W. B. & Khurana, K. K.) 529–544 (Univ. Arizona Press, Tucson, 2009).
Dalton, J. B. et al. Exogenic controls on sulfuric acid hydrate production at the surface of Europa. Planet. Space Sci. 77, 45–63 (2013).
Pospieszalska, M. & Johnson, R. Magnetospheric ion bombardment profiles of satellites: Europa and Dione. Icarus 78, 1–13 (1989).
Cassidy, T. A. et al. Magnetospheric ion sputtering and water ice grain size at Europa. Planet. Space Sci. 77, 64–73 (2013).
Nordheim, T. A. et al. The near-surface electron radiation environment of Saturn’s moon Mimas. Icarus 286, 56–68 (2017).
Kivelson, M. G. et al. Galileo magnetometer measurements: a stronger case for a subsurface ocean at Europa. Science 289, 1340–1343 (2000).
Saur, J., Strobel, D. F. & Neubauer, F. M. Interaction of the Jovian magnetosphere with Europa: constraints on the neutral atmosphere. J. Geophys. Res. 103, 19947–19962 (1998).
Schilling, N., Neubauer, F. M. & Saur, J. Time-varying interaction of Europa with the jovian magnetosphere: constraints on the conductivity of Europa’s subsurface ocean. Icarus 192, 41–55 (2007).
Schilling, N., Neubauer, F. M. & Saur, J. Influence of the internally induced magnetic field on the plasma interaction of Europa. J. Geophys. Res. 113, A03203 (2008).
Khurana, K., Kivelson, M., Hand, K. P. & Russell, C. T. in Europa (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K. K.) 545–586 (Univ. Arizona Press, Tucson, 2009).
Barnett, I. L., Lignell, A. & Gudipati, M. S. Survival depth of organics in ices under low - energy electron radiation (2 keV). Astrophys. J. 747, 13–11 (2012).
Divine, N. & Garrett, H. B. Charged particle distributions in Jupiter’s magnetosphere. J. Geophys. Res. Sp. Phys. 88, 6889–6903 (1983).
de Pater, I. & Dunn, D. E. VLA observations of Jupiter’s synchrotron radiation at 15 and 22 GHz. Icarus 163, 449–455 (2003).
Dessler, A. J. Mass-injection rate from Io into the Io plasma torus. Icarus 44, 291–295 (1980).
Paranicas, C., Mauk, B. & Ratliff, J. The ion environment near Europa and its role in surface energetics. Geophys. Res. Lett. 29, 10–13 (2002).
Johnson, R. E. et al. in Jupiter: The Planet, Satellites and Magnetosphere (eds Bagenal, F., Dowling, T. E. & Mckinnon, W. B.) 483–508 (Cambridge Univ. Press, Cambridge, 2004).
Nordell, B. & Brahme, A. Angular distribution and yield from bremsstrahlung targets (for radiation therapy). Phys. Med. Biol. 29, 797–810 (1984).
Moore, J. M. et al. in Europa (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K. K.) 329–349 (Univ. Arizona Press, Tucson, 2009).
Summons, R. E., Albrecht, P., McDonald, G. & Moldowan, J. M. Molecular biosignatures. Space Sci. Rev. 135, 133–159 (2008).
Dahl, J., Hallberg, R. & Kaplan, I. R. Effects of irradiation from uranium decay on extractable organic matter in the Alum Shales of Sweden. Org. Geochem. 12, 559–571 (1988).
Dartnell, L. R., Desorgher, L., Ward, J. M. & Coates, A. J. Modelling the surface and subsurface Martian radiation environment: Implications for astrobiology. Geophys. Res. Lett. 34, L02207 (2007).
Dartnell, L. R., Desorgher, L., Ward, J. M. & Coates, A. J. Martian sub-surface ionising radiation: biosignatures and geology. Biogeosciences 4, 545–558 (2007).
Fujii, Z. & McDonald, F. B. Radial intensity gradients of galactic cosmic rays (1972–1995) in the heliosphere. J. Geophys. Res. 102, 24201 (1997).
Morales-Olivares, O. G. & Caballero-Lopez, R. A. Radial and latitudinal gradients of galactic cosmic rays in the heliosphere at solar maximum. Adv. Sp. Res. 46, 1313–1317 (2010).
Selesnick, R. S. Cosmic ray access to Jupiter’s magnetosphere. Geophys. Res. Lett. 29, 12-1–12-4 (2002).
Kminek, G. & Bada, J. L. The effect of ionizing radiation on the preservation of amino acids on Mars. Earth Planet. Sci. Lett. 245, 1–5 (2006).
Evans, N. L., Bennett, C. J., Ullrich, S. & Kaiser, R. I. on the interaction of adenine with ionizing radiation: mechanistical studies and astrobiological implications. Astrophys. J. 730, 69 (2011).
Gerakines, P. A. & Hudson, R. L. Glycine’s radiolytic destruction in ices: first in situ laboratory measurements for Mars. Astrobiology 13, 647–655 (2013).
Gerakines, P. A., Hudson, R. L., Moore, M. H. & Bell, J. L. In situ measurements of the radiation stability of amino acids at 15–140 K. Icarus 220, 647–659 (2012).
Thomsen, M. F. & Van Allen, J. A. Motion of trapped electrons and protons in Saturn’s inner magnetosphere. J. Geophys. Res. 85, 5831 (1980).
Paterson, W. R., Frank, L. A. & Ackerson, K. L. Galileo plasma observations at Europa: ion energy spectra and moments. J. Geophys. Res. Sp. Phys. 104, 22779–22791 (1999).
Bagenal, F. et al. Plasma conditions at Europa’s orbit. Icarus 261, 1–13 (2015).
Roussos, E. et al. Electron microdiffusion in the Saturnian radiation belts: Cassini MIMI/LEMMS observations of energetic electron absorption by the icy moons. J. Geophys. Res. 112, A06214 (2007).
Desorgher, L., Flückiger, E. O., Gurtner, M., Moser, M. R. & Bütikofer, R. Atmocosmics: A Geant 4 code for computing the interaction of cosmic rays with the Earth’s atmosphere. Int. J. Mod. Phys. A 20, 6802–6804 (2005).
Agostinelli, S. et al. Geant4—a simulation toolkit. Nucl. Instrum. Methods Phys. Res. Sect. A 506, 250–303 (2003).
Acknowledgements
T.A.N. was supported by an appointment to the NASA Postdoctoral Fellowship Program at the Jet Propulsion Laboratory administered by Oak Ridge Associated Universities and Universities Space Research Association through a contract with NASA. K.P.H. acknowledges support from the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. T.A.N. and K.P.H. acknowledge the support of the Cassini Data Analysis Program (NNN13D466T).
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T.A.N. carried out the modelling of energetic electron and proton interactions at the surface of Europa as well as calculation of amino acid destruction rates. C.P. provided fit functions for the electron and proton spectra at Europa as well as guidance on the modelling of energetic electron access to Europa’s surface. K.P.H. provided overall guidance on the execution of the research as well as providing key inputs on the discussion of biosignature destruction at Europa. All authors contributed to the writing of the manuscript.
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Nordheim, T.A., Hand, K.P. & Paranicas, C. Preservation of potential biosignatures in the shallow subsurface of Europa. Nat Astron 2, 673–679 (2018). https://doi.org/10.1038/s41550-018-0499-8
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DOI: https://doi.org/10.1038/s41550-018-0499-8
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