Exogenic controls on sulfuric acid hydrate production at the surface of Europa

Dalton, J. B.; Cassidy, Timothy A.; Paranicas, C.; Shirley, James H.; Prockter, L. M.; Kamp, L. W.

doi:10.1016/j.pss.2012.05.013

Cited by 81 publications

(165 citation statements)

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“…(Note that the basemap in Figure 3 is a mesh of various resolutions, and not a good indicator of visible albedo at low resolution.) This transition occurs near 0 W and 180 W, consistent with global patterns of sulfur bombardment and electron irradiation (Dalton et al 2013). This is further evidence for the distinct nature of the dominant hydrates between the leading and trailing hemisphere, and may serve as a clue for a future spectral modeling investigation.…”

Section: Resultssupporting

confidence: 71%

“…The ratio map (Figure 3, top) is the most spatially coherent, showing the strongest 3.7 μm peak amplitude at the leading hemisphere equatorial latitudes, decreasing in amplitude uniformly outward. This distribution is consistent and anti-correlated with global patterns of electron irradiation (Dalton et al 2013) and sputtering rate ). This at first suggests a simple grain size interpretation, in which irradiation amorphizes water ice producing larger grain sizes and weaker 3 μm bands.…”

Section: Resultssupporting

confidence: 66%

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SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA’S LARGE-SCALE COMPOSITIONAL UNITS AT 3–4 μm WITH KECK NIRSPEC

Fischer

Brown

Trumbo

et al. 2016

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We present spatially resolved spectroscopic observations of Europa's surface at 3-4 μm obtained with the nearinfrared spectrograph and adaptive optics system on the Keck II telescope. These are the highest quality spatially resolved reflectance spectra of Europa's surface at 3-4 μm. The observations spatially resolve Europa's large-scale compositional units at a resolution of several hundred kilometers. The spectra show distinct features and geographic variations associated with known compositional units; in particular, large-scale leading hemisphere chaos shows a characteristic longward shift in peak reflectance near 3.7 μm compared to icy regions. These observations complement previous spectra of large-scale chaos, and can aid efforts to identify the endogenous nonice species.

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Section: Resultssupporting

confidence: 71%

Section: Resultssupporting

confidence: 66%

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA’S LARGE-SCALE COMPOSITIONAL UNITS AT 3–4 μm WITH KECK NIRSPEC

Fischer

Brown

Trumbo

et al. 2016

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“…As already mentioned above, Ding et al (2013) have demonstrated experimentaly that magnetospheric sulfur ions implanted in Europa's surface produce hydrated sulfuric acid. The production rate is high enough to explain the quantity of hydrated sulfuric acid on the surface of Europa inferred to be present by modelling the near infrared (2 µm) water ice band (Dalton et al 2013) as observed by Galileo the Near-Infrared Mapping Spectrometer (NIMS). However, the bands due to hydrated sulfuric acid in the laboratory spectra of sulfur-implanted water ice targets appear in the 1100 cm −1 region (see Fig.…”

Section: Solar System Objectsmentioning

confidence: 99%

Thermal and energetic processing of astrophysical ice analogues rich in SO₂

Kaňuchová

Boduch

Domaracka

et al. 2017

A&A

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Context. Sulfur is an abundant element in the cosmos and it is thus an important contributor to astrochemistry in the interstellar medium and in the solar system. Astronomical observations of the gas and of the solid phases in the dense interstellar/circumstellar regions have evidenced that sulfur is underabundant. The hypothesis to explain such a circumstance is that it is incorporated in some species in the solid phase (i.e. as frozen gases and/or refractory solids) and/or in the gas phase, which for different reasons have not been observed so far. Aims. Here we wish to give a contribution to the field by studying the chemistry induced by thermal and energetic processing of frozen mixtures of sulfur dioxide (one of the most abundant sulfur-bearing molecules observed so far) and water. Methods. We present the results of a series of laboratory experiments concerning thermal processing of different H 2 O:SO 2 mixtures and ion bombardment (30 keV He + ) of the same mixtures. We used in situ Fourier transform infrared (FTIR) spectroscopy to investigate the induced effects. Results. The results indicate that ionic species such as HSO − 3 , HSO − 4 , and S 2 O 2− 5 are easily produced. Energetic processing also produces SO 3 polymers and a sulfurous refractory residue. Conclusions. The produced ionic species exhibit spectral features in a region that, in astronomical spectra of dense molecular clouds, is dominated by strong silicate absorption. However, such a dominant feature is associated with some spectral features, some of which have not yet been identified. We suggest adding the sulfur-bearing ionic species to the list of candidates to help explain some of those features. In addition, we suggest that once expelled in the gas phase by sublimation, due to the temperature increase, and/or by non-thermal erosion those species would constitute a class of molecular ions not detected so far. We also suggest that molecular sulfur-bearing ions could be present on the surfaces and/or in the atmospheres of several objects in the solar system, for example icy satellites of the giant planets and comets.

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“…Both mirabilite and epsomite have been invoked to explain features in the near-infrared reflectance spectra of Europa. Linear mixture modeling of Galileo NIMS spectra has identified magnesium and sodium sulfate salts in varying concentrations across Europa's terrains (McCord et al 1998;Dalton et al 2005Dalton et al , 2013Dalton 2007;Carlson et al 2009;Dalton & Pitman 2012). Brown & Hand (2013) have tentatively identified epsomite in ground-based infrared spectra of Europa obtained from the Keck telescope by its 2.07 μm absorption.…”

Section: Implication For Europamentioning

confidence: 99%

“…Previous theoretical and experimental simulations (Fanale et al 2001;Zolotov & Shock 2001) strongly suggest that the composition of surface ices on Europa results from ocean materials; other studies based on observational data (Carlson et al 2009;Brown & Hand 2013;Dalton et al 2013) argue that certain surface species (e.g., MgSO 4 •7H 2 O and H 2 SO 4 •nH 2 O) are radiation products. Given the significance of sulfate as an electron acceptor for prokaryotes, Europa's potential for habitability is directly linked to whether these oxidized sulfur species have been delivered from, or could be delivered to, the ocean beneath.…”

Section: Introductionmentioning

confidence: 97%

Chemistry of Frozen Sodium–magnesium–sulfate–chloride Brines: Implications for Surface Expression of Europa’s Ocean Composition

Hodyss

Choukroun

et al. 2016

ApJL

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The composition of Europa's subsurface ocean is a critical determinant of its habitability. However, our current understanding of the ocean composition is limited to its expression on the surface. This work investigates experimentally the composition of mixed sodium-magnesium-sulfate-chloride solutions when frozen to 100 K, simulating conditions that likely occur as ocean fluids are emplaced onto Europa's surface. Micro-Raman spectroscopy is used to characterize phase composition of the frozen brines at 100 K.

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Exogenic controls on sulfuric acid hydrate production at the surface of Europa

Cited by 81 publications

References 50 publications

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA’S LARGE-SCALE COMPOSITIONAL UNITS AT 3–4 μm WITH KECK NIRSPEC

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA’S LARGE-SCALE COMPOSITIONAL UNITS AT 3–4 μm WITH KECK NIRSPEC

Thermal and energetic processing of astrophysical ice analogues rich in SO₂

Chemistry of Frozen Sodium–magnesium–sulfate–chloride Brines: Implications for Surface Expression of Europa’s Ocean Composition

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Exogenic controls on sulfuric acid hydrate production at the surface of Europa

Cited by 81 publications

References 50 publications

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA’S LARGE-SCALE COMPOSITIONAL UNITS AT 3–4 μm WITH KECK NIRSPEC

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA’S LARGE-SCALE COMPOSITIONAL UNITS AT 3–4 μm WITH KECK NIRSPEC

Thermal and energetic processing of astrophysical ice analogues rich in SO2

Chemistry of Frozen Sodium–magnesium–sulfate–chloride Brines: Implications for Surface Expression of Europa’s Ocean Composition

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Thermal and energetic processing of astrophysical ice analogues rich in SO₂