Acta Astronautica最新文献

{"title":"Clustering investigation of scramjet combustion processes based on contrastive learning","authors":"Hedong Liu ,&nbsp;Yuqian Chen ,&nbsp;Yue Huang ,&nbsp;Ting Song ,&nbsp;Wubingyi Shen ,&nbsp;Ye Tian ,&nbsp;Yancheng You","doi":"10.1016/j.actaastro.2025.03.036","DOIUrl":"10.1016/j.actaastro.2025.03.036","url":null,"abstract":"<div><div>The transition between combustion processes or modes of scramjet engines is high-speed and dynamic, which may lead to unstable or even runaway. It is crucial to identify the combustion state of scramjet engine for controlling and maintaining stable operation. Based on the methods of contrastive learning, a clustering network model of combustion processes is developed to deal with the schlieren image of a scramjet combustor without labels. Firstly, manual classification is performed to define and classify the combustion processes of scramjet combustor under different experimental conditions. The datasets of scramjet combustion processes are constructed by using schlieren images. Meanwhile, the unsupervised clustering of combustion processes is realized to learn its change rule upon the contrastive learning framework of examples. Subsequently, the results of manual classification and model clustering are compared and analyzed to evaluate the identification performance. The results suggest that the clustering results of the model are basically the same as those of manual classification. All evaluation indicators show a good performance using the clustering model, and the Adjusted Rand Index and Accuracy are over 0.94 and 0.89, respectively. This work indicates that the application of an unsupervised contrastive learning method is impressively efficient in the combustion state identification of scramjet.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"233 ","pages":"Pages 55-65"},"PeriodicalIF":3.1,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834608","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":"Experimental study on high-temperature thermal oxidation and laser ignition of aged boron powder","authors":"Zhicheng He,&nbsp;Jianjun Wu,&nbsp;Yuqiang Cheng,&nbsp;Zejun Hu,&nbsp;Qinhui Peng,&nbsp;Yuji Chen","doi":"10.1016/j.actaastro.2025.04.024","DOIUrl":"10.1016/j.actaastro.2025.04.024","url":null,"abstract":"<div><div>To investigate the effect of the initial surface oxide layer on boron regarding high-temperature thermal oxidation and ignition combustion performance, boron powder was subjected to aging under varying temperature and humidity conditions. The thickness of the surface oxide layer was analyzed and quantified using transmission electron microscopy (TEM) and digital microscopy software. The thermal oxidation characteristics, including the starting and ending temperatures, initiation temperature of rapid oxidation, and activation energy of the aged boron powder, were investigated through thermogravimetric analysis (TG). Additionally, the ignition delay time, flame morphology, and emission spectrum characteristics of the aged boron powder were assessed using a laser ignition experimental system. The results indicated that the surface oxide layer of boron developed gradually across different storage environments characterized by temperature and humidity. As the thickness of the initial oxide layer increased, the starting and ending temperatures of thermal oxidation exhibited minimal variation; however, both the initiation temperature of rapid oxidation and activation energy increased. Furthermore, the emission spectrum's intensity during the ignition phase of the aged boron powder diminished with an increase in oxide layer thickness, while the ignition delay time was prolonged.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"233 ","pages":"Pages 30-41"},"PeriodicalIF":3.1,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828852","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":"How to improve the attitude accuracy of the star sensor under dynamic conditions: A review","authors":"Liheng Ma ,&nbsp;Dongkai Dai ,&nbsp;Yuanman Ni","doi":"10.1016/j.actaastro.2025.03.043","DOIUrl":"10.1016/j.actaastro.2025.03.043","url":null,"abstract":"<div><div>Star sensors experience significant degradation in attitude measurement accuracy under dynamic conditions, primarily caused by motion-induced star image blurring and diminished effective stars. This review analyzes the underlying mechanisms responsible for accuracy deterioration in dynamically perturbed star sensors. As the first comprehensive survey in this field, the paper proposes a novel taxonomy classifying existing mitigation strategies into two paradigm categories: active and passive deblurring techniques and motion blur compensation methods. We critically analyzed representative approaches within each category, including optical system optimization, multi-FOV configurations, servo stabilization platforms, and algorithm-driven solutions such as image restoration and attitude-correlated frame processing. A comparative evaluation highlights the advantages and limitations of these methods through quantitative performance metrics and implementation constraints. Furthermore, the study establishes selection criteria emphasizing that optimal strategy adoption must consider application-specific requirements. This work provides both a technical reference for star sensor designers and a framework guiding future research directions in high-dynamics attitude determination.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"233 ","pages":"Pages 42-54"},"PeriodicalIF":3.1,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834607","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":"Dynamics modeling and simulation analysis of a reusable high-pressure staged combustion LOX/kerosene variable thrust rocket engine","authors":"Yuwei Liu,&nbsp;Yuqiang Cheng,&nbsp;Shuming Yang,&nbsp;Xinlin Liu,&nbsp;Jianjun Wu","doi":"10.1016/j.actaastro.2025.03.028","DOIUrl":"10.1016/j.actaastro.2025.03.028","url":null,"abstract":"<div><div>Reusable liquid propellant rocket engines are critical propulsion systems for future space launches and, with the increasing diversity of space missions, have become a prominent research focus in the aerospace field. To address the unclear response characteristics of a reusable high-pressure staged combustion LOX/kerosene variable-thrust rocket engine, a simulation platform was established for a specific engine model. This platform comprehensively considers the effects of the turbopump, valves, gas generator, thrust chamber, and regenerative cooling channels. Simulations were conducted under single-point operating conditions to investigate the system’s response characteristics across different operating conditions, the variation of system performance parameters with thrust levels, and the effects of ignition timing gaps and start-up acceleration valves on the engine start-up process. The results indicate that reducing the ignition timing gap between the gas generator and the combustion chamber effectively decreases the risk of over-temperature and over-pressure in the gas generator. Additionally, during rapid start-up with the use of an acceleration valve, the fuel valve opening for the gas generator should be minimized to prevent fuel accumulation, which could lead to over-temperature conditions.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"233 ","pages":"Pages 17-29"},"PeriodicalIF":3.1,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828851","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":"Light curves sequential comparison strategy for improved understanding of LEO uncontrolled objects","authors":"S. Kumar ,&nbsp;L. Chiavari ,&nbsp;L. Cimino ,&nbsp;S. Varanese ,&nbsp;L. Mariani ,&nbsp;M. Rossetti ,&nbsp;G. Zarcone ,&nbsp;T. Schildknecht ,&nbsp;F. Nasuti ,&nbsp;F. Piergentili","doi":"10.1016/j.actaastro.2025.04.018","DOIUrl":"10.1016/j.actaastro.2025.04.018","url":null,"abstract":"<div><div>In the framework of Space Situational Awareness activities, space debris light curve analyses have been used as a tool to study the tumbling motion of uncontrolled orbiting objects using only optical data and often without any assumptions about their geometry. Through this strategy, frequency analysis can be performed to extract the objects' rotation periods, which are necessary to predict variations in attitude for both monitoring and management purposes. In the context of international tasks and activities, the Sapienza Space System and Space Surveillance Laboratory research group at Sapienza University of Rome, on behalf of the Italian Space Agency delegation to the Inter-Agency Space Debris Coordination Committee, has created a historical record of light curve data by observing seven rocket bodies in low Earth orbit. This dataset, supplemented with further investigation over the years, has revealed the long-term evolution of the motion states, with particular attention to the recorded tumbling rates, which would be unobservable with short-term campaigns. These data allow for long-term light curve inversion and historical analyses of rotational frequency and photometric response to optical observations, which are of interest to Space Surveillance and Tracking and Space Situational Awareness services for database updates, monitoring of uncontrolled resident space objects, and future re-entry observations. In this paper, the sequential comparison strategy used to investigate the long-term evolution of space debris rotation rates is presented, with a specific focus on the SL-14 R/B (NORAD ID 18340), which has exhibited an anomalous increase in its rotation period over the years. To investigate the underlying causes of this behaviour, a dedicated attitude evolution analysis was conducted, employing various methodologies. First, attitude simulation techniques were used to explore potential root causes of this sudden acceleration, including the hypothesis of a failure in the propulsion system leading to pressurized gas leakage. Different leakage models were analysed to assess the plausibility of this scenario. Additionally, a digital twin simulation was developed to perform light curve inversion, enabling the reconstruction and validation of the object's attitude motion. The results of these analyses provide deeper insight into the dynamics of non-cooperative space objects, fostering the development of improved tracking, characterization, and predictive modelling strategies in support of Space Surveillance and Tracking activities.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"232 ","pages":"Pages 654-665"},"PeriodicalIF":3.1,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830016","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":"Dynamic combustion and response characteristics of a novel combined solid rocket motor regulated by a pintle valve","authors":"Zhengchun Chen ,&nbsp;Shuyuan Liu ,&nbsp;Limin Wang ,&nbsp;Songqi Hu","doi":"10.1016/j.actaastro.2025.04.017","DOIUrl":"10.1016/j.actaastro.2025.04.017","url":null,"abstract":"<div><div>Thrust regulation has been a major challenge to the solid rocket motor. The dynamic combustion and response characteristics of a novel combined solid rocket motor regulated by a pintle valve are numerically studied in this paper. A two-dimensional transient combustion model of the combined motor is established. The results show that as the flow regulation ratio increases, the species mixing in the combustion chamber is greatly enhanced. The combustion zone moves towards the burning surface, which enhances gas-solid heat transfer and leads to larger regression rate. With the movement of the pintle valve, the flow and combustion processes near pintle valve and pre-combustion chamber are strongly intensified. Meanwhile, the zone with the best mixing effect moves towards the burning surface, which causes the regression rate to increase from 4.96 mm/s to 13.03 mm/s with movement of the pintle valve from 0.70 s to 0.76 s. With the flow regulation ratio increasing from 1.6 to 4.0, the response time of pressure decreases by 50 % while the regulation ratios of the thrust and the regression rate reach 3.35 and 2.11, respectively. When the regulation ratios increase, the average heat release rate gradually increases as the increase of the regulation ratio intensifies the mixing and oxidation reactions between the species. In addition, during the full-scale flow regulation of the oxidizer-rich gas, the specific impulse efficiency ranges from 81 % to 88 %. It is found that there exists an optimum regulation ratio to obtain the maximum specific impulse efficiency. Based on the results, it is possible to regulate the regression rate and the thrust of the combined solid motor simultaneously. This work provides better insight into dynamic combustion and response characteristics of solid motor under flow regulation.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"233 ","pages":"Pages 1-16"},"PeriodicalIF":3.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828853","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":"Counting stars and costs: An empirical examination of space launch cost trend at NASA","authors":"Moon J. Kim","doi":"10.1016/j.actaastro.2025.04.011","DOIUrl":"10.1016/j.actaastro.2025.04.011","url":null,"abstract":"<div><div>A cornerstone of the United States space policy is fostering a robust commercial space industry to leverage the benefits of competitive market forces. Space sector stakeholders generally applaud the implementation of this policy decision in the launch industry, citing significant decreases in space launch costs in the last decade. The effectiveness of this policy can be examined through two lenses: the initial cost reduction from the transition of the domain to the private sector and the continuous cost reduction due to the forces of competitive market until reaching an equilibrium. Empirical studies have verified the first effect by comparing commercial launch service costs to those of the Shuttle program. However, the current literature faces data limitations for robust investigations of the second effect. Proprietary factors restrict access to actual launch cost data, necessitating reliance on the prices advertised by the service providers. This study addresses this knowledge gap with an empirical examination using actual launch costs incurred by the National Aeronautics and Space Administration (NASA). The statistical models in this paper reveal NASA's launch cost trends for non-recurring missions using private sector launch services, offering a more precise insight into the current dynamics of the launch market. The study's findings contribute to economic transparency, strengthening the foundation for enhanced market competition. More importantly, the results of the study open the opportunity to reassess the relevant policies to improve the ways government agencies engage with the private sector as the exploration of the unknown expands.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"232 ","pages":"Pages 633-639"},"PeriodicalIF":3.1,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143816712","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":"Effects of concomitant hypoxia and simulated microgravity on skeletal muscle, liver, and lungs in a novel experimental mouse model","authors":"Saeed Ahmad Khan ,&nbsp;Josemin Jose ,&nbsp;Gopika Ramachandran ,&nbsp;Mutasem Rawas-Qalaji ,&nbsp;Anu Ranade ,&nbsp;Asima Karim ,&nbsp;Firdos Ahmad ,&nbsp;Rizwan Qaisar","doi":"10.1016/j.actaastro.2025.04.010","DOIUrl":"10.1016/j.actaastro.2025.04.010","url":null,"abstract":"<div><h3>Background</h3><div>The hindlimb unloaded (HU) mouse is an established model of simulated microgravity with pathologies of various body organs. However, the relevant effects of concomitant hypoxia in HU mice are unknown. We have developed a novel mouse model of hypoxia and HU to better simulate spaceflight conditions. Here, we investigated the cytoarchitecture and gene expressions of skeletal muscle, lungs, and liver tissues in HU mice with hypoxia.</div></div><div><h3>Methods</h3><div>We divided male, 4-month-old male c57BL/6j mice into four groups, normoxic and hypoxic ground-based controls and normoxic and hypoxic HU mice. The hypoxic group was exposed to 15 % oxygen during the second week of HU. We investigated histology and gene expressions of markers of endoplasmic reticulum stress and necroptosis in skeletal muscle, lungs, and liver tissues.</div></div><div><h3>Results</h3><div>The HU-hypoxic mice exhibited myofibers atrophy, maintenance of myonuclei count, and reduced myonuclear domain sizes compared to normoxic ground-based and HU mice (all p &lt; 0.05). These mice also exhibited bronchial epithelial thinning and increased alveolar diameter (both p &lt; 0.05). The liver tissues of HU-hypoxic mice exhibited higher hepatic fat content than ground-based normoxic mice. Lastly, we found elevated expressions of markers of endoplasmic reticulum stress and necroptosis in skeletal muscle, liver, and lung tissues.</div></div><div><h3>Conclusion</h3><div>Altogether, our results show that exposure to hypoxia worsens the histological injuries to skeletal muscle, lungs, and liver of HU mice. Further studies are required to characterize the negative effects of hypoxia and HU on various body organs.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"232 ","pages":"Pages 580-587"},"PeriodicalIF":3.1,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143791852","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":"Effect of H2/O2 concentration gradient on detonation re-initiation behind the pre-detonator tube","authors":"Jianglong Guo ,&nbsp;Jianfeng Pan ,&nbsp;Chao Jiang ,&nbsp;Yi Zhang ,&nbsp;Chenlong Li ,&nbsp;Genglin Ge ,&nbsp;Muhammad Nauman ,&nbsp;Wenming Yang","doi":"10.1016/j.actaastro.2025.04.013","DOIUrl":"10.1016/j.actaastro.2025.04.013","url":null,"abstract":"<div><div>A numerical study on the effect of H₂/O₂ concentration gradient on detonation re-initiation behind the pre-detonator tube was carried out using an OpenFOAM based solver DCRFoam. Simulations of the processes rely on solving the Navier-Stokes equations. The results indicate that the cellular size increases with the increase of hydrogen volume fraction. And the decoupled degree of detonation is higher in the rich fuel region. The decoupled shock propagates faster but exhibit lower intensity in the rich fuel region. When the concentration gradient increases to 2.22 m^-1 and 4.44 m^-1, the unburned mixture is ignited to form a transverse detonation. When the concentration gradient increases to 5.55 m^-1 and 6.66 m^-1, the triple point in the rich fuel region is decoupled. The decoupled triple point collides with the rich fuel wall to generate a hot spot. The energy of the hot spot is too small to ignite the unburned mixture to form a transverse detonation. The diffraction, re-initiation, and self-sustained detonation processes behind the pre-detonator tube are similar under different concentration gradients. The key to the detonation re-initiation is to form a hot spot. And the formation of a transverse wave is essential to the development of self-sustained detonation. Transverse waves originate from the poor fuel region and exhibit higher intensity in the rich fuel region.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"232 ","pages":"Pages 588-599"},"PeriodicalIF":3.1,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143791853","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":"Improved Additive Manufacturing of Lunar Regolith Simulant via Digital Light Processing for In-Situ Resource Utilization on the Moon","authors":"Adolor David Aiyeki ,&nbsp;Andrey Tikhonov ,&nbsp;Svyatoslav Chugunov","doi":"10.1016/j.actaastro.2025.04.009","DOIUrl":"10.1016/j.actaastro.2025.04.009","url":null,"abstract":"<div><div>The exploration of the Moon necessitates sustainable habitat construction. Establishing a permanent base on the Moon requires solutions for challenges such as transportation costs and logistics, driving the emphasis on In-Situ Resource Utilization (ISRU) techniques including Additive Manufacturing. Given the limited availability of regolith on Earth, researchers utilize simulants in laboratory studies to advance technologies essential for future Moon missions. Despite advancements, a comprehensive understanding of the fundamental properties and processing parameters of sintered lunar regolith still needs to be studied, demonstrating the need for further research. Here, we investigated the fundamental properties of lunar regolith simulant material with respect to the stereolithography-based AM process needed for the engineering design of complex items for lunar applications. Material and mechanical characterization of milled and sintered LHS-1 lunar regolith was done. Test specimens, based on ASTM standards, were fabricated from a 70 wt.% (48.4 vol. %) LHS-1 regolith simulant suspension and sintered up to 1150°C. The compressive, tensile, and flexural strengths were (510.7 ± 133.8) MPa, (8.0 ± 0.9) MPa, and (200.3 ± 49.3) MPa respectively, surpassing values reported in previous studies. These improved mechanical properties are attributed to suspension’s powder loading, layer thickness, exposure time, and sintering temperature. A set of regolith physical and mechanical fundamental material properties was built based on laboratory evaluation and prepared for utilization, with the manufacturing of complex-shaped objects demonstrating the technology's capability for engineering design problems.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"232 ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820751","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}