Crust Samples Research Articles

Measurement and prediction of the mechanical properties of a two-component food during freezing

ABSTRACTFreezing of water-rich materials inevitably leads to changes in volume and thermal stresses. Determining and modeling the thermal stresses require the mechanical properties of the food material to be properly measured or predicted during freezing. This paper investigated mechanical properties such as the Young’s modulus and Poisson’s ratio in chicken nugget crust and crumb samples at the different freezing temperatures (‒20, ‒30, and ‒40°C). Mechanical properties were measured by compression tests at seven nugget-center temperatures and a continuous video capturing method during the freezing process. Results showed that ice formation led to a sharp increase in the Young’s modulus of samples, however, a gradual decrease in Poisson’s ratio values was observed as the nuggets’ center temperature approached the freezing point. Therefore, the greatest changes were observed at the freezing point. Kinetic and fitting equations were used to model the Young’s modulus, and the Arrhenius equation was used to describe the temperature dependence. The predicted values by the models were found in close agreement with the experimental results.

Magnetic stratigraphic dating of marine hydrogenetic ferromanganese crusts

Deep-sea hydrogenetic ferromanganese crusts are both potential polymetallic resources and records of long-term environmental changes. For palaeoceanographic studies, it is important to construct a detailed and reliable chronological framework. Here, we report the results of a detailed magnetostratigraphic and rock magnetic study of four hydrogenetic Fe-Mn crusts from the Pacific Ocean (PO-01), South China Sea (SCS-01, SCS-02) and Indian Ocean (IO-01). Two groups of characteristic remanent magnetization directions were defined with nearly antipodal normal and reversed polarities for samples PO-01, SCS-01 and SCS-02, indicating a primary record of the Earth’s magnetic field. The magnetostratigraphic framework, established via correlation with the Geomagnetic Polarity Time Scale 2012, implies growth rates of 4.82 mm/Ma, 4.95 mm/Ma, 4.48 mm/Ma and 11.28 mm/Ma for samples PO-01, SCS-01, SCS-02 and IO-01, respectively. Rock magnetic measurements revealed that the Fe-Mn crust samples from the Pacific Ocean and Indian Ocean were dominated by low coercivity, non-interacting, single-domain (SD) magnetite particles, whereas the South China Sea samples were dominated by SD/pseudo-single-domain (PSD) particles. Multidomain (MD) magnetite may also be present in all samples.

Cyanobacteria growing on tree barks possess high amount of sunscreen compound mycosporine-like amino acids (MAAs)

The present study describes cyanobacterial species composition and their dominance in biological crusts from barks of different trees, roof top of building and soil of agricultural field. An attempt was also made to explore the presence of photoprotective compounds such as mycosporine-like amino acids (MAAs) in the crust samples. Microscopic examination and growth studies revealed the presence of Oscillatoria species in all the crust samples excluding the crust of roof top of a building. Study on the abundance of dominant genera showed marked differences among various crust samples but Hapalosiphon, Lyngbya, Oscillatoria and Scytonema sp. were the most dominant genera, Oscillatoria being dominant in three crust samples. Screening for the presence of photoprotective compounds showed the presence of major peaks in the range of 308–334 nm thereby pointing to the presence of MAAs in all the crust samples. The highest amount of MAAs was found in the crust of Borassus flabellifer (15,729 nmol g dry wt−1 of bark) followed by crust of roof top (14,543 nmol g dry wt−1 of crust). MAAs were separated and partially purified employing HPLC, the most common MAA present in all the crusts was identified as mycosporine-glycine. Presence of mycosporine-glycine (M-Gly) was further confirmed by FTIR and NMR. Test of in vitro colonization on the bark of Mangifera indica and Azadirachta indica by three isolates namely Hapalosiphon, Oscillatoria and Scytonema sp. showed sign of active colonization. It is felt that identification of all the MAAs other than M-Gly may prove useful in future studies especially for assessing their significance in the protection mechanism of cyanobacteria/algae against various types of abiotic stresses.

Effects of porous structure and water plasticization on the mechanical glass transition temperature and textural properties of freeze-dried trehalose solid and cookie

This study aimed to examine the effects of porous structure and water plasticization on the mechanical glass transition temperature (Tg) of freeze-dried trehalose solid and cookie. The thermal Tg and mechanical Tg were evaluated by differential scanning calorimetry (DSC) and thermal rheological analysis (TRA), respectively. The mechanical Tg of the porous trehalose sample was slightly higher than that of the pellet sample. The mechanical Tgs for pellet and porous trehalose samples were higher than thermal Tg. Although pellet, crust, and crumb cookie samples showed indistinct glass transition behavior in the DSC thermosgrams, TRA revealed a clear glass transition. There were little differences in the mechanical Tg of the cookie samples. The mechanical Tg decreased with an increase in water content, and mechanically and thermally critical water contents (water content at Tg = 25 °C) were evaluated. Fracture properties of the cookie sample changed discontinuously at the thermally critical water content.

Depositional Age of a Fossil Whale Bone from São Paulo Ridge, South Atlantic Ocean, Based on Os Isotope Stratigraphy of a Ferromanganese Crust

AbstractWhale carcasses (whale falls) deposited on the deep seafloor are associated with a distinctive biotic community. A fossil whale bone recovered from São Paulo Ridge, South Atlantic Ocean, during cruise YK13–04 Leg 1 of R/V Yokosuka was covered by a ferromanganese (Fe–Mn) crust approximately 9 mm thick. Here, we report an age constraint for this fossil bone on the basis of Os isotopic stratigraphy (187Os/188Os ratio) of the Fe–Mn crust. Major‐ and trace‐element compositions of the crust are similar to those of Fe–Mn crusts of predominantly hydrogenous origin. Rare earth element concentrations in samples of the crust, normalized with respect to Post‐Archean average Australian Shale, exhibit flat patterns with positive Ce and negative Y anomalies. These results indicate that the Fe–Mn crust consists predominantly of hydrogenous components and that it preserves the Os isotope composition of seawater at the time of its deposition. 187Os/188Os ratios of three Fe–Mn crust samples increased from 0.904 to 1.068 in ascending stratigraphic order. The value of 1.068 from the surface slice (0–3 mm depth in the crust) was identical to that of present‐day seawater within error (~1.06). The value of 0.904 from the basal slice (6–9 mm) equaled seawater values from ca. 4–5 Ma. Because it is unknown how long the bone lay on the seafloor before the Fe–Mn crust was deposited, the Os stratigraphic age of ca. 5 Ma is a minimum age of the fossil. This is the first application, to our knowledge, of marine Os isotope stratigraphy for determining the age of a fossil whale bone. Such data may offer valuable insights into the evolution of the whale‐fall biotic community.

Noble metals in ferromanganese crusts from marginal seas of the Northwest Pacific

Based on data on the concentration of noble metals (Au, Ag, Pt, Os, Ir, and Ru) in bulk samples of ferromanganese crusts, the presence of inclusions of micro- and nanosized grains of Ag, Au, Pd, and Pt, often with impurities of other elements, as well as their chaotic distribution, three sources of incorporation of these metals into ore crusts of Far Eastern seas are suggested: seawater, postvolcanic gas–hydrothermal fluids, and hydrothermal plumes. The presence of grains of platinoids and gold in ferromanganese crusts on only some mounts may result from peculiarities in the formation of volcanic rocks on the ancient continental basement.

The in vitro mucolytic effect of xylitol and dornase alfa on chronic rhinosinusitis mucus.

The overproduction and stagnation of purulent mucus impair mucociliary clearance and exacerbate the symptoms of chronic rhinosinusitis (CRS). There is a clinical need for effective topical mucolytic agents to facilitate removal of mucus and improve postoperative outcomes. The effects of xylitol (5%) and dornase alfa (1 mg/mL) on mucus and mucus crusts were investigated. Viscoelasticity and viscosity of wet mucus derived from 30 CRS patients was measured with a plate rheometer. Postoperative dried mucus crust dissolution was measured by examining peripheral transparency, central transparency, and border definition of treated crust samples from 17 CRS patients. Xylitol and dornase alfa reduced wet mucus viscoelasticity at a frequency of 0.1 Hz significantly more than the saline control. Treatments also produced significantly lower viscosities than saline at a shear rate of 10 and 100 seconds-1 . Xylitol and dornase alfa significantly decreased mucus crust border definition relative to saline. Xylitol and dornase alfa may be efficacious mucolytics, encouraging the breakdown of postoperative mucus crusts and the reduction of viscoelasticity and viscosity of wet mucus. In vivo study is required to evaluate the potential of these agents in treating recalcitrant CRS.

Implications of hydration depletion in the in vitro starch digestibility of white bread crumb and crust

The objective of this study was to provide understanding about the efficacy of decreasing dough hydration to slow down starch digestibility in white bread. Breads were made with 45 (low hydration bread, LHB), 60 (intermediate hydration bread, IHB) and 75% (high hydration bread, HHB) water (flour basis). A hydration depletion down to 45%, which is close to the minimum hydration found in commercially available white bread, did not prevent the starch in the crumb from complete gelatinization. However, LHB and IHB crumbs were more resistant to physical breakdown during in vitro digestion than HHB crumbs, resulting in a 96.81% increase of slowly digestible starch (SDS) from 75 to 45% dough hydration. The degree of gelatinization in crust samples was significantly reduced with a depletion in the dough hydration, ranging from 29.90 to 44.36%, which led to an increase of SDS from 7.41 in HHB to 13.78% in LHB (bread basis).

Scanning SQUID microscopy of a ferromanganese crust from the northwestern Pacific: Submillimeter scale magnetostratigraphy as a new tool for age determination and mapping of environmental magnetic parameters

AbstractFerromanganese crusts record long‐term deep‐sea environmental changes. Thus, providing their reliable high‐resolution age models is important. We applied a magnetostratigraphic technique to estimate the growth rate of a ferromanganese crust using scanning SQUID (superconducting quantum interference device) microscope (SSM). SSM is designed to map the magnetic field across thin sections with submillimeter resolution. The crust sample was taken from the Takuyo‐Daigo Seamount, northwestern Pacific, and recorded a limited supply of dust and sediment from continents. After drift correction and removal of spike noises, the magnetic field values were stacked within the areas of high signal‐to‐noise ratios. By correlating the obtained profiles with a standard geomagnetic polarity timescale, we obtained an average growth rate of 3.37 ± 0.06 mm/Ma, which is consistent with that obtained by 10Be/9Be geochronology (2.93 ± 0.15 mm/Ma). S ratio mapping shows low values after ~3 Ma, associated with voids between columnar structures.

Dacite formation on Vesta: Partial melting of the eucritic crust

AbstractThe Dominion Range 2010 howardite pairing group contains an evolved lithic clast of dacite composition. The dacite contains an assemblage of plagioclase, quartz, and augite, with minor pigeonite, troilite, ilmenite, FeNi metal, K‐feldspar, and phosphates. Primary augite occurs as >1 mm oikocrysts enclosing plagioclase. Quartz is abundant, comprising approximately 30% of the clast. Textural and geochemical characteristics support the hypothesis that the dacite is a primary igneous lithology, and represents a partial melt of the eucritic crust. Numerical modeling (MELTS) suggests 10–20% partial melting of a Juvinas source could have produced the dacite lithology; quantitative trace element modeling further supports crustal partial melting as the magma source for the dacite. The dacite likely formed as evolved‐melt pockets, and thus represents a volumetrically minor lithology in the Vestan crust, although its formation provides direct support for a genetic relationship between Stannern and residual trend eucrites, and is the first identification of residual eucrite complementary melts. We propose the dacite clast is the first characterized sample of tertiary crust on Vesta.

Electrical triggering of earthquakes: results of laboratory experiments at spring-block models

Recently published results of field and laboratory experiments on the seismic/acoustic response to injection of direct current (DC) pulses into the Earth crust or stressed rock samples raised a question on a possibility of electrical earthquake triggering. A physical mechanism of the considered phenomenon is not clear yet in view of the very low current density (10−7–10−8 A/m2) generated by the pulsed power systems at the epicenter depth (5–10 km) of local earthquakes occurred just after the current injection. The paper describes results of laboratory “earthquake” triggering by DC pulses under conditions of a spring-block model simulated the seismogenic fault. It is experimentally shown that the electric triggering of the laboratory “earthquake” (sharp slip of a movable block of the spring-block system) is possible only within a range of subcritical state of the system, when the shear stress between the movable and fixed blocks obtains 0.98–0.99 of its critical value. The threshold of electric triggering action is about 20 A/m2 that is 7–8 orders of magnitude higher than estimated electric current density for Bishkek test site (Northern Tien Shan, Kirghizia) where the seismic response to the man-made electric action was observed. In this connection, the electric triggering phenomena may be explained by contraction of electric current in the narrow conductive areas of the faults and the corresponding increase in current density or by involving the secondary triggering mechanisms like electromagnetic stimulation of conductive fluid migration into the fault area resulted in decrease in the fault strength properties.

Relationships between Soil Crust Development and Soil Properties in the Desert Region of North China

This study investigated the effects of soil crust development on the underlying soil properties. The field sampling work was conducted in June 2016 in the Hobq Desert in Inner Mongolia, North China. Soil crust samples and 0–6, 6–12, 12–18, 18–24, and 24–30 cm deep underlying soil samples were taken from five representative areas of different soil crust development stages. All samples were analyzed for physicochemical properties, including water content, bulk density, aggregate content, organic matter content, enzyme activities, and microbial biomass carbon and nitrogen. The results showed that the thickness, water content, macro-aggregate (>250 μm) content, organic matter content, microbial biomass, and enzyme activities of the soil crusts gradually increased along the soil crust development gradient, while the bulk density of the soil crusts decreased. Meanwhile, the physicochemical and biological properties of the soils below the algal and moss crusts were significantly ameliorated when compared with the physical crust. Moreover, the amelioration effects were significant in the upper horizons (approx. 0–12 cm deep) and diminished quickly in the deeper soil layers.

Screening and partial purification of photoprotective pigment scytonemin from cyanobacterial crusts dwelling on the historical monuments in and around Varanasi, India

In the present investigation, biological crusts from the surface of eight historical monuments of Varanasi, India, were examined for the presence of scytonemin (a cyanobacterial photoprotective pigment) containing cyanobacterial species. Lyngbya sp. and Scytonema sp. were the dominant cyanobacteria present in all crust samples. The absorption spectroscopic data of chlorophyll, carotenoids and scytonemin showed that scytonemin was more abundant than the carotene and chlorophyll in all the crusts. Identification of these compounds was done using UV-Vis spectroscopy and High Performance Liquid Chromatography (HPLC) analysis. HPLC analysis revealed the presence of scytonemin in seven out of eight samples and peaks of scytonemin with retention time ranging from 1.4-1.9 min with corresponding absorbance maxima at 386, 300 and 252±2 nm. As per our knowledge this is the first report of its kind from monuments of Varanasi. From this study, it can be concluded that synthesis of photoprotective compounds like scytonemin and its derivatives counteract the damaging effects of solar radiation which enable cyanobacteria to colonize and inhabit almost all kinds of habitats, including extreme lithic habitats, such as rocks and walls of monuments which face prolonged high intensity solar radiation.

Outbreaks of bovine herpesvirus 2 infections in calves causing ear and facial skin lesions.

We describe 3 outbreaks of superficial dermatitis caused by bovine herpesvirus 2 (BoHV-2) in dairy breed calves. Clinically, all of the affected calves were 12-26 d of age, had alopecia and crusts on the face and ears, and were non-pruritic and afebrile. Affected animals recovered spontaneously without any treatment within 2-4 wk after onset of clinical signs based on 1 herd with follow up. Histologic examination of all skin crust or tissue samples identified neutrophilic inflammation, mild hyperkeratosis, multinucleate syncytial cells, and intranuclear inclusion bodies in the syncytial cells. Real-time PCR testing on affected surface crusts or tissue provided evidence of BoHV-2, and testing, where performed, was negative for parapoxvirus including bovine papular stomatitis virus and the ovine form of malignant catarrhal fever tested in EDTA blood samples. Bovine viral diarrhea virus also was negative by ELISA, as well as bovine herpesvirus 1 by immunohistochemistry. Direct electron microscopy of infected tissues in the first outbreak revealed herpesvirus-like particles.

Bacterial activity in hydrogenetic ferromanganese crust from the Indian Ocean: a combined geochemical, experimental and pyrosequencing study

The Afanasiy-Nikitin Seamount (ANS) in the Equatorial Indian Ocean harbors hydrogenetic ferromanganese (Fe–Mn) crusts. It was hypothesized that the bacteria associated with the crust catalyze the precipitation of metal hydroxides in seawater more than abiotic dissolution, contributing to hydrogenetic accretion on the seamount. To test this hypothesis, Fe–Mn crust samples were collected from the flanks of the ANS. Geochemical properties of water samples collected were analyzed, and simulatory laboratory experiments were conducted to quantify bacterial accretion rates. Pyrosequencing was used to delineate the community associated with the crust. The environmental parameters of the water column indicated significant differences (p Mn (0.63) > Ni (0.003) > Co (0.002 mg g−1) with added glucose (0.01%) and Fe (9.09) > Mn (0.87) > Ni (0.0043) > Co (0.0008 mg g−1) without added glucose. Unlike the hydrothermal vent sites of the Pacific where e- and ζ-Proteobacteria were reported to be dominant, the hydrogenetic Fe–Mn crusts of the ANS revealed sequences related to known Fe-, Mn- and S-oxidizing bacteria of the γ- and α-Proteobacterial groups. Thus, the different selective pressures in the two environments could be one of the factors that have brought about a difference in their bacterial diversity. Besides, the ambient nutrient levels could have triggered the participation of the Proteobacterial community of the ANS in the precipitation of Fe–Mn rich minerals.

Archaeal and bacterial communities in deep-sea hydrogenetic ferromanganese crusts on old seamounts of the northwestern Pacific.

Deep-sea ferromanganese crusts are found ubiquitously on the surface of seamounts of the world’s oceans. Considering the wide distribution of the crusts, archaeal and bacterial communities on these crusts potentially play a significant role in biogeochemical cycling between oceans and seamounts; however little is known about phylogenetic diversity, abundance and function of the crust communities. To this end, we collected the crusts from the northwest Pacific basin and the Philippine Sea. We performed comprehensive analysis of the archaeal and bacterial communities of the collected crust samples by culture-independent molecular techniques. The distance between the sampling points was up to approximately 2,000 km. Surrounding sediments and bottom seawater were also collected as references near the sampling points of the crusts, and analyzed together. 16S rRNA gene analyses showed that the community structure of the crusts was significantly different from that of the seawater. Several members related to ammonia-oxidizers of Thaumarchaeota and Betaproteobacteria were detected in the crusts at most of all regions and depths by analyses of 16S rRNA and amoA genes, suggesting that the ammonia-oxidizing members are commonly present in the crusts. Although members related to the ammonia-oxidizers were also detected in the seawater, they differed from those in the crusts phylogenetically. In addition, members of uncultured groups of Alpha-, Delta- and Gammaproteobacteria were commonly detected in the crusts but not in the seawater. Comparison with previous studies of ferromanganese crusts and nodules suggests that the common members determined in the present study are widely distributed in the crusts and nodules on the vast seafloor. They may be key microbes for sustaining microbial ecosystems there.

Magnesium isotopic variation of oceanic island basalts generated by partial melting and crustal recycling

Ocean island basalts (OIBs) are geochemically diverse in radiogenic isotopes, a feature that is commonly ascribed to record the chemical heterogeneity of their deep-mantle source, where significant compositional variation relates to variable amounts of ancient recycled crustal material. Although Mg is a major constituent of the mantle, it is still unclear whether Mg isotopes of OIBs predominantly correspond to deep-mantle source heterogeneity or processes such as partial melting. Here, we present Mg isotopic and trace-element compositional data for OIBs from the Hawaii islands, the Louisville seamounts, and for altered oceanic crust samples from the South Pacific. The δ26Mg value range of these OIBs is −0.29±0.07‰ (2SD, n=17), which is a variation approximately twice as large as the known compositional variation of the peridotitic mantle (−0.23±0.04‰, 2SD). Moreover, alkaline basalt (−0.31±0.04‰, 2SD, n=12) is relatively enriched in light Mg isotopes compared to tholeiitic basalt (−0.24±0.02‰, 2SD, n=5). In contrast, altered oceanic crust analyzed in this study has heavier Mg isotopic composition (−0.18±0.08‰, 2SD, n=13) relative to the basalts and to the peridotitic mantle. An evaluation of our and published data shows that the δ26Mg values of most OIBs negatively correlate with melting-sensitive trace-element ratios, but that they are uncorrelated with source-sensitive elemental ratios. This implies that Mg isotopic variation in most OIBs is largely controlled by variable degrees of partial melting and not by source heterogeneity. Negative correlation between Nb/Zr (or La/Sm) versus δ26Mg suggests that altered oceanic crust with heavier Mg isotopic composition is a more suitable source candidate for common OIBs. However, for a given melting degree, Louisville basalts have lower δ26Mg values than other OIBs, suggesting a different source, e.g. a peridotitic mantle. Modeling calculations suggest that melting of both garnet pyroxenite (recycled altered oceanic crust) and garnet peridotite can generate melts with low-δ26Mg signature for low-degree partial melting. Therefore, if the degree of partial melting can be independently constrained for the generation of parental OIB magma, the Mg isotopic compositions of their source can be estimated to investigate the chemical heterogeneity of the deep mantle.

Sub-volcanic xenoliths from Raoul Volcano: a window on petrogenetic processes in an intra-oceanic subduction system

ABSTRACTGabbroic and tonalitic xenoliths from c. 3 ka pyroclastic deposits on Raoul Island in the intra-oceanic Kermadec arc are samples of shallow crust formed < 2 Ma ago. Gabbros are orthocumulates composed of plagioclase, augite and orthopyroxene. Some trace element and isotopic characteristics are similar to those observed in Raoul mafic lavas, but SiO2 and incompatible trace element abundances are lower. The rare earth element (REE) patterns of the gabbros manifest strong positive Eu anomalies indicative of cumulate plagioclase. Tonalitic xenoliths comprise plagioclase, quartz, magnesiohornblende, magnetite, ilmenite and titanite. Their REE patterns feature strong negative Eu anomalies, which could indicate extensive plagioclase fractionation, but some have orthocumulate textures. In contrast to Raoul dacites, tonalitic xenoliths commonly contain amphibole. They also have higher total REE, and lower K, Ba and Rb abundances, and more evolved Sr isotope compositions. They represent a spectrum from highly fractionated felsic melts, through crystal mushes to felsic cumulates and were generated during an earlier phase in the evolution of the Raoul magmatic system.

Igneous lithologies on asteroid (4) Vesta mapped using gamma-ray and neutron data

We use data collected by the Dawn Gamma-Ray and Neutron Detector (GRaND) at Vesta to map compositions corresponding to nearly pure igneous lithologies in the howardite, eucrite, diogenite (HED) meteorite clan (samples likely from Vesta). At the ∼300-km spatial scale of GRaND measurements, basaltic eucrite occurs on only 3% of the surface, whereas cumulate eucrite and orthopyroxenitic diogenite are not detected. The basaltic eucrite region is generally coincident with an area of the surface with thick regolith, elevated H, and moderate crater density, and may represent the best compositional sample of primordial vestan crust. We observe an absence of pure orthopyroxenitic diogenite terrains in the Rheasilvia basin and its ejecta, an observation corroborated by VIR (0.1%), which suggests the south-polar crust was a polymict mixture of igneous lithologies (howardite) at the time of the Rheasilvia impact, or was a thick basaltic eucrite crust with heterogeneously distributed orthopyroxenitic diogenite plutons. The most dominant igneous composition detected (11% of the surface) corresponds to one of the least-abundant igneous lithologies in the HED meteorite collection, the Yamato Type B diogenites (plagioclase-bearing pyroxenites). The distribution of Type B diogenite is spatially correlated with post-Rheasilvia craters in the north-polar region that are in close proximity to the Rheasilvia basin antipode. This suggests that north-polar Type B plutonism may have been associated with the Rheasilvia impact event. We propose that this was either through 1) uplift of pre-existing plutons at the antipode through focusing of Rheasilvia impact stress, or 2) Rheasilvia impact antipodal crustal melting, creating magmas that underwent fractionation to produce Type B plutons.

The nature of terrains of different types on the surface of Venus and selection of potential landing sites for a descent probe of the Venera-D Mission

We discuss a change in the resurfacing regimes of Venus and probable ways of forming the terrain types that make up the surface of the planet. The interpretation of the nature of the terrain types and their morphologic features allows us to characterize their scientific priority and the risk of landing on their surface to be estimated. From the scientific point of view, two terrain types are of special interest and represent easily achievable targets: the lower unit of regional plains and the smooth plains associated with impact craters. Regional plains are probably a melting from the upper fertile mantle. The material of smooth plains of impact origin is a well-mixed and representative sample of the Venusian crust. The lower unit of regional plains is the most widespread one on the surface of Venus, and it occurs within the boundaries of all of the precalculated approach trajectories of the lander. Smooth plains of impact origin are crossed by the approach trajectories precalculated for 2018 and 2026.