Pub Date : 2024-09-12DOI: 10.1016/j.asr.2024.09.007
Simon Wing, Georgios Balasis
{"title":"Preface: Information theory and machine learning for geospace research","authors":"Simon Wing, Georgios Balasis","doi":"10.1016/j.asr.2024.09.007","DOIUrl":"https://doi.org/10.1016/j.asr.2024.09.007","url":null,"abstract":"","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-07DOI: 10.1016/j.asr.2024.09.005
T.V. Sruthi, G. Manju, K.S. Vishnupriya
The present study investigates the role of gravity wave induced seed perturbations in the occurrence of Equatorial Spread F (ESF) under the influence of the post sunset background conditions modulated by prevailing electrodynamics and neutral wind. Ionospheric foF data sets over geomagnetic equatorial station Trivandrum (8.5°N, 77°E and magnetic dip 0.68°N-corresponding to the period of study) corresponding to vernal and autumnal equinoctial periods encompassing high, low and moderate solar activity years, are used for the study.Meridional wind data is obtained either from ESA’s sun-synchronous satellite GOCE (Gravity field and steady-state Ocean Circulation Explorer) or derived using ionosonde h’F (base height of ionosphere at 2.5 MHz) data from Trivandrum (TVM- 8.5°N, 77°E and magnetic dip 0.68°N) and Sriharikota (SHAR −13.7°N, 80.2°E and magnetic dip 6.9°N-for period of study). This particular study is carried out for geomagnetically quiet days of Vernal Equinox (VE)and Autumnal Equinox (AE) seasons, which are most favoured for ESF occurrence over Indian longitudes. Considering thermospheric wind, ion-neutral collisions, and electric field effects in association with gravity wave seed, threshold curve is generated, which clearly demarcates ESF and NSF (Non spread F) days. Previous studies have addressed ESF variability in electrodynamical domain alone (wherein the layer is above a threshold level). The present study, for the first time, succeeds in demarcating ESF and NSF days by incorporating effects of electric field, neutral wind, collisional RT instability term, and gravity wave seed perturbations simultaneously irrespective of threshold height.
{"title":"On equatorial spread F occurrence: A multi-dimensional quantitative assessment","authors":"T.V. Sruthi, G. Manju, K.S. Vishnupriya","doi":"10.1016/j.asr.2024.09.005","DOIUrl":"https://doi.org/10.1016/j.asr.2024.09.005","url":null,"abstract":"The present study investigates the role of gravity wave induced seed perturbations in the occurrence of Equatorial Spread F (ESF) under the influence of the post sunset background conditions modulated by prevailing electrodynamics and neutral wind. Ionospheric foF data sets over geomagnetic equatorial station Trivandrum (8.5°N, 77°E and magnetic dip 0.68°N-corresponding to the period of study) corresponding to vernal and autumnal equinoctial periods encompassing high, low and moderate solar activity years, are used for the study.Meridional wind data is obtained either from ESA’s sun-synchronous satellite GOCE (Gravity field and steady-state Ocean Circulation Explorer) or derived using ionosonde h’F (base height of ionosphere at 2.5 MHz) data from Trivandrum (TVM- 8.5°N, 77°E and magnetic dip 0.68°N) and Sriharikota (SHAR −13.7°N, 80.2°E and magnetic dip 6.9°N-for period of study). This particular study is carried out for geomagnetically quiet days of Vernal Equinox (VE)and Autumnal Equinox (AE) seasons, which are most favoured for ESF occurrence over Indian longitudes. Considering thermospheric wind, ion-neutral collisions, and electric field effects in association with gravity wave seed, threshold curve is generated, which clearly demarcates ESF and NSF (Non spread F) days. Previous studies have addressed ESF variability in electrodynamical domain alone (wherein the layer is above a threshold level). The present study, for the first time, succeeds in demarcating ESF and NSF days by incorporating effects of electric field, neutral wind, collisional RT instability term, and gravity wave seed perturbations simultaneously irrespective of threshold height.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Turbidity (Turb) and Chlorophyll-a (Chl-a) are crucial indicators of water quality because they can reveal the presence of suspended particles and algae, respectively. Understanding the health of rivers and spotting long-term water quality changes can both benefit from monitoring these measures. Traditional methods of monitoring these parameters, like in-situ measurements, is time-consuming, expensive, and inconvenient in some places. Sentinel-2, a multispectral satellite, might offer a more workable and economical option for monitoring water quality, though. This study used 100 in-situ data collected from the Ganga River near Varanasi in the pre-monsoon season (pre-MS) and post-monsoon season (post-MS) in order to create a model for the prediction of optically active water quality parameters by combining Multispectral Instrument (MSI) data and machine learning method (Random Forest). To create spatial distribution maps for Chl-a and Turb, 14 spectral indices and band ratios were employed as independent variables. The results showed that the prediction accuracy for Turb (R = 0.91, MAE = 1.13 and MAPE=7.76 % during pre-MS and R = 0.93, MAE = 0.88 and MAPE=2.29 % during post-MS) and for Chl-a (R = 0.97, MAE = 0.59, and MAPE=2.07 % during pre-MS and R = 0.95, MAE = 0.61, and MAPE = 2.71 % during post-MS). The Ganga near Varanasi abruptly turned green due to an increase in algal bloom in May and June 2021. This study not only revealed the reasons behind the green appearance but also identified potential areas of concern or hotspots. In order to identify hotspot locations, drainage networks, point source discharge locations and LU-LC were used.
{"title":"Water quality hotspot identification using a remote sensing and machine learning approach: A case study of the River Ganga near Varanasi","authors":"Anurag Mishra, Anurag Ohri, Prabhat Kumar Singh, Shishir Gaur, Rajarshi Bhattacharjee","doi":"10.1016/j.asr.2024.09.004","DOIUrl":"https://doi.org/10.1016/j.asr.2024.09.004","url":null,"abstract":"Turbidity (Turb) and Chlorophyll-a (Chl-a) are crucial indicators of water quality because they can reveal the presence of suspended particles and algae, respectively. Understanding the health of rivers and spotting long-term water quality changes can both benefit from monitoring these measures. Traditional methods of monitoring these parameters, like in-situ measurements, is time-consuming, expensive, and inconvenient in some places. Sentinel-2, a multispectral satellite, might offer a more workable and economical option for monitoring water quality, though. This study used 100 in-situ data collected from the Ganga River near Varanasi in the pre-monsoon season (pre-MS) and post-monsoon season (post-MS) in order to create a model for the prediction of optically active water quality parameters by combining Multispectral Instrument (MSI) data and machine learning method (Random Forest). To create spatial distribution maps for Chl-a and Turb, 14 spectral indices and band ratios were employed as independent variables. The results showed that the prediction accuracy for Turb (R = 0.91, MAE = 1.13 and MAPE=7.76 % during pre-MS and R = 0.93, MAE = 0.88 and MAPE=2.29 % during post-MS) and for Chl-a (R = 0.97, MAE = 0.59, and MAPE=2.07 % during pre-MS and R = 0.95, MAE = 0.61, and MAPE = 2.71 % during post-MS). The Ganga near Varanasi abruptly turned green due to an increase in algal bloom in May and June 2021. This study not only revealed the reasons behind the green appearance but also identified potential areas of concern or hotspots. In order to identify hotspot locations, drainage networks, point source discharge locations and LU-LC were used.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-07DOI: 10.1016/j.asr.2024.09.001
N.Z. Mohd Afandi, R. Umar, N.H. Sabri, S. Safei, C. Monstein, C.C. Lau, S.N.A. Syed Zafar
Continuous observation of solar radio bursts (SRBs) throughout the year using the CALLISTO spectrometer generates a huge volume of spectral data. This study introduces a burst-classifier algorithm, which is an automated algorithm, to classify the SRB spectrum into three solar radio bursts, namely Type II (SRBT II), Type III (SRBT III) and Type IV (SRBT IV). The proposed algorithm was designed using four characteristic parameters derived from a collection of training dataset files. The characteristic parameters were derived from the intensity bursts observed on frequency channels and timesteps of the spectrum. This dataset consisted of 50 spectra of SRBT II and SRBT III, along with 40 spectra for SRBT IV, collected during the solar maximum of 2014 (Solar Cycle 24). After observations and analysis of the training dataset, each burst type was set up with a threshold. A training dataset of 80 data spectra from 2013 to 2016 was used to test the algorithm. Accuracy of the proposed algorithm was calculated using the percentage of true positives (TP) and false positives (FP). Findings demonstrate an accuracy of ∼74 % with 57 out of 80 spectra classified as TP and 23 spectra as FP.
利用 CALLISTO 光谱仪对太阳射电暴（SRBs）进行全年连续观测会产生大量光谱数据。本研究介绍了一种脉冲串分类器算法，这是一种自动算法，可将 SRB 频谱分为三种太阳射电暴，即 II 型（SRBT II）、III 型（SRBT III）和 IV 型（SRBT IV）。拟议算法的设计使用了从一组训练数据集文件中提取的四个特征参数。这些特征参数是从频谱的频率通道和时间步上观察到的强度脉冲串中提取的。该数据集包括 50 个 SRBT II 和 SRBT III 光谱，以及 40 个 SRBT IV 光谱，收集于 2014 年太阳极大期（太阳周期 24）。在对训练数据集进行观测和分析后，为每种爆发类型设置了阈值。为测试该算法，使用了由 2013 年至 2016 年的 80 个数据光谱组成的训练数据集。使用真阳性（TP）和假阳性（FP）的百分比计算所提出算法的准确性。结果表明，80 个光谱中有 57 个被归类为 TP，23 个被归类为 FP，准确率为 74%。
{"title":"Burst-classifier: Automated classification of solar radio burst type II, III and IV for CALLISTO spectra using physical properties during maximum of solar cycle 24","authors":"N.Z. Mohd Afandi, R. Umar, N.H. Sabri, S. Safei, C. Monstein, C.C. Lau, S.N.A. Syed Zafar","doi":"10.1016/j.asr.2024.09.001","DOIUrl":"https://doi.org/10.1016/j.asr.2024.09.001","url":null,"abstract":"Continuous observation of solar radio bursts (SRBs) throughout the year using the CALLISTO spectrometer generates a huge volume of spectral data. This study introduces a burst-classifier algorithm, which is an automated algorithm, to classify the SRB spectrum into three solar radio bursts, namely Type II (SRBT II), Type III (SRBT III) and Type IV (SRBT IV). The proposed algorithm was designed using four characteristic parameters derived from a collection of training dataset files. The characteristic parameters were derived from the intensity bursts observed on frequency channels and timesteps of the spectrum. This dataset consisted of 50 spectra of SRBT II and SRBT III, along with 40 spectra for SRBT IV, collected during the solar maximum of 2014 (Solar Cycle 24). After observations and analysis of the training dataset, each burst type was set up with a threshold. A training dataset of 80 data spectra from 2013 to 2016 was used to test the algorithm. Accuracy of the proposed algorithm was calculated using the percentage of true positives (TP) and false positives (FP). Findings demonstrate an accuracy of ∼74 % with 57 out of 80 spectra classified as TP and 23 spectra as FP.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-06DOI: 10.1016/j.asr.2024.08.057
Lele Qi, Xixiang Yang, Fangchao Bai, Xiaolong Deng, Yuelong Pan
Stratospheric airships, with their long endurance, high flight altitude, and large payload capacity, show promise in earth observation and mobile internet applications. However, challenges arise due to their low flight speed, limited maneuverability and energy constraints when planning trajectories in dynamic wind fields. This paper proposes a deep reinforcement learning-based method for trajectory planning of stratospheric airships. The model considers the motion characteristics of stratospheric airships and environmental factors like wind fields and solar radiation. The soft actor-critic (SAC) algorithm is utilized to assess the effectiveness of the method in various scenarios. A comparison between time-optimized and energy-optimized trajectories reveals that time-optimized trajectories are smoother with a higher speed, while energy-optimized trajectories can save up to 10% energy by utilizing wind fields and solar energy absorption. Overall, the deep reinforcement learning approach proves effective in trajectory planning for stratospheric airships in deterministic and dynamic wind fields, offering valuable insights for flight design and optimization.
{"title":"Stratospheric airship trajectory planning in wind field using deep reinforcement learning","authors":"Lele Qi, Xixiang Yang, Fangchao Bai, Xiaolong Deng, Yuelong Pan","doi":"10.1016/j.asr.2024.08.057","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.057","url":null,"abstract":"Stratospheric airships, with their long endurance, high flight altitude, and large payload capacity, show promise in earth observation and mobile internet applications. However, challenges arise due to their low flight speed, limited maneuverability and energy constraints when planning trajectories in dynamic wind fields. This paper proposes a deep reinforcement learning-based method for trajectory planning of stratospheric airships. The model considers the motion characteristics of stratospheric airships and environmental factors like wind fields and solar radiation. The soft actor-critic (SAC) algorithm is utilized to assess the effectiveness of the method in various scenarios. A comparison between time-optimized and energy-optimized trajectories reveals that time-optimized trajectories are smoother with a higher speed, while energy-optimized trajectories can save up to 10% energy by utilizing wind fields and solar energy absorption. Overall, the deep reinforcement learning approach proves effective in trajectory planning for stratospheric airships in deterministic and dynamic wind fields, offering valuable insights for flight design and optimization.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1016/j.asr.2024.08.076
Arly Black, Carolin Frueh
With heightened international interest in spacecraft activities in the vicinity of the Moon, cislunar space debris is likely to follow. Even one fragmentation event can have catastrophic and far-reaching consequences, which drives the need for appropriate debris characterization tools. How a single fragmentation plays out is highly dependent on any given initial condition in the near-chaotic cislunar region. This paper offers a means of structuring the cislunar region in terms of dynamical flow, which enables global characterization of fragmentation events without propagation of every possible case. This work investigates patterns in fragment behaviour as a function of energy, , and orbit location, and explores emergent dynamic structures in the vicinity of the Earth-Moon Lagrange point. Subsequent findings are applied to analysis of a realistic breakup event for a 500 kg satellite on an Lyapunov orbit with a Jacobi constant of 3.0165, modeled using an in–house modified version of the NASA Standard Breakup Model.
{"title":"Fragmentation characterization in the circular restricted three body problem for cislunar space domain awareness","authors":"Arly Black, Carolin Frueh","doi":"10.1016/j.asr.2024.08.076","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.076","url":null,"abstract":"With heightened international interest in spacecraft activities in the vicinity of the Moon, cislunar space debris is likely to follow. Even one fragmentation event can have catastrophic and far-reaching consequences, which drives the need for appropriate debris characterization tools. How a single fragmentation plays out is highly dependent on any given initial condition in the near-chaotic cislunar region. This paper offers a means of structuring the cislunar region in terms of dynamical flow, which enables global characterization of fragmentation events without propagation of every possible case. This work investigates patterns in fragment behaviour as a function of energy, , and orbit location, and explores emergent dynamic structures in the vicinity of the Earth-Moon Lagrange point. Subsequent findings are applied to analysis of a realistic breakup event for a 500 kg satellite on an Lyapunov orbit with a Jacobi constant of 3.0165, modeled using an in–house modified version of the NASA Standard Breakup Model.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04DOI: 10.1016/j.asr.2024.08.075
A.T. Karpachev
Based on the meticulous identification of ionization troughs, performed earlier from the CHAMP satellite data, twoadditional issueswereresolved: (1) the longitudinal effect characteristics in the position of the main ionospheric trough (MIT) were corrected, and (2) for the first time,the dependence of theMITposition on geomagnetic activity was determined foralllocaltime hours. A large dataset from the CHAMP satellite in the southern winter hemisphere under high solar activity was utilized. According to the refined data the amplitude of the longitudinal effect in the MITposition changes from ∼ 3° to ∼ 5° in the course of the day. The shape of the longitudinal effectvarieswith local time, however, the MIT in the eastern hemisphere isconsistentlylocated at higher latitudes than in the western hemisphere. The main reason for the longitudinal effect is the dependence of the equatorward boundary of auroral diffuse precipitation on the tilt angle of the Earth’s dipole. The dependence on geomagnetic activitywas determined as a linear regression Λ = Λ − Kp, where Λ is the geomagnetic latitude, and the Kp indexisconsidered for the previous6 h. The latitude Λ and coefficient exhibited pronounced dependence on local time, with Λ increasing and decreasing when moving from night to day. Because the amplitude of the longitudinal effect decreases with increasing magnetic activity, the value of alsodependson longitude. Consequently, coefficient wasdetermined separatelyforthe eastern and western hemispheres. Theaveragevaluesof vary from 1.3 − 1.4° during the day to 1.8 − 1.9° at night. Thedifference between theeastern and western hemispheres is ∼ 0.3°.
{"title":"Dependence of the main ionospheric trough position on local time, longitude and geomagnetic activity in the southern winter hemisphere","authors":"A.T. Karpachev","doi":"10.1016/j.asr.2024.08.075","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.075","url":null,"abstract":"Based on the meticulous identification of ionization troughs, performed earlier from the CHAMP satellite data, twoadditional issueswereresolved: (1) the longitudinal effect characteristics in the position of the main ionospheric trough (MIT) were corrected, and (2) for the first time,the dependence of theMITposition on geomagnetic activity was determined foralllocaltime hours. A large dataset from the CHAMP satellite in the southern winter hemisphere under high solar activity was utilized. According to the refined data the amplitude of the longitudinal effect in the MITposition changes from ∼ 3° to ∼ 5° in the course of the day. The shape of the longitudinal effectvarieswith local time, however, the MIT in the eastern hemisphere isconsistentlylocated at higher latitudes than in the western hemisphere. The main reason for the longitudinal effect is the dependence of the equatorward boundary of auroral diffuse precipitation on the tilt angle of the Earth’s dipole. The dependence on geomagnetic activitywas determined as a linear regression Λ = Λ − Kp, where Λ is the geomagnetic latitude, and the Kp indexisconsidered for the previous6 h. The latitude Λ and coefficient exhibited pronounced dependence on local time, with Λ increasing and decreasing when moving from night to day. Because the amplitude of the longitudinal effect decreases with increasing magnetic activity, the value of alsodependson longitude. Consequently, coefficient wasdetermined separatelyforthe eastern and western hemispheres. Theaveragevaluesof vary from 1.3 − 1.4° during the day to 1.8 − 1.9° at night. Thedifference between theeastern and western hemispheres is ∼ 0.3°.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04DOI: 10.1016/j.asr.2024.08.077
Mingzhen Gui, Yifeng Wei, Hua Yang, Yuqing Yang
The celestial navigation system based on star angle (SA) is a classical autonomous navigation method for the spacecraft, which directly provides the position information of the spacecraft relative to the near celestial body. But due to the relativistic effects, the star direction observed by spacecraft is inconsistent with that acquired from star ephemeris, which reduces navigation accuracy of SA. In addition, SA cannot directly provide the velocity information of the spacecraft. StarNAV is a novel celestial navigation method that utilizes the relativistic effects, which mostly provides the velocity information of the spacecraft. In this paper, the star angle modified with relativistic effects (SAMRE)/StarNAV integrated navigation method is proposed. The measurement model of SAMRE is established by considering relativistic effects in the measurement model of SA. Simulation results indicate that during the Mars approach phase, SAMRE has better navigation accuracy compared with SA, and the navigation accuracy of the SAMRE/StarNAV integrated navigation method is higher than that of SAMRE, StarNAV and SA/StarNAV, respectively. Furthermore, the paper analyses the impact of measurement errors on the navigation accuracy of SAMRE/StarNAV.
基于星角（SA）的天体导航系统是一种经典的航天器自主导航方法，它直接提供航天器相对于近天体的位置信息。但由于相对论效应，航天器观测到的星体方向与星历表获得的星体方向不一致，从而降低了 SA 的导航精度。此外，SA 无法直接提供航天器的速度信息。StarNAV 是一种利用相对论效应的新型天体导航方法，主要提供航天器的速度信息。本文提出了利用相对论效应修正星角（SAMRE）/StarNAV 集成导航方法。通过在 SA 测量模型中考虑相对论效应，建立了 SAMRE 的测量模型。仿真结果表明，在火星接近阶段，SAMRE 与 SA 相比具有更好的导航精度，SAMRE/StarNAV 集成导航方法的导航精度分别高于 SAMRE、StarNAV 和 SA/StarNAV。此外，本文还分析了测量误差对 SAMRE/StarNAV 导航精度的影响。
{"title":"Star angle modified with relativistic effects/StarNAV integrated navigation method for Mars exploration","authors":"Mingzhen Gui, Yifeng Wei, Hua Yang, Yuqing Yang","doi":"10.1016/j.asr.2024.08.077","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.077","url":null,"abstract":"The celestial navigation system based on star angle (SA) is a classical autonomous navigation method for the spacecraft, which directly provides the position information of the spacecraft relative to the near celestial body. But due to the relativistic effects, the star direction observed by spacecraft is inconsistent with that acquired from star ephemeris, which reduces navigation accuracy of SA. In addition, SA cannot directly provide the velocity information of the spacecraft. StarNAV is a novel celestial navigation method that utilizes the relativistic effects, which mostly provides the velocity information of the spacecraft. In this paper, the star angle modified with relativistic effects (SAMRE)/StarNAV integrated navigation method is proposed. The measurement model of SAMRE is established by considering relativistic effects in the measurement model of SA. Simulation results indicate that during the Mars approach phase, SAMRE has better navigation accuracy compared with SA, and the navigation accuracy of the SAMRE/StarNAV integrated navigation method is higher than that of SAMRE, StarNAV and SA/StarNAV, respectively. Furthermore, the paper analyses the impact of measurement errors on the navigation accuracy of SAMRE/StarNAV.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04DOI: 10.1016/j.asr.2024.08.074
A.V. Satyakumar, Shreekumari Patel
Petavius, a complex crater from the late Imbrian epoch, features a giant central peak, numerous smaller peaks, and an inner terraced wall arising nearly 3 km above the crater floor. The region has seen periods of tectonic and volcanic activity. A meter-scale detailed mapping of LROC- Narrow Angle Camera (NAC) images was carried out to understand the tectonic features and associated volcanic history under this crater. We found many fragmented blocks, fields of striated boulders, grabens, layering near grabens and striated boulders, rock exposures, and many fractures from NAC mapping, indicating magmacreating pressure underneath the floor of a crater. The fractures identified from NAC images are probably linked with an underlying magmatic sill of high-density bodies. Crater size-frequency distribution analysis indicates that magmatic activity likely persisted for ∼2.75 Ga in the Petavius crater. It is noteworthy that this relatively recent age of volcanism has not been reported previously. The crustal thickness of the study region varies from 27 to 40 km; at the mapped tectonic features and volcanic regions, the crustal thickness of 30–34 km is found. The unique tectonic environment of the Petavius crater, in combination with the associated morphological variation and numerous exposures of mafic, suggests that the crater formed in phases associated with its structural and morphologic features and is derived from the lower crust. The morphometric analysis and previous studies support a model of magmatic intrusion and sill formation within the fractured crust beneath the crater floor; such a sill would be a likely source both for effusive mare material erupted through floor fractures into low-lying portions of the crater floor. The tectonic system on the floor of the crater was the result of post-impact processes.
{"title":"Morphological and chronological mapping of Petavius crater, nearside of the Moon","authors":"A.V. Satyakumar, Shreekumari Patel","doi":"10.1016/j.asr.2024.08.074","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.074","url":null,"abstract":"Petavius, a complex crater from the late Imbrian epoch, features a giant central peak, numerous smaller peaks, and an inner terraced wall arising nearly 3 km above the crater floor. The region has seen periods of tectonic and volcanic activity. A meter-scale detailed mapping of LROC- Narrow Angle Camera (NAC) images was carried out to understand the tectonic features and associated volcanic history under this crater. We found many fragmented blocks, fields of striated boulders, grabens, layering near grabens and striated boulders, rock exposures, and many fractures from NAC mapping, indicating magmacreating pressure underneath the floor of a crater. The fractures identified from NAC images are probably linked with an underlying magmatic sill of high-density bodies. Crater size-frequency distribution analysis indicates that magmatic activity likely persisted for ∼2.75 Ga in the Petavius crater. It is noteworthy that this relatively recent age of volcanism has not been reported previously. The crustal thickness of the study region varies from 27 to 40 km; at the mapped tectonic features and volcanic regions, the crustal thickness of 30–34 km is found. The unique tectonic environment of the Petavius crater, in combination with the associated morphological variation and numerous exposures of mafic, suggests that the crater formed in phases associated with its structural and morphologic features and is derived from the lower crust. The morphometric analysis and previous studies support a model of magmatic intrusion and sill formation within the fractured crust beneath the crater floor; such a sill would be a likely source both for effusive mare material erupted through floor fractures into low-lying portions of the crater floor. The tectonic system on the floor of the crater was the result of post-impact processes.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The temperature, pressure and specific humidity data of Sentinel-6 (S6) products are compared with the ECMWF Reanalysis v5 (ERA5) and radio sounding in 2022. The overall STD of temperature, pressure and specific humidity for S6-ERA5 and S6-Radiosonde are 0.74 ℃, 0.45 hPa, 0.3 g/kg, 1.33 ℃, 0.51 hPa, 0.34 g/kg respectively. The study found that the consistency of these three atmospheric parameters between S6 and ERA5 is better than that between S6 and radiosonde. In the aspect of temporal characteristics, the specific humidity STD of S6-ERA5 decrease successively in summer, autumn, spring and winter. In the aspect of spatial characteristics, S6 has better retrieval ability of temperature values in the troposphere, but the maximum negative bias value of temperature between S6 and ERA5 is −1.57 ℃ at 41.7 km. The pressure bias values of S6 and ERA5 fluctuate greatly below the troposphere. In addition, the STD values of S6-ERA5 and S6-Radiosonde specific humidity data both show the decreasing characteristics in sequence from low to high latitudes.
{"title":"Comparison of temperature, pressure and specific humidity derived from Sentinel-6 with ERA5 and radiosonde","authors":"Huizhong Zhu, Guangsheng Liu, Xiang Gao, Shuaimin Wang, Chunhua Jiang","doi":"10.1016/j.asr.2024.09.003","DOIUrl":"https://doi.org/10.1016/j.asr.2024.09.003","url":null,"abstract":"The temperature, pressure and specific humidity data of Sentinel-6 (S6) products are compared with the ECMWF Reanalysis v5 (ERA5) and radio sounding in 2022. The overall STD of temperature, pressure and specific humidity for S6-ERA5 and S6-Radiosonde are 0.74 ℃, 0.45 hPa, 0.3 g/kg, 1.33 ℃, 0.51 hPa, 0.34 g/kg respectively. The study found that the consistency of these three atmospheric parameters between S6 and ERA5 is better than that between S6 and radiosonde. In the aspect of temporal characteristics, the specific humidity STD of S6-ERA5 decrease successively in summer, autumn, spring and winter. In the aspect of spatial characteristics, S6 has better retrieval ability of temperature values in the troposphere, but the maximum negative bias value of temperature between S6 and ERA5 is −1.57 ℃ at 41.7 km. The pressure bias values of S6 and ERA5 fluctuate greatly below the troposphere. In addition, the STD values of S6-ERA5 and S6-Radiosonde specific humidity data both show the decreasing characteristics in sequence from low to high latitudes.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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