Pub Date : 2026-01-28DOI: 10.1016/j.actaastro.2026.01.054
Willem Oliveira
The navigation algorithms proposed in the literature to achieve pinpoint landing for space exploration missions require initialization with state estimates from ground. This limits the missions that can be accomplished and significantly increases operation costs. This paper introduces an orbit determination (OD) algorithm, which can be used to autonomously initialize existing terrain absolute navigation (TAN) algorithms with pinpoint landing accuracy. Visual data is collected over the course of two orbit periods. This data is used to estimate the Keplerian orbit parameters of the trajectory. The estimated orbit parameters are used to initialize a crater-based TAN system independently from ground telemetry, thus providing a fully autonomous navigation system with pinpoint landing capability.
An extensive test campaign was performed using both simulated measurements and rendered images. The algorithm was shown to successfully enable TAN initialization.
{"title":"Autonomous optical flow-based initial orbit determination","authors":"Willem Oliveira","doi":"10.1016/j.actaastro.2026.01.054","DOIUrl":"10.1016/j.actaastro.2026.01.054","url":null,"abstract":"<div><div>The navigation algorithms proposed in the literature to achieve pinpoint landing for space exploration missions require initialization with state estimates from ground. This limits the missions that can be accomplished and significantly increases operation costs. This paper introduces an orbit determination (OD) algorithm, which can be used to autonomously initialize existing terrain absolute navigation (TAN) algorithms with pinpoint landing accuracy. Visual data is collected over the course of two orbit periods. This data is used to estimate the Keplerian orbit parameters of the trajectory. The estimated orbit parameters are used to initialize a crater-based TAN system independently from ground telemetry, thus providing a fully autonomous navigation system with pinpoint landing capability.</div><div>An extensive test campaign was performed using both simulated measurements and rendered images. The algorithm was shown to successfully enable TAN initialization.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 237-250"},"PeriodicalIF":3.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072616","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 : 2026-01-28DOI: 10.1016/j.actaastro.2026.01.067
Yan Zhang , Yongjun Wang , Jin Wang , Chengdan He , Wenfeng Li , Huzhong Zhang , Yasheng Li , Detian Li
This study proposes a geometric model based on the Monte Carlo method to enable precise characterization of porous media structures in lunar soil and validates its reliability by numerically reconstructing experimental investigations into the effects of adsorption behavior on water migration at −100 °C. Based on this model, the prolonging effect of the regolith on ice retention time was quantitatively analyzed, and the influence mechanisms of key parameters such as temperature, thickness, and specific surface area were systematically elucidated. The study indicates that the particle size distribution of lunar soil can be described by a unified cumulative probability distribution, and the reconstruction model based on the Monte Carlo method can effectively characterize pore structure features. The time required for the regolith to achieve saturated adsorption shows a linear dependence on its thickness. The additional retention time of water ice is most sensitive to temperature variations. At temperatures not exceeding 110 K, even a regolith layer thinner than 1 m can extend the preservation of water ice by several hundred million years. However, once the temperature exceeds 110 K, the protective capacity of the overlying layer declines exponentially within the narrow temperature range of 110 K–120 K. In warmer lunar regions, the regolith's capacity to retain water ice is limited. Even deeply buried water ice will gradually dissipate over extended geological timescales. Based on the mechanisms described above, this study suggests that in permanently shadowed regions with temperatures below 110 K, water ice may be detectable within the uppermost 1 m of the regolith. In contrast, in regions with temperatures ranging from 120 K to 140 K, the required detection depth may extend to tens of meters. This study provides a theoretical foundation for understanding the distribution and preservation mechanisms of water ice on the lunar surface. The methodologies developed and the conclusions drawn provide valuable scientific insights for future in-situ detection missions targeting lunar polar regions.
本研究提出了一种基于蒙特卡罗方法的几何模型，以精确表征月球土壤中的多孔介质结构，并通过数值重建吸附行为对−100°C水迁移影响的实验研究来验证其可靠性。基于该模型，定量分析了风化层对冰保持时间的延长作用，系统阐述了温度、厚度、比表面积等关键参数的影响机理。研究表明，月壤粒径分布可以用统一的累积概率分布来描述，基于蒙特卡罗方法的重构模型可以有效表征孔隙结构特征。风化层达到饱和吸附所需的时间与其厚度呈线性关系。水冰的额外滞留时间对温度变化最为敏感。在温度不超过110 K的情况下，即使是薄于1米的风化层也能将水冰的保存时间延长几亿年。然而，一旦温度超过110 K，在110 K - 120 K的狭窄温度范围内，上覆层的保护能力呈指数级下降。在温暖的月球地区，风化层保持水冰的能力是有限的。即使深埋的水冰也会随着地质时间的延长而逐渐消散。基于上述机制，本研究表明，在温度低于110 K的永久阴影区域，可能在风化层最上面1米内检测到水冰。相比之下，在温度从120 K到140 K的区域，所需的探测深度可能延伸到几十米。该研究为了解月球表面水冰的分布和保存机制提供了理论基础。所开发的方法和得出的结论为未来针对月球极地地区的原位探测任务提供了宝贵的科学见解。
{"title":"Numerical simulation of water migration in lunar soil based on the Monte Carlo model","authors":"Yan Zhang , Yongjun Wang , Jin Wang , Chengdan He , Wenfeng Li , Huzhong Zhang , Yasheng Li , Detian Li","doi":"10.1016/j.actaastro.2026.01.067","DOIUrl":"10.1016/j.actaastro.2026.01.067","url":null,"abstract":"<div><div>This study proposes a geometric model based on the Monte Carlo method to enable precise characterization of porous media structures in lunar soil and validates its reliability by numerically reconstructing experimental investigations into the effects of adsorption behavior on water migration at −100 °C. Based on this model, the prolonging effect of the regolith on ice retention time was quantitatively analyzed, and the influence mechanisms of key parameters such as temperature, thickness, and specific surface area were systematically elucidated. The study indicates that the particle size distribution of lunar soil can be described by a unified cumulative probability distribution, and the reconstruction model based on the Monte Carlo method can effectively characterize pore structure features. The time required for the regolith to achieve saturated adsorption shows a linear dependence on its thickness. The additional retention time of water ice is most sensitive to temperature variations. At temperatures not exceeding 110 K, even a regolith layer thinner than 1 m can extend the preservation of water ice by several hundred million years. However, once the temperature exceeds 110 K, the protective capacity of the overlying layer declines exponentially within the narrow temperature range of 110 K–120 K. In warmer lunar regions, the regolith's capacity to retain water ice is limited. Even deeply buried water ice will gradually dissipate over extended geological timescales. Based on the mechanisms described above, this study suggests that in permanently shadowed regions with temperatures below 110 K, water ice may be detectable within the uppermost 1 m of the regolith. In contrast, in regions with temperatures ranging from 120 K to 140 K, the required detection depth may extend to tens of meters. This study provides a theoretical foundation for understanding the distribution and preservation mechanisms of water ice on the lunar surface. The methodologies developed and the conclusions drawn provide valuable scientific insights for future in-situ detection missions targeting lunar polar regions.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 189-201"},"PeriodicalIF":3.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072617","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}
Microgravity exposure alters cardiovascular loading, yet its impact on left atrial flow dynamics and thrombotic risk remains poorly understood. This study investigates how spaceflight-relevant microgravity-induced changes in cardiac outflow affect left atrial hemodynamics in healthy individuals and patients with atrial fibrillation.
Methods
Patient-specific left atrial models were generated for three healthy individuals and three AF patients. Computational fluid dynamics (CFD) simulations were performed using each patient's baseline mitral outflow waveform and two modified waveforms representing short- and long-duration post-flight cardiac loading changes derived from echocardiographic observations. Hemodynamic metrics included left atrial velocity, time averaged wall shear stress, oscillatory shear index, relative residence time, and stasis volume, which were used to assess thrombogenic flow conditions.
Results
Post-flight, microgravity-associated modifications to mitral outflow conditions produced distinct hemodynamic responses across cohorts. In healthy individuals, short-duration post-flight loading reduced time-averaged wall shear stress from 1.51 to 1.00 Pa and increased velocity-defined stasis from 19.6 % to 64.2 %, indicating substantially reduced atrial washout. Under long-duration post-flight conditions, these metrics recovered toward or above baseline values (time-averaged wall shear stress 1.68 Pa; stasis 18.5 %), consistent with hemodynamic adaptation. In contrast, patients with atrial fibrillation exhibited high baseline stasis and showed minimal changes in time-averaged wall shear stress, oscillatory shear, or relative residence time across all loading conditions. Across all cohorts, the left atrial appendage consistently demonstrated the lowest shear and highest residence time.
Conclusion
These findings indicate that spaceflight-related microgravity exposure may transiently increase atrial flow stasis and thrombotic risk in individuals with normal atrial function, while individuals with atrial fibrillation remain in a persistently high-risk hemodynamic state that is relatively insensitive to microgravity-induced loading changes. This study provides the first patient-specific, chamber-level computational assessment of how spaceflight-documented cardiac adaptations influence left atrial hemodynamics and highlights the importance of accounting for duration-dependent hemodynamic adaptation when assessing thrombotic risk associated with human spaceflight.
{"title":"Microgravity-induced alterations in left atrial hemodynamics and thrombogenic risk: Insights from healthy and atrial fibrillation models","authors":"Grace Hoeppner , Ahmad Bshennaty , Brennan Vogl , Ghasaq Saleh , Mohamad Alkhouli , Hoda Hatoum","doi":"10.1016/j.actaastro.2026.01.058","DOIUrl":"10.1016/j.actaastro.2026.01.058","url":null,"abstract":"<div><h3>Background</h3><div>Microgravity exposure alters cardiovascular loading, yet its impact on left atrial flow dynamics and thrombotic risk remains poorly understood. This study investigates how spaceflight-relevant microgravity-induced changes in cardiac outflow affect left atrial hemodynamics in healthy individuals and patients with atrial fibrillation.</div></div><div><h3>Methods</h3><div>Patient-specific left atrial models were generated for three healthy individuals and three AF patients. Computational fluid dynamics (CFD) simulations were performed using each patient's baseline mitral outflow waveform and two modified waveforms representing short- and long-duration post-flight cardiac loading changes derived from echocardiographic observations. Hemodynamic metrics included left atrial velocity, time averaged wall shear stress, oscillatory shear index, relative residence time, and stasis volume, which were used to assess thrombogenic flow conditions.</div></div><div><h3>Results</h3><div>Post-flight, microgravity-associated modifications to mitral outflow conditions produced distinct hemodynamic responses across cohorts. In healthy individuals, short-duration post-flight loading reduced time-averaged wall shear stress from 1.51 to 1.00 Pa and increased velocity-defined stasis from 19.6 % to 64.2 %, indicating substantially reduced atrial washout. Under long-duration post-flight conditions, these metrics recovered toward or above baseline values (time-averaged wall shear stress 1.68 Pa; stasis 18.5 %), consistent with hemodynamic adaptation. In contrast, patients with atrial fibrillation exhibited high baseline stasis and showed minimal changes in time-averaged wall shear stress, oscillatory shear, or relative residence time across all loading conditions. Across all cohorts, the left atrial appendage consistently demonstrated the lowest shear and highest residence time.</div></div><div><h3>Conclusion</h3><div>These findings indicate that spaceflight-related microgravity exposure may transiently increase atrial flow stasis and thrombotic risk in individuals with normal atrial function, while individuals with atrial fibrillation remain in a persistently high-risk hemodynamic state that is relatively insensitive to microgravity-induced loading changes. This study provides the first patient-specific, chamber-level computational assessment of how spaceflight-documented cardiac adaptations influence left atrial hemodynamics and highlights the importance of accounting for duration-dependent hemodynamic adaptation when assessing thrombotic risk associated with human spaceflight.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 61-72"},"PeriodicalIF":3.4,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081604","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 : 2026-01-27DOI: 10.1016/j.actaastro.2026.01.060
Sven Schwertfeger , Elisa Da Ros , Marcel Bursy , Andreas Wicht , Daniel Pardo , Ankush Sharma , Subash Sachidananda , Alexander Ling , Markus Krutzik
This manuscript reports on the development and qualification of an ECDL-based, fiber-coupled laser system at a wavelength of nm for space applications. We designed and developed the optical and mechanical configuration, along with the laser driving and thermal management electronics, to meet space compatibility requirements. Validation tests were conducted on off-the-shelf components to assess their suitability for satellite deployment. The final system integrates all components into a compact design optimized for CubeSat platforms.
{"title":"A 698 nm laser system for excitation of fluorescent quantum light sources on a CubeSat mission","authors":"Sven Schwertfeger , Elisa Da Ros , Marcel Bursy , Andreas Wicht , Daniel Pardo , Ankush Sharma , Subash Sachidananda , Alexander Ling , Markus Krutzik","doi":"10.1016/j.actaastro.2026.01.060","DOIUrl":"10.1016/j.actaastro.2026.01.060","url":null,"abstract":"<div><div>This manuscript reports on the development and qualification of an ECDL-based, fiber-coupled laser system at a wavelength of <span><math><mrow><mi>λ</mi><mo>=</mo><mn>698</mn></mrow></math></span> nm for space applications. We designed and developed the optical and mechanical configuration, along with the laser driving and thermal management electronics, to meet space compatibility requirements. Validation tests were conducted on off-the-shelf components to assess their suitability for satellite deployment. The final system integrates all components into a compact design optimized for CubeSat platforms.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 91-98"},"PeriodicalIF":3.4,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048208","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 : 2026-01-27DOI: 10.1016/j.actaastro.2026.01.061
Francesca Ottoboni, Andrea Muciaccia, Camilla Colombo
The massive growth of space activities over the past decades has lead to an increase of the space debris population, which is threatening the safety of space operations and active satellites. Several fragmentation events caused by catastrophic collisions and explosions have single-handedly contributed to the increase in the number of space debris, highlighting the importance of the reconstruction of such events to gain insight on the breakups and decrease the collision risk they cause to active satellites.
This work proposes a fragmentation reconstruction approach for this purpose, which combines pruning and clustering criteria with a backward propagation to identify the epoch of the fragmentation and the involved objects. The model was tested by using publicly available Two-Line-Elements data. The problem of the unreliability of such data is addressed by modifying the original approach to account for uncertainty, multiplying the original Two-Line-Elements data and choosing the optimal set of objects for the reconstruction. The optimal values of the pruning filters thresholds for the method are also investigated to identify the most effective criteria. Moreover, the reciprocal influence of the filters is assessed through a sensitivity analysis. The proposed approach is applied to two real fragmentation events to compare the accuracy of the reconstruction with and without the uncertainty quantification. The method proves to be effective in the evaluation of the epoch of the breakup as well as the identification of the fragments and their parent.
{"title":"Reconstruction of in-orbit breakup events over the short term","authors":"Francesca Ottoboni, Andrea Muciaccia, Camilla Colombo","doi":"10.1016/j.actaastro.2026.01.061","DOIUrl":"10.1016/j.actaastro.2026.01.061","url":null,"abstract":"<div><div>The massive growth of space activities over the past decades has lead to an increase of the space debris population, which is threatening the safety of space operations and active satellites. Several fragmentation events caused by catastrophic collisions and explosions have single-handedly contributed to the increase in the number of space debris, highlighting the importance of the reconstruction of such events to gain insight on the breakups and decrease the collision risk they cause to active satellites.</div><div>This work proposes a fragmentation reconstruction approach for this purpose, which combines pruning and clustering criteria with a backward propagation to identify the epoch of the fragmentation and the involved objects. The model was tested by using publicly available Two-Line-Elements data. The problem of the unreliability of such data is addressed by modifying the original approach to account for uncertainty, multiplying the original Two-Line-Elements data and choosing the optimal set of objects for the reconstruction. The optimal values of the pruning filters thresholds for the method are also investigated to identify the most effective criteria. Moreover, the reciprocal influence of the filters is assessed through a sensitivity analysis. The proposed approach is applied to two real fragmentation events to compare the accuracy of the reconstruction with and without the uncertainty quantification. The method proves to be effective in the evaluation of the epoch of the breakup as well as the identification of the fragments and their parent.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 326-337"},"PeriodicalIF":3.4,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174653","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 : 2026-01-25DOI: 10.1016/j.actaastro.2026.01.055
Kārlis Šļumba, Brendan T. Scott, Mark B. Jaksa
It is essential to understand the geotechnical properties of the ground before anything can be built on Earth, the Moon, or elsewhere. The cone penetrometer is a simple but very important instrument that yields quantitative and qualitative information about the geotechnical properties of the material. Quantitative information is the penetration resistance from which density and layering can be inferred, and ground improvement can be evaluated. Qualitative information includes identifying layering and inhomogeneities, as well as the existence of boulders.
Cone penetrometers are often proposed for space missions (e.g., Beagle 2, InSight, Philae) and were even used by Apollo astronauts. All cone penetrometers that have been used extra-terrestrially so far have either experienced difficulties with penetration or were designed to penetrate less than 100 mm deep and stop before encountering any meaningful resistance. An optimally developed dynamic cone penetrometer might work better because it requires less reaction force.
This research consists of the development of a bespoke dynamic cone penetrometer with variable cone size and hammering energy. Further, this instrument is tested in a large-scale regolith compaction chamber with lunar highlands regolith simulant LHS-1E at a wide range of densities to find the optimal setup where penetration captures enough data by moving slowly but also does not stagnate. Results from dynamic cone penetration tests at many different densities are compared and successfully correlated to cone penetration and nuclear density gauge test results. Calculated coefficients allow for the conversion directly between dynamic and regular cone penetration tests at any density, which shows promise for greater use of dynamic cone penetrometers in lunar applications.
{"title":"Dynamic Cone Penetration Test in Lunar Highlands Regolith Simulant","authors":"Kārlis Šļumba, Brendan T. Scott, Mark B. Jaksa","doi":"10.1016/j.actaastro.2026.01.055","DOIUrl":"10.1016/j.actaastro.2026.01.055","url":null,"abstract":"<div><div>It is essential to understand the geotechnical properties of the ground before anything can be built on Earth, the Moon, or elsewhere. The cone penetrometer is a simple but very important instrument that yields quantitative and qualitative information about the geotechnical properties of the material. Quantitative information is the penetration resistance from which density and layering can be inferred, and ground improvement can be evaluated. Qualitative information includes identifying layering and inhomogeneities, as well as the existence of boulders.</div><div>Cone penetrometers are often proposed for space missions (e.g., Beagle 2, InSight, Philae) and were even used by Apollo astronauts. All cone penetrometers that have been used extra-terrestrially so far have either experienced difficulties with penetration or were designed to penetrate less than 100 mm deep and stop before encountering any meaningful resistance. An optimally developed dynamic cone penetrometer might work better because it requires less reaction force.</div><div>This research consists of the development of a bespoke dynamic cone penetrometer with variable cone size and hammering energy. Further, this instrument is tested in a large-scale regolith compaction chamber with lunar highlands regolith simulant LHS-1E at a wide range of densities to find the optimal setup where penetration captures enough data by moving slowly but also does not stagnate. Results from dynamic cone penetration tests at many different densities are compared and successfully correlated to cone penetration and nuclear density gauge test results. Calculated coefficients allow for the conversion directly between dynamic and regular cone penetration tests at any density, which shows promise for greater use of dynamic cone penetrometers in lunar applications.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 172-188"},"PeriodicalIF":3.4,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047959","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 : 2026-01-24DOI: 10.1016/j.actaastro.2026.01.037
M.B. Agir , N.H. Crisp , K.L. Smith , P.C.E. Roberts , Z. Xiang , M. Newsam , M. Griffiths
The intake of an atmosphere-breathing electric propulsion system plays a pivotal role in capturing and collimating atmospheric residuals prior to the propulsion stage. Accurate assessment of intake performance necessitates accounting for rarefied gas dynamics, flow compression, and gas-surface interactions. In this study, the DSMC solver, dsmcFoam, is rigorously validated against fundamental benchmarks, including Clausing empirical cases and comparisons with the PICLas solver. Furthermore, dsmcFoam-dsmcFoam comparison is also conducted and observed deviations between our results and existing dsmcFoam results in the literature highlight the critical importance of careful simulation setup and procedural rigour. A systematic analysis of the simulation workflow, supplemented by additional computational strategies, demonstrates their pronounced impact on intake performance metrics. Furthermore, distinct definitions for efficiency – namely, collection efficiency and transmission efficiency for vacuum, standalone, and integrated configurations – are introduced, establishing a comprehensive framework for evaluating intake performance across varying operational altitudes and surface properties. The findings confirm that (i) dsmcFoam represents a reliable tool for ABEP intake design, providing a foundation for further developments, (ii) a structured and generic simulation procedure tailored for ABEP intakes is essential, and (iii) conventional efficiency metrics for ABEP intakes needs reconsideration for broader applicability and accurate performance evaluation.
{"title":"Efficiency Metrics and Numerical Simulation Procedure for Atmosphere-Breathing Electric Propulsion (ABEP) Intake Designs","authors":"M.B. Agir , N.H. Crisp , K.L. Smith , P.C.E. Roberts , Z. Xiang , M. Newsam , M. Griffiths","doi":"10.1016/j.actaastro.2026.01.037","DOIUrl":"10.1016/j.actaastro.2026.01.037","url":null,"abstract":"<div><div>The intake of an atmosphere-breathing electric propulsion system plays a pivotal role in capturing and collimating atmospheric residuals prior to the propulsion stage. Accurate assessment of intake performance necessitates accounting for rarefied gas dynamics, flow compression, and gas-surface interactions. In this study, the DSMC solver, dsmcFoam, is rigorously validated against fundamental benchmarks, including Clausing empirical cases and comparisons with the PICLas solver. Furthermore, dsmcFoam-dsmcFoam comparison is also conducted and observed deviations between our results and existing dsmcFoam results in the literature highlight the critical importance of careful simulation setup and procedural rigour. A systematic analysis of the simulation workflow, supplemented by additional computational strategies, demonstrates their pronounced impact on intake performance metrics. Furthermore, distinct definitions for efficiency – namely, collection efficiency and transmission efficiency for vacuum, standalone, and integrated configurations – are introduced, establishing a comprehensive framework for evaluating intake performance across varying operational altitudes and surface properties. The findings confirm that (i) dsmcFoam represents a reliable tool for ABEP intake design, providing a foundation for further developments, (ii) a structured and generic simulation procedure tailored for ABEP intakes is essential, and (iii) conventional efficiency metrics for ABEP intakes needs reconsideration for broader applicability and accurate performance evaluation.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 14-31"},"PeriodicalIF":3.4,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047965","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 : 2026-01-23DOI: 10.1016/j.actaastro.2026.01.053
Yan Wang , Yaxuan Li , Xinfu Liu
This paper investigates the Mars landing guidance problem in hazardous terrains. Disturbances during landing, including parameter uncertainties and external forces, may cause the guidance problem infeasible, preventing the lander from avoiding the terrains. To ensure a safe landing, it is crucial, though challenging, to maintain the recursive feasibility of the guidance problem in each guidance cycle. To this end, we propose a two-phase guidance framework, where recursive feasibility is considered only in the first phase and the terminal constraints in this phase are significantly relaxed. This turns the recursive feasibility requirement into the assured satisfaction of the terrain avoidance constraint under disturbances in each guidance cycle. The main contribution of this work lies in analytically deriving a feasible control set and proving that, as long as the control command is within this set, the state at the next guidance cycle must be able to reach the required terminal state while satisfying the terrain avoidance constraint. This guarantees the recursive feasibility of the guidance problem, provided it is feasible in the initial time. As a result, guidance commands in the first phase can be generated by the well-known ZEM/ZEV guidance law, and then simply saturated by the derived feasible control set. In the second phase, the terrain avoidance constraint no longer needs to be considered and the ZEM/ZEV guidance law is applied to drive the lander to the desired location with a safe touchdown velocity. Numerical examples demonstrate that the proposed method can ensure recursive feasibility of the guidance problem under disturbances and is capable of achieving meter-level landing accuracy.
{"title":"Feasibility-guaranteed analytical mars landing guidance in hazardous terrains with disturbances","authors":"Yan Wang , Yaxuan Li , Xinfu Liu","doi":"10.1016/j.actaastro.2026.01.053","DOIUrl":"10.1016/j.actaastro.2026.01.053","url":null,"abstract":"<div><div>This paper investigates the Mars landing guidance problem in hazardous terrains. Disturbances during landing, including parameter uncertainties and external forces, may cause the guidance problem infeasible, preventing the lander from avoiding the terrains. To ensure a safe landing, it is crucial, though challenging, to maintain the recursive feasibility of the guidance problem in each guidance cycle. To this end, we propose a two-phase guidance framework, where recursive feasibility is considered only in the first phase and the terminal constraints in this phase are significantly relaxed. This turns the recursive feasibility requirement into the assured satisfaction of the terrain avoidance constraint under disturbances in each guidance cycle. The main contribution of this work lies in analytically deriving a feasible control set and proving that, as long as the control command is within this set, the state at the next guidance cycle must be able to reach the required terminal state while satisfying the terrain avoidance constraint. This guarantees the recursive feasibility of the guidance problem, provided it is feasible in the initial time. As a result, guidance commands in the first phase can be generated by the well-known ZEM/ZEV guidance law, and then simply saturated by the derived feasible control set. In the second phase, the terrain avoidance constraint no longer needs to be considered and the ZEM/ZEV guidance law is applied to drive the lander to the desired location with a safe touchdown velocity. Numerical examples demonstrate that the proposed method can ensure recursive feasibility of the guidance problem under disturbances and is capable of achieving meter-level landing accuracy.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 1-13"},"PeriodicalIF":3.4,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033441","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 : 2026-01-23DOI: 10.1016/j.actaastro.2026.01.040
Valentina Zancan, Paolo Trucco, Giorgio Locatelli
The space sector is transitioning from an infrastructure-driven legacy paradigm toward a commercially driven New Space paradigm. Historically characterized by high barriers to entry and demand anchored on institutional needs, the sector now faces competitive pricing, rapid technological change, and expanding commercial use cases that reshape the design and development of space assets. The Earth Observation (EO) segment exemplifies this transition, as the growing commoditization of EO data led to new development logics and organizational practices. Similar to other sectors experiencing rapid change, this transition is not without challenges. A central challenge for legacy EO organizations lies in reconfiguring the processes, organizational structures, and decision rules, i.e. the “micro-foundations”, that govern EO solution development. Understanding how to reconfigure such micro-foundations is of practical importance for operating within the current New Space paradigm, yet it is an under-researched perspective for space organizations. Drawing on product-service system development and Operations Management literature, this study investigates how micro-foundations shape EO solution development strategies in legacy and New Space contexts. Using a multiple-case study based on semi-structured interviews and secondary data, we build on the Decoupling Point (DP) concept from operations management and propose an EO DP strategy conceptual framework. This framework explains how and where customer and user requirements enter the EO value chain and influence design and development activities, and how DP positioning revolves across organizational boundaries and inter-organizational settings. Our findings indicate that legacy space organizations adopt downstream DP strategies, in which user needs influence EO solution development mainly at later stages, reinforcing technology-push logics and limited integration of commercial needs. Conversely, New Space organizations employ dynamic DP strategies that combine customization, modularity, and standardization, enabling user needs to shape upstream design and development decisions. Importantly, we find that DP positioning in New Space organizations is not confined within firm boundaries but increasingly emerges through inter-organizational collaborations. This study contributes to research on the Space Economy by offering a fine-grained, micro-foundational explanation of diverse EO solution development strategies and their evolution. For practitioners and policymakers, the findings highlight multiple pathways for legacy organizations to maintain relevance in an evolving EO market without undermining their core capabilities and heritage.
{"title":"“Getting things done” or “Doing the right things”? Micro-foundations of product-service strategies in Earth Observation","authors":"Valentina Zancan, Paolo Trucco, Giorgio Locatelli","doi":"10.1016/j.actaastro.2026.01.040","DOIUrl":"10.1016/j.actaastro.2026.01.040","url":null,"abstract":"<div><div>The space sector is transitioning from an infrastructure-driven legacy paradigm toward a commercially driven New Space paradigm. Historically characterized by high barriers to entry and demand anchored on institutional needs, the sector now faces competitive pricing, rapid technological change, and expanding commercial use cases that reshape the design and development of space assets. The Earth Observation (EO) segment exemplifies this transition, as the growing commoditization of EO data led to new development logics and organizational practices. Similar to other sectors experiencing rapid change, this transition is not without challenges. A central challenge for legacy EO organizations lies in reconfiguring the processes, organizational structures, and decision rules, i.e. the “micro-foundations”, that govern EO solution development. Understanding how to reconfigure such micro-foundations is of practical importance for operating within the current New Space paradigm, yet it is an under-researched perspective for space organizations. Drawing on product-service system development and Operations Management literature, this study investigates how micro-foundations shape EO solution development strategies in legacy and New Space contexts. Using a multiple-case study based on semi-structured interviews and secondary data, we build on the Decoupling Point (DP) concept from operations management and propose an EO DP strategy conceptual framework. This framework explains how and where customer and user requirements enter the EO value chain and influence design and development activities, and how DP positioning revolves across organizational boundaries and inter-organizational settings. Our findings indicate that legacy space organizations adopt downstream DP strategies, in which user needs influence EO solution development mainly at later stages, reinforcing technology-push logics and limited integration of commercial needs. Conversely, New Space organizations employ dynamic DP strategies that combine customization, modularity, and standardization, enabling user needs to shape upstream design and development decisions. Importantly, we find that DP positioning in New Space organizations is not confined within firm boundaries but increasingly emerges through inter-organizational collaborations. This study contributes to research on the Space Economy by offering a fine-grained, micro-foundational explanation of diverse EO solution development strategies and their evolution. For practitioners and policymakers, the findings highlight multiple pathways for legacy organizations to maintain relevance in an evolving EO market without undermining their core capabilities and heritage.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 263-279"},"PeriodicalIF":3.4,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033432","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 : 2026-01-23DOI: 10.1016/j.actaastro.2026.01.033
Liu Yuan , Bin Li , Xin Tian , Wei Liang , Peng Lv , Jizhang Sang
The exponential growth of mega-constellation satellites, typified by SpaceX’s Starlink, poses unprecedented challenges for existing space surveillance, particularly when tracking uncooperative spacecrafts executing continuous orbit-raising/deorbiting maneuvers. This situation makes the conventional orbit determination (OD) and prediction (OP) struggle with three critical issues: insufficient observational data, unknown maneuvering parameters, and the cumulative effects of unmodeled thrust. To address these issues, this study proposes a piecewise estimation-based OD method by developing a semi-analytical thrust acceleration (TA) model. The TA model employs time-explicit polynomial expansions with state-dependent coefficients to characterize the continuous low-thrust effect. The OD system integrates a piecewise least-squares estimation algorithm with dynamic compensation, enabling accurate TA resolution within one-day observation windows. Specifically, the OP system incorporates the latest TA estimate to account for the future continuous low-thrust effect. Experiments with sparse radar observations of Starlink satellites demonstrate the effectiveness of the proposed method. The TA estimation errors remain below 0.5% relative to the reference obtained from precise ephemerides. The OP capabilities maintain one-day and two-day position accuracy below 2 and 4 km, respectively, improving by more than 60% compared to the unified OD method. More importantly, the approach exhibits operational robustness, achieving OD convergence with initial TA errors up to 35%. These advantages make the proposed approach a practicable solution for autonomous catalog maintenance of maneuvering spacecraft.
{"title":"Orbit determination and prediction for uncooperative spacecrafts with continuous low-thrust maneuver via piecewise estimation","authors":"Liu Yuan , Bin Li , Xin Tian , Wei Liang , Peng Lv , Jizhang Sang","doi":"10.1016/j.actaastro.2026.01.033","DOIUrl":"10.1016/j.actaastro.2026.01.033","url":null,"abstract":"<div><div>The exponential growth of mega-constellation satellites, typified by SpaceX’s Starlink, poses unprecedented challenges for existing space surveillance, particularly when tracking uncooperative spacecrafts executing continuous orbit-raising/deorbiting maneuvers. This situation makes the conventional orbit determination (OD) and prediction (OP) struggle with three critical issues: insufficient observational data, unknown maneuvering parameters, and the cumulative effects of unmodeled thrust. To address these issues, this study proposes a piecewise estimation-based OD method by developing a semi-analytical thrust acceleration (TA) model. The TA model employs time-explicit polynomial expansions with state-dependent coefficients to characterize the continuous low-thrust effect. The OD system integrates a piecewise least-squares estimation algorithm with dynamic compensation, enabling accurate TA resolution within one-day observation windows. Specifically, the OP system incorporates the latest TA estimate to account for the future continuous low-thrust effect. Experiments with sparse radar observations of Starlink satellites demonstrate the effectiveness of the proposed method. The TA estimation errors remain below 0.5% relative to the reference obtained from precise ephemerides. The OP capabilities maintain one-day and two-day position accuracy below 2 and 4 km, respectively, improving by more than 60% compared to the unified OD method. More importantly, the approach exhibits operational robustness, achieving OD convergence with initial TA errors up to 35%. These advantages make the proposed approach a practicable solution for autonomous catalog maintenance of maneuvering spacecraft.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 99-111"},"PeriodicalIF":3.4,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033433","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号