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Introduction: Asa part of the Hayabusa2 initial analysis [1], we analyzed eighteen Ryugu "stone" samples of 1 ~ 8 mm in size: seven stones from the 1st touch down site and eleven from the 2nd touch down site. Ryugu stones were analyzed first using X-rays. UV, visible, near-infrared mid-infrared, and mutes probes for surface reflectance spectra, internal 3D structure and element distribution [2], crystal structures, and bulk composition of light elements such as C, N, and 0. Measurements for magnetic, thermal, and physical properties mine some stones were also performed. TOF-SDIS analysis of fluid inclusions is being continued [3]. Small particles separated from some stones were ana-lyzed by IR-CT [4]. Based on 3D-CT images of individual stones, objects of interests were identified, separated by pFIE cutting, and exposed by polishing on the surface of epoxy disks. FE.EPMAJFE-SEM analysis was made on ~40 polished epoxy disks for chemical composition and textural observation [5-9]. FIB sections and small (~15 μ in diameter) fragments were separated from the polished surface and analyzed by rod, S170.1, XRF, and nano-CT. Results and discussion: Eighteen stone 2D and 3D images indicate that Ryon samples are breccias of small fragments (< ~1mm in size) of basically CI chondrite mineralogy [10]. Most of the fragments are heavily altered and consists mainly of phyllosilicates. carbonates (dolomite and brannerite), Fe sulfides and oxides, and phosphates (F-bearing hydroxyapatite); this mineralogy we call the major lithology. The mineralogy of the fragments of the major lithology shows some diversity. the abundance and shape of carbonates and phosphates differ among fragments. On the other band, some fragments in many stones are less altered and contain anhydrous silicates such as olivine and low-Ca pyroxene of typically Mr#>97 but down to Mg#~50, which we call the less-altered litbology. In the less-altered lithology, the abundance of olivine and pyroxene differs between fragments and some fragments contain them up to - 10 volti. Therefore, fragments with the less-altered lithology can be classified as CL-type thou-drite material. Most, but not all. fragments with the less-altered lithology contain only calcite as carbonate, phosphides (FeNi)3P and (Fe, Ni)2P instead of apatite. and poorly-crystallized amorphous silicates. Small (<20μm in size) type-I barred and porphyritic chondrules and CAI with spinel+hibonite-tennskite assemblages also occur. GaIS-ble ob-jects are abundant in the least-altered fragments. In summary, mineralogical and physical properties of Ryugu samples reveal incipient to advanced aqueous alteration in its parent asteroid. [ABSTRACT FROM AUTHOR]

At the final stage of terrestrial planet formation, known as the grant impact stage, a few tens of Mars-sized protoplanets collide with one another to form terrestrial planets. Almost all previous studies on the orbital and accretional evolution of protoplanets in this stage have been based on the assumption of perfect accretion, where two colliding protoplanets always merge. However, recent impact simulations have shown that collisions among protoplanets are not always merging events, that is, two colliding protoplanets sometimes move apart after the collision (hit-and-run collision). As a first step toward studying the effects of such imperfect accretion of protoplanets on terrestrial planet formation, we investigated the merging criteria for collisions of rocky protoplanets. Using the smoothed particle hydrodynamic method, we performed more than 1000 simulations of giant impacts with various parameter sets, such as the mass ratio of protoplanets, γ, the total mass of two protoplanets, MT, the impact angle, ϑ, and the impact velocity, vimp. We investigated the critical impact velocity, vcr, at the transition between merging and hit-and-run collisions. We found that the normalized critical impact velocity, vcr/vesc, depends on γ, and ϑ, but does not depend on MT, where vesc is the two-body escape velocity. We derived a simple formula for vcr/vesc, as a function of γ and ϑ (Equation (16)), and applied it to the giant impact events obtained by N-body calculations in the previous studies. We found that 40% of these events should not be merging events. [ABSTRACT FROM AUTHOR]

One of the unique aspects of Earth is that it has a fractionally large Moon, which is thought to have formed from a Moon-forming disk generated by a giant impact. The Moon stabilizes the Earth's spin axis at least by several degrees and contributes to Earth's stable climate. Given that impacts are common during planet formation, exomoons, which are moons around planets in extrasolar systems, should be common as well, but no exomoon has been confirmed. Here we propose that an initially vapor-rich moon-forming disk is not capable of forming a moon that is large with respect to the size of the planet because growing moonlets, which are building blocks of a moon, experience strong gas drag and quickly fall toward the planet. Our impact simulations show that terrestrial and icy planets that are larger than ~1.3-1.6R ⊕ produce entirely vapor disks, which fail to form a fractionally large moon. This indicates that (1) our model supports the Moon-formation models that produce vapor-poor disks and (2) rocky and icy exoplanets whose radii are smaller than ~1.6R ⊕ are ideal candidates for hosting fractionally large exomoons., (© 2022. The Author(s).)

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 ([Formula: see text] [Formula: see text] [Formula: see text][Formula: see text], where [Formula: see text] is the oxygen fugacity, [Formula: see text] is [Formula: see text], and [Formula: see text] is [Formula: see text] 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., (© 2021. The Author(s).)

The combination of dexamethasone, high-dose cytarabine, and cisplatin (DHAP) is used as salvage chemotherapy for relapsed or refractory lymphoma. It includes the administration of cisplatin in a single dose of 100 mg/m 2 , and renal toxicity is a common adverse event. In this study, we retrospectively analyzed the risk factors for renal toxicity (≥ grade 2) in 74 patients who received DHAP as salvage chemotherapy. Regarding maximal renal toxicities, 38 (51.4%), 6 (8.1%), and 1 (1.4%) patients had grade 2, 3, and 4 toxicities, respectively. Multivariate analyses revealed that overweight (body mass index ≥ 25) was an independent predictive factor for renal toxicity of ≥ grade 2 (odds ratio [OR] 4.08, P = 0.032). A subgroup analysis for patients with diffuse large B cell lymphoma treated with DHAP as second-line therapy (n = 44) confirmed that overweight was an independent risk factor (OR 5.28, P = 0.049). In conclusion, we demonstrated that overweight was an independent risk factor for renal toxicity of ≥ grade 2 in patients who received DHAP. Further clinical studies will be needed to identify a method to decrease renal toxicities after the administration of cisplatin.

Throughout the history of the solar system, Mars has experienced continuous asteroidal impacts. These impacts have produced impact-generated Mars ejecta, and a fraction of this debris is delivered to Earth as Martian meteorites. Another fraction of the ejecta is delivered to the moons of Mars, Phobos and Deimos. Here, we studied the amount and condition of recent delivery of impact ejecta from Mars to its moons. Using state-of-the-art numerical approaches, we report, for the first time, that materials delivered from Mars to its moons are physically and chemically different from the Martian meteorites, which are all igneous rocks with a limited range of ages. We show that Mars ejecta mixed in the regolith of its moons potentially covers all its geological eras and consists of all types of rocks, from sedimentary to igneous. A Martian moons sample-return mission will bring such materials back to Earth, and the samples will provide a wealth of "time-resolved" geochemical information about the evolution of Martian surface environments.

This paper presents a case study of microbe transportation in the Mars-satellites system. We examined the spatial distribution of potential impact-transported microbes on the Martian moons using impact physics by following a companion study (Fujita et al., in this issue). We used sterilization data from the precede studies (Patel et al., 2018; Summers, 2017). We considered that the microbes came mainly from the Zunil crater on Mars, which was formed during 1.0-0.1 Ma. We found that 70-80% of the microbes are likely to be dispersed all over the moon surface and are rapidly sterilized due to solar and galactic cosmic radiation except for those microbes within a thick ejecta deposit produced by natural meteoroids. The other 20-30% might be shielded from radiation by thick regolith layers that formed at collapsed layers in craters produced by Mars rock impacts. The total number of potentially surviving microbes at the thick ejecta deposits is estimated to be 3-4 orders of magnitude lower than at the Mars rock craters. The microbe concentration is irregular in the horizontal direction due to Mars rock bombardment and is largely depth-dependent due to the radiation sterilization. The surviving fraction of transported microbes would be only ∼1 ppm on Phobos and ∼100 ppm on Deimos, suggesting that the transport processes and radiation severely affect microbe survival. The microbe sampling probability from the Martian moons was also investigatesd. We suggest that sample return missions from the Martian moons are classified into Unrestricted Earth-Return missions for 30 g samples and 10 cm depth sampling, even in our conservative scenario. We also conducted a full statistical analysis pertaining to sampling the regolith of Phobos to include the effects of uncertainties in input parameters on the sampling probability. The most likely probability of microbial contamination for return samples is estimated to be two orders of magnitude lower than the 10 -6 criterion defined by the planetary protection policy of the Committee on Space Research (COSPAR)., (Copyright © 2019 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.)

Potential microbial contamination of Martian moons, Phobos and Deimos, which can be brought about by transportation of Mars ejecta produced by meteoroid impacts on the Martian surface, has been comprehensively assessed in a statistical approach, based on the most probable history of recent major gigantic meteoroid collisions on the Martian surface. This article is the first part of our study to assess potential microbial density in Mars ejecta departing from the Martian atmosphere, as a source of the second part (Kurosawa et al., 2019) where statistical analysis of microbial contamination probability is conducted. Potential microbial density on the Martian surface as the source of microorganisms was estimated by analogy to the terrestrial areas having the similar arid and cold environments, from which a probabilistic function was deduced as the asymptotic limit. Microbial survival rate during hypervelocity meteoroid collisions was estimated by numerical analysis of impact phenomena with and without taking internal friction and plastic deformation of the colliding meteoroid and the target ground into consideration. Trajectory calculations of departing ejecta through the Martian atmosphere were conducted with taking account of aerodynamic deceleration and heating by the aid of computational fluid dynamic analysis. It is found that Mars ejecta smaller than 0.03 m in diameter hardly reach the Phobos orbit due to aerodynamic deceleration, or mostly sterilized due to significant aerodynamic heating even though they can reach the Phobos orbit and beyond. Finally, the baseline dataset of microbial density in Mars ejecta departing for Martian moons has been presented for the second part of our study., (Copyright © 2019 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.)

Understanding the origins of the diversity in terrestrial planets is a fundamental goal in Earth and planetary sciences. In the Solar System, Venus has a similar size and bulk composition to those of Earth, but it lacks water. Because a richer variety of exoplanets is expected to be discovered, prediction of their atmospheres and surface environments requires a general framework for planetary evolution. Here we show that terrestrial planets can be divided into two distinct types on the basis of their evolutionary history during solidification from the initially hot molten state expected from the standard formation model. Even if, apart from their orbits, they were identical just after formation, the solidified planets can have different characteristics. A type I planet, which is formed beyond a certain critical distance from the host star, solidifies within several million years. If the planet acquires water during formation, most of this water is retained and forms the earliest oceans. In contrast, on a type II planet, which is formed inside the critical distance, a magma ocean can be sustained for longer, even with a larger initial amount of water. Its duration could be as long as 100 million years if the planet is formed together with a mass of water comparable to the total inventory of the modern Earth. Hydrodynamic escape desiccates type II planets during the slow solidification process. Although Earth is categorized as type I, it is not clear which type Venus is because its orbital distance is close to the critical distance. However, because the dryness of the surface and mantle predicted for type II planets is consistent with the characteristics of Venus, it may be representative of type II planets. Also, future observations may have a chance to detect not only terrestrial exoplanets covered with water ocean but also those covered with magma ocean around a young star.

The atmospheric compositions of Venus and Earth differ significantly, with the venusian atmosphere containing about 50 times as much 36Ar as the atmosphere on Earth. The different effects of the solar wind on planet-forming materials for Earth and Venus have been proposed to account for some of this difference in atmospheric composition, but the cause of the compositional difference has not yet been fully resolved. Here we propose that the absence or presence of an ocean at the surface of a protoplanet during the giant impact phase could have determined its subsequent atmospheric amount and composition. Using numerical simulations, we demonstrate that the presence of an ocean significantly enhances the loss of atmosphere during a giant impact owing to two effects: evaporation of the ocean, and lower shock impedance of the ocean compared to the ground. Protoplanets near Earth's orbit are expected to have had oceans, whereas those near Venus' orbit are not, and we therefore suggest that remnants of the noble-gas rich proto-atmosphere survived on Venus, but not on Earth. Our proposed mechanism explains differences in the atmospheric contents of argon, krypton and xenon on Venus and Earth, but most of the neon must have escaped from both planets' atmospheres later to yield the observed ratio of neon to argon.

The components of an object and the moisture in it can be estimated by measuring the degree of spectral polarization of scattered light from that object. In this paper the degree of spectral polarization of scattered light from CuSO(4), CuCl(2), Fe(2)O(3), SiC, S, NiCl(2), and CoCl(2) as models of soil was measured and compared with that of volcanic ash and natural soil. From these results it is estimated that Fe appears in natural soil and Si appears in volcanic ash. The field capacity point of soil was obtained from measurements of the degree of spectral polarization, and it was detected more clearly in a shorter wavelength region (about 400 nm).

It is of great significance to experiment with a simulator for remote sensing to confirm the properties and meaning of remote-sensed information and to forecast certain phenomena. This paper describes a simulator for remote sensing. The simulator, suitable for the measurement of soil moisture, consists of an optical source, a polarimeter, orbital guides for them, and a sample stage. SiC and MgO were used as soil models. The moisture in beach sand was also estimated. The degree of polarization increases with the moisture content and particle size of the sample. The field capacity point of each sample is determined by means of the polarimeter.

A field-averaging spectrograph camera utilizing a continuous interference filter and a step tablet has been investigated and its characteristics measured. Using color patches, the values obtained with the camera are compared with those obtained by a spectroradiometer and a self-spectrophotometer. The results obtained with the photographic method show slightly higher values than those of the other methods in the measured wavelength region. In the measurement of spectral reflectances of two-color patches with different ratios of area within a field of view angle, the same reversal point of the relative reflectance curves is observed with this camera as the spectroradiometer. Therefore, the function of a field-averaging spectrograph camera is the same as a spectroradiometer, which is widely used for remote sensing applications at the present time. Moreover, it is more compact, portable, and lower priced than conventional instruments. The spectral reflectances of scenes were measured by photographic and spectroradiometer methods in field experiments. The spectral image of soil photographed by a beam split camera used with the field-averaging spectrograph camera is displayed in false color.