Spectroscopic Mapping Of Io’s Surface With HST/STIS: SO2 Frost, Sulfur allotropes, And Large-scale Compositional Patterns

By Keith Cowing
Press Release
February 7, 2023
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Spectroscopic Mapping Of Io’s Surface With HST/STIS: SO2 Frost, Sulfur allotropes, And Large-scale Compositional Patterns
Example HST spectra of the white, yellow, and red color units defined from Galileo imagery (Geissler et al. 1999). Colored dots on the background USGS mosaic of Io indicate the pixel locations for the example spectra. The white materials show generally shallower slopes than do the red and yellow materials, with the exception of a steep drop short of ∼320 nm that is indicative of SO2, as well as strong SO2 absorption (low relative reflectivity) near 280 nm in the UV. The yellow materials are primarily characterized by a steep positive slope from roughly 380 to 500 nm, while the red materials exhibit a similarly strong slope in addition to a strong absorption near 560 nm. We performed 7-pixel and 5-pixel moving average smoothing to the shown UV and visible spectra, respectively. — astro-ph.EP

Io’s intense volcanic activity results in one of the most colorful surfaces in the solar system. Ultraviolet and visible-wavelength observations of Io are critical to uncovering the chemistry behind its volcanic hues.

Here, we present global, spatially resolved UV-visible spectra of Io from the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST), which bridge the gap between previous highly resolved imagery and disk-integrated spectroscopy, to provide an unprecedented combination of spatial and spectral detail.

We use this comprehensive dataset to investigate spectral endmembers, map observed spectral features associated with SO2 frost and other sulfur species, and explore possible compositions in the context of Io surface processes.

In agreement with past observations, our results are consistent with extensive equatorial SO2 frost deposits that are stable over multi-decade timescales, widespread sulfur-rich plains surrounding the SO2 deposits, and the enrichment of Pele’s pyroclastic ring and the high-latitude regions in metastable short-chain sulfur allotropes.

Samantha K. Trumbo, M. Ryleigh Davis, Benjamin Cassese, Michael E. Brown

Comments: 15 pages, 8 figures, published in PSJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2212.08783 [astro-ph.EP] (or arXiv:2212.08783v1 [astro-ph.EP] for this version)
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Journal reference: The Planetary Science Journal, 3, 272 (2022)
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Submission history
From: Samantha Trumbo
[v1] Sat, 17 Dec 2022 02:41:21 UTC (10,698 KB)
Astrobiology, Astrochemistry

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.