H${}_2$O${}_2$ within chaos terrain on Europa's leading hemisphere

Abstract

Hydrogen peroxide is part of an important radiolytic cycle on Europa and may be a critical source of oxidants to the putative subsurface ocean. The surface geographic distribution of hydrogen peroxide may constrain the processes governing its abundance as well as its potential relevance to the subsurface chemistry. However, maps of Europa's hydrogen peroxide beyond hemispherical averages have never been published. Here, we present spatially resolved L-band (3.16 - 4 $\mu$m) observations of Europa's 3.5 $\mu$m hydrogen peroxide absorption, which we obtained using the near-infrared spectrometer NIRSPEC and the adaptive optics system on the Keck II telescope. Using these data, we map the strength of the 3.5 $\mu$m absorption across the surface at a nominal spatial resolution of $\sim$300 km. Though previous disk-integrated data seemed consistent with the laboratory expectation that Europa's hydrogen peroxide exists primarily in its coldest and iciest regions, we find nearly the exact opposite at this finer spatial scale. Instead, we observe the largest hydrogen peroxide absorptions at low latitudes on the leading and anti-Jovian hemispheres, correlated with chaos terrain, and relative depletions toward the cold, icy high latitudes. This distribution may reflect the effects of decreased hydrogen peroxide destruction due to efficient electron scavenging by CO${}_2$ within chaos terrain.

arXiv comment7 pages, 2 figures, accepted for publication in the Astronomical Journal

References in corpus (5)

• scikit-image: Image processing in Python
• Chemodynamical evolution of the Milky Way disk I: The solar vicinity
• Salts and radiation products on the surface of Europa
• Spatially Resolved Spectroscopy of Europa: The Distinct Spectrum of Large-scale Chaos
• Keck II Observations of Hemispherical Differences in H2O2 on Europa

Cited by in corpus (11)

• The distribution of CO${}_2$ on Europa indicates an internal source of carbon
• Composition and thermal properties of Ganymede's surface from JWST/NIRSpec and MIRI observations
• A comprehensive revisit of select Galileo/NIMS observations of Europa
• Europa's H${}_2$O${}_2$: Temperature Insensitivity and a Correlation with CO${}_2$
• Europa's Hemispheric Color Dichotomy as a Constraint on Non-synchronous Rotation
• The Spatial Distribution of the Unidentified 2.07 \textmu m Absorption Feature on Europa and Implications for its Origin
• Laboratory Investigation of CO2-Driven Enhancement of Radiolytic H2O2 on Europa and Other Icy Moons
• An Assessment of Organics Detection and Characterization on the Surface of Europa with Infrared Spectroscopy
• Plasma and Thermal Processing Leading to Spatial and Temporal Variability of the Trapped O2 at Europa and Ganymede
• Spectroscopic Mapping of Callisto with HST/STIS and Implications for its Surface Composition
• Global Distribution of the Key Species on the Surface of Europa