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Laboratory predictions for the night-side surface ice glow of Europa


Europa’s surface continuously experiences high fluxes of charged particles due to the presence of Jupiter’s strong magnetic field. These high-energy charged particles, including electrons, interact with the ice- and salt-rich surface, resulting in complex physical and chemical processes. Here, we report that Europa ice analogues emit characteristic spectral signatures in the visible region when exposed to high-energy electron radiation. The strongest emission (ice glow) we observed was centred at ~525 nm. We found that the presence of sodium chloride and carbonate strongly quenched, while epsomite enhanced, the radiation-induced ice glow. These emission characteristics could be used to determine the chemical composition of Europa’s surface during night-time low-altitude fly-bys of spacecraft such as the Europa Clipper. We estimate that the Europa Clipper Wide Angle Camera could record between 500 and 280,000 counts per second through different colour filters, depending on the chemical composition of Europa’s surface. Though we focus here on Europa, our study may be relevant to other bodies exposed to high doses of ionizing radiation, such as Io and Ganymede. With its extreme radiation environment, rich surface geology and compositional diversity, the radiation-induced ice glow on Europa could enable more precise surface characterization and provide unique night-time views.

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Fig. 1: Visible light emission from a crystalline water-ice core cooled to 100 K by liquid nitrogen flow as it was being irradiated by 10.5 MeV electrons.
Fig. 2: Electron energy and flux dependence of water ice luminescence under simulated Europa surface conditions.
Fig. 3: MeV electron-induced ice glow from salty ice surfaces.
Fig. 4: Effect of temperature on electron-induced emission from water ice.
Fig. 5: Estimates of signals to be detected by the WAC pixels from Europa’s surface ice glow based on analogue laboratory studies.

Data availability

The data that support the figures and table within this paper and other findings of this study are available from the corresponding author upon reasonable request. Source data are provided with this paper.


  1. 1.

    Clark, K. et al. Return to Europa: overview of the Jupiter Europa orbiter mission. Adv. Space Res. 48, 629–650 (2011).

    ADS  Google Scholar 

  2. 2.

    Hand, K. P., Carlson, R. W. & Chyba, C. F. Energy, chemical disequilibrium, and geological constraints on Europa. Astrobiology 7, 1006–1022 (2007).

    ADS  Google Scholar 

  3. 3.

    Pappalardo, R. T. et al. Does Europa have a subsurface ocean? Evaluation of the geological evidence. J. Geophys. Res. 104, 24015–24055 (1999).

    ADS  Google Scholar 

  4. 4.

    Pappalardo, R. T., McKinnon, W. B. & Khurana, K. (eds) Europa (Univ. of Arizona Press, 2009).

  5. 5.

    Pappalardo, R. T. et al. Science potential from a Europa lander. Astrobiology 13, 740–773 (2013).

    ADS  Google Scholar 

  6. 6.

    Nordheim, T. A., Hand, K. P. & Paranicas, C. Preservation of potential biosignatures in the shallow subsurface of Europa. Nat. Astron. 2, 673–679 (2018).

    ADS  Google Scholar 

  7. 7.

    Patterson, G. W., Paranicas, C. & Prockter, L. M. Characterizing electron bombardment of Europa’s surface by location and depth. Icarus 220, 286–290 (2012).

    ADS  Google Scholar 

  8. 8.

    Dalton, J. III et al. Exogenic controls on sulfuric acid hydrate production at the surface of Europa. Planet. Space Sci. 77, 45–63 (2013).

    ADS  Google Scholar 

  9. 9.

    Fanale, F. P. et al. Tyre and Pwyll: Galileo orbital remote sensing of mineralogy versus morphology at two selected sites on Europa. J. Geophys. Res. Planets 105, 22647–22655 (2000).

    ADS  Google Scholar 

  10. 10.

    Hanley, J., Chevrier, V. F., Barrows, R. S., Swaffer, C. & Altheide, T. S. Near- and mid-infrared reflectance spectra of hydrated oxychlorine salts with implications for Mars. J. Geophys. Res. Planets 120, 1415–1426 (2015).

    ADS  Google Scholar 

  11. 11.

    Hanley, J., Dalton, J. B., Chevrier, V. F., Jamieson, C. S. & Barrows, R. S. Reflectance spectra of hydrated chlorine salts: the effect of temperature with implications for Europa. J. Geophys. Res. Planets 119, 2370–2377 (2014).

    ADS  Google Scholar 

  12. 12.

    Ligier, N., Poulet, F., Carter, J., Brunetto, R. & Gourgeot, F. VLT/SINFONI observations of Europa: new insights into the surface composition. Astron. J. 151, 163 (2016).

    ADS  Google Scholar 

  13. 13.

    Shirley, J. H., Dalton, J. B., Prockter, L. M. & Kamp, L. W. Europa’s ridged plains and smooth low albedo plains: distinctive compositions and compositional gradients at the leading side-trailing side boundary. Icarus 210, 358–384 (2010).

    ADS  Google Scholar 

  14. 14.

    Sparks, W. B. et al. Hubble Space Telescope observations of Europa in and out of eclipse. Int. J. Astrobiol. 9, 265–271 (2010).

    ADS  Google Scholar 

  15. 15.

    de Kleer, K. & Brown, M. E. Europa’s optical aurora. Astron. J. 156, 167 (2018).

    ADS  Google Scholar 

  16. 16.

    Roth, L. et al. Europa’s far ultraviolet oxygen aurora from a comprehensive set of HST observations. J. Geophys. Res. Space Phys. 121, 2143–2170 (2016).

    ADS  Google Scholar 

  17. 17.

    Grossweiner, L. I. & Matheson, M. S. Fluorescence and thermoluminescence of ice. J. Chem. Phys. 22, 1514–1526 (1954).

    ADS  Google Scholar 

  18. 18.

    Nash, D. B., Matson, D. L., Johnson, T. V. & Fanale, F. P. Na-D line emission from rock specimens by proton bombardment: implications for emissions from Jupiter’s satellite Io. J. Geophys. Res. 80, 1875–1879 (1975).

    ADS  Google Scholar 

  19. 19.

    Nelson, R. M. & Nash, D. B. Spectral reflectance change and luminescence of selected salts during 2–10 KeV proton bombardment: implications for Io. Icarus 39, 277–285 (1979).

    ADS  Google Scholar 

  20. 20.

    Buxton, G. V., Gillis, H. A. & Klassen, N. V. Two types of localized excess electrons in crystalline D2O ice. Can. J. Chem. 55, 2385–2395 (1977).

    Google Scholar 

  21. 21.

    Sitharamarao, D. & Duncan, J. Molecular excitation of water by γ-irradiation. J. Phys. Chem. 67, 2126–2132 (1963).

    Google Scholar 

  22. 22.

    Miyazaki, T., Kamiya, Y., Fueki, K. & Yasui, M. New band of emission from high-energy-electron-irradiated ice at very low temperature. J. Phys. Chem. 96, 9558–9561 (1992).

    Google Scholar 

  23. 23.

    Henderson, B. L., Gudipati, M. S. & Bateman, F. B. Leeb hardness of salty Europa ice analogs exposed to high-energy electrons. Icarus 322, 114–120 (2019).

    ADS  Google Scholar 

  24. 24.

    Grossweiner, L. I. & Matheson, M. S. Luminescence of ice and tritiated ice. J. Chem. Phys. 20, 1654–1655 (1952).

    ADS  Google Scholar 

  25. 25.

    Ghormley, J. A. Luminescence of ice subjected to ionizing radiation. J. Chem. Phys. 24, 1111–1112 (1956).

    ADS  Google Scholar 

  26. 26.

    Steen, H. B. Radioluminescence of H2O and D2O ice spectral characteristics. Chem. Phys. Lett. 35, 508–510 (1975).

    ADS  Google Scholar 

  27. 27.

    Petrik, N. G. & Kimmel, G. A. Low-energy electron-stimulated luminescence of thin H2O and D2O layers on Pt(111). J. Phys. Chem. B 109, 15835–15841 (2005).

    Google Scholar 

  28. 28.

    Kimmel, G. A., Orlando, T. M., Cloutier, P. & Sanche, L. Low-energy (5–40 eV) electron-stimulated desorption of atomic hydrogen and metastable emission from amorphous ice. J. Phys. Chem. B 101, 6301–6303 (1997).

    Google Scholar 

  29. 29.

    Quickenden, T. I., Trotman, S. M. & Sangster, D. F. Pulse radiolytic studies of the ultraviolet and visible emissions from purified H2O ice. J. Chem. Phys. 77, 3790–3802 (1982).

    ADS  Google Scholar 

  30. 30.

    Miyazaki, T., Nagasaka, S., Kamiya, Y. & Tanimura, K. Formation of excited hydroxyl radicals in high-energy-electron-irradiated ice at very low temperature. J. Phys. Chem. 97, 10715–10719 (1993).

    Google Scholar 

  31. 31.

    Matich, A. J., Bakker, M. G., Lennon, D., Quickenden, T. I. & Freeman, C. G. Oxygen luminescence from UV-excited (H2O and D2O) ices. J. Phys. Chem. 97, 10539–10553 (1993).

    Google Scholar 

  32. 32.

    Gudipati, M. S. & Kalb, M. Rydberg and charge-transfer states of atomic oxygen in Ar and Kr matrices: identification of two distinct sites. Chem. Phys. Lett. 307, 27–34 (1999).

    ADS  Google Scholar 

  33. 33.

    Park, S. H., Hyun, J. Y. & Shin, I. A lysosomal chloride ion-selective fluorescent probe for biological applications. Chem. Sci. 10, 56–66 (2019).

    Google Scholar 

  34. 34.

    Takeuchi, T. & Sumida, J. Indirect detection of halide ions via fluorescence quenching of quinine sulfate in microcolumn ion chromatography. Anal. Sci. 20, 983–985 (2004).

    Google Scholar 

  35. 35.

    Ryan, K. J., Pool, J., Lovelady, H. & Osterman, S. N. Design, fabrication, and test of a patterned optical filter array for the Europa Imaging System (EIS). Proc. SPIE 10706, 1070655 (2018).

    Google Scholar 

  36. 36.

    Turtle, E. et al. The Europa Imaging System (EIS): high-resolution, 3-D insight into Europa’s geology, ice shell, and potential for current activity. EPSC Abstracts 13, EPSC-DPS2019-832-2 (2019).

    Google Scholar 

  37. 37.

    Paranicas, C., Cooper, J. F., Garrett, H. B., Johnson, R. E. & Sturner, S. J. in Europa (eds Pappalardo, R. T. et al.) 529–544 (Univ. of Arizona Press, 2009).

  38. 38.

    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).

    ADS  Google Scholar 

  39. 39.

    Jun, I., Garrett, H. B., Swimm, R., Evans, R. W. & Clough, G. Statistics of the variations of the high-energy electron population between 7 and 28 jovian radii as measured by the Galileo spacecraft. Icarus 178, 386–394 (2005).

    ADS  Google Scholar 

  40. 40.

    Hirano, Y. & Yamamoto, S. Estimation of the fractions of luminescence of water at higher energy than Cerenkov-light threshold for various types of radiation. J. Biomed. Opt. 24, 066005 (2019).

    ADS  Google Scholar 

  41. 41.

    Cessateur, G., Barthelemy, M. & Peinke, I. Photochemistry-emission coupled model for Europa and Ganymede. J. Space Weather Space Clim. 6, A17 (2016).

    ADS  Google Scholar 

  42. 42.

    Zappala, G. et al. Set-up and methods for SiPM Photo-Detection Efficiency measurements. J. Instrum. 11, P08014 (2016).

    Google Scholar 

  43. 43.

    Janesick, J. et al. Mk x Nk gated CMOS imager. SPIE Opt. Eng. Appl. 9211, 921106 (2014).

    Google Scholar 

  44. 44.

    Gallina, G. et al. Characterization of SiPM avalanche triggering probabilities. IEEE Trans. Electron Dev. 66, 4228–4234 (2019).

    ADS  Google Scholar 

  45. 45.

    Hsieh, C. A., Tsai, C. M., Tsui, B. Y., Hsiao, B. J. & Lin, S. D. Photon-detection-probability simulation method for CMOS single-photon avalanche diodes. Sensors 20, 436 (2020).

    Google Scholar 

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This work was supported by JPL’s internal R&TD funds as well as funding from NASA Solar System Workings and Habitable Worlds Programs. Experiments were performed at the NIST and data analysed at JPL. This work was conducted by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Certain commercial equipment is identified in this paper to adequately describe the experimental procedure. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology or the Jet Propulsion Laboratory, California Institute of Technology.

Author information




M.S.G. conceived the idea. M.S.G. and B.L.H. conducted the experimental work at NIST. B.L.H. and M.S.G. conducted the data analysis. M.S.G. and B.L.H. wrote the manuscript. F.B.B. provided experimental support, beam operations and monitoring of the electron flux.

Corresponding author

Correspondence to Murthy S. Gudipati.

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The authors declare no competing interests.

Additional information

Peer review information Nature Astronomy thanks Timothy Cassidy and Anna Pollmann for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 An example of an original raw emission spectrum (red line) showing spikes caused by the high-energy MeV electron radiation environment in spite of shielding by lead bricks.

These spikes are effectively removed by percentile filter option in the Origin Labs plotting program. Processed spectrum is shown below the raw spectrum (black line). Spectra are displaced along y-axis for visibility. Source data

Supplementary information

Supplementary Data 1

Describes computational steps to convert lab data into counts per second at the WAC, estimates of aurorae counts.

Source data

Source Data Fig. 2

Raw data, normalization, smoothing and calibrations.

Source Data Fig. 3

Ascii data.

Source Data Fig. 4

Raw data, normalization, smoothing and calibrations.

Source Data Fig. 5

Ascii data.

Source Data Extended Data Fig. 1

Ascii data.

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Gudipati, M.S., Henderson, B.L. & Bateman, F.B. Laboratory predictions for the night-side surface ice glow of Europa. Nat Astron 5, 276–282 (2021).

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