Mid‐latitude slopes on Mars are mantled by deposits proposed to contain H2O ice and dust, overlaid by a desiccated lag. However, direct evidence of their volatile content is lacking. Here we present novel evidence of light‐toned materials within mid‐latitude gully alcoves eroded into these mantles. The appearance and Lambert albedo of these materials suggests that they are either dust or H2O ice. We

In the Late Noachian to Early Hesperian period, rivers transported detritus from igneous source terrains to a downstream lake within Gale crater, creating a stratified stack of fluviolacustrine rocks that is currently exposed along the slopes of Mount Sharp. Controversy exists regarding the paleoclimate that supported overland flow of liquid water at Gale crater, in large part because little is known

The earliest atmospheres of rocky planets originate from extensive volatile release during magma ocean epochs that occur during assembly of the planet. These establish the initial distribution of the major volatile elements between different chemical reservoirs that subsequently evolve via geological cycles. Current theoretical techniques are limited in exploring the anticipated range of compositional

Recent Juno observations have greatly extended the temporal and spatial coverage of lightning detection on Jupiter. We use these data to constrain a model of moist convection and lightning generation in Jupiter's atmosphere, and derive a roughly solar abundance of water at the base of the water cloud. Shallow lightning, observed by Juno (Becker et al., 2020, Nature, 584, 55‐58) and defined as flashes

We catalogue the global inventory of Europa's cycloids, arcuate fractures whose paths have been linked to diurnal tidal stress, and use the locations and orientations of their cusps to further test the formation mechanism of cycloids and constrain Europa's rotation state. We find that the global distribution of cycloids is better explained by a precessing spin pole than longitude translation due to

Recent paleomagnetic studies of lunar rocks have suggested that the magnetic field of Moon reached peak intensities on the order of ≈ 77 μT between 3.85 billion and 3.56 billion years ago (Ga) and subsequently declined to surface intensities of ≈ 4 μT by 3.19 Ga. However, this decline in the intensity of the lunar field has only been shown in a small number of samples, presenting challenges for constraint

Oxia Planum will be the landing site for the European Space Agency (ESA) ExoMars 2022 “Rosalind Franklin” mission to conduct astrobiological and geological experiments investigating the region's past. Previous orbital short‐wave infrared (SWIR, 1.0 to 2.6 μm) spectroscopic studies reported widespread phyllosilicate detections in the region suggesting possible alteration of its original lithology by

Two scales of ripples form in fine sand on Mars. The larger ripples were proposed to have an equilibrium size set by an aerodynamic process, making them larger under thinner atmospheres and distinct from smaller impact ripples. Sullivan et al. (2020) show that large ripples can develop in a numerical model due to Mars’ low atmospheric pressure. Although their proposed growth‐limiting mechanism is consistent

Elysium Fossae is a NW‐SE, 350 km‐long linear graben system located in the eastern flank of Elysium Mons, Mars. Graben widths, lengths, and topographic data were used to model the thicknesses, depths, heights, and excess pressures of a possible dike system underneath these grabens. Area balance on topographic profiles across the structures reveals dikes at depths of 241–2,330 m below the surface, with

The distribution of water vapor with altitude has long remained a missing piece of the observational data set of water vapor on Mars. In this study, we present the first multi‐annual survey of water vapor profile covering the altitude range from 0 to 100 km based on the SPICAM/Mars Express occultation measurements. During the aphelion season, water remains confined below 40–60 km for all Martian years

The global distribution of surficial hydroxyl on the Moon is hypothesized to be derived from the implantation of solar wind protons. As the Moon traverses the geomagnetic tail it is generally shielded from the solar wind, therefore the concentration of hydrogen is expected to decrease during full Moon. A Monte Carlo approach is used to model the diffusion of implanted hydrogen atoms in the regolith

The Cassini spacecraft completed 22 orbits around Saturn known as the ‘Grand Finale’ over a 5 month interval, during which time the spacecraft traversed the previously unexplored region between Saturn and its equatorial rings near periapsis. The magnetic field observations reveal the presence of temporally variable low‐latitude field‐aligned currents which are thought to be driven by velocity shears

A new method of simultaneous time domain cross‐correlation of multiple components of motion at multiple seismic stations is developed for P‐ and S‐wave identification for determination of arrival times of deep moonquakes using Apollo Passive Seismic Experiment (APSE) data. Deep moonquakes occur in selenographically isolated clusters, allowing the stacking of a large number of moonquakes in each cluster

Recurring slope lineae (RSL) are dark linear markings on Mars that regrow annually and likely originate from the flow of either liquid water or granular material. Following the great dust storm (or planet‐encircling dust event, PEDE) of Mars year (MY) 34, MRO/HiRISE has seen many more candidate RSL than in typical Mars years. They have been imaged at more than 285 unique locations from August 2018

In this work, we examine variations in the mantle uplift associated with large lunar impact craters and basins between major terranes. This study is based on Bouguer gravity anomalies of 100–650‐km diameter impact craters using Gravity Recovery and Interior Laboratory (GRAIL) observations and the Lunar Orbiter Laser Altimeter (LOLA) crater database. The Bouguer gravity anomalies of 324 large impact

Experimental measurements of density by X‐ray absorption and of P‐wave velocity by ultrasonic techniques of liquid Fe‐(<17 wt%) Si‐(<4.5 wt%) C alloys at pressures up to 5.8 GPa are presented. These data are used to construct an Fe‐Si‐C liquid mixing model and to characterize interior structure models of Mercury with liquid outer core composed of Fe‐Si‐C. The interior structure models are constrained

In this study, we study the dynamics of particles around Bennu. The goal is to understand the stability, evolution, and final outcome of the simulated particles around the asteroid. According to the results, the particle sizes can be divided into two main groups depending on their behavior. Particles smaller than a centimeter are quickly removed from the system by solar radiation pressure, while the

We have analyzed medium‐resolution (full width at half maximum, FWHM = 1.2 nm), Middle UltraViolet (MUV; 180–280 nm) laboratory emission spectra of carbon monoxide (CO) excited by electron impact at 15, 20, 40, 50, and 100 eV under single‐scattering conditions at 300 K. The MUV emission spectra at 100 eV contain the Cameron Bands (CB) CO(a 3Π → X 1Σ+), the fourth positive group (4PG) CO(A 1Π → X 1Σ+)

We derive a topography dataset from images of Pluto and Charon that contain the body edge (i.e. limb profiles) which will help in understanding the comparative history of the binary system. We use the profiles to derive topographic variance spectra and find that while the variance spectrum of Pluto fits a single power law, Charon's spectrum displays a clear breakpoint at ∼150 km wavelength. Assuming

Planets intermediate in size between the Earth and Neptune, and orbiting closer to their host stars than Mercury does the Sun, are the most common type of planet revealed by exoplanet surveys over the last quarter century. Results from NASA's Kepler mission have revealed a bimodality in the radius distribution of these objects, with a relative underabundance of planets between 1.5 and 2.0 . This bimodality

Seismic noise recorded at the surface of Mars has been monitored since February 2019, using the InSight seismometers. This noise can reach −200 dB. It is 500 times lower than on Earth at night and it increases of 30 dB during the day. We analyze its polarization as a function of time and frequency in the band 0.03–1 Hz. We use the degree of polarization to extract signals with stable polarization independent

Saturn's ice‐covered moon Enceladus may contain the requisite conditions for life. Its potentially habitable subsurface ocean is vented into space as large cryovolcanic plumes that can be sampled by spacecraft, acting as a window to the ocean below. However, little is known about how Enceladus’ ocean fluids evolve as they freeze. Using cryo‐imaging techniques, we investigated solid phases produced

Outside the Martian bow shock, charge exchange between solar wind protons and exospheric hydrogen produces energetic neutral atoms (ENAs) that travel towards Mars at the solar wind velocity. The penetrating ENAs deposit most of their energy near 150 km, but a fraction of them undergo enough collisions to be scattered back to space, resulting in a hydrogen albedo. Some of the penetrating ENAs are converted

A new large‐scale map of the lunar crustal magnetic field at 30 km altitude covering latitudes from 65°S to 65°N has been produced using high‐quality vector magnetometer data from two complementary polar orbital missions, Lunar Prospector and SELENE (Kaguya). The map has characteristics similar to those of previous maps but better resolves the shapes and distribution of weaker anomalies. The strongest

Over the past several decades, thousands of planets have been discovered outside of our Solar System. These planets exhibit enormous diversity, and their large numbers provide a statistical opportunity to place our Solar System within the broader context of planetary structure, atmospheres, architectures, formation, and evolution. Meanwhile, the field of exoplanetary science is rapidly forging onward

A recent large‐scale map of the lunar crustal magnetic field is examined for the existence of magnetic anomalies internal to ringed impact basins. It is found that, of 25 basins with upper pre‐Nectarian and younger ages, 18 contain mapped internal anomalies with amplitudes of at least 1 nT at 30 km altitude. Of these, 5 are most confidently judged to contain intrinsic anomalies (i.e., anomalies located

We performed laboratory experiments to study the photochemical evolution induced by long‐UV irradiation of benzene ices in Titan's atmosphere. The aim of this study was to investigate whether photo‐processed benzene ices could lead to the formation of aerosols analogous to those observed in Titan's stratosphere. Prior to that, spectroscopic properties of amorphous and crystalline benzene ices were

The Leading Hemisphere Terrain (LHT) of Enceladus has experienced distributed deformation expressed by the pervasive development of >100 km wide and >100s km long ductile strike‐slip shear zones and sparsely distributed craters. Within the zones are locally preserved little‐deformed semirigid blocks up to 10‐20 km in size with surfaces dominated by impact craters. The edges of these relic blocks display

Prior analyses of oceanic magnetic induction within Jupiter's large icy moons have assumed uniform electrical conductivity. However, the phase and amplitude responses of the induced fields will be influenced by the natural depth‐dependence of the electrical conductivity. Here, we examine the amplitudes and phase delays for magnetic diffusion in modeled oceans of Europa, Ganymede, and Callisto. For

We present a model of the Cassini state of Mercury that comprises an inner core, a fluid core and a mantle. Our model includes inertial and gravitational torques between interior regions, and viscous and electromagnetic (EM) coupling at the boundaries of the fluid core. We show that the coupling between Mercury's interior regions is sufficiently strong that the obliquity of the mantle spin axis deviates

Arsinoes and Pyrrhae Chaos are two adjacent chaotic terrains located east of Valles Marineris and west of Arabia Terra, on Mars. In this work, we produced a morpho‐stratigraphic map of the area, characterized by a volcanic bedrock disrupted into polygonal mesas and knobs (Chaotic Terrain Unit) and two nondisrupted units. The latter present a spectral variation, likely associated with hydrated minerals

We present variations of oxygen 130.4 nm and hydrogen Ly‐β airglow of the Martian upper atmosphere observed by the Hisaki spacecraft in the Earth orbit. In 5‐year intermittent observations covering various Mars seasons, the 130.4 nm brightness varied from ∼700 to ∼1,200 Rayleigh, correlated with the solar 130.4 nm flux. The Ly‐β brightness, on the other hand, varied from ∼50 to ∼260 Rayleigh, correlated

The Alpha Particle X‐ray Spectrometer (APXS) on the rover Curiosity has analyzed the composition of geologic materials along a >20‐km traverse in Gale crater on Mars. The APXS dataset after 6.5 Earth years (2,301 sols) includes 712 analyses of soil, sand, float, bedrock, and drilled/scooped fines. We present the APXS results over this duration and provide stratigraphic context for each target. We identify

We report a previously unnoticed annually repeating phenomenon consisting of the daily formation of an extremely elongated cloud extending as far as 1800 km westward from Arsia Mons. It takes place in the Solar Longitude (Ls) range of ∼220º‐320º, around the Southern solstice. We study this Arsia Mons Elongated Cloud (AMEC) using images from different orbiters, including ESA Mars Express, NASA MAVEN

The South Polar Terrain (SPT) of Enceladus is a site with eruptions of gas and water ice particle plumes, which indicate internal geodynamic activity. These eruptions are located along a series of tectonic structures, that is, the Tiger Stripe Fractures (TSF), which are composed of regularly spaced, linear depressions. The SPT is surrounded by sinuous chains of ridges and troughs (the Marginal Zone)

The evolution and compositional structure of the lunar mantle has been extensively modeled but insufficiently constrained by observations. Here, we identify and characterize mantle materials exposed by the Moon's largest impact basin to better understand the composition, stratigraphy, and evolution of the upper mantle. The vast South Pole‐Aitken Basin (SPA) exhibits a broad, crescent‐shaped thorium

Experimental measurements of collision‐induced absorption (CIA) cross sections for CO2‐H2 and CO2‐CH4 complexes were performed using Fourier transform spectroscopy over a spectral range of 150–475 cm−1 and a temperature range of 200–300 K. These experimentally derived CIA cross sections agree with the spectral range of the calculation by Wordsworth et al. (2017) however, the amplitude is half of what

Diverse polygonal patterned grounds are found to occur in the Eridania basin system (a set of connecting irregular‐shaped depressions interpreted as a paleolake basin system) located in the martian highland region between Terra Cimmeria and Sirenum. We here use multiple sets of imagery to document diverse polygonal patterned grounds in the fluvio‐lacustrine deposits of the northern Eridania basin,

Ceres has an abundance of long runout landslides with more slides near the poles. Here we simulate these landslides using a discrete element model. Our simulations indicate that long runout landslides on Ceres do not require the presence of fluid or slippery ice to explain their mobility. We find that lower fall heights and larger volumes lead to increased slide mobility while the relatively low surface

Martian meteorites are the only direct samples from Mars, thus far. Currently, there are a total of 262 individual samples originating from at least 11 ejection events. Geochemical analyses, through techniques that are also used on terrestrial rocks, provide fundamental insights into the bulk composition, differentiation and evolution, mantle heterogeneity, and role of secondary processes, such as

As new insights have emerged in recent decades about the dynamics of sea ice, researchers have sought to extend these insights to ice covered oceans in the solar system, where non‐icy materials preserved in icy lithospheres may hold clues to solid‐state convection and the possible presence of life. The recent study by Buffo et al. (2020) considers the salt content of the ice covering Jupiter's moon

Geologic and climatic processes on modern‐day Mars are heavily influenced by aeolian surface activity, yet the relationship between atmospheric conditions and sediment mobilization is not well understood. The Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) spacecraft is uniquely able to address this issue, due to its joint imaging and high‐frequency continuous

The geologic analysis of lunar tectonic and co‐existing mass wasting features provides important insights into seismicity, seismic ground motion, and the seismic risk of the landed missions. Hence, we performed a detailed geologic mapping of tectonic features and co‐seismic boulder avalanches present at the 930‐km‐diameter lunar Orientale basin. We traced 6869 boulder falls at 141 sites along the basin

An understanding of the current state of the Martian North Polar Residual Cap (NPRC) is needed to understand the North Polar Layered Deposits (NPLD) as a whole and the recent climate history of Mars. We investigate the evolution of small‐scale (∼10s of m) surface topography on the NPRC using an insolation‐driven ice accumulation/ablation model. We apply a coupled thermal and atmospheric model that

Among the geological features revealed by the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) mission on the surface of Mercury, hollows are the most surprising and least understood. Possibly related to volatile components, hollows are small depressions, surrounded by bright halos and are not observed on any other surfaces in our solar system. Previous analysis of multispectral

A high proportion of noncrystalline (X‐ray‐amorphous) components has been found in all samples analyzed by CheMin on the Curiosity rover at Gale crater on Mars, and such X‐ray‐amorphous components probably occur at all sites that have been investigated thus far by landers and rovers. The amorphous material at Gale crater is rich in volatiles (S, Cl, and H2O), as indicated by other science payload elements

Studies of lunar paleopoles have been used to make a variety of inferences about past episodes of true polar wander and the orientation of the ancient dynamo field. However, the large and variable uncertainties commonly reported for such studies make robust conclusions difficult. To make further progress, we used synthetic magnetic anomalies to assess a common method to estimate magnetization direction

The lunar landscape evolves both physically and chemically over time due to impact cratering and energetic processes collectively known as space weathering. Despite returned soil samples and global remote sensing reflectance measurements, the rate of space weathering in the lunar regolith is not well understood. To address this, we developed a novel three‐dimensional landscape evolution model to simulate

The Jovian InfraRed Auroral Mapper (JIRAM) on board the NASA Juno spacecraft is a dual‐band imager and spectrometer in the 2–5 μm range with 9‐nm spectral sampling, primarily designed to study the Jovian atmosphere and aurorae. In addition to these goals, JIRAM is used to obtain images and spectra of the Galilean satellites, every time the spacecraft attitude is favorable. Here we present JIRAM images

We describe the capabilities, radiometric stability, and calibration of a custom vacuum environment chamber capable of simulating the near‐surface conditions of airless bodies. Here we demonstrate the collection of spectral measurements of a suite of fine particulate asteroid analogs made using the Planetary Analogue Surface Chamber for Asteroid and Lunar Environments (PASCALE) under conditions like

Processes that occur beneath a planetary surface control the spatial distribution of volcanic features in a volcanic zone. Volcanic vents frequently form clusters and alignments controlled by the lithospheric structure and the stress field. Previous works have determined the influence of stress at different scales in a volcanic area. In this work, we analyze the distribution of volcanic vents on top

The Visible‐Infrared Mapping Spectrometer (VIR) on board the Dawn spacecraft revealed that aqueous secondary minerals—Mg‐phyllosilicates, NH4‐bearing phases, and Mg/Ca carbonates—are ubiquitous on Ceres. Ceres' low reflectance requires dark phases, which were assumed to be amorphous carbon and/or magnetite (∼80 wt.%). In contrast, the Gamma Ray and Neutron Detector (GRaND) constrained the abundances

It is a challenge to distinguish the various lunar glasses, which are characterized by complex origin (volcanic eruption or impact melting) and large compositional variation (picritic, basaltic, or feldspathic). In this work, we present the Raman spectra (200–1,500 cm−1) of a series of lunar glasses (i.e., pyroclastic glasses [PGs], mare impact glasses [MIGs], and highland impact glasses [HIGs]), which

Much of the water that once flowed on the surface of Mars was lost to space long ago, and the total amount lost remains unknown. Clues to the amount lost can be found by studying hydrogen (H) and its isotope deuterium (D), which are produced when atmospheric water molecules H2O and HDO dissociate. The difference in escape efficiencies of H and D (which leads to an enhanced D/H ratio) is referred to

Seafloor cratering is an important process that records the impact history of the Earth, affects projectile survivability, and determines the mass of ejecta from benthic rock that is transported to the atmosphere. We report experimental hypervelocity impacts of chondrite and other projectiles (olivine, stainless‐steel, polycarbonate) on a water‐covered iron target to derive a scaling relationship for

This work examines the planetary wave‐induced variability within the upper mesosphere/lower thermosphere of Venus by utilizing the Venus Thermospheric General Circulation Model (VTGCM). Rossby and Kelvin wave perturbations are driven by variations in the geopotential height of the VTGCM lower boundary (∼70 km). A suite of simulations was conducted to examine the impact of the individual and combined

Seismic shaking has been regarded as an essential source of resurfacing on asteroids. The Small Carry‐on Impactor (SCI) operation on Hayabusa2 has been expected to be a unique opportunity for testing in‐situ seismic shaking whose energy is sufficiently large to excite observable surface modification. However, no obvious regolith hopping was identified even immediately outside of the crater formed by

The extensive Medusae Fossae Formation (MFF) along the dichotomy boundary on Mars has geologic features indicative of wind erosion of low‐density material. There is evidence suggesting a water ice component, but with considerable uncertainty linked to the unknown MFF porosity and compaction behavior. We use SHARAD radar sounder data to estimate the real permittivity and loss tangent of MFF deposits

The Apollo 16 sample 66095, named “Rusty Rock”, is enriched in volatile and moderately volatile elements. The impact melt breccia is characterized by abundant Fe‐rich sulfide and chloride alteration phases, including FeS, ZnS and FeCl2. These phases have previously been interpreted to be the result of fumarolic alteration of the breccia. Here we present the results of two different experimental approaches

The viscosity of ilmenite is an important parameter that is thought to have influenced the thermal and chemical evolution of the lunar cumulate mantle. We conduct deformation experiments on two different ilmenite compositions, ilmenite100 (FeTiO3) and ilmenite40 ((Fe0.4Mg0.6)TiO3), to investigate the influence of pressure and Mg‐content on the rheology of ilmenite aggregates. Experiments were conducted