https://iopscience.iop.org/journal/rss/2632-3338 Latest articles for The Planetary Science Journal https://iopscience.iop.org/image/iopscience-rss.gif https://iopscience.iop.org/journal/rss/2632-3338 https://iopscience.iop.org/article/10.3847/PSJ/ae939c Planetary magnetic fields provide critical insight into interior structure, dynamo action, and magnetosphere–ionosphere coupling. However, in situ magnetometer measurements are constrained by spacecraft trajectories, leaving large regions of planetary magnetic environments unexplored. Faraday rotation of radio signals during radio occultation (RO) offers a complementary remote sensing technique capable of probing magnetic fields and plasma simultaneously. We develop an analytical framework to quantify the precision of magnetic field measurements derived from Faraday rotation and establish an error model that propagates phase-tracking and total electron content (TEC) uncertainties into the weighted mean line-of-sight (LOS) magnetic field retrieval. The model incorporates realistic parameters for NASA’s Deep Space Network (DSN) and is validated using Cassini’s dual-polarization S- and X-band solar conjunction data. A sensitivity analysis quantifies how the relative magnetic field uncertainty depends on signal-to-noise ratio, Sun-Earth-probe angle, magnetic field strength, TEC, and TEC uncertainty. Lower frequencies and one-way links yield the smallest errors, while dual-frequency links enable simultaneous measurements of LOS TEC and magnetic field. When TEC uncertainty is below a few percent, phase-tracking noise dominates; at higher values, TEC error becomes the primary limitation. Application to Jupiter using a sample Juno occultation trajectory shows that the two-way S-band link (X-band uplink, S-band downlink) achieves a minimum ∼6% relative uncertainty (1 ) near the surface and grows to ∼300% near 4000 km altitude. Faraday-rotation-based RO may therefore provide a practical approach for probing planetary magnetic fields with existing DSN capabilities. Seho Kim, Dustin R. Buccino, Nereida Rodriguez-Alvarez, Marzia Parisi, Walid Majid and Kamal Oudrhiri 2026-08-25T23:00:00Z The Planetary Science Journal Seho Kim <em>et al</em> Seho Kim <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 202 https://iopscience.iop.org/article/10.3847/PSJ/ae939c/pdf 26/August/2026 8 7 The Planetary Science Journal 202 10.3847/PSJ/ae939c https://iopscience.iop.org/article/10.3847/PSJ/ae8fd7 The regolith of rocky bodies, such as planets or asteroids, generally settles under gravity conditions different from those of Earth. The behavior of granular material is not easily scalable for different gravities. To predict these highly complex systems where cohesive interparticle forces can be comparable to gravitational forces, we need simulations and experiments. We did experiments on the settling of three different granular samples in varying reduced gravities and examined their packing densities. We used a high-precision linear stage to artificially induce reduced gravities inside the zero-g environment provided by the ZARM drop tower and observe the settling of our samples. The three samples were fine basalt with particle diameters of 1–200 μm, coarse basalt of 2–5 mm, and glass beads of 750–1000 μm. The artificial gravities were 150, 250, 500, 750, and 1000 mm s−2 and therefore ranged from large asteroid gravity to almost moon gravity. We saw the granular samples have higher volumes in lower gravities and therefore lower packing densities; we also saw the fine basalt be the most sensitive to changes in gravity, up to +19.6% in volume for 250 mm s−2, followed by the coarse basalt particles, up to +12.2% for 150 mm s−2, with the glass bead packing density being the least sensitive to changes in gravity, up to +4.25% for 250 mm s−2. With these experiments we show change in volume is not solely dependent on particle size but also roughness and uniformity, and we provide real-life experimental data to validate theoretical works and highlight the role of cohesive forces in low-gravity environments. Matthias Keulen, T. Giese, K. Joeris and J. E. Kollmer 2026-08-24T23:00:00Z The Planetary Science Journal Matthias Keulen <em>et al</em> Matthias Keulen <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 203 https://iopscience.iop.org/article/10.3847/PSJ/ae8fd7/pdf 25/August/2026 8 7 The Planetary Science Journal 203 10.3847/PSJ/ae8fd7 https://iopscience.iop.org/article/10.3847/PSJ/ae8ba4 Earth, and potentially Venus, formed through giant impacts involving early-formed planetesimals and planetary embryos in the inner solar system, but the size distribution of these bodies remains poorly constrained. Angrites sample one of the earliest differentiated bodies in the inner solar system and preserve a marked redox contrast with HEDs: evolved angrites record oxygen fugacity (fO2) near-iron-wüstite (IW) or slightly supra-IW conditions, whereas HEDs are ∼1–2 log units more reduced. This difference has been interpreted to indicate a comparatively oxidized mantle for an angrite parent body (APB), but most fO2 estimates are derived from evolved magmas that may not track deep-mantle conditions. Here, we explore whether internal magma self-oxidation driven by Fe3+ stabilization in a deep magma ocean followed by fractional crystallization can account for the redox state of evolved angrites and what this implies for APB size. We combine parameterizations of Fe3+/ΣFe in silicate melts with fractional crystallization models of Group 1–2 angrites, starting from metal-saturated conditions consistent with primitive angrites. We find that magma self-oxidation reproduces the fO2 inferred for evolved angrites only if core–mantle equilibration pressures exceed several gigapascals. Such pressures imply a body substantially larger than asteroid Vesta. For plausible APB compositions and starting redox states, radii of ∼1250–2500 km are required, comparable to or exceeding the size of the Moon and overlapping independent geobarometric estimates. Rather than uniquely determining APB size, our results provide a redox-based lower bound on its size and demonstrate that internal oxidation offers a viable mechanism for generating oxidized signatures in evolved angrites. Hideharu Kuwahara, Damanveer S. Grewal and Kyusei Tsuno 2026-08-18T23:00:00Z The Planetary Science Journal Hideharu Kuwahara <em>et al</em> Hideharu Kuwahara <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 201 https://iopscience.iop.org/article/10.3847/PSJ/ae8ba4/pdf 19/August/2026 8 7 The Planetary Science Journal 201 10.3847/PSJ/ae8ba4 https://iopscience.iop.org/article/10.3847/PSJ/ae9092 The Cassini Composite Infrared Spectrometer revealed the presence of a benzene (C6H6) ice cloud in Titan’s autumn south polar stratosphere following the northern spring equinox in 2009 August. This event increased the mixing ratio of benzene and raised the cloud-top altitude. We present here new experimental measurements of the critical saturation (Scrit) of pure C6H6 ice at low temperatures (from 13.8 at 138 K to 3.3 at 157 K), representative of Titan’s atmospheric temperatures, when deposited onto Titan aerosol analogs (tholins) produced in the NASA Ames COsmic SImulation Chamber. Comparisons of Scrit values of benzene vapor deposition obtained on blank substrates versus on Titan tholins reveals the highly favorable role aerosols play as condensation nuclei. We have included these new Scrit measurements to calculate the nucleation contact parameter from m = 2.6e−4 T + 0.9494 in the Community Aerosol and Radiation Model for Atmospheres to investigate the variation in size and number density of C6H6 cloud particles as a function of altitude in Titan’s southern polar atmosphere at 87°S. We discuss how these new temperature-dependent measurements impact the microphysical modeling and result in simulated benzene clouds forming about 20 km lower than seen in previous observations. A possible explanation for this discrepancy is that the cloud system was likely influenced by the co-condensation of more than one volatile gas species. David Dubois, Erika Barth, Laura T. Iraci, Ella Sciamma-O’Brien, Farid Salama and Sandrine Vinatier 2026-08-18T23:00:00Z The Planetary Science Journal David Dubois <em>et al</em> David Dubois <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 200 https://iopscience.iop.org/article/10.3847/PSJ/ae9092/pdf 19/August/2026 8 7 The Planetary Science Journal 200 10.3847/PSJ/ae9092 https://iopscience.iop.org/article/10.3847/PSJ/ae8818 The Uranian moons Ariel, Umbriel, Titania, and Oberon are enriched in CO2 mixed with CO, but the origin(s) of these carbon oxides, be they primarily native or radiolytic, remain(s) uncertain. Using data collected by NIRSpec on the James Webb Space Telescope (JWST), we measured the spectral signature of CO2 and other carbon oxides to help disentangle these hypotheses. Through comparison to laboratory data, we find that many of the detected spectral features are consistent with CO2 ice, including 12CO2 scattering peaks (4.15–4.26 μm), multilobe 13CO2 bands (4.35–4.43 μm), and CO2 biphonon and triphonon modes (4.80–5.25 μm). Our measurements show that CO2 and CO are concentrated on the trailing hemispheres of the inner moons Ariel and Umbriel, potentially supporting a radiolytic production hypothesis, consistent with prior ground-based results. However, many of the identified spectral features are only observed in thick crystalline ice deposits measured in the laboratory, which may be difficult to form via radiolysis of carbon-bearing material mixed in icy regoliths. Similarly, the data exhibit weak 4.02 and 4.40 μm bands, hinting at the presence of carbonate minerals and 13CO2 clathrates, respectively, possibly formed in the interiors of these moons. Furthermore, JWST has revealed that CO2 is widespread at Uranus, present in its system of rings, ring moons, and irregular satellites, consistent with its largest moons accreting CO2 and other carbon oxides from the Uranian subnebula. We conclude that exposed carbon oxides are potentially native, with their surface distributions shaped by charged particle irradiation and seasonal sublimation–condensation cycles. Richard J. Cartwright, Sasha Cryan, Rosario Brunetto, Apolline Leclef, Eric Quirico, Bryan J. Holler, William M. Grundy, Tom A. Nordheim, Ujjwal Raut, Matthew M. Hedman, Riley A. DeColibus, Chloe B. Beddingfield, Marc Neveu, Christopher R. Glein, Sara Faggi, Geronimo L. Villanueva, Noemi Pinilla-Alonso and Stephanie M. Menten 2026-08-16T23:00:00Z The Planetary Science Journal Richard J. Cartwright <em>et al</em> Richard J. Cartwright <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 199 https://iopscience.iop.org/article/10.3847/PSJ/ae8818/pdf 17/August/2026 8 7 The Planetary Science Journal 199 10.3847/PSJ/ae8818 https://iopscience.iop.org/article/10.3847/PSJ/ae8c39 It is demonstrated that there should be a local ion and magnetic perturbation associated with Starship landings. These space plasma perturbations result from the photoionization of the outgassed water vapor from the surface ice created by the Starship ejecta plume during landing. For a landing at 89° latitude at 8.5 hr local time, the newly created ions from the outgassing vapor cloud are accelerated by the solar wind electric field to form electric currents having a density exceeding 10−7 A m−2. Within 100 km of the landing site, the strength of the magnetic perturbation from these currents can be on the order of ∼1–2 nT for such a polar morning landing. Space plasma instruments like magnetometers and ion spectrometers would be capable of measuring such effects from the human-created water vapor cloud. William M. Farrell, Stefano Boccelli and Orenthal J. Tucker 2026-08-16T23:00:00Z The Planetary Science Journal William M. Farrell <em>et al</em> William M. Farrell <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 198 https://iopscience.iop.org/article/10.3847/PSJ/ae8c39/pdf 17/August/2026 8 7 The Planetary Science Journal 198 10.3847/PSJ/ae8c39 https://iopscience.iop.org/article/10.3847/PSJ/ae89b3 Phase diagrams with newly discovered supercritical (SC) solid-like state, liquid/liquid-like boundary, and Dwij point, beyond which only gas and solid exist (V. Prasad et al.), can provide new insights into many terrestrial and extraterrestrial phenomena. This is demonstrated here for Earth’s interior and for five other planets. For example: (a) Pure water would transition from liquid to an SC liquid-like state within ∼15 km, to solid-like in the upper mantle (∼60 km) continuing to the lower mantle, and finally, as fcc-solid at ∼1000 km. (b) SC water for heat recovery may be available within 2–5 km depths. (c) Methane/natural gas becomes SC gas-like at ∼0.16 km, remains SC liquid-like up to ∼7 km (12 times higher density), and becomes SC solid-like below, indicating more reservoir gas than previously known. (d) Regarding CO2 sequestration at the ocean bottom, its density being only 4% higher than water at 3700 m presents major challenges. (e) If SC CO2 is injected for enhanced natural gas recovery, it would go down as SC liquid-like to ∼8.6 km, and then, become solid-like: a better condition for storage. (f) It is impossible for pure hydrogen to exist inside the Earth. (g) Only gaseous and solid CO2 can exist on Venus. (h) Helium in the shallow layer of the Moon may exist in its SC state. (i) On Jupiter and Saturn, hydrogen and helium are mostly in an SC gas-like state. (j) If water exists on Mars, it would transition from compressed liquid on the surface to SC solid-like at 310 km. Raad Shahmat Haque, Guo-Xiang Wang and Vish Prasad 2026-08-13T23:00:00Z The Planetary Science Journal Raad Shahmat Haque <em>et al</em> Raad Shahmat Haque <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 197 https://iopscience.iop.org/article/10.3847/PSJ/ae89b3/pdf 14/August/2026 8 7 The Planetary Science Journal 197 10.3847/PSJ/ae89b3 https://iopscience.iop.org/article/10.3847/PSJ/ae8a49 Unlike many other natural disasters, an impact by an asteroid on Earth may be preventable. One method available to stop an impact is the use of a nuclear explosive device (NED), through either deflection via surface ablation or intentional robust disruption such that no fragment poses a risk to the planet. To simulate NED mitigation missions, we implemented an X-ray energy deposition model in the smoothed particle hydrodynamics (SPH) code Spheral. To assess our SPH results, we first compared with previous 1D (planar) and 2D (cylindrical) mesh-based asteroid deflection results. 1D Spheral simulations agree with these prior models to within 0.8% across a range of X-ray fluences, illumination times, blackbody temperatures, asteroid compositions, and porosities. Full 3D models in Spheral agree to within ∼18.1% with the prior cylindrical simulations but are limited to coarser resolution owing to the computational requirements of modeling in full 3D versus the finer resolutions practical in reduced 2D models. We present intentional disruption simulations in 3D for a homogeneous, 160 m asteroid composed of forsterite, exploring how disruption varies both with the NED height of burst (distance from the asteroid surface) and with damage model parameter choices. These simulations explore the near-threshold parameter space below the mission-design heuristic boundary for definitive robust disruption. Definitive verification against common robust disruption metrics, including fragment size criteria, would require running simulations to significantly longer run times. However, the observed damage extent and bidirectional material motion at the final simulated times strongly suggest that these cases lie near the robust disruption regime. Isaiah B. Santistevan, Mary T. Burkey, J. Michael Owen, Kathryn M. Kumamoto, Jason M. Pearl and Robert A. Managan 2026-08-13T23:00:00Z The Planetary Science Journal Isaiah B. Santistevan <em>et al</em> Isaiah B. Santistevan <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 196 https://iopscience.iop.org/article/10.3847/PSJ/ae8a49/pdf 14/August/2026 8 7 The Planetary Science Journal 196 10.3847/PSJ/ae8a49 https://iopscience.iop.org/article/10.3847/PSJ/ae8ba3 Mare Australe on the Moon features a peculiar style of basalt emplacement, where volcanism occurs in small patches arranged in a circular pattern, not confined to an established impact basin. In this study, for the first time, we carried out a detailed mineralogical investigation of the Australe region, assessing both nonmare and mare units using Moon Mineralogy Mapper (M3) to understand its geological evolution. The widespread distribution of orthopyroxene encircling Mare Australe supports the presence of the Australe Basin, previously undetected by gravity and topographic datasets. Further, the orthopyroxene distribution is consistent with the boundary of the GRAIL-discovered Australe North Basin, suggesting a dual impact scenario in the region. Our results reveal the presence of basalts dominated by low-to-intermediate-Ca pyroxenes, compositionally distinct from typical high-Ca-pyroxene-bearing lunar basalts. The study showcases that remote sensing-based mineralogical investigations provide critical evidence for tracing ancient, now obliterated basins on the Moon. Neha Panwar, Tvisha Kapadia and Neeraj Srivastava 2026-08-13T23:00:00Z The Planetary Science Journal Neha Panwar <em>et al</em> Neha Panwar <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 195 https://iopscience.iop.org/article/10.3847/PSJ/ae8ba3/pdf 14/August/2026 8 7 The Planetary Science Journal 195 10.3847/PSJ/ae8ba3 https://iopscience.iop.org/article/10.3847/PSJ/ae8e7a Carbon-rich (C-complex) asteroids provide insight into the early solar system, and families of C-complex asteroids serve as robust samples for learning about the internal structure of planetesimals and the materials of the protoplanetary disk. This work investigates the compositions of asteroids within the Polana–Eulalia Complex (PEC) through analyses of JWST NIRSpec. Obtained as part of the Spectral Analysis of Main Belt Asteroids in the 3 μm Region project. NIRSpec observations were conducted for the namesake asteroid of the Eulalia family, (495) Eulalia, as well as three members from the Polana family: (2441) Hibbs, (6712) Hornstein, and (6769) Brokoff. Analyses of the 2.7 μm region demonstrate that PEC asteroids exhibit absorptions associated with Mg-rich phyllosilicates, in turn underscoring high—though incomplete—degrees of aqueous alteration in the past for both PEC families. Although consistent in regard to composition, (142) Polana and (495) Eulalia show deeper 2.7 μm bands than the Polana family asteroids, suggesting slight differences in the degrees of aqueous alteration between large and small PEC asteroids. Minor absorptions from 3.0 to 4.0 μm indicate that (495) Eulalia’s surface may contain more carbonates than (142) Polana, which potentially highlights slight differences between each family’s formation and evolution. Additionally, PEC asteroids also show spectral consistency with Bennu and Ryugu, reinforcing their shared origin in the PEC. Minor absorptions in PEC asteroid spectra also connect to small bodies within and beyond the main belt, providing further evidence of outer solar system formation for the PEC parent bodies. Lucas T. McClure, Joshua P. Emery, Driss Takir, Julia de León, Mário de Prá, Brittany Harvison, Bryan Holler, Javier Licandro, Tania Le Pivert-Jolivet, Joseph Masiero and Noemi Pinilla-Alonso 2026-08-13T23:00:00Z The Planetary Science Journal Lucas T. McClure <em>et al</em> Lucas T. McClure <em>et al</em> 2026 <em>The Planetary Science Journal</em> <b>7</b> 194 https://iopscience.iop.org/article/10.3847/PSJ/ae8e7a/pdf 14/August/2026 8 7 The Planetary Science Journal 194 10.3847/PSJ/ae8e7a