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Earth’s surface environment is largely influenced by its budget of major volatile elements: carbon (C), nitrogen (N), and hydrogen (H). Although the volatiles on Earth are thought to have been delivered by chondritic materials, the elemental composition of the bulk silicate Earth (BSE) shows depletion in the order of N, C, and H. Previous studies have concluded that non-chondritic materials are needed for this depletion pattern. Here, we model the evolution of the volatile abundances in the atmosphere, oceans, crust, mantle, and core through the accretion history by considering elemental partitioning and impact erosion. We show that the BSE depletion pattern can be reproduced from continuous accretion of chondritic bodies by the partitioning of C into the core and H storage in the magma ocean in the main accretion stage and atmospheric erosion of N in the late accretion stage. This scenario requires a relatively oxidized magma ocean ( log 10 f O 2 ≳ IW - 2 , where f O 2 is the oxygen fugacity, IW is log 10 f O 2 IW , and f O 2 IW is f O 2 at the iron-wüstite buffer), the dominance of small impactors in the late accretion, and the storage of H and C in oceanic water and carbonate rocks in the late accretion stage, all of which are naturally expected from the formation of an Earth-sized planet in the habitable zone.

NASA’s InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed in Elysium Planitia on Mars on 26 November 2018. It aims to determine the interior structure, composition and thermal state of Mars, as well as constrain present-day seismicity and impact cratering rates. Such information is key to understanding the differentiation and subsequent thermal evolution of Mars, and thus the forces that shape the planet’s surface geology and volatile processes. Here we report an overview of the first ten months of geophysical observations by InSight. As of 30 September 2019, 174 seismic events have been recorded by the lander’s seismometer, including over 20 events of moment magnitude Mw = 3–4. The detections thus far are consistent with tectonic origins, with no impact-induced seismicity yet observed, and indicate a seismically active planet. An assessment of these detections suggests that the frequency of global seismic events below approximately Mw = 3 is similar to that of terrestrial intraplate seismic activity, but there are fewer larger quakes; no quakes exceeding Mw = 4 have been observed. The lander’s other instruments—two cameras, atmospheric pressure, temperature and wind sensors, a magnetometer and a radiometer—have yielded much more than the intended supporting data for seismometer noise characterization: magnetic field measurements indicate a local magnetic field that is ten-times stronger than orbital estimates and meteorological measurements reveal a more dynamic atmosphere than expected, hosting baroclinic and gravity waves and convective vortices. With the mission due to last for an entire Martian year or longer, these results will be built on by further measurements by the InSight lander.Geophysical and meteorological measurements by NASA’s InSight lander on Mars reveal a planet that is seismically active and provide information about the interior, surface and atmospheric workings of Mars.

The date of the Moon-forming impact places an important constraint on Earth’s origin. Lunar age estimates range from about 30 Myr to 200 Myr after Solar System formation. Central to this age debate is the greater abundance of 182W inferred for the silicate Moon than for the bulk silicate Earth. This compositional difference has been explained as a vestige of less late accretion to the Moon than to the Earth after core formation. Here we present high-precision trace element composition data from inductively coupled plasma mass spectrometry for a wide range of lunar samples. Our measurements show that the Hf/W ratio of the silicate Moon is higher than that of the bulk silicate Earth. By combining these data with experimentally derived partition coefficients, we found that the 182W excess in lunar samples can be explained by the decay of the now extinct 182Hf to 182W. 182Hf was only extant for the first 60 Myr after the Solar System formation. We conclude that the Moon formed early, approximately 50 Myr after the Solar System, and that the excess 182W of the silicate Moon is unrelated to late accretion.

In the absence of global plate tectonics, mantle convection and plume–lithosphere interaction are the main drivers of surface deformation on Venus. Among documented tectonic structures, circular volcano-tectonic features known as coronae may be the clearest surface manifestations of mantle plumes and hold clues to the global Venusian tectonic regime. Yet, the exact processes underlying coronae formation and the reasons for their diverse morphologies remain controversial. Here we use three-dimensional thermomechanical numerical simulations of impingement of a thermal mantle plume on the Venusian lithosphere to assess the origin and diversity of large Venusian coronae. The ability of the mantle plume to penetrate into the Venusian lithosphere results in four main outcomes: lithospheric dripping, short-lived subduction, embedded plume and plume underplating. During the first three scenarios, plume penetration and spreading induce crustal thickness variations that eventually lead to a final topographic isostasy-driven topographic inversion from circular trenches surrounding elevated interiors to raised rims surrounding inner depressions, as observed on many Venusian coronae. Different corona structures may represent not only different styles of plume–lithosphere interactions but also different stages in evolution. A morphological analysis of large existing coronae leads to the conclusion that at least 37 large coronae (including the largest Artemis corona) are active, providing evidence for widespread ongoing plume activity on Venus.Thermomechanical modelling shows that the formation and diverse morphologies of coronae on Venus can be explained by interactions between the lithosphere and impinging mantle plumes. Some corona structures are consistent with ongoing plume activity.

Many interpretations have been proposed to explain the presence of jarosite within Martian surficial sediments, including the possibility that it precipitated within paleo-ice deposits owing to englacial weathering of dust. However, until now a similar geochemical process was not observed on Earth nor in other planetary settings. We report a multi-analytical indication of jarosite formation within deep ice. Below 1000 m depth, jarosite crystals adhering on residual silica-rich particles have been identified in the Talos Dome ice core (East Antarctica) and interpreted as products of weathering involving aeolian dust and acidic atmospheric aerosols. The progressive increase of ice metamorphism and re-crystallization with depth, favours the relocation and concentration of dust and the formation of acidic brines in isolated environments, allowing chemical reactions and mineral neo-formation to occur. This is the first described englacial diagenetic mechanism occurring in deep Antarctic ice and supports the ice-weathering model for jarosite formation on Mars, highlighting the geologic importance of paleo ice-related processes on this planet. Additional implications concern the preservation of dust-related signals in deep ice cores with respect to paleoclimatic reconstructions and the englacial history of meteorites from Antarctic blue ice fields. The authors report in-situ formation of jarosite witin the Talos Dome ice core (East Antarctica) and show that this ferric-potassium sulfate mineral is present in ice deeper than 1000 meters and progressively increases with depth. This has implications for the presence and formation mechanisms of jarosite observed on Mars.

The lunar basalt samples returned by the Chang’e-5 mission erupted about 2.0 billion years ago during the late period of the Moon’s secular cooling. The conditions of mantle melting in the source region and the migration of magma through the thick lithosphere that led to this relatively late lunar volcanism remain open questions. Here we combine quantitative textural analyses of Chang’e-5 basaltic clasts, diffusion chronometry, clinopyroxene geothermobarometers and crystallization simulations to establish a holistic picture of the dynamic magmatic–thermal evolution of these young lunar basalts. We find that the Chang’e-5 basalts originated from an olivine-bearing pyroxenite mantle source (10–13 kbar or 250 ± 50 km; 1,350 ± 50 °C), similar to Apollo 12 low-Ti basalts. We propose these magmas then ascended through the plumbing system and accumulated mainly at the top of the lithospheric mantle (~2–5 kbar or 40–100 km, 1,150 ± 50 °C), where they stalled at least several hundred days and evolved via high-degree fractional crystallization. Finally, the remaining evolved melts erupted rapidly onto the surface over several days. Our magmatic–thermal evolution model indicates abundant low-solidus pyroxenites in the mantle source with a slightly enhanced inventory of radioactive elements can explain the prolonged, but declining, lunar volcanism up to about 2 billion years ago and beyond.The lunar basalts sampled by the Chang’e-5 mission originated from melting of a clinopyroxene-rich mantle source enhanced in radioactive elements, potentially explaining this late lunar volcanism, according to sample analysis and crystallization modelling.

Many icy Solar System bodies possess subsurface oceans. On Pluto, Sputnik Planitia’s location near the equator suggests the presence of a subsurface ocean and a locally thinned ice shell. To maintain an ocean, Pluto needs to retain heat inside. On the other hand, to maintain large variations in its thickness, Pluto’s ice shell needs to be cold. Here we show, by thermal evolution and viscous relaxation calculations, that the presence of a thin layer of clathrate hydrates (gas hydrates) at the base of the ice shell can explain both the long-term survival of the ocean and the maintenance of shell thickness contrasts. Clathrate hydrates act as a thermal insulator, preventing the ocean from completely freezing while keeping the ice shell cold and immobile. The most likely clathrate guest gas is methane, derived from precursor bodies and/or cracking of organic materials in the hot rocky core. Nitrogen molecules initially contained and/or produced later in the core would probably not be trapped as clathrate hydrates, instead supplying the nitrogen-rich surface and atmosphere. The formation of a thin clathrate hydrate layer cap to a subsurface ocean may be an important generic mechanism to maintain long-lived subsurface oceans in relatively large but minimally heated icy satellites and Kuiper belt objects.Pluto’s subsurface ocean and thickness variation in its ice shell may be maintained by a layer of methane clathrates forming an insulating cap to the ocean, according to calculations of thermal evolution and viscous relaxation.

The detection of liquid water by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) at the base of the south polar layered deposits in Ultimi Scopuli has reinvigorated the debate about the origin and stability of liquid water under present-day Martian conditions. To establish the extent of subglacial water in this region, we acquired new data, achieving extended radar coverage over the study area. Here, we present and discuss the results obtained by a new method of analysis of the complete MARSIS dataset, based on signal processing procedures usually applied to terrestrial polar ice sheets. Our results strengthen the claim of the detection of a liquid water body at Ultimi Scopuli and indicate the presence of other wet areas nearby. We suggest that the waters are hypersaline perchlorate brines, known to form at Martian polar regions and thought to survive for an extended period of time on a geological scale at below-eutectic temperatures. MARSIS provides enhanced coverage of the south polar region where there have been indications of a subglacial lake. These new data confirm the presence of a lake and suggest the existence of a complex hydrologic system including various smaller liquid bodies, probably composed of salty brines.

The mass-independent calcium isotope composition of inner-Solar-System bodies is correlated with their masses and accretion ages, indicating a rapid growth for the precursors of Earth and the Moon during the protoplanetary disk’s lifetime. Like Earth, like moon Variation in the isotopic composition of material within the early inner Solar System is usually thought to reflect spatial heterogeneity in the protoplanetary disk. Martin Schiller and co-authors find that the calcium isotope composition of samples from the parent bodies of ureilite and angrite meteorites, as well as from Vesta, Mars and Earth, are correlated to the masses of their inferred parent asteroids and planets. This provides a proxy for their accretion timescales and implies a rapid 'secular' evolution of the bulk calcium isotope composition of the disk in the rocky-planet-forming region. The authors infer that this secular evolution reflects the introduction of pristine outer-Solar-System material to the thermally processed inner protoplanetary disk associated with the accretion of mass to the proto-Sun. They also conclude that the indistinguishable calcium isotope composition of the Earth and the Moon implies that the Moon-forming impact involved protoplanets that completed their accretion near the end of the disk's lifetime. Nucleosynthetic isotope variability among Solar System objects is often used to probe the genetic relationship between meteorite groups and the rocky planets (Mercury, Venus, Earth and Mars), which, in turn, may provide insights into the building blocks of the Earth–Moon system 1 , 2 , 3 , 4 , 5 . Using this approach, it has been inferred that no primitive meteorite matches the terrestrial composition and the protoplanetary disk material from which Earth and the Moon accreted is therefore largely unconstrained 6 . This conclusion, however, is based on the assumption that the observed nucleosynthetic variability of inner-Solar-System objects predominantly reflects spatial heterogeneity. Here we use the isotopic composition of the refractory element calcium to show that the nucleosynthetic variability in the inner Solar System primarily reflects a rapid change in the mass-independent calcium isotope composition of protoplanetary disk solids associated with early mass accretion to the proto-Sun. We measure the mass-independent 48 Ca/ 44 Ca ratios of samples originating from the parent bodies of ureilite and angrite meteorites, as well as from Vesta, Mars and Earth, and find that they are positively correlated with the masses of their parent asteroids and planets, which are a proxy of their accretion timescales. This correlation implies a secular evolution of the bulk calcium isotope composition of the protoplanetary disk in the terrestrial planet-forming region. Individual chondrules from ordinary chondrites formed within one million years of the collapse of the proto-Sun 7 reveal the full range of inner-Solar-System mass-independent 48 Ca/ 44 Ca ratios, indicating a rapid change in the composition of the material of the protoplanetary disk. We infer that this secular evolution reflects admixing of pristine outer-Solar-System material into the thermally processed inner protoplanetary disk associated with the accretion of mass to the proto-Sun. The identical calcium isotope composition of Earth and the Moon reported here is a prediction of our model if the Moon-forming impact involved protoplanets or precursors that completed their accretion near the end of the protoplanetary disk’s lifetime.

It remains contentious whether the meteoritic material delivered to the terrestrial planets after the end of core formation was rich or poor in water and other volatiles. As Venus’s atmosphere has probably experienced less volatile recycling over its history than Earth’s, it may be possible to constrain the volatile delivery to the primitive Venusian atmosphere from the planet’s present-day atmospheric composition. Here we investigate the long-term evolution of Venus using self-consistent numerical simulations of global thermochemical mantle convection coupled with both an atmospheric evolution model and a late accretion N-body delivery model. We found that atmospheric escape is only able to remove a limited amount of water over the history of the planet, and that the late accretion of wet material exceeds this sink and would result in a present-day atmosphere that is too rich in volatiles. A preferentially dry composition of the late accretion impactors is most consistent with measurements of atmospheric H2O, CO2 and N2. Hence, we suggest that the late accreted material delivered to Venus was mostly dry enstatite chondrite, consistent with isotopic data for Earth, with less than 2.5% (by mass) wet carbonaceous chondrites. In this scenario, the majority of Venus’s and Earth’s water would have been delivered during the main accretion phase.Venus’s atmospheric composition suggests limited water delivery to the terrestrial planets by late accretion, according to numerical simulations of the interior and atmospheric evolution of Venus under various late accretion scenarios.