Pub Date : 2026-07-01Epub Date: 2026-02-09DOI: 10.1016/j.actaastro.2026.02.012
Alexander H. Ferdinand Ferguson, Jacob Haqq-Misra
As humans make ambitious efforts toward long-duration activities beyond Earth, new challenges will continue to emerge that highlight the need for governance frameworks capable of managing shared resources and technical standards in order to sustain human life in these hostile environments. Earth-based governance models of cooperative sovereignty can inform governance mechanisms for future Mars settlements, particularly regarding inter-settlement relations and the technical coordination required for multiple independent settlements to coexist. This study analyzes the International Telecommunication Union (ITU) and the Universal Postal Union (UPU), two of the oldest international organizations, which have successfully established evolving standards across sovereign nations. This analysis of the development and governance structures of these two organizations, and how they resolved key sovereignty issues, reveals principles that could be applicable to future settlements beyond Earth, particularly on Mars. Key insights include the strategic necessity of institutional neutrality, the management of asymmetric power relations, and the governance of shared resources under conditions of mutual vulnerability. The study distinguishes between a “Survival Layer” of technical standards essential for immediate safety and an “Operational Layer” governing economic and political activities, suggesting different governance approaches for each. Although some of these examples of cooperative sovereignty on Earth might not be sufficient for Mars due to its unique environment, lessons from the ITU and UPU case studies offer valuable strategies for designing flexible and sustainable governance models that can function from inception through explicit Earth-based coordination.
{"title":"Cooperative sovereignty on Mars: Lessons from the International Telecommunication Union and Universal Postal Union","authors":"Alexander H. Ferdinand Ferguson, Jacob Haqq-Misra","doi":"10.1016/j.actaastro.2026.02.012","DOIUrl":"10.1016/j.actaastro.2026.02.012","url":null,"abstract":"<div><div>As humans make ambitious efforts toward long-duration activities beyond Earth, new challenges will continue to emerge that highlight the need for governance frameworks capable of managing shared resources and technical standards in order to sustain human life in these hostile environments. Earth-based governance models of cooperative sovereignty can inform governance mechanisms for future Mars settlements, particularly regarding inter-settlement relations and the technical coordination required for multiple independent settlements to coexist. This study analyzes the International Telecommunication Union (ITU) and the Universal Postal Union (UPU), two of the oldest international organizations, which have successfully established evolving standards across sovereign nations. This analysis of the development and governance structures of these two organizations, and how they resolved key sovereignty issues, reveals principles that could be applicable to future settlements beyond Earth, particularly on Mars. Key insights include the strategic necessity of institutional neutrality, the management of asymmetric power relations, and the governance of shared resources under conditions of mutual vulnerability. The study distinguishes between a “Survival Layer” of technical standards essential for immediate safety and an “Operational Layer” governing economic and political activities, suggesting different governance approaches for each. Although some of these examples of cooperative sovereignty on Earth might not be sufficient for Mars due to its unique environment, lessons from the ITU and UPU case studies offer valuable strategies for designing flexible and sustainable governance models that can function from inception through explicit Earth-based coordination.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 47-53"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-06DOI: 10.1016/j.actaastro.2026.02.010
Giacomo Franchini , Patrick Roncagliolo , Davide Graziato , Alessandro Ruggiero Chiminelli , Andrea Merlo , Marcello Chiaberge
In recent years, space agencies and private companies have shown a renewed interest in Moon exploration, with the ultimate goal of having a permanent human presence on the surface by the 2030s. A crucial step in this direction involves deploying robotic missions. To this purpose, at Thales Alenia Space Italia S.p.A., a versatile, multipurpose four-wheeled robotic platform with active suspensions has been designed as a common reference mobility system able to perform a multitude of tasks on the Moon, spanning from South Pole exploration to In Situ Resource Utilization. In this context, we propose a state estimation framework based on factor graph optimization to perform sensor fusion and estimation of rover odometry. The implementation relies on the ROS 2 package Fuse, which has been optimized and extended with 3D sensors and motion models. The paper contributions are twofold: firstly, we developed a method for estimating the rover’s linear and angular body velocities based on data from the wheel-steer-suspension assembly encoders. Three-dimensional components of the body velocity and the associated covariance matrix are computed by accurately determining the plane of instantaneous motion of the rover. Secondly, dedicated sensor models are used to fuse the estimated body velocities with readings from the on-board IMU and with odometry input computed from a visual pipeline. The latter can be obtained both from a stereo camera by matching visual features, or by registering point clouds gathered by time-of-flight sensors, allowing autonomous navigation in any lighting condition. Constraints derived from different sensors are joined by leveraging a motion model that encapsulates the entire span of locomotion modalities allowed by the rover geometry. The method has been validated in simulations built on Project Chrono and with the rover prototype navigating in a representative facility. Results demonstrate that the framework is highly optimized, efficiently facilitating the integration of multiple sensor readings from various sources, delivering fused odometry outputs at a high frequency, and ensuring accurate and real-time state updates.
{"title":"A novel state estimation framework for a four-wheeled lunar rover with active articulated suspensions","authors":"Giacomo Franchini , Patrick Roncagliolo , Davide Graziato , Alessandro Ruggiero Chiminelli , Andrea Merlo , Marcello Chiaberge","doi":"10.1016/j.actaastro.2026.02.010","DOIUrl":"10.1016/j.actaastro.2026.02.010","url":null,"abstract":"<div><div>In recent years, space agencies and private companies have shown a renewed interest in Moon exploration, with the ultimate goal of having a permanent human presence on the surface by the 2030s. A crucial step in this direction involves deploying robotic missions. To this purpose, at Thales Alenia Space Italia S.p.A., a versatile, multipurpose four-wheeled robotic platform with active suspensions has been designed as a common reference mobility system able to perform a multitude of tasks on the Moon, spanning from South Pole exploration to In Situ Resource Utilization. In this context, we propose a state estimation framework based on factor graph optimization to perform sensor fusion and estimation of rover odometry. The implementation relies on the ROS 2 package <em>Fuse</em>, which has been optimized and extended with 3D sensors and motion models. The paper contributions are twofold: firstly, we developed a method for estimating the rover’s linear and angular body velocities based on data from the wheel-steer-suspension assembly encoders. Three-dimensional components of the body velocity and the associated covariance matrix are computed by accurately determining the plane of instantaneous motion of the rover. Secondly, dedicated sensor models are used to fuse the estimated body velocities with readings from the on-board IMU and with odometry input computed from a visual pipeline. The latter can be obtained both from a stereo camera by matching visual features, or by registering point clouds gathered by time-of-flight sensors, allowing autonomous navigation in any lighting condition. Constraints derived from different sensors are joined by leveraging a motion model that encapsulates the entire span of locomotion modalities allowed by the rover geometry. The method has been validated in simulations built on Project Chrono and with the rover prototype navigating in a representative facility. Results demonstrate that the framework is highly optimized, efficiently facilitating the integration of multiple sensor readings from various sources, delivering fused odometry outputs at a high frequency, and ensuring accurate and real-time state updates.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 54-70"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-05DOI: 10.1016/j.actaastro.2026.01.059
William Veber Moisés da Silva , André Fernando de Castro da Silva , Vinicius Malatesta , Cornelis Henricus Venner
Scramjet engines offer great potential for hypersonic propulsion and space access, but efficient combustion remains challenging due to the extremely short residence time for fuel–air mixing and burning. This study presents a parametric investigation of a cavity flameholder with upstream transverse hydrogen injection applied to the HyShot-IV scramjet combustor geometry, using RANS-based CFD simulations in Ansys CFX. The model incorporates the – SST turbulence model and the Burning Velocity Model to analyze the impact of cavity aspect ratio (AR) on key performance parameters, including mixing efficiency, combustion-chamber efficiency, flame stabilization, and pressure recovery. Six configurations were examined: one baseline without a cavity and five cavity cases with . Results demonstrate that cavity flameholders significantly enhance combustion performance by generating recirculation zones, stabilizing the flame, and intensifying turbulence, which collectively promote efficient fuel–air mixing, and these favorable effects are further amplified with increasing AR. Case E () achieved the highest performance, with mixing and combustion efficiencies of 72.3% and 72.5%, respectively, at the expense of a moderate reduction in pressure recovery to 53.8%. Conversely, smaller cavities, such as in Case A (), provided limited mixing improvements, with a mixing efficiency of 55.9%, yet retained higher pressure recovery at 56.7%. Key flow features observed include shear layers, cavity expansion shocks, and counter-rotating vortex pairs (CVPs), which interact with shock waves and boundary layers to enhance fuel distribution and combustion. Larger cavities, such as in Cases D () and E, promoted earlier hydrogen consumption and sustained combustion zones. The baseline configuration, lacking a cavity, exhibited the lowest performance metrics, with poor mixing efficiency (51.3%) and delayed combustion, underscoring the importance of cavity-induced structures for efficient scramjet operation.
{"title":"Parametric evaluation of a cavity flameholder with transverse reacting hydrogen injection applied to a scramjet combustor","authors":"William Veber Moisés da Silva , André Fernando de Castro da Silva , Vinicius Malatesta , Cornelis Henricus Venner","doi":"10.1016/j.actaastro.2026.01.059","DOIUrl":"10.1016/j.actaastro.2026.01.059","url":null,"abstract":"<div><div>Scramjet engines offer great potential for hypersonic propulsion and space access, but efficient combustion remains challenging due to the extremely short residence time for fuel–air mixing and burning. This study presents a parametric investigation of a cavity flameholder with upstream transverse hydrogen injection applied to the HyShot-IV scramjet combustor geometry, using RANS-based CFD simulations in Ansys CFX. The model incorporates the <span><math><mi>k</mi></math></span>–<span><math><mi>ω</mi></math></span> SST turbulence model and the Burning Velocity Model to analyze the impact of cavity aspect ratio (AR) on key performance parameters, including mixing efficiency, combustion-chamber efficiency, flame stabilization, and pressure recovery. Six configurations were examined: one baseline without a cavity and five cavity cases with <span><math><mrow><mi>A</mi><mi>R</mi><mo>∈</mo><mrow><mo>{</mo><mn>3</mn><mo>.</mo><mn>2</mn><mo>;</mo><mspace></mspace><mn>4</mn><mo>.</mo><mn>0</mn><mo>;</mo><mspace></mspace><mn>4</mn><mo>.</mo><mn>5</mn><mo>;</mo><mspace></mspace><mn>5</mn><mo>.</mo><mn>75</mn><mo>;</mo><mspace></mspace><mn>7</mn><mo>.</mo><mn>0</mn><mo>}</mo></mrow></mrow></math></span>. Results demonstrate that cavity flameholders significantly enhance combustion performance by generating recirculation zones, stabilizing the flame, and intensifying turbulence, which collectively promote efficient fuel–air mixing, and these favorable effects are further amplified with increasing AR. Case E (<span><math><mrow><mi>A</mi><mi>R</mi><mo>=</mo><mn>7</mn><mo>.</mo><mn>0</mn></mrow></math></span>) achieved the highest performance, with mixing and combustion efficiencies of 72.3% and 72.5%, respectively, at the expense of a moderate reduction in pressure recovery to 53.8%. Conversely, smaller cavities, such as in Case A (<span><math><mrow><mi>A</mi><mi>R</mi><mo>=</mo><mn>3</mn><mo>.</mo><mn>2</mn></mrow></math></span>), provided limited mixing improvements, with a mixing efficiency of 55.9%, yet retained higher pressure recovery at 56.7%. Key flow features observed include shear layers, cavity expansion shocks, and counter-rotating vortex pairs (CVPs), which interact with shock waves and boundary layers to enhance fuel distribution and combustion. Larger cavities, such as in Cases D (<span><math><mrow><mi>A</mi><mi>R</mi><mo>=</mo><mn>5</mn><mo>.</mo><mn>75</mn></mrow></math></span>) and E, promoted earlier hydrogen consumption and sustained combustion zones. The baseline configuration, lacking a cavity, exhibited the lowest performance metrics, with poor mixing efficiency (51.3%) and delayed combustion, underscoring the importance of cavity-induced structures for efficient scramjet operation.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 156-177"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-01DOI: 10.1016/j.actaastro.2026.01.062
Yiming Ke , Hao Zhu , Shuting Wang , Yuanjun Zhang , Hui Tian , Guobiao Cai
Hybrid rocket motors (HRMs) are gaining widespread application due to their advantages, including high safety, ease of thrust control, and multiple restart capability. However, nozzle ablation remains a critical technical bottleneck limiting their development. This study presents a numerical investigation of nozzle mechanical erosion in HRMs under overload conditions. The mechanical erosion of nozzles for four propellant grain configurations tube, star, single-channel wheel, and multi-channel wheel were computationally analyzed. The results reveal a strong correlation between nozzle mechanical erosion and the propellant-grain type, as well as a significant dependence on motor overload conditions. Under certain operating scenarios, the peak erosion rate increases by more than threefold compared with that under non-overload conditions. As overload increases, the peak erosion rate initially rises and then stabilizes. For the motor configurations studied, when the overload exceeds 10 g, the maximum erosion rate remains nearly constant. Furthermore, the magnitude of the overload effect on erosion and particle distribution varies with grain type. Overall, the influence of overload is more pronounced for single-channel grains than for multi-channel grain. Within the single-channel grains, the degree of influence decreases in the following order: cylindrical, star, and wheel grain. It is worth noting that this study focuses on the mechanical erosion of HRMs nozzle under overload conditions and does not consider the effect of overload on the combustion state.
{"title":"Numerical simulation and analysis of nozzle mechanical erosion in hybrid rocket motors under overload conditions","authors":"Yiming Ke , Hao Zhu , Shuting Wang , Yuanjun Zhang , Hui Tian , Guobiao Cai","doi":"10.1016/j.actaastro.2026.01.062","DOIUrl":"10.1016/j.actaastro.2026.01.062","url":null,"abstract":"<div><div>Hybrid rocket motors (HRMs) are gaining widespread application due to their advantages, including high safety, ease of thrust control, and multiple restart capability. However, nozzle ablation remains a critical technical bottleneck limiting their development. This study presents a numerical investigation of nozzle mechanical erosion in HRMs under overload conditions. The mechanical erosion of nozzles for four propellant grain configurations tube, star, single-channel wheel, and multi-channel wheel were computationally analyzed. The results reveal a strong correlation between nozzle mechanical erosion and the propellant-grain type, as well as a significant dependence on motor overload conditions. Under certain operating scenarios, the peak erosion rate increases by more than threefold compared with that under non-overload conditions. As overload increases, the peak erosion rate initially rises and then stabilizes. For the motor configurations studied, when the overload exceeds 10 g, the maximum erosion rate remains nearly constant. Furthermore, the magnitude of the overload effect on erosion and particle distribution varies with grain type. Overall, the influence of overload is more pronounced for single-channel grains than for multi-channel grain. Within the single-channel grains, the degree of influence decreases in the following order: cylindrical, star, and wheel grain. It is worth noting that this study focuses on the mechanical erosion of HRMs nozzle under overload conditions and does not consider the effect of overload on the combustion state.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 122-140"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-10DOI: 10.1016/j.actaastro.2026.02.005
Cong Xue , Guanghui Sun , Xiangyu Shao
This paper presents a novel predefined-time sliding mode controller for the space tethered satellite (STS) system, incorporating a radial basis function neural network (RBFNN). First, a nonlinear dynamical model of the STS deployment is derived. Then, a modified nonsingular terminal sliding surface and corresponding nonsingular terminal sliding mode controller (NTSMC) with RBFNN are introduced. The predefined-time control ensures system convergence within a specified time, meeting mission requirements. Additionally, the RBFNN is employed to estimate and compensate for external disturbances, thus enhancing the system’s disturbance rejection capability. Meanwhile, the stability and predefined-time convergence of the proposed NTSMC are proved based on the Lyapunov theorem. Finally, numerical simulations of STS deployment are conducted, demonstrating the effectiveness and advantages of the proposed control scheme.
{"title":"Predefined-time sliding mode control with RBF neural network for space tethered satellite deployment","authors":"Cong Xue , Guanghui Sun , Xiangyu Shao","doi":"10.1016/j.actaastro.2026.02.005","DOIUrl":"10.1016/j.actaastro.2026.02.005","url":null,"abstract":"<div><div>This paper presents a novel predefined-time sliding mode controller for the space tethered satellite (STS) system, incorporating a radial basis function neural network (RBFNN). First, a nonlinear dynamical model of the STS deployment is derived. Then, a modified nonsingular terminal sliding surface and corresponding nonsingular terminal sliding mode controller (NTSMC) with RBFNN are introduced. The predefined-time control ensures system convergence within a specified time, meeting mission requirements. Additionally, the RBFNN is employed to estimate and compensate for external disturbances, thus enhancing the system’s disturbance rejection capability. Meanwhile, the stability and predefined-time convergence of the proposed NTSMC are proved based on the Lyapunov theorem. Finally, numerical simulations of STS deployment are conducted, demonstrating the effectiveness and advantages of the proposed control scheme.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 178-186"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146153016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-04DOI: 10.1016/j.actaastro.2026.02.004
Salvatore Rea , Riccardo Bevilacqua , Emanuela Gaglio
This work characterizes linearized CR3BP propagation accuracy in the cislunar region through convergence analysis and Monte Carlo robustness assessment over hundreds of initial conditions. Results quantify order error scaling with timestep, identify phase-space regions where linearization remains valid, and provide practical guidelines for relinearization cadence selection in Earth–Moon mission design.
{"title":"On the analytical study and convergence properties of state-dependent linearization of the CR3BP in the cislunar region","authors":"Salvatore Rea , Riccardo Bevilacqua , Emanuela Gaglio","doi":"10.1016/j.actaastro.2026.02.004","DOIUrl":"10.1016/j.actaastro.2026.02.004","url":null,"abstract":"<div><div>This work characterizes linearized CR3BP propagation accuracy in the cislunar region through convergence analysis and Monte Carlo robustness assessment over hundreds of initial conditions. Results quantify order error scaling with timestep, identify phase-space regions where linearization remains valid, and provide practical guidelines for relinearization cadence selection in Earth–Moon mission design.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 38-46"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-05DOI: 10.1016/j.actaastro.2026.02.007
Sage O. Sherman, Allison P. Hayman
Degraded mental performance is a risk for astronauts on long duration spaceflight missions for which non-invasive, unobtrusive countermeasures are currently under investigation. Inducing neuromodulation using non-invasive brain stimulation (NiBS) techniques may be a useful and safe countermeasure approach to stimulate neural processes, but to date a synthesis of promising techniques has not been performed. This work evaluates four NiBS techniques: transcranial electrical stimulation (tES), transcranial magnetic stimulation (TMS), transcranial photobiomodulation (tPBM), and stochastic resonance (SR). We identify each technique's most promising attributes for efficacy in improving human performance while demonstrating the ability to be administered in a spaceflight environment. The evaluation scored each technology on three variables related to supporting human performance and mental health, and three variables related to crew and mission implementation. This analysis suggests that the separate NiBS techniques map better to addressing these specific variables. However, none of the techniques evaluated have currently been demonstrated in space. It is unknown whether the spaceflight environment affects the brain and its neural mechanisms in a way that impacts its interaction with NiBS techniques. We recommend continued investment to address these limitations. Further, the methods in this paper to assess emergent medical countermeasures may be applied for other technologies and be directed toward specific mission requirements, be it spaceflight, ground-studies, or field assessments.
{"title":"Evaluation of non-invasive brain stimulation techniques for use on long duration spaceflight missions","authors":"Sage O. Sherman, Allison P. Hayman","doi":"10.1016/j.actaastro.2026.02.007","DOIUrl":"10.1016/j.actaastro.2026.02.007","url":null,"abstract":"<div><div>Degraded mental performance is a risk for astronauts on long duration spaceflight missions for which non-invasive, unobtrusive countermeasures are currently under investigation. Inducing neuromodulation using non-invasive brain stimulation (NiBS) techniques may be a useful and safe countermeasure approach to stimulate neural processes, but to date a synthesis of promising techniques has not been performed. This work evaluates four NiBS techniques: transcranial electrical stimulation (tES), transcranial magnetic stimulation (TMS), transcranial photobiomodulation (tPBM), and stochastic resonance (SR). We identify each technique's most promising attributes for efficacy in improving human performance while demonstrating the ability to be administered in a spaceflight environment. The evaluation scored each technology on three variables related to supporting human performance and mental health, and three variables related to crew and mission implementation. This analysis suggests that the separate NiBS techniques map better to addressing these specific variables. However, none of the techniques evaluated have currently been demonstrated in space. It is unknown whether the spaceflight environment affects the brain and its neural mechanisms in a way that impacts its interaction with NiBS techniques. We recommend continued investment to address these limitations. Further, the methods in this paper to assess emergent medical countermeasures may be applied for other technologies and be directed toward specific mission requirements, be it spaceflight, ground-studies, or field assessments.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 71-81"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-06DOI: 10.1016/j.actaastro.2026.02.009
Kun Wang , Roberto Armellin , Adam Evans , Harry Holt , Zheng Chen
Machine learning techniques have demonstrated their effectiveness in achieving autonomy and optimality for nonlinear and high-dimensional dynamical systems. However, traditional black-box machine learning methods often lack formal stability guarantees, which are critical for safety-sensitive aerospace applications. This paper proposes a comprehensive framework that combines control Lyapunov functions with supervised learning to provide certifiably stable, time- and fuel-optimal guidance for relative motion rendezvous maneuvers. A novel neural candidate Lyapunov function is first developed that ensures positive definiteness. Subsequently, a control policy is formulated wherein the thrust direction is chosen to minimize the time derivative of the Lyapunov function, while the throttle level is set to the minimum required value. This approach guarantees that all control Lyapunov function loss terms are either naturally satisfied or replaced by the derived control policy. To jointly supervise the Lyapunov function and the control policy, a simple loss function is introduced, leveraging optimal state-control pairs obtained through a polynomial map based method. Consequently, the trained neural network not only certifies the Lyapunov function but also generates a near-optimal guidance policy, even for the bang–bang fuel-optimal problem. Furthermore, the framework is easily extensible to nonlinear control-affine systems. Extensive numerical simulations are presented to validate the proposed method.
{"title":"Learning-based optimal guidance for spacecraft close-proximity operations with certified stability","authors":"Kun Wang , Roberto Armellin , Adam Evans , Harry Holt , Zheng Chen","doi":"10.1016/j.actaastro.2026.02.009","DOIUrl":"10.1016/j.actaastro.2026.02.009","url":null,"abstract":"<div><div>Machine learning techniques have demonstrated their effectiveness in achieving autonomy and optimality for nonlinear and high-dimensional dynamical systems. However, traditional black-box machine learning methods often lack formal stability guarantees, which are critical for safety-sensitive aerospace applications. This paper proposes a comprehensive framework that combines control Lyapunov functions with supervised learning to provide certifiably stable, time- and fuel-optimal guidance for relative motion rendezvous maneuvers. A novel neural candidate Lyapunov function is first developed that ensures positive definiteness. Subsequently, a control policy is formulated wherein the thrust direction is chosen to minimize the time derivative of the Lyapunov function, while the throttle level is set to the minimum required value. This approach guarantees that all control Lyapunov function loss terms are either naturally satisfied or replaced by the derived control policy. To jointly supervise the Lyapunov function and the control policy, a simple loss function is introduced, leveraging optimal state-control pairs obtained through a polynomial map based method. Consequently, the trained neural network not only certifies the Lyapunov function but also generates a near-optimal guidance policy, even for the bang–bang fuel-optimal problem. Furthermore, the framework is easily extensible to nonlinear control-affine systems. Extensive numerical simulations are presented to validate the proposed method.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 1-19"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-06DOI: 10.1016/j.actaastro.2026.02.008
Xiaoyu Fu, Stefania Soldini
Autonomous orbital maintenance is a fundamental component of spacecraft autonomy and has become an active area of research. This study investigates the feasibility of implementing an autonomous onboard Target Point Approach (TPA) for the stationkeeping of periodic orbits, enabled by supervised learning. A stochastic optimization framework based on the TPA is first employed to generate optimal stationkeeping parameters from a range of initial state deviations. Based on these solutions, a large balanced dataset is constructed and used to train supervised learning models, including a multilayer perceptron (MLP) classifier to distinguish feasible from infeasible initial deviations, and MLP regressors to predict optimal stationkeeping parameters directly from initial deviations. The trained models are then integrated into an onboard TPA-based stationkeeping framework and evaluated through large-scale simulations involving 100,000 initial state deviations for a candidate Near Rectilinear Halo Orbit (NRHO). The simulation results demonstrate the effectiveness and robustness of the proposed approach. Furthermore, regularities observed from the large-scale stationkeeping analysis are identified and analysed, providing insight into the structure of the stationkeeping solution space and the learning-enabled decision process.
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Effective thermal management is a cornerstone of satellite functionality, ensuring reliability and operational success in extreme space environments. This study comprehensively reviews the state-of-the-art in satellite thermal management systems, encompassing both passive and active techniques. Passive systems, including multilayer insulation (MLI), thermal coatings, and phase-change materials (PCMs), offer energy efficiency and reliability for baseline thermal regulation. Conversely, active systems, such as heat pipes, loop heat pipes (LHPs), and mechanically pumped fluid loops (MPFLs), provide dynamic adaptability to manage high-power loads and fluctuating environmental conditions. The paper also explores recent advancements in thermal management, such as smart materials, variable-emittance coatings, and hybrid systems that combine the benefits of both passive and active approaches. Furthermore, the integration of computational techniques, such as the finite element method (FEM) and computational fluid dynamics (CFD), has significantly enhanced the prediction of thermal performance. Experimental validation through thermal-vacuum testing is also discussed as a critical step in refining and ensuring the accuracy of these systems. By integrating advances in materials, technologies, and modeling methods, this review highlights emerging trends and challenges in satellite thermal management. The findings underline the importance of hybrid systems, material innovations, and computational modeling in addressing the evolving demands of next-generation satellite missions. Future directions are proposed to guide continued research and development in this vital area of aerospace engineering.
{"title":"Advances in satellite thermal management systems: Challenges, innovations, and future directions","authors":"Shaik Zaidaan , Ziyad Mulla , Ruaa Nakkar , Izhar Ullah , Abrar H. Baluch , Naef A.A. Qasem","doi":"10.1016/j.actaastro.2026.02.002","DOIUrl":"10.1016/j.actaastro.2026.02.002","url":null,"abstract":"<div><div>Effective thermal management is a cornerstone of satellite functionality, ensuring reliability and operational success in extreme space environments. This study comprehensively reviews the state-of-the-art in satellite thermal management systems, encompassing both passive and active techniques. Passive systems, including multilayer insulation (MLI), thermal coatings, and phase-change materials (PCMs), offer energy efficiency and reliability for baseline thermal regulation. Conversely, active systems, such as heat pipes, loop heat pipes (LHPs), and mechanically pumped fluid loops (MPFLs), provide dynamic adaptability to manage high-power loads and fluctuating environmental conditions. The paper also explores recent advancements in thermal management, such as smart materials, variable-emittance coatings, and hybrid systems that combine the benefits of both passive and active approaches. Furthermore, the integration of computational techniques, such as the finite element method (FEM) and computational fluid dynamics (CFD), has significantly enhanced the prediction of thermal performance. Experimental validation through thermal-vacuum testing is also discussed as a critical step in refining and ensuring the accuracy of these systems. By integrating advances in materials, technologies, and modeling methods, this review highlights emerging trends and challenges in satellite thermal management. The findings underline the importance of hybrid systems, material innovations, and computational modeling in addressing the evolving demands of next-generation satellite missions. Future directions are proposed to guide continued research and development in this vital area of aerospace engineering.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"244 ","pages":"Pages 82-121"},"PeriodicalIF":3.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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