6,497 research outputs found
Effect of Topographic Degradation on Small Lunar Craters: Implications for Regolith Thickness Estimation
No full textThis website contains the derived data in the manuscript Effect of Topographic Degradation on Small Lunar Craters: Implications for Regolith Thickness Estimation by Xi Yang, Wenzhe Fa, Jun Du, Minggang Xie, and Tiantian Liu that is published in Geophysical Research Letters
Regolith Properties in the Chang'E-5 Landing Region of the Moon: Results from Multi-Source Remote Sensing Observations
No full textThis website contains the derived data in the manuscript Regolith Properties in the Chang'E-5 Landing Region of the Moon: Results from Multi-Source Remote Sensing Observations by Bojun Jia, Wenzhe Fa, Minggang Xie, Yushan Tai, and Xiaofeng Liu that is published in Journal of Geophysical Research: Planets
Modeling and simulation for ground penetrating radar study of the subsurface structure of the moon
No full textA ground penetrating radar (GPR) is currently within the scope of China's Chang-E 3 lunar mission, with the purpose of studying the subsurface structure of the Moon. In this study, the key factors affecting a lunar GPR performance are discussed firstly. Geometrical optics and ray tracing approaches are used to simulate GPR echoes from the lunar subsurface, with considering the transmission, attenuation, reflection and geometrical spreading of radar waves in lunar subsurface as well as the antenna directivity. Taking Sinus Iridum region as an example, radargrams are simulated on the basis of lunar surface topography and regolith composition. Finally, potential scientific return from GPR echoes is also discussed. ?2012 IEEE.EI
Modeling the Evolution of Lunar Regolith: 2. Growth Rate and Spatial Distribution
No full text<p>The datasets related to the work of of<em> <strong>Modeling the Evolution of Lunar Regolith: 2. Growth Rate and Spatial Distribution.</strong></em></p>
<p>This website contains the derived data in the manuscript of<em> <strong>Modeling the Evolution of Lunar Regolith: 2. Growth Rate and Spatial Distribution</strong> </em>by Mingwei Zhang, Wenzhe Fa, Emily M. Barnard, and Vincent R. Eke, which is submitted to<em> <strong>Journal of Geophysical Research: Planets</strong>.</em></p>
Morphological Characterization of Decimeter- to Hectometer-Scale Impact Craters on the Moon
No full textThis website contains the topography data and the derived data in the manuscript of Morphological Characterization of Decimeter- to Hectometer-Scale Impact Craters on the Moon by Yueyang Li, Wenzhe Fa, and Bojun Jia, which is submitted to Geophysical Research Letters for publication.
Please cite the following references when using CE-3/4/5 DTM and DOM data.
Liu, Z., Di, K., Peng, M., Wan, W., Liu, B., Li, L., … Chen, H. (2015). High precision landing site mapping and rover localization for Chang’E-3 mission. Science China Physics, Mechanics & Astronomy, 58, 1–11. https://doi.org/10.1007/s11433-014-5612-0
Tang, Z., Liu, J., Wang, X., Ren, X., Chen, W., Yan, W., … Li, C. (2020). Physical and mechanical characteristics of lunar soil at the Chang’E-4 landing site. Geophysical Research Letters, 47(22), e2020GL089499. https://doi.org/10.1029/2020GL089499
Wu, B., Li, Y., Liu, W. C., Wang, Y., Li, F., Zhao, Y., and Zhang, H. (2021), Centimeter-resolution topographic modeling and fine-scale analysis of craters and rocks at the Chang’E-4 landing site, Earth Planet. Sci. Lett., 553, 116666. https://doi.org/10.1016/j.epsl.2020.116666
Guo, D., Fa, W., Wu, B., Li, Y., & Liu, Y. (2021). Millimeter- to Decimeter-Scale Surface Slope and Roughness of the Moon at the Chang’e-4 Exploration Region. Geophysical Research Letters, 48, e2021GL094931. https://doi.org/10.1029/2021GL094931
Bo, Z., Di, K., Liu, Z., Yue, Z., Liu, J., & Shi, K. (2022). A catalogue of meter-scale impact craters in the Chang’E-5 landing area measured from centimeter resolution descent imagery. Icarus, 378, 114943. https://doi.org/10.1016/j.icarus.2022.11494
Simulation for ground penetrating radar (GPR) study of the subsurface structure of the Moon
No full textGround penetrating radar (GPR) is currently within the scope of China's Chang-E 3 lunar mission, to study the shallow subsurface of the Moon. In this study, key factors that could affect a lunar GPR performance, such as frequency, range resolution, and antenna directivity, are discussed firstly. Geometrical optics and ray tracing techniques are used to model GPR echoes, considering the transmission, attenuation, reflection, geometrical spreading of radar waves, and the antenna directivity. The influence on A-scope GPR echoes and on the simulated radargrams for the Sinus Iridum region by surface and subsurface roughness, dielectric loss of the lunar regolith, radar frequency and bandwidth, and the distance between the transmit and receive antennas are discussed. Finally, potential scientific return about lunar subsurface properties from GPR echoes is also discussed. Simulation results suggest that subsurface structure from several to hundreds of meters can be studied from GPR echoes at P and VHF bands, and information about dielectric permittivity and thickness of subsurface layers can be estimated from GPR echoes in combination with regolith composition data. (C) 2013 Elsevier B.V. All rights reserved.Geosciences, MultidisciplinaryMining & Mineral ProcessingSCI(E)EI4ARTICLE,SI98-1089
Reduced sensitivity of fa/fa Zucker rats to adrenomedullin
No full textRat adrenomedullin is a peptide vasodepressor that may be of importance in the pathogenesis of hypertensive disease. Because of the known link between obesity and hypertension, we hypothesized that decreased responsiveness to adrenomedullin might be seen in an obese rodent model. In this study, the in vivo vasodilator actions of exogenous adrenomedullin were compared in anesthetized lean (n = 7) and obese (fa/fa) Zucker rats (n = 8). Adrenomedullin dose dependently lowered mean arterial pressure in both phenotypes, but the half-maximal dose (ID50) was 2-fold higher in fa/fa rats (1.7 +/- 0.22 vs. 0.83 +/- 0.06 nmol/kg). Moreover, the duration of effect was markedly reduced in the fa/fa rats, to 1-2 min from about 5 min in the lean animals. There was no evidence for an increased rate of degradation of adrenomedullin in the fa/fa rats. Although the rats used in this study were not hypertensive, adrenomedullin had reduced sensitivity and duration of action. The evidence suggests possible defects at the target receptor or altered metabolism of adrenomedullin in obesity.LR: 20061115; PUBM: Print; JID: 0372712; 0 (Peptides); 0 (Vasodilator Agents); 148498-78-6 (Adrenomedullin); ppublishSource type: Electronic(1
High frequency thermal emission from the lunar surface and near surface temperature of the Moon from Chang'E-2 microwave radiometer
No full textNear surface temperature of the Moon and thermal behaviors of the lunar regolith can provide important information for constraining thermal and magmatic evolution models of the Moon and engineering constrains for in situ lunar exploration system. In this study, China's Chang'E-2 (CE-2) microwave radiometer (MRM) data at high frequency channels are used to investigate near surface temperature of the Moon given the penetration ability of microwave into the desiccated and porous lunar regolith. Factors that affect high frequency brightness temperature (TB), such as surface slope, solar albedo and dielectric constant, are analyzed first using a revised Racca's temperature model. Radiative transfer theory is then used to model thermal emission from a semi-infinite regolith medium, with considering dielectric constant and temperature profiles within the regolith layer. To decouple the effect of diurnal temperature variation in the uppermost lunar surface, diurnal averaged brightness temperatures at high frequency channels are used to invert mean diurnal surface and subsurface temperatures based on their bilinear profiles within the regolith layer. Our results show that, at the scale of the spatial resolution of CE-2 MRM, surface slope of crater wall varies typically from about 20 degrees to 30 degrees, and this causes a variation in TB about 10-15 K. Solar albedo can give rise to a TB difference of about 5-10 K between maria and highlands, whereas a similar to 2-8 K difference can be compensated by the dielectric constant on the other hand. Inversion results indicate that latitude (phi) variations of the mean diurnal surface and subsurface temperatures follow simple rules as cos(030) phi and cos(0.36) phi, respectively. The inverted mean diurnal temperature profiles at the Apollo 15 and 17 landing sites are also compared with the Apollo heat flow experiment data, showing an inversion uncertainty <4 K for surface temperature and <1 K for subsurface temperature. (C) 2014 Elsevier Inc. All rights reserved.Astronomy & AstrophysicsSCI(E)[email protected]
Circular polarization ratio characteristics of impact craters from Mini-RF observations and implications for ice detection at the polar regions of the Moon
No full textIn an attempt to reduce the ambiguity on radar detection of water ice at the permanently shadowed regions near the lunar poles, radar echo strength and circular polarization ratio (CPR) of impact craters are analyzed using the Miniature Radio Frequency (Mini-RF) radar data from the Lunar Reconnaissance Orbiter mission. Eight typical craters, among over 70 craters, are selected and classified into four categories based on their locations and CPR characteristics: polar anomalous, polar fresh, nonpolar anomalous, and nonpolar fresh. The influences on CPR caused by surface slope, rocks, and dielectric constant are analyzed quantitatively using high-resolution topography data and optical images. A two-component mixed model for CPR that consists of a normal surface and a rocky surface is developed to study the effect of rocks that are perched on lunar surface and buried in regolith. Our analyses show that inner wall of a typical bowl-shaped crater can give rise to a change of about 30 degrees in local incidence angle of radar wave, which can further result in a CPR difference of about 0.2. There is a strong correlation between Mini-RF CPR and rock abundance that is obtained from high-resolution optical images, and predictions from the two-component mixed model match well with the observed CPRs and the estimated rock abundances. Statistical results show that there is almost no apparent difference in CPR characteristics between the polar and nonpolar anomalous craters, or between the polar and nonpolar fresh craters. The enhanced CPR in the interior of anomalous craters is most probably caused by rocks that are perched on lunar surface or buried in regolith, instead of ice deposits as suggested in previous studies.Geochemistry & GeophysicsSCI(E)4ARTICLE81582-160811
Identification of biochemical defects in pancreatic islets of fa/fa rats: a developmental study
No full textAdult obese (fa/fa) Zucker rats hypersecrete insulin in response to glucose and other secretagogues. Functional changes in islet alpha 2-adrenoceptors (8) and glycolytic regulation (9) have been reported. In this study, the development of these biochemical lesions in islets isolated from suckling (3 week old) and weanling (5 week old) lean and fa/fa rats was investigated and compared to results in adult animals. Glucose (15 mM)-induced insulin secretion was inhibited by mannoheptulose (MH) in lean (n = 8) but not fa/fa (n = 10) adult rats, indicating loss of sensitivity of glucokinase to competitive inhibition. Sensitivity to MH was somewhat reduced in the islets of 3- and 5-week-old fa/fa (n = 7 and 12) compared to lean (n = 15 and 9) rats, requiring 30-100 fold higher concentrations to achieve significant inhibition. At 3 weeks of age fa/fa rats did not differ from lean controls in either islet insulin content or body weight, but both parameters were increased in fa/fa rats by 5 weeks. The presence of altered alpha 2-adrenoceptor function in fa/fa rats could not be confirmed in this study. Unlike the previous report, prazosin did not antagonize alpha 2-agonist mediated inhibition of insulin secretion. The presence of defective regulation of the glycolytic pathway by mannoheptulose in suckling and weanling rats may contribute to development of hyperinsulinemia in fa/fa rats.LR: 20061115; PUBM: Print; JID: 9305691; 0 (Receptors, Adrenergic, alpha); 11061-68-0 (Insulin); 50-99-7 (Glucose); 654-29-5 (Mannoheptulose); EC 2.7.1.2 (Glucokinase); ppublishSource type: Electronic(1
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