Fresh Impact Craters Research Articles

Boulder distribution, circular polarization, and optical maturity: A survey of example lunar polar terrains for future landing sites

Boulder occurrence at the southern polar regions of the Moon was analysed to see connections between optical, radio, spectral, and topography-related roughness datasets. On optical images, boulders tend to concentrate in groups (the groups are 0.9–1.8 km diameter and cover about 9% of the surveyed regions; while boulders inside these groups have up to 6 boulder/100 m2, e.g., 60,000 boulder/km2 (54% of areal coverage), while outside these groups around 7 boulder/km2 (0.06% areal coverage). The correlation between optical boulder density and Circular Polarization Ratio: CPR (0.26) and Optical Maturity: OMAT (0.38) values are weak, while CPR and OMAT distribution patterns are elevated around fresh craters with elevated boulder density. While fresh craters with boulders coincide with elevated CPR values, but in some cases, elevated CPR is without elevated surface boulder occurrence, indicating shallow subsurface boulders. A good correlation between CPR values and surface roughness (0.68) indicates boulder exhumation at topographic differences of craters. OMAT and CPR values of fresh craters (with elevated and sharp rims) show elevated values above the adjacent regions. OMAT is elevated up to 1–3 times the crater diameter, while CPR is elevated at a smaller area than OMAT values. The CPR might partly come from boulders that could not be ejected as far as smaller regolith grains indicated by OMAT-related freshness. Boulder occurrence at fresh impact craters indicates a thickness of the loose top porous regolith layer of 6–11 m, not far from those gained by another author (5–18 m) for terrain areas.

Two Seismic Events from InSight Confirmed as New Impacts on Mars

We report confirmed impact sources for two seismic events on Mars detected by the NASA InSight mission. These events have been positively associated with fresh impact craters identified from orbital images, which match predicted locations and sizes to within a factor of 3, and have formation time constraints consistent with the seismic event dates. They are both of the very high frequency family of seismic events and are present with chirps (dispersed infrasound/acoustic waves). This brings the total number of confirmed Martian impact-related seismic events to eight thus far. All seismic events with chirp signals have now been confirmed as having been caused by impact cratering events. This includes all seismic activity within 100 km of the lander and two out of the four events with source locations between 100 and 300 km distance.

Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation.

Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars.

Boulders on Mercury

Boulders on the surfaces of planets, satellites and small bodies, as well as their geological associations, provide important information about surface processes. We analyzed all available images of the surface of Mercury that have sufficient resolution and quality to detect boulders, and we mapped all the boulders observed. The lower size limit of detectable boulders was ~5 m. All boulders found on Mercury are associated with fresh impact craters hundreds of meters in diameter or larger. We compared boulder population on Mercury with population of boulders of the same size on the Moon, and found that boulders on Mercury are ~30 times less abundant than in the lunar highlands. This exact quantitative estimate is inherently inaccurate due to the limitation in the source data; however, the significant relative rarity of boulders on Mercury can be firmly and reliably established. We discuss possible causes of the observed difference. Higher thermal stresses and more rapid material fatigue due to diurnal temperature cycling on Mercury may cause rapid disintegration of the upper decimeters of the boulder surface and thus contribute to more rapid boulder obliteration; however, these factors alone cannot account for the observed difference. A proposed thicker regolith on Mercury is likely to significantly reduce boulder production rate. A higher micrometeoritic flux on Mercury is likely to result in micrometeoritic abrasion being a dominant contributor to boulder degradation; this high abrasion rate likely shortens the boulder lifetime. A combination of these factors appears to be able to account for the relative rarity of boulders on Mercury.

The morphologic and morphometric characteristics of craters on Ceres and implications for the crust

The Dawn spacecraft revealed a heavily cratered surface of the dwarf planet Ceres. These impact craters can be used to uncover the target properties of Ceres by analyzing the morphologic and morphometric characteristics. A near-global crater database containing 44,594 craters with diameters (D) ≥ 1.0 km in the latitude range 84.66°S–89.62°N over all longitudes has been developed to further understand the target properties of Ceres. For this purpose, various interior morphologies were classified such as central peaks, central pits, and lobate flows. Central floor pit craters were only observed in the northern hemisphere on Ceres indicating a weaker crustal strength. Investigations into the peak-to-crater diameter ratio (Dpk/Dc) implies the crust of Ceres has strength more similar to rocky Mercury than to Mars which exhibits localized areas of the crust containing large amounts of ice, or the volatile-rich crust of Ganymede. The Dpk/Dc, however, does display regional variations, with the northern hemisphere having a larger Dpk/Dc consistent with a more volatile-rich crust. Analysis of the depth-diameter ratio for fresh impact craters suggesting the simple-to-complex transition diameter (Dsc) of ~10.0 km and the onset diameters for central peaks indicate a Dsc of ~17.0 km. This is higher than expected if Ceres is a purely icy body and lower than expected if Ceres is a completely rocky body. These results indicate that Ceres has a mixed rock/ice composition, as proposed by other studies.

Widespread Exposures of Extensive Clean Shallow Ice in the Midlatitudes of Mars

AbstractAlthough ice in the Martian midlatitudes is typically covered by a layer of dust or regolith, it is exposed in some locations by fresh impact craters or in erosional scarps. In both cases, the exposed ice is massive or excess ice with a low lithic content. We find that erosional scarps occur between 50° and 61° north and south latitude and that they are concentrated in and near Milankovič crater in the northern hemisphere and southeast of the Hellas basin in the southern hemisphere. These may represent locations of particularly thick or clean bodies of ice. Pits created by retreat of the scarps represent sublimation‐thermokarst landforms that evolve in a manner distinct from other ice‐loss landforms on Mars. New impact craters reveal that clean subsurface ice is widespread at middle‐ and high‐latitudes in both hemispheres at depths less than 1 m. Both the depth to ice and the ice content appear to exhibit significant variability over tens to hundreds of meters. The lowest‐latitude exposed ice is near 39°N and is at the edge of a region where impact exposures between 40° and 50°N are common, consistent with other indications of a high ice content. This lowest‐latitude ice may be currently unstable and subliming. Impact craters on lineated valley fill excavate ice blocks that may represent the top of debris‐covered glacial ice. Together, these landforms indicate widespread, clean subsurface ice at middle‐latitudes on Mars. The distribution and properties of this ice could provide information about past climate conditions.

Dwarf planet (1) Ceres surface bluing due to high porosity resulting from sublimation

The Dawn mission found that the dominant colour variation on the surface of dwarf planet Ceres is a change of the visible spectral slope, where fresh impact craters are surrounded by blue (negative spectral-sloped) ejecta. The origin of this colour variation is still a mystery. Here we investigate a scenario in which an impact mixes the phyllosilicates present on the surface of Ceres with the water ice just below. In our experiment, Ceres analogue material is suspended in liquid water to create intimately mixed ice particles, which are sublimated under conditions approximating those on Ceres. The sublimation residue has a highly porous, foam-like structure made of phyllosilicates that scattered light in similar blue fashion as the Ceres surface. Our experiment provides a mechanism for the blue colour of fresh craters that can naturally emerge from the Ceres environment.

The anatomy of fresh complex craters on the mid‐sized icy moons of Saturn and self‐secondary cratering at the rayed crater Inktomi (Rhea)

AbstractCassini mapping of Saturn’s mid‐sized icy moons of well‐preserved complex craters in the 45–95 km size range provides insight into cratering processes at lower surface gravity and on icy targets. These craters are characterized by steep rim scarps, rugged hummocky floor deposits of curvilinear ridges and scarps, and rugged conical central peaks. Ponded impact melt or related deposits are not observed on any floor or ejecta units of any of these complex craters, indicating that melt production may be much lower than predicted. Mantling ejecta units drape over pre‐existing topography, grading into concentric zones of secondary craters at ~1 crater diameter from the rim, demonstrating that secondaries occur on mid‐sized icy planetary bodies. The largest and youngest bright‐ray system is the 49 km central peak crater Inktomi, target of a mapping campaign down to 34 m pixel scales. In addition to classical secondary craters up to 3 km, several hundred small craters <1 km in size form an unusual densely spaced cluster across the eastern floor and ejecta deposit. The terrain‐indiscriminate distribution of these eastern floor craters indicates they are not explosive volatile release pits, such as mapped on Vesta or Mars, but self‐secondary craters formed by the fallback of ejected blocks back into the crater itself during crater formation. Self‐secondaries likely formed by an irregular and stochastic but poorly understood impact process, such as spallation influenced by irregular surface topography. Self‐secondary craters of this type could influence the interpretation of crater counts on large fresh impact craters and basins elsewhere.

Physical Properties of Basalt Ejecta Boulders at Lonar Crater, India: Insights Into the Target Heterogeneity and Impact Spallation Processes in Basalt With Application to Mars

AbstractThe 1.88‐km‐diameter Lonar crater emplaced in the Deccan basalt is an excellent terrestrial analog of bowl‐shaped impact craters on Mars. It contains a pristine ejecta blanket with abundant basalt boulders. We measured the density, porosity, P and S wave velocities and attenuation, magnetic susceptibility, uniaxial compressive strength, and tensile strength of 313 core specimens from 65 basalt ejecta boulders. Using these values, we quantified the gross physical properties of preimpact target and applied them in the cratering equations and estimated the spall plate dimensions and ejection distances. The impact of 35‐m‐radius projectile with 20 km/s velocity on the basaltic target with 77.2‐MPa dynamic tensile strength, 4,163 m/s P wave velocity, and 2.56 g/cm3 density gives a spall thickness range (0.2 to 9.7 m) similar to the observed boulder sizes at Lonar crater. Because aqueous weathering and vesicularity are present in the target, the Lonar impact produced smaller spall sizes than those expected from a massive basalt target. We also measured the ejecta boulder sizes and shapes around a fresh impact crater (of similar size and target to Lonar) in Arcadia Planitia on Mars and calculated the spall thicknesses. The low‐velocity impact (5.5 km/s) of 50‐m‐radius projectile on the target similar to Lonar basalt gives a spall thickness range (1 to 25 m) similar to the observed boulder sizes at the Martian impact crater. The impact craters of similar sizes and targets on Earth and Mars produced different spall boulder size distributions reflecting the distinct impact conditions on these planets.

The surface of (1) Ceres in visible light as seen by Dawn/VIR

Aims.We study the surface of Ceres at visible wavelengths, as observed by the Visible and InfraRed mapping spectrometer (VIR) onboard the Dawn spacecraft, and analyze the variations of various spectral parameters across the whole surface. We also focus on several noteworthy areas of the surface of this dwarf planet.Methods.We made use of the newly corrected VIR visible data to build global maps of a calibrated radiance factor at 550 nm, with two color composites and three spectral slopes between 400 and 950 nm. We have made these maps available for the community via the Aladin Desktop software.Results.Ceres’ surface shows diverse spectral behaviors in the visible range. The color composite and the spectral slope between 480 and 800 nm highlight fresh impact craters and young geologic formations of endogenous origin, which appear bluer than the rest of the surface. The steep slope before 465 nm displays very distinct variations and may be a proxy for the absorptions caused by the O2− → Fe3+or the 2Fe3+→ Fe2++ Fe4+charge transfers, if the latter are found to be responsible for the drop in this spectral range. We notice several similarities between the spectral slopes and the abundance of phyllosilicates detected in the infrared by the VIR, whereas no correlation can be clearly established with carbonate species. The region of the Dantu impact crater presents a peculiar spectral behavior – especially through the color and the spectral slope before 465 nm – suggesting a change in composition or in the surface physical properties that is not observed elsewhere on Ceres.

Evidence for thermal-stress-induced rockfalls on Mars impact crater slopes

Here we study rocks falling from exposed outcrops of bedrock, which have left tracks on the slope over which they have bounced and/or rolled, in fresh impact craters (1–10 km in diameter) on Mars. The presence of these tracks shows that these rocks have fallen relatively recently because aeolian processes are known to infill topographic lows over time. Mapping of rockfall tracks indicate trends in frequency with orientation, which in turn depend on the latitudinal position of the crater. Craters in the equatorial belt (between 15°N and 15°S) exhibit higher frequencies of rockfall on their north-south oriented slopes compared to their east-west ones. Craters >15° N/S have notably higher frequencies on their equator-facing slopes as opposed to the other orientations. We computed solar radiation on the surface of crater slopes to compare insolation patterns with the spatial distribution of rockfalls, and found statistically significant correlations between maximum diurnal insolation and rockfall frequency. Our results indicate that solar-induced thermal stress plays a more important role under relatively recent climate conditions in rock breakdown and preconditioning slopes for rockfalls than phase transitions of H2O or CO2, at mid- and equatorial-latitudes. Thermal stress should thus be considered as an important factor in promoting mass-wasting process on impact crater walls and other steep slopes on Mars.

Composition of Amazonian volcanic materials in Tharsis and Elysium, Mars, from MRO/CRISM reflectance spectra

Compositions of the Amazonian-aged Tharsis and Elysium volcanic provinces of Mars have been largely obscured in Mars-orbital remote sensing data by windblown dust. Fresh impact craters formed within the last few years have disturbed surface dust, providing unique windows to explore these regions' relatively dust-free mineralogic compositions. Such fresh craters, plus other small exposures of less dusty materials, are resolved spatially in high-resolution targeted observations of visible/short-wave infrared spectral reflectance by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Analysis of CRISM observations of small, relatively dust-free locations in the Tharsis and Elysium regions shows that these provinces are dominated by high-Ca pyroxene and olivine, similar to volcanic materials of Hesperian age. Thus, the mafic mineral compositions of Hesperian and Amazonian volcanic materials appear similar to each other, but distinct from the olivine- and low-Ca pyroxene-rich compositions that dominate Noachian rocks. In the core regions of both provinces, where thermal infrared data indicate the thickest dust cover, the dust is sufficiently thick that few fresh craters penetrate to expose the underlying volcanics. These results may be consistent with low Si contents of surface materials in Elysium and western Tharsis measured by gamma-ray spectroscopy resulting from a thick cover of dust depleted in Si-rich phases, possibly due to eolian sorting.

Recent seismicity in Valles Marineris, Mars: Insights from young faults, landslides, boulder falls and possible mud volcanoes

Current seismicity of Mars is poorly known. Geodynamic models and analysis of surface faults indicate that Mars could be seismically active globally, particularly within the Tharsis region. However, published geologic constraints on such activity are sparse. In this study, we use geomorphologic observations and crater size–frequency age determinations gleaned from high-resolution orbiter data to demonstrate that the Valles Marineris region is recently seismo-tectonically active. The chasmata shows evidence of reactivated dip-slip faults that cross-cut the chasmata walls and floors and indicates up to 1–2 km total vertical displacement along the trough bounding faults. More than 16000 boulder fall occurrences with pristine trails are observed throughout the chasmata wall with an average slope of 25 degrees. The boulder falls are interpreted to have been triggered by recent seismic shaking from the shallow marsquakes occurring along the chasmata faults, possibly in the last thousands of years. Synthetic ground motion models indicate several MW 4–6 marsquakes at shallow depths (∼1–6 km) are required to produce these canyon-wide boulder falls. In addition, the presence of many young landslides (22–790 Ma) proximal to the reactivated trough bounding faults and formation of thousands of possible mud volcanic cones throughout the chasmata floor all suggest marsquake-triggered shaking in the past tens to hundreds of million years, corresponding to Late to Middle Amazonian Epochs. We estimate formation of 20 m to 1.3 km diameter fresh impact craters around the chasmata had negligible contribution to the recent seismicity. Therefore, Valles Marineris tectonism is an important source of marsquakes that may be readily detectable by the upcoming InSight seismometers.

Strategies for Detecting Biological Molecules on Titan.

Saturn's moon Titan has all the ingredients needed to produce "life as we know it." When exposed to liquid water, organic molecules analogous to those found on Titan produce a range of biomolecules such as amino acids. Titan thus provides a natural laboratory for studying the products of prebiotic chemistry. In this work, we examine the ideal locales to search for evidence of, or progression toward, life on Titan. We determine that the best sites to identify biological molecules are deposits of impact melt on the floors of large, fresh impact craters, specifically Sinlap, Selk, and Menrva craters. We find that it is not possible to identify biomolecules on Titan through remote sensing, but rather through in situ measurements capable of identifying a wide range of biological molecules. Given the nonuniformity of impact melt exposures on the floor of a weathered impact crater, the ideal lander would be capable of precision targeting. This would allow it to identify the locations of fresh impact melt deposits, and/or sites where the melt deposits have been exposed through erosion or mass wasting. Determining the extent of prebiotic chemistry within these melt deposits would help us to understand how life could originate on a world very different from Earth. Key Words: Titan-Prebiotic chemistry-Solar system exploration-Impact processes-Volcanism. Astrobiology 18, 571-585.

An Assessment of Regional Variations in Martian Modified Impact Crater Morphology

AbstractImpact craters on Mars have been extensively modified by ancient geologic processes that may have included rainfall and surface runoff, snow and ice, denudation by lava flows, burial by eolian material, or others. Many of these processes can leave distinct signatures on the morphometry of the modified impact crater as well as the surrounding landscape. To look for signs of potential regional differences in crater modification processes, we conducted an analysis of different morphometric parameters related to modified impact craters located in the Margaritifer Sinus, Sinus Sabaeus, Iapygia, Mare Tyrrhenum, Aeolis, and Eridania quadrangles, including depth, crater wall slope, crater floor slope, the curvature between the interior wall and the crater floor slope, and the curvature between the interior wall and surrounding landscape. A Welch's t test analysis comparing these parameters shows that fresh impact craters (Type 4) have consistent morphologies regardless of their geographic location examined in this study, which is not unexpected. Modified impact craters both in the initial (Type 3) and terminal stages (Type 1) of modification also have statistically consistent morphologies. This would suggest that the processes that operated in the late Noachian were globally ubiquitous, and that modified craters eventually reached a stable crater morphology. However, craters preserved in advanced (but not terminal) stages of modification (Type 2) have morphologies that vary across the quadrangles. It is possible that these variations reflect spatial differences in the types and intensity of geologic processes that operated during the Noachian, implying that the ancient climate also varied across regions.

Exposed H2O-rich areas detected on Ceres with the dawn visible and infrared mapping spectrometer

H2O-rich materials are locally exposed at the surface of Ceres as discovered from infrared reflectance spectra of the Visible and InfraRed mapping spectrometer (VIR) of the Dawn mission. Nine locations on Ceres exhibit diagnostic absorption bands of the H2O molecule at 2.00, 1.65 and 1.28 µm. The detections are all consistent with H2O ice mixed with low-albedo components. All the reported H2O exposures occur at latitudes poleward of 30° in fresh craters near rim shadows, have a surface area < 7 km2, and are associated with one or more surface features such as a morphological flow or landslide, fractures, high albedo, or a pole-facing slope (one case is confirmed to be adjacent to persistent shadow). In four occurrences, these detections are associated with small (< 0.1 km2) high-albedo areas that can be recognized in high-resolution imagery (∼35 m/pixel) from the Framing Camera (FC). Since all these observations are compatible with an H2O-rich subsurface, the replenishment of surficial H2O likely comes from the ice that is present underneath. In four other occurrences, H2O is detected on walls and floors of fresh impact craters, either in the shadow or adjacent to shadows, which suggests that local thermodynamical conditions may also favor the concentration of H2O in these areas.

The Ac-5 (Fejokoo) quadrangle of Ceres: Geologic map and geomorphological evidence for ground ice mediated surface processes

NASA's Dawn spacecraft arrived at Ceres on March 6, 2015, and has been studying the dwarf planet through a series of successively lower orbits. Throughout these mission phases Dawn obtained photographic, mineralogical, elemental abundance, and gravity data. Ceres is the largest object in the asteroid belt with a mean diameter of ∼940 km. The Dawn Science Team conducted a geologic mapping campaign for Ceres similar to the one that was implemented on the asteroid Vesta (Dawn's previous target), including production of a Survey- and High Altitude Mapping Orbit (HAMO)-based global map, and a series of 15 Low Altitude Mapping Orbit (LAMO)-based quadrangle maps. In this paper we present the LAMO-based geologic map of the Ac-5 Fejokoo Quadrangle (21–66°N and 270–360°E) and discuss its implications. The Ac-5 quadrangle is primarily composed of ancient cratered terrain punctuated with several moderately fresh impact craters of geologic interest, six large tholi that are possibly cryovolcanic in origin, and an abundance of flows that well represent the full spectrum of mass wasting features observed on Ceres. The Fejokoo quadrangle hosts the majority of Oxo crater, the site of the first spectroscopic detection of H2O ice on the surface of Ceres. The H2O detection is closely related to two distinctive morphological units interpreted as possible high water ice content landslides. These observations and interpretations are consistent with ground ice mediated surface processes on Ceres.

Viscous relaxation as a prerequisite for tectonic resurfacing on Ganymede: Insights from numerical models of lithospheric extension

Ganymede’s bright terrain formed during a near-global resurfacing event (or events) that produced both heavily tectonized and relatively smooth terrains. The mechanism(s) by which resurfacing occurred on Ganymede (e.g., cryovolcanic or tectonic), and the relationship between the older, dark and the younger, bright terrain are fundamental to understanding the geological evolution of the satellite. Using a two-dimensional numerical model of lithospheric extension that has previously been used to successfully simulate surface deformation consistent with grooved terrain morphologies, we investigate whether large-amplitude preexisting topography can be resurfaced (erased) by extension (i.e., tectonic resurfacing). Using synthetically produced initial topography, we show that when the total relief of the initial topography is larger than 25–50 m, periodic groove-like structures fail to form. Instead, extension is localized in a few individual, isolated troughs. These results pose a challenge to the tectonic resurfacing hypothesis. We further investigate the effects of preexisting topography by performing suites of simulations initialized with topography derived from digital terrain models of Ganymede’s surface. These include dark terrain, fresh (relatively deep) impact craters, smooth bright terrain, and a viscously relaxed impact crater. The simulations using dark terrain and fresh impact craters are consistent with our simulations using synthetic topography: periodic groove-like deformation fails to form. In contrast, when simulations were initialized with bright smooth terrain topography, groove-like deformation results from a wide variety of heat flow and surface temperature conditions. Similarly, when a viscously relaxed impact crater was used, groove-like structures were able to form during extension. These results suggest that tectonic resurfacing may require that the amplitude of the initial topography be reduced before extension begins. We emphasize that viscous relaxation may be the key to enabling tectonic resurfacing, as the heat fluxes associated with groove terrain formation are also capable of reducing crater topography through viscous relaxation. For long-wavelength topography (large craters) viscous relaxation is unavoidable. We propose that the resurfacing of Ganymede occurred through a combination of viscous relaxation, tectonic resurfacing, cryovolcanism and, at least in a few cases, band formation. Variations in heat flow and strain magnitudes across Ganymede likely produced the complex variety of terrain types currently observed.

Red Dragon drill missions to Mars

We present the concept of using a variant of a Space Exploration Technologies Corporation (SpaceX) Dragon space capsule as a low-cost, large-capacity, near-term, Mars lander (dubbed “Red Dragon”) for scientific and human precursor missions. SpaceX initially designed the Dragon capsule for flight near Earth, and Dragon has successfully flown many times to low-Earth orbit (LEO) and successfully returned the Dragon spacecraft to Earth. Here we present capsule hardware modifications that are required to enable flight to Mars and operations on the martian surface. We discuss the use of the Dragon system to support NASA Discovery class missions to Mars and focus in particular on Dragon's applications for drilling missions. We find that a Red Dragon platform is well suited for missions capable of drilling deeper on Mars (at least 2 m) than has been accomplished to date due to its ability to land in a powered controlled mode, accommodate a long drill string, and provide payload space for sample processing and analysis. We show that a Red Dragon drill lander could conduct surface missions at three possible targets including the ice-cemented ground at the Phoenix landing site (68 °N), the subsurface ice discovered near the Viking 2 (49 °N) site by fresh impact craters, and the dark sedimentary subsurface material at the Curiosity site (4.5 °S).

Spectral investigation of quadrangle AC-H 3 of the dwarf planet Ceres – The region of impact crater Dantu

Mapping Ceres’ surface composition in the Dantu region, located between 21°–66°N and 90°–180°E, offers the unique possibility to investigate changes in the surface composition related to different stratigraphic levels of Ceres’ crust. Dantu is located in a huge depression named Vendimia Planitia, which possibly represents a completely degraded impact basin formed in the beginning of Ceres’ geological history. Most parts of this depression are characterized by strong phyllosilicate absorptions, which are stronger than elsewhere on Ceres’ surface. This spectral signature possibly is related to the material emplaced at the time of the Vendimia impact event excavating material from deeper regions of Ceres’ crust. Subsequent impacts in this basin reach far deeper into Ceres’ crust than any impact events outside of Vendemia Planitia, which could explain the spectral signature of Dantu, possibly pointing to a higher concentration of ammonium-bearing phyllosilicates in Ceres’ deeper crust. Spectral differences with respect to the small fresh craters on Dantu's floor are probably related to grain size effects causing a bluish visible slope as observed by fresh impact craters on other places on Ceres. The local enrichment of carbonates in the Dantu area could also be associated with the impact event and may have been formed by additional impact-triggered and/or post-impact alteration processes.