Acta Astronautica最新文献

{"title":"LUnar Geology Orbiter concept to study lunar Irregular Mare Patches and lava tubes from orbit","authors":"Petr Brož ,&nbsp;Sam Poppe ,&nbsp;Kimberly Sofge ,&nbsp;Martin Stárek ,&nbsp;Ricardo Gomes ,&nbsp;Petr Boháček ,&nbsp;Akos Kereszturi ,&nbsp;Anna Łosiak ,&nbsp;Francesco Sauro ,&nbsp;Ernst Hauber ,&nbsp;Martin Divoký ,&nbsp;Pavel Trojánek ,&nbsp;Michael Písařík ,&nbsp;Tomáš Kohout ,&nbsp;Henrik Hargitai ,&nbsp;Roman Bohovic ,&nbsp;Jaan Viru ,&nbsp;Mihkel Pajusalu ,&nbsp;Leonardo Carrer ,&nbsp;Lorenzo Bruzzone ,&nbsp;Ricardo Pozzobon","doi":"10.1016/j.actaastro.2025.04.066","DOIUrl":"10.1016/j.actaastro.2025.04.066","url":null,"abstract":"<div><div>The LUnar Geology Orbiter (LUGO) mission is proposed to study surface and subsurface geological features on the Moon that have not yet been the dedicated target of previous missions, with the goal of understanding its thermal evolution and supporting human exploration and future permanent settlements. The objectives of LUGO aim to clarify two important knowledge gaps: 1) to characterize Irregular Mare Patches (IMPs), enigmatic volcanic landforms located on the near side of the Moon, and to provide insights into their age and formational processes; and 2) to detect lava tubes and characterize their general shapes to evaluate their potential as future astronaut habitats. Such a mission would lead to discoveries regarding the improved dating, vertical structure, and shallow subsurface plumbing system of IMPs, as well as the existence, occurrence, and physical characteristics of several lava tubes. To achieve the scientific objectives, the mission is proposed to carry an instrument payload consisting of 1) a ground-penetrating radar with a frequency between 15 and 30 MHz, 2) a narrow-angle camera with a spatial scale better than 25 cm per pixel, 3) a hyperspectral camera with a spectral range from 500 to 1650 nm, and 4) a light detection and ranging sensor using single-photon detection at 1550 nm. LUGO may also characterize other geological targets, such as floor-fractured craters, thanks to its ability to cover long swaths of the lunar surface from its orbit. Furthermore, LUGO will serve as a technological blueprint for future missions that will help uncover the relationship between the geological and morphological characteristics at the lunar surface and the geological structure and stratigraphy of the shallow lunar crust.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 154-174"},"PeriodicalIF":3.1,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143912588","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}

{"title":"The protection of AI-based space systems from a data-driven governance perspective","authors":"Giovanni Tricco ,&nbsp;Roser Almenar ,&nbsp;Kaili Ayers ,&nbsp;Rihab Ben Moussa ,&nbsp;Thomas Graham ,&nbsp;Simisola Iyiola ,&nbsp;Sanghoon Lee ,&nbsp;Terezie Němcová ,&nbsp;Asiimwe Joshua Opota ,&nbsp;Tushar Sharma ,&nbsp;Raelee Toh ,&nbsp;Jieyu Yuan","doi":"10.1016/j.actaastro.2025.04.063","DOIUrl":"10.1016/j.actaastro.2025.04.063","url":null,"abstract":"<div><div>Space infrastructures have long represented the pinnacle of technological and engineering achievements. This complexity has been further amplified by the advent of the new space race, where private actors are taking the lead, alongside states, in deploying thousands of satellites in outer space. The outer space environment of 2040 will look very different from today. Spacecraft will necessitate more frequent maneuvers to avoid potential collisions, with the need to be more conscious of their surroundings. Indeed, as the frequency of events and the number of space objects rises, decision-making tasks will increasingly challenge human operators, especially as physical and temporal margins diminish. Such complexity is enveloping thanks to the synergy of space technologies and Artificial Intelligence (AI), which is transforming the functioning of space systems.</div><div>The forward trajectory clarifies the significance that AI in outer space will retain in the years ahead. The <em>Corpus Juris Spatialis</em> finds itself at a crossroads, faced with the defiance of withstanding the technological advances catalyzed by the impending integration of AI into all facets of space missions. Given the ubiquitous nature of AI, its implementation will invariably pose multifaceted legal challenges across diverse aspects of International Space Law. The acquired autonomy of space assets prompts crucial questions regarding the legal standards applicable to AI in outer space, and how these autonomous space systems should be protected against hostile interference.</div><div>The main purpose of this paper, presented by the Space Law and Policy Project Group of the Space Generation Advisory Council (SGAC), is to examine the pivotal legal dimensions stemming from the automation of space-based applications from a ‘data-driven governance’ standpoint. The increase in production and acquisition of space data will just augment the sophistication of AI systems, therefore necessitating their data assets to be reliable, accurate, and consistent to safeguard the long-term success of AI technologies in space missions. The paper aims to address the overarching legal challenges posed by the integration of AI into outer space operations, specifically on cybersecurity, intellectual property, and data governance, which are critical for safeguarding autonomous systems. By examining the various nuances of these domains, it seeks to contribute to a comprehensive understanding of the legal landscape of the current AI-space pairing. Ultimately, the conclusion will offer a set of recommendations to pave the way for a secure, ethical evolution of autonomous space systems in the near future.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 73-86"},"PeriodicalIF":3.1,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906629","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}

{"title":"Iterative control method for quasi-Sun-pointing attitude of solar power satellites","authors":"Yuting Wu ,&nbsp;Jiarui Luo ,&nbsp;Qingjun Li ,&nbsp;Shunan Wu ,&nbsp;Yuanyuan Li","doi":"10.1016/j.actaastro.2025.05.001","DOIUrl":"10.1016/j.actaastro.2025.05.001","url":null,"abstract":"<div><div>Quasi-Sun-pointing (QSP) attitude for ultra-large solar array of solar power satellites solves problems of enormous control fuel consumption and large-amplitude structural vibrations for Sun-pointing attitude and the problem of low solar radiation capturing efficiency for gravity-gradient-stabilized attitude. However, the control of QSP attitude meets great challenges because analytical solution for the QSP attitude has not been obtained, and consequently the objective attitude is unknown. Thus, an iterative control method for QSP attitude is proposed based on dichotomy or secant methods, which is free of objective attitude. Firstly, the attitude dynamic equations of the solar array are established. Then, the continuous process of attitude motion is divided into multiple periods. The initial conditions of the odd periods are adjusted using iterative methods to find the accurate initial conditions of the QSP attitude. In even periods, quintic polynomial trajectory planning and feedforward-feedback controller are employed to obtain the prescribed terminal attitude conditions of even periods, which are also initial conditions of odd periods. Finally, the proposed iterative control method is validated through numerical simulations considering the influences of inertial parameters, structural flexibility, and control frequency. Numerical results reveal that QSP attitude can be obtained if the control frequency is one order smaller than the lowest natural frequency of the structure.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 175-185"},"PeriodicalIF":3.1,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143912589","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}

{"title":"Acoustic detection of the liquid–vapor interface in settled propellant tanks","authors":"Kevin M. Crosby ,&nbsp;Justin Wheeler ,&nbsp;Teagan Steineke ,&nbsp;Sikiel Graves ,&nbsp;Eric A. Hurlbert","doi":"10.1016/j.actaastro.2025.04.032","DOIUrl":"10.1016/j.actaastro.2025.04.032","url":null,"abstract":"<div><div>This study presents a vibration-based method for detecting the liquid–vapor interface in settled propellant tanks. A theoretical framework is introduced to predict the vibrational response of patch sensors mounted on the tank wall and actuated by a broad-band acoustic excitation. The theory predicts the form of response transitions between wetted and dry conditions as the interface moves past the sensor location. Relationships between the instantaneous location of the liquid–vapor interface and the measured root-mean-square (RMS) response signal are established in a scale-free manner that does not depend on physical properties of the tank or fluid. A computational model, implementing a modified Euler–Bernoulli beam approach, is developed to simulate sensor response, with the interface treated as a boundary between two distinct mass densities on the beam. Experimental results, obtained from a model propellant tank, show that the liquid–vapor interface is detected with an average error in the full tank volume estimate of 0.7% across the measurement range from 4% to 90% fill. These findings demonstrate a promising non-invasive technique for liquid–vapor interface detection in settled conditions, with potential applications in spacecraft propellant management and in-space refueling systems following appropriate engineering qualification for the space environment.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 141-153"},"PeriodicalIF":3.1,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906635","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}

{"title":"Hypergravity influences mouse erythrocyte membrane lipid composition and antioxidant potential","authors":"Angela Maria Rizzo ,&nbsp;Giampaolo Murgia ,&nbsp;Antonio Lentini ,&nbsp;Stefania Zava ,&nbsp;Francesca Ferranti ,&nbsp;Sara Tavella ,&nbsp;Daniela Santucci ,&nbsp;Jack J.W.A. van Loon ,&nbsp;Irma Colombo ,&nbsp;Paola Antonia Corsetto","doi":"10.1016/j.actaastro.2025.04.061","DOIUrl":"10.1016/j.actaastro.2025.04.061","url":null,"abstract":"<div><div>To support safe human space exploration, it is important to understand how different effectors, including gravitational forces, influence living organisms. Indeed, altered levels of gravity affect the physiological function of multiple cells, tissues, and organs in living organisms. Previous studies suggested that microgravity modifies plasma membrane permeability and cellular metabolism in erythrocyte, modifying cholesterol and phospholipid levels. However, to support human safe space exploration, it is also relevant to understand the effects of hypergravity. Therefore, the aim of this study was to investigate <em>in vivo</em> the impact of hypergravity on lipid phenotype and oxidative stress in mouse erythrocytes.</div><div>Animals were housed in the Italian Space Agency's Mice Drawer System (MDS-ASI), a facility designed to house rodents on the International Space Station (ISS) and adapted by Thales Alenia Space to the Large Diameter Centrifuge (LDC-ESA), to expose mice to a 3×<em>g</em> environment for 14 days. After exposure, a tissue-sharing protocol allowed us to purify and analyze erythrocytes.</div><div>Our results show that the exposure of mice to altered gravity induced the reduction of unsaturation degree in erythrocyte membranes correlated to a lower stearoyl-CoA desaturase (SCD-1) activity. Moreover, the hypergravity induced both a decline in antioxidant defences, indicated by the significant decrease in total glutathione, and a grow of the inflammatory status, supported by an increase in the AA/EPA ratio.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 99-105"},"PeriodicalIF":3.1,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906631","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}

{"title":"Stability and form-finding of shelters subjected to moonquakes of the lunar south polar region","authors":"Seungil Lee ,&nbsp;Terry Bennett ,&nbsp;Scott T. Smith ,&nbsp;David A. Kring","doi":"10.1016/j.actaastro.2025.04.030","DOIUrl":"10.1016/j.actaastro.2025.04.030","url":null,"abstract":"<div><div>As humanity re-engages in lunar exploration missions, plans are being developed for base construction in the lunar south polar region to support long-term human presence. It is therefore essential to evaluate the structural stability of lunar shelters to protect the lunar base and infrastructure from hazards such as moonquakes. Compression structures such as arches and domes, made from earth or lunar-derived materials, may be suitable lunar structures. This study aims to evaluate the stability of dome structures under seismic loads from moonquakes and then propose appropriate design options. The equivalent lateral force (ELF) method was applied to convert the ground accelerations obtained from probabilistic seismic hazard analysis (PSHA) results for the lunar south polar regions into seismic lateral loads. Thrust network analysis (TNA) is then employed to (i) evaluate the stability of dome shelters subjected to seismic lateral loads, and (ii) investigate the impact of variations in dome shelter design and seismic hazard levels. The findings of this paper present key design criteria for dome shelters through form-finding optimisation based on seismic hazards in the lunar south polar regions. The calculated minimum required thickness-to-radius ratios provide preliminary design guidelines for dome shelters that protect lunar habitats and infrastructure.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 106-116"},"PeriodicalIF":3.1,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906632","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}

{"title":"Adaptive guidance for low-thrust formation flight mission in Circular Relative Orbit","authors":"Dario Ruggiero ,&nbsp;Takahiro Ito ,&nbsp;Elisa Capello ,&nbsp;Yuichi Tsuda","doi":"10.1016/j.actaastro.2025.04.026","DOIUrl":"10.1016/j.actaastro.2025.04.026","url":null,"abstract":"<div><div>Spacecraft formation flight is increasingly pivotal in the design of new space missions. This demands an high level of autonomy to optimize science time, and the development of advanced mission concepts to surpass current technological limitations. Recently, Low Earth Orbit (LEO) has been explored as solution for experimental validation of novel formation flight technologies. LEO is related to proximity formation flight missions, which require active guidance algorithms to ensure mission success and safe operations. An efficient guidance algorithm is proposed to enhance the autonomy of proximity formation flight missions, enabling variable formations and reconfiguration while ensuring safety. The optimal formation trajectory problem, conceptualized as Circular Relative Orbit, addresses the relative motion with respect to a reference orbit. Rigorous Lyapunov design is proposed to ensure convergence to the desired trajectory, guaranteeing closed-loop system stability. It incorporates an Artificial Potential Field function to deal with the formation flight problem. Initial simulations are conducted to assess the effectiveness of the proposed approach within the restricted Two-Body dynamics framework. The algorithm is applied to accomplish a space interferometer deploying mission in LEO, demonstrating its efficacy through a compact implementation. Finally, the algorithm’s general and wider effectiveness is validated with elliptical and L2 Halo reference orbits.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 13-25"},"PeriodicalIF":3.1,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895188","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}

{"title":"Evolution of oxide composition, liquidus temperature, and viscosity during lunar molten regolith electrolysis","authors":"B. Schneiderman ,&nbsp;M. Lensing ,&nbsp;E. McMurchie ,&nbsp;J. Stokes ,&nbsp;G. Brennecka ,&nbsp;C. Dreyer ,&nbsp;C. Brice ,&nbsp;Z. Yu ,&nbsp;J. Kim","doi":"10.1016/j.actaastro.2025.04.055","DOIUrl":"10.1016/j.actaastro.2025.04.055","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The design and implementation of systems for molten lunar regolith electrolysis (MRE) benefit significantly from detailed modeling of the composition trajectory and evolution of composition-dependent thermophysical properties of regolith-derived oxides during this process. Two properties of interest are the liquidus temperature and viscosity of the molten oxide. The liquidus temperature evolution governs both the minimum reactor temperature and the extent of viable electrolysis at reasonably achievable reactor temperatures, while the viscosity is essential to the design of reactor outlet flow paths. This paper presents a strategy for modeling the oxide composition trajectory in MRE using the integrated thermochemical modeling software FactSage and calculating liquidus and viscosity evolution curves from the same software. This strategy was employed to model MRE of a lunar highlands regolith simulant composition. In contrast to previously employed modeling strategies, composition trajectory modeling in FactSage allows consideration of parallel species reduction during electrolysis, supporting detailed predictions of the compositions of reduced metallic products as a function of electrolysis reaction progress, which is quantified by the oxygen extraction yield parameter &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. For the regolith simulant composition modeled, it is suggested that a means of isolating ferrosilicon produced in the early stages of MRE from aluminum produced in more advanced stages should be implemented near &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; = 0.30 to maintain the usability of each metallic product. The calculated liquidus temperature evolution from FactSage suggests a minimum reactor temperature requirement of 1675 °C, which allows electrolysis to progress to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; = 0.37, beyond which the liquidus rises above practical operating limits. Preliminary differential scanning calorimetry experiments indicate FactSage is more accurate than existing regression models at predicting liquidus evolution. The viscosity evolution predicted by FactSage is compared to the prediction of five models from the literature. Spindle viscometry experiments on select compositions indicate that FactSage outperforms all the literature models at least for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; ≤ 0.165, demonstrating agreement to within 28 % between 1300 and 1600 °C for this composition range, which is attributed to its incorporation of a quasichemical model for bridging oxygen concentration in silicate melts. The advantages of using this model diminish for compositions beyond &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; = 0.30, which only conta","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 1-12"},"PeriodicalIF":3.1,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892156","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}

{"title":"Autonomous optical navigation for DESTINY+: Enhancing misalignment robustness in flyby observations with a rotating telescope","authors":"Takayuki Hosonuma ,&nbsp;Takeshi Miyabara ,&nbsp;Naoya Ozaki ,&nbsp;Ko Ishibashi ,&nbsp;Yuta Suzaki ,&nbsp;Peng Hong ,&nbsp;Masayuki Ohta ,&nbsp;Takeshi Takashima","doi":"10.1016/j.actaastro.2025.04.023","DOIUrl":"10.1016/j.actaastro.2025.04.023","url":null,"abstract":"<div><div><span><math><msup><mrow><mtext>DESTINY</mtext></mrow><mrow><mtext>+</mtext></mrow></msup></math></span> is an upcoming JAXA Epsilon medium-class mission to flyby multiple asteroids including Phaethon. As an asteroid flyby observation instrument, a telescope mechanically capable of single-axis rotation, named TCAP, is mounted on the spacecraft to track and observe the target asteroids during flyby. As in past flyby missions utilizing rotating telescopes, TCAP is also used as a navigation camera for autonomous optical navigation during the closest-approach phase. To mitigate the degradation of the navigation accuracy, past missions performed calibration of the navigation camera’s alignment before starting optical navigation. However, such calibration requires capturing large number of images by the navigation camera and downlinking them to the ground station. In the case of small spacecraft with limited link capacity, such as <span><math><msup><mrow><mtext>DESTINY</mtext></mrow><mrow><mtext>+</mtext></mrow></msup></math></span>, such ground-in-the-loop calibration requires significant operational time to complete and imposes constraints on the operation sequence. From the above background, the <span><math><msup><mrow><mtext>DESTINY</mtext></mrow><mrow><mtext>+</mtext></mrow></msup></math></span> team has studied the possibility of reducing operational costs by allowing TCAP alignment errors to remain. This paper describes an autonomous optical navigation algorithm robust to the misalignment of rotating telescopes, proposed in this context. In the proposed method, the misalignment of the telescope is estimated simultaneously with the spacecraft’s orbit relative to the flyby target. To deal with the nonlinearity between the misalignment and the observation value, the proposed method utilizes the unscented Kalman filter, instead of the extended Kalman filter widely used in past studies. The proposed method was evaluated with numerical simulations on a PC and with hardware-in-the-loop simulation, taking the Phaethon flyby in the <span><math><msup><mrow><mtext>DESTINY</mtext></mrow><mrow><mtext>+</mtext></mrow></msup></math></span> mission as an example. In the example case, the misalignment-induced navigation accuracy degradation of 4.6<!--> <!-->km-<span><math><mrow><mn>1</mn><mi>σ</mi></mrow></math></span> can be reduced to 0.1<!--> <!-->km-<span><math><mrow><mn>1</mn><mi>σ</mi></mrow></math></span> by the proposed method. The required time to run one-cycle of the navigation process on the onboard computer for the <span><math><msup><mrow><mtext>DESTINY</mtext></mrow><mrow><mtext>+</mtext></mrow></msup></math></span> mission is less than 0.18<!--> <!-->s. These results validate that the proposed method can mitigate the misalignment-induced degradation of the optical navigation accuracy with reasonable computational costs suited for onboard computers.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 117-130"},"PeriodicalIF":3.1,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906633","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}

{"title":"Investigation on combustor performance of a ramp-based solid rocket scramjet with ethylene addition","authors":"Jiebo Zhang ,&nbsp;Suyi Dou ,&nbsp;Xu Wang ,&nbsp;Mengxiong Li ,&nbsp;Qingchun Yang ,&nbsp;Xu Xu","doi":"10.1016/j.actaastro.2025.04.028","DOIUrl":"10.1016/j.actaastro.2025.04.028","url":null,"abstract":"<div><div>High combustion efficiency and low total pressure loss are essential for improving the performance of solid rocket scramjets. This study conducted direct-connect experiments to investigate the combustor performance of a ramp-based solid rocket scramjet with ethylene addition, simulating a Mach 6 flight condition with an equivalence ratio of 0.56. Ramps were installed near the exit of the combustor, expected to function as a throat and control the shock train intensity in the isolator. A boron-containing, oxygen-poor gas generator was used to generate a fuel-rich mixture, which was injected into the combustor for further combustion with the inflow air. Wall pressure along the combustor was measured, and other flow parameters were calculated using a one-dimensional analysis method. The experimental results indicate that subsonic combustion occurs within the combustor, and the ramps are confirmed as the throat. Raising the ramp height intensifies the blockage, thereby enhancing the shock train intensity. Ethylene addition boosts the total heat release, further enhancing the shock train intensity. The enhanced shock train increases the temperature and pressure, thereby promoting combustion. Furthermore, the enhanced shock train decreases Mach number, resulting in a reduction in total pressure loss. Therefore, raising the ramp height and adding ethylene both improve thrust and specific impulse. These findings offer novel insights into the design of solid rocket scramjets with high combustion efficiency and low total pressure loss.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"234 ","pages":"Pages 131-140"},"PeriodicalIF":3.1,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906634","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}