Pub Date : 2026-06-01Epub Date: 2026-01-30DOI: 10.1016/j.actaastro.2026.01.057
Hugh Chen, Samuel T. Hart, Álvaro Romero-Calvo
CubeSat cold-gas propulsion increasingly relies on two-phase, self-pressurizing propellants stored in conformal tanks. However, state-of-the-art propellant management strategies for these systems result in significant inefficiencies in volume or power management, limiting the total V budget and the mission lifetime. These challenges highlight the need for a more compact propellant management approach. The VAporization for PrOpellant Repositioning (VAPOR) experiment investigates the feasibility of repositioning an ullage gas bubble of R-236fa using thermally-induced phase change in various propellant management devices (PMDs). These devices utilize a heat source to vaporize propellant near the outlet, inducing pressure-driven bubble condensation in colder regions of the tank. Capillary structures are integrated to retain vapor near the heater and promote bubble coalescence, facilitating extraction and routing to thrusters. Building upon iterative designs across two parabolic flight campaigns, six thermocapillary PMDs are evaluated, culminating in three thermal start basket architectures. Patch heater PMDs initiate ullage generation in under 1 s and sustain the highest boiling rates, whereas sponge-based start baskets exhibit an average initiation time of s with more modest ullage generation. All capillary structures successfully capture the generated vapor. Collectively, results establish thermocapillary PMDs as a compact alternative to conventional two-tank systems for CubeSat cold-gas propulsion.
{"title":"Thermal propellant management devices for CubeSat cold gas propulsion","authors":"Hugh Chen, Samuel T. Hart, Álvaro Romero-Calvo","doi":"10.1016/j.actaastro.2026.01.057","DOIUrl":"10.1016/j.actaastro.2026.01.057","url":null,"abstract":"<div><div>CubeSat cold-gas propulsion increasingly relies on two-phase, self-pressurizing propellants stored in conformal tanks. However, state-of-the-art propellant management strategies for these systems result in significant inefficiencies in volume or power management, limiting the total <span><math><mi>Δ</mi></math></span>V budget and the mission lifetime. These challenges highlight the need for a more compact propellant management approach. The VAporization for PrOpellant Repositioning (VAPOR) experiment investigates the feasibility of repositioning an ullage gas bubble of R-236fa using thermally-induced phase change in various propellant management devices (PMDs). These devices utilize a heat source to vaporize propellant near the outlet, inducing pressure-driven bubble condensation in colder regions of the tank. Capillary structures are integrated to retain vapor near the heater and promote bubble coalescence, facilitating extraction and routing to thrusters. Building upon iterative designs across two parabolic flight campaigns, six thermocapillary PMDs are evaluated, culminating in three thermal start basket architectures. Patch heater PMDs initiate ullage generation in under 1 s and sustain the highest boiling rates, whereas sponge-based start baskets exhibit an average initiation time of <span><math><mrow><mn>6</mn><mo>.</mo><mn>9</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>3</mn></mrow></math></span> s with more modest ullage generation. All capillary structures successfully capture the generated vapor. Collectively, results establish thermocapillary PMDs as a compact alternative to conventional two-tank systems for CubeSat cold-gas propulsion.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 291-304"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089678","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 : 2026-06-01Epub 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":"2026-06-01","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 : 2026-06-01Epub 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":"2026-06-01","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 : 2026-06-01Epub Date: 2026-02-05DOI: 10.1016/j.actaastro.2026.01.070
Josef L. Richmond , Joshua R. Machacek , Christine Charles , Roderick W. Boswell
Electrostatic dust-cleaning with low-energy electron beams is a promising countermeasure against regolith contamination expected during sustained Lunar surface operations. Laboratory demonstrations, however, typically neglect the vacuum ultraviolet (VUV) component of solar radiation that dominates photoelectric charging on the Lunar dayside. Here we quantify, for the first time, the influence of a sun-like VUV spectrum on electron-beam-driven dust removal from spacesuit fabrics. Beta-cloth samples deliberately contaminated with OPRLJSCN Lunar Mare simulant were exposed to (i) a thermionic electron beam ( cm−2, 120 eV) and (ii) VUV fluxes generated by a mixed-gas 13.56 MHz RF plasma lamp that reproduces the solar spectrum in the 115–160 nm range. Three illumination regimes were tested: no VUV (dark), lunar-equivalent VUV (0.3 mW cm−2), and elevated VUV (5 mW cm−2). The inclusion of VUV photons significantly lowered the threshold beam current density and energy to initiate dust mobilisation, with the filament bias needed to initiate lift-off falling from –93 V (dark) to –52 V (lunar-equivalent VUV) and –37 V (elevated VUV), while the required beam current density dropped by up to two orders of magnitude. Dust removal efficiency improved from 76% after 72 s (dark) to 85% in 48 s (lunar VUV) and 95% in only 9 s under strong illumination. Furthermore, the mean particle size reduced with increasing VUV flux from (brushing) to (dark). Results indicate that the Solar VUV can be exploited to reduce power requirements and cleaning time for electron-beam dust mitigation, and motivates inclusion of realistic illumination environments in future mitigation trials.
{"title":"Electron-beam lunar dust mitigation under solar-like vacuum ultraviolet illumination","authors":"Josef L. Richmond , Joshua R. Machacek , Christine Charles , Roderick W. Boswell","doi":"10.1016/j.actaastro.2026.01.070","DOIUrl":"10.1016/j.actaastro.2026.01.070","url":null,"abstract":"<div><div>Electrostatic dust-cleaning with low-energy electron beams is a promising countermeasure against regolith contamination expected during sustained Lunar surface operations. Laboratory demonstrations, however, typically neglect the vacuum ultraviolet (VUV) component of solar radiation that dominates photoelectric charging on the Lunar dayside. Here we quantify, for the first time, the influence of a sun-like VUV spectrum on electron-beam-driven dust removal from spacesuit fabrics. Beta-cloth samples deliberately contaminated with OPRLJSCN Lunar Mare simulant were exposed to (i) a thermionic electron beam (<span><math><mrow><mn>30</mn><mspace></mspace><mi>μ</mi><mi>A</mi></mrow></math></span> cm<sup>−2</sup>, <span><math><mo>≤</mo></math></span> 120 eV) and (ii) VUV fluxes generated by a mixed-gas 13.56 MHz RF plasma lamp that reproduces the solar spectrum in the 115–160 nm range. Three illumination regimes were tested: no VUV (dark), lunar-equivalent VUV (0.3 mW cm<sup>−2</sup>), and elevated VUV (5 mW cm<sup>−2</sup>). The inclusion of VUV photons significantly lowered the threshold beam current density and energy to initiate dust mobilisation, with the filament bias needed to initiate lift-off falling from –93 V (dark) to –52 V (lunar-equivalent VUV) and –37 V (elevated VUV), while the required beam current density dropped by up to two orders of magnitude. Dust removal efficiency improved from 76% after 72 s (dark) to 85% in 48 s (lunar VUV) and 95% in only 9 s under strong illumination. Furthermore, the mean particle size reduced with increasing VUV flux from <span><math><mrow><mn>29</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> (brushing) to <span><math><mrow><mn>16</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> (dark). Results indicate that the Solar VUV can be exploited to reduce power requirements and cleaning time for electron-beam dust mitigation, and motivates inclusion of realistic illumination environments in future mitigation trials.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 338-345"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134799","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 : 2026-06-01Epub Date: 2026-01-29DOI: 10.1016/j.actaastro.2026.01.044
Xi Wang , Gang He , Yan-ping Tian , Yu-xin Zhao , Qian-cheng Wang , Yi-long Zhao
The boundary layer on the surface of supersonic and hypersonic vehicles exerts a significant influence on inlet performance. The diverter is widely utilized to expel the boundary layer directly, thereby enhancing the inlet’s efficiency. This paper establishes a simplified research model of the diverter and investigates the characteristics and mechanisms of the complex three-dimensional flow both within and external to the diverter using oil-flow visualization, pressure measurement, and Nanoparticle-based Planar Laser Scattering (NPLS) techniques. The results indicate that the flow within the diverter exhibits three states: choked, critical, and unchoked. In the choked and critical states, the separation line on the flat plate forms a ”bow” shape, and secondary separation phenomena are observed. In contrast, the separation zone in the unchoked state exhibits quasi-conical flow characteristics. Additionally, as the diverter height increases, the separation angle of the separation line increases and approaches that of swept shock wave/boundary layer interactions under the same deflection conditions. Furthermore, with an increase in the diverter height, the flow state within the diverter transitions from the choked state to the critical state, and ultimately to the unchoked state. Regarding the diverter as two symmetric, back-to-back side-compression inlets, the inviscid effects of the diverter height increase are examined through the inlet starting theory. The results shows that the inviscid factor plays a limited role in the diverter’s flow-passing capability. In future, the viscous effects of the diverter height increase would be examined with high-precision simulation results.
{"title":"Study on the mechanism of supersonic diverter flow","authors":"Xi Wang , Gang He , Yan-ping Tian , Yu-xin Zhao , Qian-cheng Wang , Yi-long Zhao","doi":"10.1016/j.actaastro.2026.01.044","DOIUrl":"10.1016/j.actaastro.2026.01.044","url":null,"abstract":"<div><div>The boundary layer on the surface of supersonic and hypersonic vehicles exerts a significant influence on inlet performance. The diverter is widely utilized to expel the boundary layer directly, thereby enhancing the inlet’s efficiency. This paper establishes a simplified research model of the diverter and investigates the characteristics and mechanisms of the complex three-dimensional flow both within and external to the diverter using oil-flow visualization, pressure measurement, and Nanoparticle-based Planar Laser Scattering (NPLS) techniques. The results indicate that the flow within the diverter exhibits three states: choked, critical, and unchoked. In the choked and critical states, the separation line on the flat plate forms a ”bow” shape, and secondary separation phenomena are observed. In contrast, the separation zone in the unchoked state exhibits quasi-conical flow characteristics. Additionally, as the diverter height increases, the separation angle of the separation line increases and approaches that of swept shock wave/boundary layer interactions under the same deflection conditions. Furthermore, with an increase in the diverter height, the flow state within the diverter transitions from the choked state to the critical state, and ultimately to the unchoked state. Regarding the diverter as two symmetric, back-to-back side-compression inlets, the inviscid effects of the diverter height increase are examined through the inlet starting theory. The results shows that the inviscid factor plays a limited role in the diverter’s flow-passing capability. In future, the viscous effects of the diverter height increase would be examined with high-precision simulation results.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 315-325"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072609","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 : 2026-06-01Epub Date: 2026-01-30DOI: 10.1016/j.actaastro.2025.12.035
Darren McKnight , Erin Dale , Joe Cassady , Andy Ratcliffe , Satomi Kawamoto , Alessandro Rossi , Dmitriy Grishko
The growth of orbital debris in number and mass in low Earth orbit (LEO) has been a subject of analysis for decades. The global community established the 25-yr debris mitigation rule 20–25 years ago and at that time many started assembling long lists of number, mass, and nationality of abandoned hardware. In 2020, a team of 19 experts from 13 countries assembled to create a definitive list of 50 objects that would most likely directly drive debris growth in LEO. This list was provided as a “priority list” for active debris removal (ADR) operations. Since 2020, continued accumulation of derelict objects coupled with the rapid increase of operational satellites has occurred. This combination has motivated the authors to update the 2020 Top 50 List. The new list considers (a) aggregate collision risk (i.e., probability of collision x consequence) since January 1, 2022, (b) orbital persistence of fragments (if a collision occurs), (c) proximity to existing altitudes where aggregate statistical risk of the population is the largest (meaning clusters centered around 775 km, 840 km, 1000 km, and 1400 km), (d) mass of object, and (e) coupling between removing objects on the list.
The paper is enabled through the application of new analytic tools created by LeoLabs based on empirical observations of close approaches in LEO merged with open-source tagging of objects in the public catalogue with known masses. It is important to note the coauthors abide by the philosophy that many viable models can be used to derive the top 50 objects to be removed from LEO. The benefit of the current approach applies a team approach to adjusting filters to a single model; however, the implication is not that this model is the only way to select the top 50 objects. In essence, one of the most critical aspects of any attempt to identify the objects whose retrieval will decrease the debris-generating potential in LEO is to identify key features of objects such as mass, probability of collision (especially with other massive objects), altitude, etc. A comparison of the 2020 Top 50 List and the new 2025 Top 50 List is provided to illuminate key lessons for debris hazard evolution and to motivate operationalization of ADR.
{"title":"Top 50 List for 2025","authors":"Darren McKnight , Erin Dale , Joe Cassady , Andy Ratcliffe , Satomi Kawamoto , Alessandro Rossi , Dmitriy Grishko","doi":"10.1016/j.actaastro.2025.12.035","DOIUrl":"10.1016/j.actaastro.2025.12.035","url":null,"abstract":"<div><div>The growth of orbital debris in number and mass in low Earth orbit (LEO) has been a subject of analysis for decades. The global community established the 25-yr debris mitigation rule 20–25 years ago and at that time many started assembling long lists of number, mass, and nationality of abandoned hardware. In 2020, a team of 19 experts from 13 countries assembled to create a definitive list of 50 objects that would most likely directly drive debris growth in LEO. This list was provided as a “priority list” for active debris removal (ADR) operations. Since 2020, continued accumulation of derelict objects coupled with the rapid increase of operational satellites has occurred. This combination has motivated the authors to update the 2020 Top 50 List. The new list considers (a) aggregate collision risk (i.e., probability of collision x consequence) since January 1, 2022, (b) orbital persistence of fragments (if a collision occurs), (c) proximity to existing altitudes where aggregate statistical risk of the population is the largest (meaning clusters centered around 775 km, 840 km, 1000 km, and 1400 km), (d) mass of object, and (e) coupling between removing objects on the list.</div><div>The paper is enabled through the application of new analytic tools created by LeoLabs based on empirical observations of close approaches in LEO merged with open-source tagging of objects in the public catalogue with known masses. It is important to note the coauthors abide by the philosophy that many viable models can be used to derive the top 50 objects to be removed from LEO. The benefit of the current approach applies a team approach to adjusting filters to a single model; however, the implication is not that this model is the only way to select the top 50 objects. In essence, one of the most critical aspects of any attempt to identify the objects whose retrieval will decrease the debris-generating potential in LEO is to identify key features of objects such as mass, probability of collision (especially with other massive objects), altitude, etc. A comparison of the 2020 Top 50 List and the new 2025 Top 50 List is provided to illuminate key lessons for debris hazard evolution and to motivate operationalization of ADR.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 346-357"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089657","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 : 2026-06-01Epub Date: 2026-01-20DOI: 10.1016/j.actaastro.2026.01.042
Tobias Degen , John C. Barentine , Gyula I.G. Józsa , Thomas Walter , Jacqueline Degen
We propose retroreflective coatings on satellites to mitigate sunlight reflections that cause disruptive trails in astronomical observations. By redirecting sunlight back toward the Sun, this approach reduces apparent brightness without creating thermal burdens, while also enhancing satellite tracking capabilities—offering a timely and practical pathway to address impacts from growing satellite constellations.
{"title":"Mitigating satellite trails through retroreflective coatings: A proposal for preserving the night sky","authors":"Tobias Degen , John C. Barentine , Gyula I.G. Józsa , Thomas Walter , Jacqueline Degen","doi":"10.1016/j.actaastro.2026.01.042","DOIUrl":"10.1016/j.actaastro.2026.01.042","url":null,"abstract":"<div><div>We propose retroreflective coatings on satellites to mitigate sunlight reflections that cause disruptive trails in astronomical observations. By redirecting sunlight back toward the Sun, this approach reduces apparent brightness without creating thermal burdens, while also enhancing satellite tracking capabilities—offering a timely and practical pathway to address impacts from growing satellite constellations.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 202-206"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014254","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 : 2026-06-01Epub Date: 2026-01-22DOI: 10.1016/j.actaastro.2026.01.050
M.J. Burchell, L.A. Alesbrook, M. van Ginneken, P.J. Wozniakiewicz
The growth in the number of satellites in Low Earth Orbit, coupled with the possibility of their catastrophic disruption, may lead to more orbital debris, which in turn has increased the risk of damage to spacecraft arising from impacts by small pieces of debris. There is thus an urgent need to monitor the small particle population in Low Earth Orbit, using a new generation of dust detectors. Various designs are in preparation, and several use the principle of observing particles via their impact penetration of thin films. Previously, most laboratory studies of penetration of thin films have used spherical impactors for ease. However, these are not representative of the shapes of orbital debris. Accordingly, here, impacts are reported at 5 km s−1, by various shaped projectiles (sizes typically 0.5–2 mm) on thin (12.5 μm thick) Kapton films. The shapes used were spheres, rods, cubes and platelets, and represent a selection of the shapes present in the orbital debris population that arises from catastrophic disruption of spacecraft. The size and shape of the holes in the Kapton arising from the impacts, are shown to reflect the size and cross-sectional area of an impactor as it passes through the film; even the presence of angular corners in the impactors can be seen in the holes. However, due to the variable aspect of an individual impactor presented to the film during an impact, identification of the exact 3-dimensional shape cannot be obtained from the 2-dimensional hole. Nevertheless, with minor exceptions it is possible to separate more spherical (i.e., natural dust) impactors from the other shapes (i.e. variously shaped anthropogenic debris).
低地球轨道卫星数量的增加，加上它们可能遭受灾难性破坏，可能导致更多的轨道碎片，这反过来又增加了小碎片撞击造成航天器损坏的风险。因此，迫切需要使用新一代的尘埃探测器来监测近地轨道上的小颗粒数量。各种设计正在准备中，其中一些利用了通过粒子对薄膜的冲击穿透来观察粒子的原理。以前，为了方便起见，大多数关于薄膜穿透的实验室研究都使用球形撞击器。然而，这些并不能代表轨道碎片的形状。因此，在这里，各种形状的弹丸（尺寸通常为0.5-2毫米）在薄（12.5 μm厚）Kapton薄膜上以5 km s - 1的速度撞击。所使用的形状有球体、棒状、立方体和血小板，这些形状代表了由于航天器灾难性破坏而产生的轨道碎片群中存在的一些形状。撞击产生的孔的大小和形状反映了撞击物穿过薄膜时的大小和横截面积；在孔中甚至可以看到撞击器中存在的棱角。然而，由于单个冲击体在冲击过程中呈现在薄膜上的可变方面，因此无法从二维孔中获得准确的三维形状。然而，除了少数例外，有可能将更球形（即天然尘埃）的撞击物与其他形状（即各种形状的人为碎片）分开。
{"title":"Hypervelocity perforation of thin films applicable to debris detection in Low Earth Orbit","authors":"M.J. Burchell, L.A. Alesbrook, M. van Ginneken, P.J. Wozniakiewicz","doi":"10.1016/j.actaastro.2026.01.050","DOIUrl":"10.1016/j.actaastro.2026.01.050","url":null,"abstract":"<div><div>The growth in the number of satellites in Low Earth Orbit, coupled with the possibility of their catastrophic disruption, may lead to more orbital debris, which in turn has increased the risk of damage to spacecraft arising from impacts by small pieces of debris. There is thus an urgent need to monitor the small particle population in Low Earth Orbit, using a new generation of dust detectors. Various designs are in preparation, and several use the principle of observing particles via their impact penetration of thin films. Previously, most laboratory studies of penetration of thin films have used spherical impactors for ease. However, these are not representative of the shapes of orbital debris. Accordingly, here, impacts are reported at 5 km s<sup>−1</sup>, by various shaped projectiles (sizes typically 0.5–2 mm) on thin (12.5 μm thick) Kapton films. The shapes used were spheres, rods, cubes and platelets, and represent a selection of the shapes present in the orbital debris population that arises from catastrophic disruption of spacecraft. The size and shape of the holes in the Kapton arising from the impacts, are shown to reflect the size and cross-sectional area of an impactor as it passes through the film; even the presence of angular corners in the impactors can be seen in the holes. However, due to the variable aspect of an individual impactor presented to the film during an impact, identification of the exact 3-dimensional shape cannot be obtained from the 2-dimensional hole. Nevertheless, with minor exceptions it is possible to separate more spherical (i.e., natural dust) impactors from the other shapes (i.e. variously shaped anthropogenic debris).</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 73-90"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033457","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}
This paper investigates a synchronous near-optimal control strategy for continuous-time spacecraft pursuit-evasion (PE) games subject to actuator saturation and incomplete information regarding the evader’s control weights. First, the evader’s unknown control weight parameters are identified online using a saturation-aware estimator, enabling real-time information acquisition by the pursuer. Second, to compute the synchronous control laws, a pre-training approximate dynamic programming (ADP) framework is proposed, which integrates offline neural network-based (NN-based) value function initialization with online iterative correction to approximately solve the Hamilton–Jacobi–Isaacs (HJI) equation. Furthermore, the sufficient conditions for the uniform ultimate boundedness (UUB) of the PE game system are analyzed via Lyapunov analysis. Finally, numerical simulations validate the effectiveness and robustness of the proposed method.
{"title":"Spacecraft pursuit-evasion game with incomplete information: A pre-training approximate dynamic programming method","authors":"Jiancheng Zhang, Yidi Wang, Wei Zheng, Meijiao Zhao","doi":"10.1016/j.actaastro.2026.01.071","DOIUrl":"10.1016/j.actaastro.2026.01.071","url":null,"abstract":"<div><div>This paper investigates a synchronous near-optimal control strategy for continuous-time spacecraft pursuit-evasion (PE) games subject to actuator saturation and incomplete information regarding the evader’s control weights. First, the evader’s unknown control weight parameters are identified online using a saturation-aware estimator, enabling real-time information acquisition by the pursuer. Second, to compute the synchronous control laws, a pre-training approximate dynamic programming (ADP) framework is proposed, which integrates offline neural network-based (NN-based) value function initialization with online iterative correction to approximately solve the Hamilton–Jacobi–Isaacs (HJI) equation. Furthermore, the sufficient conditions for the uniform ultimate boundedness (UUB) of the PE game system are analyzed via Lyapunov analysis. Finally, numerical simulations validate the effectiveness and robustness of the proposed method.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 251-262"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146109805","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 : 2026-06-01Epub Date: 2026-01-20DOI: 10.1016/j.actaastro.2026.01.041
Chenran Li , Xu Yan , Hang Yang , Dingjie Wang , Hongbo Zhang , Weimin Bao
For star sensors operating in space, star images are susceptible to blur degradation caused by complicated motions, leading to difficulties in star identification and reduced accuracy in star spots extraction. Although deep learning methods have been applied to mitigate these issues, their performance is often limited by the neglect of physical motion information. To address this, we embed angular velocity data to guide the network in establishing the relationship between angular velocity and blur parameters. Furthermore, considering the sparse nature of star spot features, we introduce the Convolutional Block Attention Module (CBAM) to enhance the feature saliency of star regions and their motion trajectories. A dedicated feature fusion module is also designed to effectively integrate inertial data and visual representations, facilitating joint learning of physical motion patterns and image features. Simulation experiments indicate that the proposed method significantly improves image restoration quality compared to the baseline U-Net, achieving a 16.84 % increase in PSNR and reducing the centroid error to 0.0836 pixels. Experiments based on in-orbit observation data validate the effectiveness of our method in real-world scenarios.
{"title":"Star image motion deblurring via angular velocity assisted U-Net with feature fusion and CBAM","authors":"Chenran Li , Xu Yan , Hang Yang , Dingjie Wang , Hongbo Zhang , Weimin Bao","doi":"10.1016/j.actaastro.2026.01.041","DOIUrl":"10.1016/j.actaastro.2026.01.041","url":null,"abstract":"<div><div>For star sensors operating in space, star images are susceptible to blur degradation caused by complicated motions, leading to difficulties in star identification and reduced accuracy in star spots extraction. Although deep learning methods have been applied to mitigate these issues, their performance is often limited by the neglect of physical motion information. To address this, we embed angular velocity data to guide the network in establishing the relationship between angular velocity and blur parameters. Furthermore, considering the sparse nature of star spot features, we introduce the Convolutional Block Attention Module (CBAM) to enhance the feature saliency of star regions and their motion trajectories. A dedicated feature fusion module is also designed to effectively integrate inertial data and visual representations, facilitating joint learning of physical motion patterns and image features. Simulation experiments indicate that the proposed method significantly improves image restoration quality compared to the baseline U-Net, achieving a 16.84 % increase in PSNR and reducing the centroid error to 0.0836 pixels. Experiments based on in-orbit observation data validate the effectiveness of our method in real-world scenarios.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 358-370"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014780","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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