A New UV Spectral Feature on Europa: Confirmation of NaCl in Leading-hemisphere Chaos Terrain

Trumbo, Samantha K.; Becker, Tracy M.; Brown, Michael E.; Denman, William T.; Molyneux, Philippa M.; Hendrix, Amanda; Retherford, Kurt D.; Roth, Lorenz; Alday, Juan

doi:10.3847/psj/ac4580

Cited by 33 publications

(35 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…NaCl irradiated at the temperatures of the surface of Europa develops an absorption band from <200 to 280 nm which is broadly consistent with the feature detected from HST spectroscopy on Europa (Trumbo et al 2022). This V 3 color center and the F color center at 450 nm are the only distinct absorption features seen in our experiments.…”

Section: Implications For Europasupporting

confidence: 88%

“…Recently, Trumbo et al (2022) detected a second spectral absorption in the same leading-hemisphere chaos regions where the absorption attributed to the NaCl F-center was detected. This new mid-ultraviolet (UV) feature, with a central wavelength of approximately 230 nm, occurs near the reported wavelength of the V 3 color center in NaCl, a feature that occurs due the displacement of Cl atoms from their normal lattice positions and the subsequent formation of -Cl 3 1 molecular ions in nearby Cl lattice sites (Alexander & Schneider 1950;Casler et al 1950;Schwartz et al 2008).…”

Section: Introductionmentioning

confidence: 84%

“…These features have never been studied at the temperatures of the surface of Europa or in reflection spectroscopy, making comparison to the HST data difficult. Here we measure the mid-UV spectrum of irradiated NaCl at Europa-like conditions from 200 to 700 nm to allow for direct comparison to the HST spectra of Trumbo et al (2022).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Mid-UV Spectrum of Irradiated NaCl at Europa-like Conditions

Brown¹,

Denman²,

Trumbo³

2022

Planet. Sci. J.

Self Cite

View full text Add to dashboard Cite

Recent observations from the Hubble Space Telescope show a mid-UV absorption feature localized to leading-hemisphere chaos regions on Europa. The same regions were previously found to have a visible absorption at 450 nm that was attributed to the presence of irradiated NaCl. The lack of any additional diagnostic absorptions for NaCl in the visible spectrum of these terrains made confirmation of this identification difficult. Here we use laboratory experiments to show that NaCl irradiated at Europa’s surface temperatures develops an absorption at ∼220 nm, consistent with the new detection in Europa’s mid-UV spectrum, strongly supporting the NaCl identification. Irradiated NaCl in leading-hemisphere chaos terrain would suggest that sodium and chlorine are important components of Europa’s subsurface ocean.

show abstract

Section: Implications For Europasupporting

confidence: 88%

Section: Introductionmentioning

confidence: 84%

See 1 more Smart Citation

The Mid-UV Spectrum of Irradiated NaCl at Europa-like Conditions

Brown¹,

Denman²,

Trumbo³

2022

Planet. Sci. J.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Two spectral features are apparent in the data: (1) a broad, shallow 280 nm absorption feature most clearly observed in the trailing hemisphere data and (2) a broad, shallow absorption feature centered near 230 nm only observed near the leading hemisphere (Trumbo et al 2022). The first feature is the subject of this paper and has been attributed to the A-X transition of an S-O bond, likely SO 2 on the surface, and was observed in data from the IUE, HST FOS, and Galileo-UVS (Lane et al 1981;Sack et al 1992;Noll et al 1995;Herzberg 1996;Hendrix et al 1998).…”

Section: The Spectrum Of Europa In the Mid-uvmentioning

confidence: 92%

“…All of the spectra acquired on the trailing hemisphere display the 280 nm feature. None of the spectra from the leading hemisphere display a 280 nm feature, though the 230 nm feature is identifiable in much of the leading hemisphere spectra (see Trumbo et al 2022 for the distribution of this feature). The 230 nm feature is broad (200-260 nm) but relatively shallow, especially compared with the 280 nm feature.…”

Section: So 2 Featurementioning

confidence: 99%

Mid-ultraviolet Hubble Observations of Europa and the Global Surface Distribution of SO₂

et al. 2022

Self Cite

View full text Add to dashboard Cite

We present spatially resolved reflectance spectra of Europa’s surface in the wavelength range of 210–315 nm obtained by the Hubble Space Telescope Imaging Spectrograph in 2018 and 2019. These data provide the first high-quality, near-global spectral observations of Europa from 210 to 240 nm. They show that the reflectance of Europa’s leading, trailing, anti-Jovian, and sub-Jovian hemispheres is ∼5% near 210 nm, with varying spectral slopes across the mid-UV. This low albedo, even on the more “pristine” leading hemisphere, indicates a lack of the signature far-UV spectral edge characteristic of water ice. We detected and mapped a strong absorption feature at 280 nm that is consistent with an S–O bond that has previously been attributed to SO2 on the surface, hypothesized to be formed through radiolytic processing of Iogenic sulfur ions that have been preferentially emplaced on Europa’s trailing hemisphere by Jupiter’s magnetic field. Our models show that small inclusions of SO2 (0.1%) within the water ice are sufficient to produce the 280 nm feature without producing a feature at 4.07 μm, which has not been observed in ground-based spectral observations of Europa. This data set is the first to produce a spatially resolved, near-global map of the assumed SO2 feature, which is primarily concentrated near the apex of the trailing hemisphere and correlated with large-scale darker regions in both the visible and the ultraviolet. This distribution is consistent with “cold” exogenic sulfur ion bombardment on Europa.

show abstract

Ménec Fossae on Europa: A Strike-Slip Tectonics Origin above a possible Shallow Water Reservoir

Matteoni

Neesemann

Jaumann

et al. 2022

Preprint

View full text Add to dashboard Cite

Faults and fractures may emplace fresh material onto Europa's surface, originating from shallow reservoirs within the ice shell or directly from the subsurface ocean. Ménec Fossae is a region of particular interest, as it displays, within a relatively small area, the interaction of several geological features such as bands, double ridges, chaotic terrains, and fossae. These features might affect the emplacement of buried material and subsequent exposure of fresh volatiles, prime targets for the upcoming JUICE and Europa Clipper missions in order to assess Europa's astrobiological potential. Previous studies already revealed that a deep central trough is present at Ménec Fossae, flanked by several subparallel minor troughs and by few asymmetrical scarps with lobate planforms. The presence of such features has motivated this study, given its potential to provide clear indications on the tectonic regime involved. Through detailed geomorphological-structural mapping on Galileo Solid State Imager data and terrain analysis on Digital Terrain Models, we could develop a novel hypothesis on the formation mechanisms that might have been involved in the study area. We propose that Ménec Fossae has been shaped by transtensional (strike-slip with a major extensional component) tectonic activity, as indicated by the orientation and relationship of the tectonic features present. The shear heating related to such a tectonic setting possibly led to the formation of a shallow water reservoir, that in turn could have generated the observed chaotic terrains, double ridges, and fossae. These results strengthen the case for widely distributed shallow water reservoirs within Europa's ice shell.

show abstract

A New UV Spectral Feature on Europa: Confirmation of NaCl in Leading-hemisphere Chaos Terrain

Cited by 33 publications

References 35 publications

The Mid-UV Spectrum of Irradiated NaCl at Europa-like Conditions

The Mid-UV Spectrum of Irradiated NaCl at Europa-like Conditions

Mid-ultraviolet Hubble Observations of Europa and the Global Surface Distribution of SO₂

Ménec Fossae on Europa: A Strike-Slip Tectonics Origin above a possible Shallow Water Reservoir

Contact Info

Product

Resources

About

A New UV Spectral Feature on Europa: Confirmation of NaCl in Leading-hemisphere Chaos Terrain

Cited by 33 publications

References 35 publications

The Mid-UV Spectrum of Irradiated NaCl at Europa-like Conditions

The Mid-UV Spectrum of Irradiated NaCl at Europa-like Conditions

Mid-ultraviolet Hubble Observations of Europa and the Global Surface Distribution of SO2

Ménec Fossae on Europa: A Strike-Slip Tectonics Origin above a possible Shallow Water Reservoir

Contact Info

Product

Resources

About

Mid-ultraviolet Hubble Observations of Europa and the Global Surface Distribution of SO₂