The article focuses on comparing the primary effects of the two most widely used ground-based models of microgravity physiological effects — Dry Immersion (DI) and antiorthostatic hypokinesia – Head-Down Bed Rest (HDBR). Despite their global prevalence, no direct comparison of their effects has been made until now. The study presents findings from two experiments of equal duration (21 days), applying the same assessment methods across various human physiological systems.
{"title":"The effect of Dry immersion and Head-Down tilt Bed Rest of the same duration on the human body: first results","authors":"E.S. Tomilovskaya, A.A. Puchkova, I.V. Rukavishnikov, T.A. Shigueva, A.V. Shpakov, O.I. Orlov","doi":"10.1016/j.actaastro.2025.12.016","DOIUrl":"10.1016/j.actaastro.2025.12.016","url":null,"abstract":"<div><div>The article focuses on comparing the primary effects of the two most widely used ground-based models of microgravity physiological effects — Dry Immersion (DI) and antiorthostatic hypokinesia – Head-Down Bed Rest (HDBR). Despite their global prevalence, no direct comparison of their effects has been made until now. The study presents findings from two experiments of equal duration (21 days), applying the same assessment methods across various human physiological systems.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 568-580"},"PeriodicalIF":3.4,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790392","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 : 2025-12-08DOI: 10.1016/j.actaastro.2025.12.013
Haoyi Wang , Shuo Yan , Yu Wang , Shiming Zhou , Jianzhong Ding , Chunjie Wang
Lunar polar resource studies necessitate probes capable of large-scale exploration on complex terrain. Aiming at creating a walking–leaping multimode probe for the lunar surface, this paper proposes a probe leg configuration synthesis method that combines the atlas and screw constraint methods. The reciprocity between wrench and twist is used to establish design constraints for the probe leg's landing cushion requirement, and freedom constraints are derived from the walking function requirement. Using the screw constraint method, three leg configurations, namely, series, parallel, and hybrid, were synthesized to obtain candidate solutions that met the design principles. The degree-of-freedom distribution of these solutions was visualized using the atlas method. Compared with existing wheeled mobile detectors, walking–leaping detectors require higher repeated buffering capabilities in the legs. This paper proposes a method for analyzing detector buffering capacity based on the Lie group distance and based on this, analyzes the buffering capacity of the legs. The proposed design and analysis methods for the multimode mobile leg configuration are universal, enabling leg configuration synthesis for diverse lunar probes and other multimode mobile mechanisms operating on complex terrains.
{"title":"Configuration synthesis of multifunctional leg mechanism for mobile lunar probes","authors":"Haoyi Wang , Shuo Yan , Yu Wang , Shiming Zhou , Jianzhong Ding , Chunjie Wang","doi":"10.1016/j.actaastro.2025.12.013","DOIUrl":"10.1016/j.actaastro.2025.12.013","url":null,"abstract":"<div><div>Lunar polar resource studies necessitate probes capable of large-scale exploration on complex terrain. Aiming at creating a walking–leaping multimode probe for the lunar surface, this paper proposes a probe leg configuration synthesis method that combines the atlas and screw constraint methods. The reciprocity between wrench and twist is used to establish design constraints for the probe leg's landing cushion requirement, and freedom constraints are derived from the walking function requirement. Using the screw constraint method, three leg configurations, namely, series, parallel, and hybrid, were synthesized to obtain candidate solutions that met the design principles. The degree-of-freedom distribution of these solutions was visualized using the atlas method. Compared with existing wheeled mobile detectors, walking–leaping detectors require higher repeated buffering capabilities in the legs. This paper proposes a method for analyzing detector buffering capacity based on the Lie group distance and based on this, analyzes the buffering capacity of the legs. The proposed design and analysis methods for the multimode mobile leg configuration are universal, enabling leg configuration synthesis for diverse lunar probes and other multimode mobile mechanisms operating on complex terrains.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 462-480"},"PeriodicalIF":3.4,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790471","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 : 2025-12-08DOI: 10.1016/j.actaastro.2025.12.010
Adam Gelman, Josiah Jackson, Triston Hooks
Plant-microorganism interactions in crop production represent a critical and under-researched aspect of controlled environment agriculture (CEA) and bioregenerative life support systems (BLSS). Beneficial microorganisms have been shown to enhance plant resistance to pathogens, response to abiotic stress, and ability to uptake nutrients through the roots. The objectives of the current research were: 1) to demonstrate hydroponic crop production with lunar regolith for in-situ resource utilization (ISRU) within BLSS; and 2) to investigate the utility of microorganisms in hydroponic and BLSS via inoculation of lunar regolith simulant in a Bato bucket system. Dwarf tomatoes (c.v. Red Robin) were grown in coco coir-amended lunar regolith simulant (LRS) over 6 weeks, excluding germination and emergence stages, in a 2-factor factorial design (substrate x inoculation). Dwarf tomato ripe fruit yield and total fruit yield from plants grown in LRS was not significantly different from those grown in the control substrate (perlite). However, dwarf tomato shoot biomass (both fresh and dry weight) was significantly lower in LRS compared to perlite, indicating a negative impact to vegetative plant growth in lunar regolith. Interestingly, the Brix (soluble sugar content) of ripe fruit was not significantly different between treatment groups, indicating a possible lack of plant salinity stress from the LRS. Microbial inoculation showed no significant impact on any plant response variable. Multiple non-significant trends indicate that extending the duration of this type of study may reveal positive effects of microbial inoculation on plant biomass in both LRS and perlite, warranting further investigation. 16S Amplicon sequencing performed on substrate samples showed a trend of increasing community alpha diversity in the microbiome over time in both LRS and perlite. This pattern indicates that the total number of different bacterial species increases over time with exposure to the greenhouse environment and with plant growth.
作物生产中的植物-微生物相互作用是控制环境农业（CEA）和生物再生生命支持系统（BLSS）的一个关键和研究不足的方面。有益微生物已被证明可以增强植物对病原体的抵抗力，对非生物胁迫的反应，以及通过根吸收营养的能力。目前的研究目标是：1)在BLSS内示范利用月壤进行水培作物的原位资源利用（ISRU）；2)通过在Bato桶系统中接种模拟月球风化物，研究微生物在水培和BLSS中的应用。采用2因素析因设计（底物x接种），将矮番茄（c.v. Red Robin）在椰壳改良的月球风化模拟物（LRS）中生长6周，不包括萌发和出苗期。在LRS中栽培的矮生番茄成熟果实产量和总果实产量与对照基质（珍珠岩）中栽培的矮生番茄差异不显著。然而，与珍珠岩相比，LRS矮生番茄地上部生物量（鲜重和干重）显著降低，表明LRS对月球风化层营养植物生长有负面影响。有趣的是，成熟果实的糖度（可溶性糖含量）在处理组之间没有显著差异，这可能表明LRS没有对植物施加盐度胁迫。微生物接种对植株各响应变量均无显著影响。多个不显著趋势表明，延长这类研究的持续时间可能会揭示微生物接种对LRS和珍珠岩植物生物量的积极影响，值得进一步研究。对底物样品进行的16S扩增子测序显示，随着时间的推移，LRS和珍珠岩中微生物组的群落α多样性都有增加的趋势。这种模式表明，不同细菌种类的总数随着暴露于温室环境和植物生长的时间而增加。
{"title":"Characterization of hydroponic dwarf tomato growth in microbially inoculated lunar regolith simulant","authors":"Adam Gelman, Josiah Jackson, Triston Hooks","doi":"10.1016/j.actaastro.2025.12.010","DOIUrl":"10.1016/j.actaastro.2025.12.010","url":null,"abstract":"<div><div>Plant-microorganism interactions in crop production represent a critical and under-researched aspect of controlled environment agriculture (CEA) and bioregenerative life support systems (BLSS). Beneficial microorganisms have been shown to enhance plant resistance to pathogens, response to abiotic stress, and ability to uptake nutrients through the roots. The objectives of the current research were: 1) to demonstrate hydroponic crop production with lunar regolith for in-situ resource utilization (ISRU) within BLSS; and 2) to investigate the utility of microorganisms in hydroponic and BLSS via inoculation of lunar regolith simulant in a Bato bucket system. Dwarf tomatoes (c.v. Red Robin) were grown in coco coir-amended lunar regolith simulant (LRS) over 6 weeks, excluding germination and emergence stages, in a 2-factor factorial design (substrate x inoculation). Dwarf tomato ripe fruit yield and total fruit yield from plants grown in LRS was not significantly different from those grown in the control substrate (perlite). However, dwarf tomato shoot biomass (both fresh and dry weight) was significantly lower in LRS compared to perlite, indicating a negative impact to vegetative plant growth in lunar regolith. Interestingly, the Brix (soluble sugar content) of ripe fruit was not significantly different between treatment groups, indicating a possible lack of plant salinity stress from the LRS. Microbial inoculation showed no significant impact on any plant response variable. Multiple non-significant trends indicate that extending the duration of this type of study may reveal positive effects of microbial inoculation on plant biomass in both LRS and perlite, warranting further investigation. 16S Amplicon sequencing performed on substrate samples showed a trend of increasing community alpha diversity in the microbiome over time in both LRS and perlite. This pattern indicates that the total number of different bacterial species increases over time with exposure to the greenhouse environment and with plant growth.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 695-712"},"PeriodicalIF":3.4,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840521","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 : 2025-12-06DOI: 10.1016/j.actaastro.2025.12.008
Ranjana Shivakumar , Asaf Bolker , Siu Hon Tsang , Nurit Atar , Ronen Verker , Irina Gouzman , Milan Shrestha , Edwin Hang Tong Teo
Shape memory polymers (SMPs) are smart materials that change shape when exposed to external stimuli such as heat, light, or electricity. Thermally triggered SMPs are attractive for satellite deployment systems because they are lightweight, compact, and highly deformable, with excellent thermal, mechanical, and shape memory properties. However, low thermal conductivity and modest transition temperatures limit their use as space actuators. We report the development and on-orbit testing of a novel high-temperature smart composite material that combines shape memory polyimide (SMPI)—a polyimide-based SMP—and three-dimensional graphene (3D-C) foam. The 3D-C/SMPI composite demonstrates significantly improved thermal conductivity (850 %), a high glass transition temperature (Tg) > 150 °C, and excellent thermal stability (5 % weight loss at 500 °C). It also shows good shape memory behaviour and uses internal resistive heating for shape transformations. Reliability and long-term stability were assessed through ground-based space-environment simulations, and on-orbit shape transformation was demonstrated aboard the VELOX-AM microsatellite in low-Earth orbit, validating the material for deployable space structures. These results position 3D-C/SMPI as a promising candidate material for thermally triggered, durable deployment mechanisms in space.
{"title":"Development and on-orbit testing of 3D-graphene infused shape memory polyimide composite","authors":"Ranjana Shivakumar , Asaf Bolker , Siu Hon Tsang , Nurit Atar , Ronen Verker , Irina Gouzman , Milan Shrestha , Edwin Hang Tong Teo","doi":"10.1016/j.actaastro.2025.12.008","DOIUrl":"10.1016/j.actaastro.2025.12.008","url":null,"abstract":"<div><div>Shape memory polymers (SMPs) are smart materials that change shape when exposed to external stimuli such as heat, light, or electricity. Thermally triggered SMPs are attractive for satellite deployment systems because they are lightweight, compact, and highly deformable, with excellent thermal, mechanical, and shape memory properties. However, low thermal conductivity and modest transition temperatures limit their use as space actuators. We report the development and on-orbit testing of a novel high-temperature smart composite material that combines shape memory polyimide (SMPI)—a polyimide-based SMP—and three-dimensional graphene (3D-C) foam. The 3D-C/SMPI composite demonstrates significantly improved thermal conductivity (850 %), a high glass transition temperature (T<sub>g</sub>) > 150 °C, and excellent thermal stability (5 % weight loss at 500 °C). It also shows good shape memory behaviour and uses internal resistive heating for shape transformations. Reliability and long-term stability were assessed through ground-based space-environment simulations, and on-orbit shape transformation was demonstrated aboard the VELOX-AM microsatellite in low-Earth orbit, validating the material for deployable space structures. These results position 3D-C/SMPI as a promising candidate material for thermally triggered, durable deployment mechanisms in space.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 234-249"},"PeriodicalIF":3.4,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689404","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}
The rapid expansion of mega-constellations in low Earth orbits has posed significant challenges to space traffic management, necessitating periodic inspections of satellites to ensure the sustainability of the space environment when economically feasible. This study addresses the orbital design challenge associated with inspecting numerous satellites distributed across multiple orbital planes through flybys by proposing an innovative orbital-plane-based inspection strategy. The proposed methodology reformulates the multi-satellite flyby problem into a multi-rendezvous trajectory planning problem by proposing an analytical approach to determine a maneuver-free inspection orbit that enables flyby of all satellites within a specific orbital plane. Additionally, a three-layer global optimization framework is developed to tackle this problem. The first layer establishes an approximate cost evaluation model for orbital plane visitation sequences, utilizing a genetic algorithm to identify the optimal sequence from a vast array of candidate planes, thereby maximizing inspection targets while minimizing fuel consumption. The second layer constructs a mixed-integer programming model to locally refine the rendezvous epochs and orbital parameters of each inspection orbit to reduce the total velocity increment. The third layer accurately computes the optimal impulsive maneuvers and trajectories between inspection orbits. In contrast to traditional low-Earth orbit rendezvous optimization frameworks, the proposed framework fully leverages the adjustable freedom in inclination and right ascension of the ascending node (RAAN) of inspection orbits, significantly reducing the total velocity increment. Simulation results demonstrate that the proposed method can effectively address the trajectory optimization problem associated with constellation inspection for tens of thousands of satellites.
{"title":"Global optimization of multi-flyby trajectories for multi-orbital-plane constellations inspection","authors":"An-yi Huang, Hong-xin Shen, Zhao Li, Cong Sun, Chao Sheng, Zheng-zhong Kuai","doi":"10.1016/j.actaastro.2025.12.012","DOIUrl":"10.1016/j.actaastro.2025.12.012","url":null,"abstract":"<div><div>The rapid expansion of mega-constellations in low Earth orbits has posed significant challenges to space traffic management, necessitating periodic inspections of satellites to ensure the sustainability of the space environment when economically feasible. This study addresses the orbital design challenge associated with inspecting numerous satellites distributed across multiple orbital planes through flybys by proposing an innovative orbital-plane-based inspection strategy. The proposed methodology reformulates the multi-satellite flyby problem into a multi-rendezvous trajectory planning problem by proposing an analytical approach to determine a maneuver-free inspection orbit that enables flyby of all satellites within a specific orbital plane. Additionally, a three-layer global optimization framework is developed to tackle this problem. The first layer establishes an approximate cost evaluation model for orbital plane visitation sequences, utilizing a genetic algorithm to identify the optimal sequence from a vast array of candidate planes, thereby maximizing inspection targets while minimizing fuel consumption. The second layer constructs a mixed-integer programming model to locally refine the rendezvous epochs and orbital parameters of each inspection orbit to reduce the total velocity increment. The third layer accurately computes the optimal impulsive maneuvers and trajectories between inspection orbits. In contrast to traditional low-Earth orbit rendezvous optimization frameworks, the proposed framework fully leverages the adjustable freedom in inclination and right ascension of the ascending node (RAAN) of inspection orbits, significantly reducing the total velocity increment. Simulation results demonstrate that the proposed method can effectively address the trajectory optimization problem associated with constellation inspection for tens of thousands of satellites.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 417-429"},"PeriodicalIF":3.4,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689405","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 : 2025-12-06DOI: 10.1016/j.actaastro.2025.12.011
Lu Wang , Xi-Ming Zhu , Tian-Yuan Ji , Hai-Xing Wang , Yang Zhao , Hao Yan , Xu-Hui Liu , Wei Mao , Li-Qiu Wei , Da-Ren Yu
Micro-cathode arc thrusters (μ-CAT) hold critical applications in the national economy, serving as primary propulsion systems for orbit maintenance and formation flying missions of small satellites. Compared to steady-state thrusters (e.g., Hall thrusters or ion thrusters), the performance and lifetime of the μ-CAT depend on the ablation state of the cathode. However, it is challenging to characterize ablation-driven plasma properties due to the lack of a method to determine the time-resolved metal ion densities from cathode ablation during single-pulse discharge. In this work, we present an OES method to determine the Ti+ and Ti2+ ion densities based on ionic lines from different ionization states, and observe the “three-stage evolution” of the plasma inside the electrode channel of the micro-cathode arc thruster with capacitive discharge mode based on the high-speed imaging subsystem. The time-resolved Ti+ and Ti2+ ion densities during the interelectrode plasma and the early stage of the anode spot period are determined by synchronously triggering the power processing unit of the μ-CAT and optical emission spectroscopy subsystem. Besides, the impulse bit during a single pulse is obtained, supported by the determined ion densities and time-of-flight ion velocity monitoring method. Our method will help improve the engineering test efficiency and accelerate the design and development of the μ-CAT.
{"title":"Investigation on the ion evolution in different ionization states inside the electrode channel of the micro-cathode arc thruster by time-resolved optical image and emission spectroscopy","authors":"Lu Wang , Xi-Ming Zhu , Tian-Yuan Ji , Hai-Xing Wang , Yang Zhao , Hao Yan , Xu-Hui Liu , Wei Mao , Li-Qiu Wei , Da-Ren Yu","doi":"10.1016/j.actaastro.2025.12.011","DOIUrl":"10.1016/j.actaastro.2025.12.011","url":null,"abstract":"<div><div>Micro-cathode arc thrusters (μ-CAT) hold critical applications in the national economy, serving as primary propulsion systems for orbit maintenance and formation flying missions of small satellites. Compared to steady-state thrusters (e.g., Hall thrusters or ion thrusters), the performance and lifetime of the μ-CAT depend on the ablation state of the cathode. However, it is challenging to characterize ablation-driven plasma properties due to the lack of a method to determine the time-resolved metal ion densities from cathode ablation during single-pulse discharge. In this work, we present an OES method to determine the Ti<sup>+</sup> and Ti<sup>2+</sup> ion densities based on ionic lines from different ionization states, and observe the “three-stage evolution” of the plasma inside the electrode channel of the micro-cathode arc thruster with capacitive discharge mode based on the high-speed imaging subsystem. The time-resolved Ti<sup>+</sup> and Ti<sup>2+</sup> ion densities during the interelectrode plasma and the early stage of the anode spot period are determined by synchronously triggering the power processing unit of the μ-CAT and optical emission spectroscopy subsystem. Besides, the impulse bit during a single pulse is obtained, supported by the determined ion densities and time-of-flight ion velocity monitoring method. Our method will help improve the engineering test efficiency and accelerate the design and development of the μ-CAT.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 313-327"},"PeriodicalIF":3.4,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704960","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 : 2025-12-06DOI: 10.1016/j.actaastro.2025.12.014
P.V. Kozlov, G. Ya Gerasimov, V. Yu Levashov, N.G. Bykova, I.E. Zabelinsky
This paper proposes a new method for recording the emission characteristics of high-temperature air in shock tubes, in which the measuring equipment of the shock tube registered the radiative heat flux ahead of the shock wave front in the direction of its movement. The experiments were conducted on the DDST-M shock tube at shock wave velocities from 8.6 to 10 km/s and a pressure ahead of the shock wave front equal to 0.25 Torr. The range of emission wavelengths from 190 to 700 nm was studied, where both molecular bands and atomic lines of nitrogen and oxygen contribute to the emission. The measured emission spectrograms were analyzed. A comparison of the obtained results with the measurement data obtained using the traditional time-integrated method, in which the radiation heat flux is recorded through a window in the side surface of the shock tube perpendicular to the axis of the tube as the “plug” of shock-heated gas passes by the window. The features of the measurement process during emission registration by various methods were analyzed using the SPECTRUM computational procedure. An assessment was made of the influence of self-absorption on the recorded spectral characteristics of molecular bands and atomic emission lines.
{"title":"Method of radiative heat flux registration ahead front of strong shock wave","authors":"P.V. Kozlov, G. Ya Gerasimov, V. Yu Levashov, N.G. Bykova, I.E. Zabelinsky","doi":"10.1016/j.actaastro.2025.12.014","DOIUrl":"10.1016/j.actaastro.2025.12.014","url":null,"abstract":"<div><div>This paper proposes a new method for recording the emission characteristics of high-temperature air in shock tubes, in which the measuring equipment of the shock tube registered the radiative heat flux ahead of the shock wave front in the direction of its movement. The experiments were conducted on the DDST-M shock tube at shock wave velocities from 8.6 to 10 km/s and a pressure ahead of the shock wave front equal to 0.25 Torr. The range of emission wavelengths from 190 to 700 nm was studied, where both molecular bands and atomic lines of nitrogen and oxygen contribute to the emission. The measured emission spectrograms were analyzed. A comparison of the obtained results with the measurement data obtained using the traditional time-integrated method, in which the radiation heat flux is recorded through a window in the side surface of the shock tube perpendicular to the axis of the tube as the “plug” of shock-heated gas passes by the window. The features of the measurement process during emission registration by various methods were analyzed using the SPECTRUM computational procedure. An assessment was made of the influence of self-absorption on the recorded spectral characteristics of molecular bands and atomic emission lines.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 284-292"},"PeriodicalIF":3.4,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689421","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 : 2025-12-05DOI: 10.1016/j.actaastro.2025.12.007
Zhili Peng , Bo Zhong , Longfei Li , Wei Yao , Xiaodong Chen
This study investigates the dynamic atomization characteristics of kerosene impinging jets under high-pressure conditions using a coupled Eulerian–Eulerian and Eulerian–Lagrangian framework. By systematically analyzing the effects of injector pressure differences and inlet/outlet pressure oscillations, the research provides critical insights into spray dynamics and combustion stability. Results indicate that increasing the pressure difference shortens liquid sheet breakup length and suppresses droplet mass flow rate fluctuations. Pressure oscillations induce periodic deformations in the liquid sheet, altering the spray’s overall structure. Voronoi tessellation analysis reveals distinct droplet clustering patterns in the impinging-jet spray, suggesting vortex-driven modulation of the spray field. Detailed visualization and analysis of the temporospatial distribution of mass flow rate density and droplet size during primary atomization show that mass flow rate density peaks in the central region and diminishes toward the periphery, while droplet size distribution follows an inverse trend. The Sauter mean diameter (SMD) exhibits non-monotonic axial variation with pressure differences. Under inlet/outlet pressure oscillations, SMD decreases rapidly downstream, with the reduction rate positively correlated to oscillation amplitude. Notably, SMD fluctuations under pressure oscillations significantly exceed those induced by pressure differences. Furthermore, inlet/outlet pressure oscillations generally reduce SMD, though SMD variability increases with oscillation amplitude. Time-lag analysis reveals substantial phase delays between pressure oscillation and atomization parameters: the mass flow rate oscillations of injectors and generated droplets exhibit a half-period delay, while the delay between injector mass flow rate and droplet SMD oscillations extends to a full period. These findings advance injector design optimization and stability prediction in liquid rocket engines by elucidating the atomization process’s dependence on operational parameters under realistic combustion chamber conditions.
{"title":"Numerical investigation of pressure oscillation effects on dynamic spray characteristics in kerosene impinging-jet atomization","authors":"Zhili Peng , Bo Zhong , Longfei Li , Wei Yao , Xiaodong Chen","doi":"10.1016/j.actaastro.2025.12.007","DOIUrl":"10.1016/j.actaastro.2025.12.007","url":null,"abstract":"<div><div>This study investigates the dynamic atomization characteristics of kerosene impinging jets under high-pressure conditions using a coupled Eulerian–Eulerian and Eulerian–Lagrangian framework. By systematically analyzing the effects of injector pressure differences and inlet/outlet pressure oscillations, the research provides critical insights into spray dynamics and combustion stability. Results indicate that increasing the pressure difference shortens liquid sheet breakup length and suppresses droplet mass flow rate fluctuations. Pressure oscillations induce periodic deformations in the liquid sheet, altering the spray’s overall structure. Voronoi tessellation analysis reveals distinct droplet clustering patterns in the impinging-jet spray, suggesting vortex-driven modulation of the spray field. Detailed visualization and analysis of the temporospatial distribution of mass flow rate density and droplet size during primary atomization show that mass flow rate density peaks in the central region and diminishes toward the periphery, while droplet size distribution follows an inverse trend. The Sauter mean diameter (SMD) exhibits non-monotonic axial variation with pressure differences. Under inlet/outlet pressure oscillations, SMD decreases rapidly downstream, with the reduction rate positively correlated to oscillation amplitude. Notably, SMD fluctuations under pressure oscillations significantly exceed those induced by pressure differences. Furthermore, inlet/outlet pressure oscillations generally reduce SMD, though SMD variability increases with oscillation amplitude. Time-lag analysis reveals substantial phase delays between pressure oscillation and atomization parameters: the mass flow rate oscillations of injectors and generated droplets exhibit a half-period delay, while the delay between injector mass flow rate and droplet SMD oscillations extends to a full period. These findings advance injector design optimization and stability prediction in liquid rocket engines by elucidating the atomization process’s dependence on operational parameters under realistic combustion chamber conditions.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 293-312"},"PeriodicalIF":3.4,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689414","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 : 2025-12-05DOI: 10.1016/j.actaastro.2025.11.049
Shuai Chou , Qiangqiang Zhao , Jialong Zhu , Dewen Yu , Jinhua Zhang , Jun Hong
Mesh antennas are widely used in space due to their light weight, high storage ratio and high gain. Because of manufacturing and assembly errors, the actual shape of the mesh antenna, which determines its electric performance, inevitably deviates from its ideal one. Establishing a precise model that is consistent with the node positions and tension distribution of the actual antenna is the key to improving the adjustment efficiency. However, the establishment of this precise model relies on the attainment of all cable tensions, which is quite costly and inefficient in practical engineering, especially for the very large mesh antenna. As for this intractable problem, this study proposes a novel shape adjustment method for mesh antennas based on tension estimation to achieve efficient adjustment. First, the constraint conditions for the tension distribution of the mesh antenna are derived by means of the structural equilibrium equation. On this basis, according to the Bayesian decision theory, the tension distribution is estimated by maximizing the probability density function under constraint conditions. Then, with the help of the approximated tension distribution, the shape adjustment optimization model is established and solved so as to achieve efficient adjustment. To verify the effectiveness of the proposed method, this study conducts comprehensive numerical simulations and practical experiments. The results indicate that the proposed method can achieve a higher-efficiency shape adjustment.
{"title":"An efficient tension-estimation-based shape adjustment method for large mesh antennas","authors":"Shuai Chou , Qiangqiang Zhao , Jialong Zhu , Dewen Yu , Jinhua Zhang , Jun Hong","doi":"10.1016/j.actaastro.2025.11.049","DOIUrl":"10.1016/j.actaastro.2025.11.049","url":null,"abstract":"<div><div>Mesh antennas are widely used in space due to their light weight, high storage ratio and high gain. Because of manufacturing and assembly errors, the actual shape of the mesh antenna, which determines its electric performance, inevitably deviates from its ideal one. Establishing a precise model that is consistent with the node positions and tension distribution of the actual antenna is the key to improving the adjustment efficiency. However, the establishment of this precise model relies on the attainment of all cable tensions, which is quite costly and inefficient in practical engineering, especially for the very large mesh antenna. As for this intractable problem, this study proposes a novel shape adjustment method for mesh antennas based on tension estimation to achieve efficient adjustment. First, the constraint conditions for the tension distribution of the mesh antenna are derived by means of the structural equilibrium equation. On this basis, according to the Bayesian decision theory, the tension distribution is estimated by maximizing the probability density function under constraint conditions. Then, with the help of the approximated tension distribution, the shape adjustment optimization model is established and solved so as to achieve efficient adjustment. To verify the effectiveness of the proposed method, this study conducts comprehensive numerical simulations and practical experiments. The results indicate that the proposed method can achieve a higher-efficiency shape adjustment.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 621-634"},"PeriodicalIF":3.4,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689417","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 : 2025-12-05DOI: 10.1016/j.actaastro.2025.12.009
Guanzhong Chen , Zhengrui Li , Guanhua Feng , Wenhao Li , Yuxian Yue
Very Low Earth Orbit (VLEO) has attracted growing attention due to its unique advantages in Earth observation and communication applications; however, it also faces severe challenges arising from atmospheric perturbations. Although orbital decay caused by atmospheric drag can now be compensated by high-efficiency electric propulsion systems, the evolution of the spacecraft’s dynamic state under the influence of atmospheric winds continues to pose substantial challenges for attitude and orbit control in long-duration VLEO missions, warranting further systematic investigation. However, quantitative analyses describing this effect remain limited, particularly those employing coupled aerodynamic attitude–orbit dynamics models that comprehensively account for atmospheric density, temperature, and wind variations.
To address this issue, an analytical expression for the variation of orbital inclination (i) in a near-circular VLEO orbit (e0.001) is first derived based on the Gaussian Variational Equations in this paper. The derivation elucidates the mechanism through which the orbital angular momentum vector gradually evolves towards the North Pole under the influence of atmospheric winds. In parallel, the study investigates the effect of winds on the Right Ascension of the Ascending Node (), showing that this influence is transmitted mainly through changes in inclination (i). Subsequently, a numerical simulation platform was developed that integrates high-fidelity atmospheric density (NRLMSIS2.1) and wind (HWM14) models to systematically investigate the effects of attitude control strategies and Local Time of Ascending Node (LTAN) selection on long-term orbital evolution. Finally, the proposed theoretical and simulation framework was validated through comparison with in-orbit attitude and orbital data from the Tianxing-1 VLEO satellite, demonstrating good agreement.
The analytical model developed in this study accurately captures the dominant effects of atmospheric wind perturbations and confirms the existence of significant attitude–orbit coupling under complex, spatiotemporally varying atmospheric conditions. Validation using in-orbit data demonstrates that accurately modeling the inclination variation induced by atmospheric winds provides an effective means of precisely predicting the long-term evolution of orbital elements. This research provides a critical theoretical foundation and a validated modeling method for precise orbit design, constellation maintenance, and mission planning of future VLEO constellations.
{"title":"Evolution analysis of orbital characteristics of VLEO satellites in long-term flight under the influence of atmospheric winds","authors":"Guanzhong Chen , Zhengrui Li , Guanhua Feng , Wenhao Li , Yuxian Yue","doi":"10.1016/j.actaastro.2025.12.009","DOIUrl":"10.1016/j.actaastro.2025.12.009","url":null,"abstract":"<div><div>Very Low Earth Orbit (VLEO) has attracted growing attention due to its unique advantages in Earth observation and communication applications; however, it also faces severe challenges arising from atmospheric perturbations. Although orbital decay caused by atmospheric drag can now be compensated by high-efficiency electric propulsion systems, the evolution of the spacecraft’s dynamic state under the influence of atmospheric winds continues to pose substantial challenges for attitude and orbit control in long-duration VLEO missions, warranting further systematic investigation. However, quantitative analyses describing this effect remain limited, particularly those employing coupled aerodynamic attitude–orbit dynamics models that comprehensively account for atmospheric density, temperature, and wind variations.</div><div>To address this issue, an analytical expression for the variation of orbital inclination (i) in a near-circular VLEO orbit (e<span><math><mo><</mo></math></span>0.001) is first derived based on the Gaussian Variational Equations in this paper. The derivation elucidates the mechanism through which the orbital angular momentum vector gradually evolves towards the North Pole under the influence of atmospheric winds. In parallel, the study investigates the effect of winds on the Right Ascension of the Ascending Node (<span><math><mi>Ω</mi></math></span>), showing that this influence is transmitted mainly through changes in inclination (i). Subsequently, a numerical simulation platform was developed that integrates high-fidelity atmospheric density (NRLMSIS2.1) and wind (HWM14) models to systematically investigate the effects of attitude control strategies and Local Time of Ascending Node (LTAN) selection on long-term orbital evolution. Finally, the proposed theoretical and simulation framework was validated through comparison with in-orbit attitude and orbital data from the Tianxing-1 VLEO satellite, demonstrating good agreement.</div><div>The analytical model developed in this study accurately captures the dominant effects of atmospheric wind perturbations and confirms the existence of significant attitude–orbit coupling under complex, spatiotemporally varying atmospheric conditions. Validation using in-orbit data demonstrates that accurately modeling the inclination variation induced by atmospheric winds provides an effective means of precisely predicting the long-term evolution of orbital elements. This research provides a critical theoretical foundation and a validated modeling method for precise orbit design, constellation maintenance, and mission planning of future VLEO constellations.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"240 ","pages":"Pages 481-496"},"PeriodicalIF":3.4,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689412","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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