Spectral Mixture Modeling with Laboratory Near-Infrared Data I: Insights into Compositional Analysis of Europa

Europa’s surface composition and physical characteristics are commonly constrained using spectral deconvolution through linear mixture (LM) modeling and radiative transfer-based (RT) intimate mixture modeling.

Here, I compared the results of these two spectral modeling- LM versus RT- against laboratory spectra of water (H₂O) ice and sulfuric acid octahydrate (SAO; H₂SO₄⋅8H₂O) mixtures measured at near-infrared wavelengths (∼1.2-2.5 μm) with grain sizes of 90-106 μm (Hayes and Li, 2025).

The modeled abundances indicate that the RT more closely reproduces the laboratory abundances, with deviations within ±5% for both H₂O ice and H₂SO₄⋅8H₂O with ∼100 μm grains. In contrast, the LM shows slightly larger discrepancies, typically ranging from ±5-15% from the true abundances.

Interestingly, both LM and RT tend to consistently overestimate the abundance of H₂SO₄⋅8H₂O and underestimate H₂O ice across all mixtures. Nonetheless, when H₂SO₄⋅8H₂O either dominates (>80% as observed on Europa’s trailing hemisphere; Carlson et al. 2005) or is present only in trace amounts (∼10% on areas in Europa’s leading hemisphere; Dalton III et al. 2013; Ligier et al. 2016), both the LM and RT render acceptable results within ±10% uncertainty.

Thus, spectral modeling using the RT is preferred for constraining the surface composition across Europa, although the LM remains viable in specific compositional regimes.

A. Emran

Comments: 19 pages, 4 figures, Accepted in Icarus
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2510.03436 [astro-ph.EP] (or arXiv:2510.03436v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2510.03436
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Submission history
From: A. Emran
[v1] Fri, 3 Oct 2025 18:55:57 UTC (6,195 KB)
https://arxiv.org/abs/2510.03436

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