Mars Surface Composition Detector (MarSCoDe) is one of the major payloads onboard the Zhurong rover. The laser-induced breakdown spectroscopy (LIBS) component within MarSCoDe is capable of acquiring ...LIBS emission from 240 to 850 nm at targets ranging from 1.6 to 7 m. To address the previous issue of the indirect uncertainty estimation on the calibrations of other Martian LIBS, a recently developed natural gradient boosting probabilistic prediction (NGBoost) ensemble learning method was adopted for the LIBS calibration of MarSCoDe. Probabilistic Major Element Composition (PMEC) models based on NGBoost were established with the capacity of predicting the concentrations of 8 major element oxides (SiO2, TiO2, Al2O3, Fe2O3T, MgO, CaO, Na2O, K2O) in the form of normal distributions. The models were trained based on a ground spectral repository from MarSCoDe LIBS records of various reference samples. Optimizations for robustness and performance of the models were carried out with tunable max-pooling feature extraction and cross-validation-controlled hyperparameter tuning. The models were tested on an independent portion of the ground spectral repository and were checked with LIBS spectra of onboard calibration targets from Mars for their accuracy, error significancy relative to predicted uncertainty, consistency among single and averaged shots, and tolerance to mocked wavelength shifts. The PMEC models are presumably competent for basic elemental analysis of Martian silicate soil and rock along Zhurong's expedition. The limitation and interpretability of the models were also discussed to guide further works.
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•We developed a probabilistic calibration for the elemental analysis of Martian LIBS.•The calibration predicts Ca, Mg, Si, Al, Fe, Na, K, and Ti in their oxide forms.•The calibration can also quantify the uncertainty of its prediction conveniently.•The calibration was optimized and evaluated by laboratory data and Mars data.•The calibration meets the basic need of Zhurong's exploration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Chang'E-2 (CE2) lunar orbiter was the second robotic orbiter of the Chinese Lunar Exploration Program, as well as the pioneer robotic orbiter in the soft landing project in the second phase of ...the program. It used a two-line stereo camera to acquire stereo images with global coverage at a resolution of 7 m. The stereo images have a large potential for producing the best lunar topographic map. However, errors and uncertainties in the interior orientation (IO) and exterior orientation (EO) parameters of the camera seriously affected the accuracy of the global topographic mapping. In this paper, a global adjustment method is proposed to eliminate the effects of these errors. The error models are represented by a Chebyshev polynomial. The polynomial coefficients were estimated as unknowns using five lunar laser ranging retroreflector (LRRR) points as ground control points in the adjustment. The experimental results show that the planimetric and height deviations between the neighboring strips were 5 and 2 m (less than 1 pixel), respectively, which were decreased by 32.6 and 31.5 times, respectively, relative to those derived from the original EO parameters. The large inconsistencies in the CE2 trajectory data were significantly reduced after the adjustment. In comparison with the LRRR positions, the planimetric and height errors ranged from 21 to 97 m and −19 to 10 m, respectively. A new seamless mosaic and high precision absolute position topographic map has been generated using this method.
High-resolution optical cameras have always been important scientific payloads in Mars exploration missions, and the Mars topographic data produced by their detection data can provide support for ...scientific research on Mars geomorphology and geological structure evolution. As of December 2021, there are still relatively few high-resolution image data at the sub-meter level on the Martian surface, with about 2.6% global coverage and even more limited stereo coverage (just about 0.4%). At the same time, there are still some difficulties in data acquisition and terrain reconstruction processing methods for high-resolution Mars images that need to be solved. This paper described how we designed the in-orbit stereo imaging strategy based on the characteristics of the High Resolution Imaging Camera (HiRIC) of China's first Mars exploration mission (Tianwen-1), studied the technical solutions for HiRIC stereo image photogrammetry processing, and produced a topographic dataset for the "Tianwen-1" landing area, including digital orthophoto map (DOM) with a GSD (ground sample distance) of 0.7, 3.5m, and digital elevation model (DEM) with a GSD of 3.5m. Precision analysis results show that this topographic data has good consistency in planar position and elevation compared with the existing Mars terrain data, and has advantages in spatial resolution and terrain detail expression, which will be widely used in the geological background study of the "Tianwen-1" landing area, as well as landing site positioning, Martian surface remote operation planning and other Mars scientific research and engineering tasks.
Ischemic stroke (IS) is a fearful disease that can cause a variety of immune events. Nevertheless, precise immune-related mechanisms have yet to be systematically elucidated. This study aimed to ...identify immune-related signatures using machine learning and to validate them with animal experiments and single cell analysis.
In this study, we screened 24 differentially expressed genes (DEGs) while identifying immune-related signatures that may play a key role in IS development through a comprehensive strategy between least absolute shrinkage and selection operation (LASSO) regression, support vector machine (SVM) and immune-related genes. In addition, we explored immune infiltration using the CIBERSORT algorithm. Finally, we performed validation in mouse brain tissue and single cell analysis.
We identified 24 DEGs for follow-up analysis. ID3 and SLC22A4 were finally identified as the better immune-related signatures through a comprehensive strategy among DEGs, LASSO, SVM and immune-related genes. RT-qPCR, western blot, and immunofluorescence revealed a significant decrease in ID3 and a significant increase in SLC22A4 in the middle cerebral artery occlusion group. Single cell analysis revealed that ID3 was mainly concentrated in endothelial_2 cells and SLC22A4 in astrocytes in the MCAO group. A CIBERSORT finds significantly altered levels of immune infiltration in IS patients.
This study focused on immune-related signatures after stroke and ID3 and SLC22A4 may be new therapeutic targets to promote functional recovery after stroke. Furthermore, the association of ID3 and SLC22A4 with immune cells may be a new direction for post-stroke immunotherapy.
On May 15, 2021, Tianwen-1 successfully landed in the Utopia Planitia of Mars, and its rover Zhurong began to carry out an in-situ science exploration of the Mars surface. To determine the location, ...driving direction, and exploration targets of the rover, it is necessary to provide decision support for the in-situ science exploration of the rover and ensure the achievement of the scientific objectives, which pose significant challenges to the ground science team. Based on the classical research on Lunar and planetary localization, navigation and exploration target selection, and the recent study of pan-location cartographic theory, a pan-location mapping method for an in-situ rover exploration is proposed. In addition, a pan-location reference system, mapping data model, and mapping method are designed to realize the localization and visualization of the landing platform, rover, and exploration targets. The mapping method has been successfully applied to the localization, navigation, and science exploration of the target selection involved in the in-situ exploration of the Zhurong rover. The results of this study not only provide vital support to the implementation of the Tianwen-1 mission; they can also be used as instructions for other future in-situ Lunar and planetary exploration missions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of this paper is to propose a more practical mountain fire spread model for fire behavior prediction and management in Southwest forest area of China. These areas are covered mainly with ...spatial heterogeneous flammable forest and are characterized by undulating terrain and steep slopes. This model can produce more accurate fire propagation maps by combining CA (Cellular Automaton) framework with Wang Zhengfei fire physical velocity model in fine scale. Considering the inherent uncertainties of fire propagation, the model has been built on multi-dimension geophysical and environmental components and also sound knowledge of fire spread physical mechanism. Regarding small fuel patches as spatial homogenous cells, this approach makes it easier to generate higher level complex fire behavior maps from CA simple local rules and local behavior integrated with high resolution vegetation images, fine scale terrain maps and surface wind field. Because the model focuses primarily on the study of surface fire front propagation behavior, it attempts to simplify complex fuel modeling. Additionally, this Wang-Geophysical-CA model is able to analyze the time series spatial pattern of fire-front spread and model local behavior instead of the final fire spread pattern of the conventional approach. In this work, not only single influence verification tests have been made, but also simulation tests with multiple influences are carried out to demonstrate the capability of the model with fine scale vegetation maps, surface wind field, terrain, moisture content and man-made structures. Consequently, it is believable that the model predictions are in good agreement with experimental data for steady-state fire simulation. The proposed model helps to gain a greater understanding of the fire front spread local behavior and can quickly generate a sequence of complex fire front contours. It enables local managers to plan practical fire prevention activities in Southwest forest area of China as well as improve fire management skills, and will enhance the effectiveness of fire fighting strategies.
For the Time Delay Integration (TDI) staggered line-scanning thermal infrared imager, a Computational Imaging (CI) approach is developed to achieve higher spatial resolution images. After a thorough ...analysis of the causes of non-uniform image displacement and degradation for multi-channel staggered TDI arrays, the study aims to approach one-dimensional (1D) sub-pixel displacement estimation and superposition of images from time-division multiplexing scanning lines. Under the assumption that a thermal image is 2D piecewise C(2) smooth, a sparse-and-smooth deconvolution algorithm with L1-norm regularization terms combining the first and second order derivative operators is proposed to restore high frequency components and to suppress aliasing simultaneously. It is theoretically and experimentally demonstrated, with simulation and airborne thermal infrared images, that this is a state-of-the-art practical CI method to reconstruct clear images with higher frequency components from raw thermal images that are subject to instantaneous distortion and blurring.
Landforms on the Martian surface are critical to understanding the nature of surface processes in the recent past. However, modern hydroclimatic conditions on Mars remain enigmatic, as explanations ...for the formation of observed landforms are ambiguous. We report crusts, cracks, aggregates, and bright polygonal ridges on the surfaces of hydrated salt-rich dunes of southern Utopia Planitia (~25°N) from in situ exploration by the Zhurong rover. These surface features were inferred to form after 1.4 to 0.4 million years ago. Wind and CO
frost processes can be ruled out as potential mechanisms. Instead, involvement of saline water from thawed frost/snow is the most likely cause. This discovery sheds light on more humid conditions of the modern Martian climate and provides critical clues to future exploration missions searching for signs of extant life, particularly at low latitudes with comparatively warmer, more amenable surface temperatures.
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