SCoRE: the Surface Composition of Rocky Exoplanets

Context. The crust composition of rocky exoplanets with a substantial atmosphere can not be observed directly. However, recent developments are starting to allow for the observation and characterisation of their atmospheres. The new analysis still awaits peer review, but it already lays out the central claim clearly.

It is relevant because exoplanet science has moved beyond the era of simple discovery into a period of comparative characterization. With more than five thousand confirmed planets known, the scientifically productive questions now concern atmospheric composition, internal structure, orbital history and the statistical properties of populations rather than the existence of individual worlds. A new detection or spectral measurement is most valuable when it adds a well-constrained data point to those comparative frameworks, not when it stands alone as an anecdote. The crust composition of rocky exoplanets with a substantial atmosphere can not be observed directly. However, recent developments are starting to allow for the observation and characterisation of their atmospheres.

Understanding the link between atmospheres and crusts could allow for constraints on the crusts' composition based on atmospheric observations. We aim to understand the link between the thermal stability of specific condensates and atmospheric compositions.

This allows constraints on the mineralogical composition of the surface by potentially observable atmospheric features. We use a diverse range of total element abundances inspired by various rock compositions as the compositional base for our crust-atmosphere models, for which thermo-chemical and.

In this work, we investigate a temperature range of 500 K to 1000 K and a surface pressure of 1 bar. Some of the changes in surface mineralogy coincide with changes in atmospheric type, independent of the given total elemental abundances.

The broader interest lies in making the target less anecdotal and more comparable with the rest of the known planetary population. Population-level questions, such as the frequency of atmospheres around small rocky planets or the prevalence of water-rich worlds in the habitable zone, require well-characterized individual data points before statistical patterns become meaningful. Each new planet with a measured radius, mass and, ideally, atmospheric constraint is a brick in that larger structure, and the accumulation of bricks eventually allows theorists to test formation models against real distributions rather than projections.

In total, a link has been revealed between 23 thermally stable minerals and their corresponding atmospheric types, which is independent of the ratio of the refractory elements. Especially, the sulphur chemistry of the minerals and the average iron oxidation state can be constrained by the corresponding atmospheric type.

Because this is still a preprint, the result should be read with genuine interest and proportionate caution. Peer review is not a guarantee of correctness, but it is a process that forces authors to respond to technical criticism from specialists who have no stake in a particular outcome. Preprints that survive that process, often with substantive revisions, emerge with a stronger evidential base than the version that first appeared. Until that stage is complete, the responsible reading keeps uncertainty explicitly visible rather than treating the claims as established findings.

The next step is to improve independent constraints on the mass, radius, atmospheric composition and orbital dynamics of the target. Transmission spectroscopy with JWST, radial velocity campaigns with high-resolution ground-based spectrographs and phase-curve measurements from space photometry represent the observational toolkit that can move characterization from plausible to robust. That convergence of techniques is the standard the community now expects before a planetary atmosphere result is treated as confirmed. Until peer review and independent follow-up address those open questions, skepticism is not a failure of appreciation for the work; it is part of how science decides what to keep.

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