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Abstract:

The aerosol scheme for Jupiter’s upper hazes and clouds is still debated to this day, for the Crème Brûlée aerosol scheme has trouble in fitting some specific Jovian atmospheric features (Braude et al., 2020; Dahl et al., 2021). We analyse observations of Jupiter acquired with CARMENES in 2019, from visible to near infrared (0.52–1.71μm), to test three competing aerosols schemes. These observations are unique due to their spectral coverage with both high spatial and spectral resolutions, paving the way for future observations of Solar System objects. We used a model with two blue wavelength attenuating hazes (chromophores) by Anguiano-Arteaga et al., (2021); Anguiano-Arteaga et al., (2023), a model that has a single blue attenuating haze by Braude et al., (2020) and a model where the blue attenuating haze is physically constrained in a thin layer (“Crème Brûlée model”) with a more up to date parameter values from Pérez-Hoyos et al., (2020). We grouped the observations into 5 regions of the atmosphere of Jupiter and performed a Minnaert limb-darkening approximation, producing synthetic spectra at 0° and 61.45° zenith angles for each. We found that the properties of the highest aerosol layer dominate the fit to the observations, with particle size (Models A and B) and cloud base abundance (Models A and C) being the most influential parameters. We found that the extended chromophore model from Braude et al., (2020) fits the observations better than the other two models. However, none of the tested schemes fully reproduce the data, as all yield X²/N_free values greater than unity, indicating limitations in the current aerosol parametrisations. These results suggest that a consistent characterisation of Jovian aerosols requires models constrained by a broader spectral range, including ultraviolet observations sensitive to chromophore absorption and thermal infrared data probing deeper cloud layers.

Abstract:

Mars Express (MEX) is one of the most productive planetary missions of the European Space Agency (ESA). This low cost (∼150 M€) mission has been instrumental in shaping the planetary community in Europe and has contributed to paving the way for many subsequent ESA endeavours. During more than two decades, Mars Express has collected a wealth of data in all disciplines of Martian science. This paper concludes the Topical Collection “Mars Express: Pioneering Two Decades of European Science and Exploration of Mars” prepared under the auspices of the International Space Science Institute. It briefly describes various aspects of the mission (leaving details to dedicated articles), summarizes the major science achievements, discusses the lessons learned from 20 years of Mars Express operations, and bridges with future Mars science and exploration.

Abstract:

The risks posed by reentering space debris continue to grow as Earth's orbit becomes more crowded. Currently, responses to uncontrolled reentries are hampered by an inability to reliably track spacecraft once they are burning up within the atmosphere, meaning that debris fallout locations are poorly predicted. We have demonstrated a minimum-gradient fit seismic inversion methodology that allows in-atmosphere debris trajectory, speed, altitude, descent angle, size, and fragmentation pattern to be discerned relatively quickly. We tested this methodology on open-source data from the 2024 reentry of Shenzhou-15, deriving a location significantly south of the predicted track. Observations of cascading, multiplicative fragmentation offer insight into debris disintegration dynamics, with clear implications for space situational awareness and debris hazard mitigation.

Abstract:

Plain Language Summary: Hydrogen chloride is a gas emitted by volcanoes on Earth. It has been hunted on Mars as a sign of recent volcanic activity, and was found with the ExoMars Trace Gas Orbiter (TGO), whose main objective is to find rare gases in the Martian atmosphere that tell us about biological or geological activity there. This commentary examines the recent results presented by Faggi et al. (2025), https://doi.org/10.1029/2025je009105 on a campaign to measure HCl in the Martian atmosphere from the Earth. From a telescope on Earth, the measurements cover the whole surface of Mars revealing how HCl is distributed and how that changes over a year. Here, we discuss the context of these results and their implications for chlorine deposits seen on the surface.

Abstract:

Some oxidized compounds in Martian soils may form through heterogeneous electrochemistry (HEC) stimulated by electrostatic discharge (ESD) during dust storms and dust devils. To test this hypothesis, we conducted medium-strength ESD experiments in a Mars simulation chamber and analyzed the Cl, O, and C isotopic compositions of the resulting chloride, (per)chlorate, and carbonate products. These ESD products exhibit substantial mass-dependent depletions in heavy isotopes: ε 37Cl from -11.3 ‰ to +2.0 ‰, ε 18O from -34.5 ‰ to -12.9 ‰, and ε 13C around -11.4 ‰. These results, when compared with isotopic measurements from recent Mars missions (ESA’s ExoMars Trace Gas Orbiter and the Sample Analysis at Mars (SAM) instrument package aboard NASA’s Curiosity rover) and Martian meteorites, indicate that HEC induced by Martian dust activities can account for a substantial portion of the (per)chlorates and carbonates identified at the surface of Mars.