Acta Astronautica最新文献

{"title":"The effect of spatial non-uniformity on multiple transient modes of detonation onset in a three-dimensional channel","authors":"","doi":"10.1016/j.actaastro.2024.09.038","DOIUrl":"10.1016/j.actaastro.2024.09.038","url":null,"abstract":"<div><div>The study of the transient combustion modes is one of the key topics when considering the safety of space flights. Control of detonation onset has a dual application. First, the search for ways to prevent detonation modes in case of accidental fuel releases for fire safety issues of launch systems and the avoidance of accidents with rocket engines at a launch site and in near-Earth space. Second, the study of detonation and the possibility of using it to create propulsion systems based on detonation combustion of fuel. The paper shows the effect of the presence of spatial non-uniformities on the promotion of detonation in the chamber. Various geometries with and without obstacles and cavities are considered. It is demonstrated that the presence of obstacles accelerates the transition to the detonation process on the one hand, but on the other hand the presence of obstacles in combustion chamber could be the cause of incidental uncontrolled ignition, which ruins stable operation of an engine. The results of theoretical studies of the working cycle of the combustion chamber of a pulsed detonation engine are presented. Theoretical estimates for thrust characteristics are obtained.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322564","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":"Machine learning methods for modeling the kinetics of combustion in problems of space safety","authors":"","doi":"10.1016/j.actaastro.2024.09.039","DOIUrl":"10.1016/j.actaastro.2024.09.039","url":null,"abstract":"<div><div>Combustion is a complex physical and chemical process, which is considered both in the modeling of new propulsion systems with high energy efficiency and sufficient safety, and in the modeling of explosion safety and fire extinguishing problems. Fundamental research of this process is one of the key factors responsible for the safety of current and future space flights. Modeling the behavior of chemically reacting systems is computationally complex problem. It is necessary to take into account many details and processes, such as multicomponent structure, diffusion, turbulence, chemical transformations, etc. The modeling of chemical kinetics is the most computationally complex stage. In this paper, we consider the problem of approximating chemical kinetics for modeling the detonation of a hydrogen-air mixture using neural networks. The dataset for training the neural network were prepared using the principal component analysis from the results of numerical modeling of detonation in a narrow channel. The results of the obtained neural network showed that the presented model is capable of approximating chemical kinetics processes without significant restrictions on the range of pressure, temperature or the choice of the used time step.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326492","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":"Heating patterns and temperature distribution of projectile surface in lunar regolith penetration","authors":"","doi":"10.1016/j.actaastro.2024.09.019","DOIUrl":"10.1016/j.actaastro.2024.09.019","url":null,"abstract":"<div><p>During penetration, a large quantity of friction-induced heat is generated, significantly increasing the projectile surface temperature. Considering that the temperature variation depends on the physical properties of the target being penetrated, understanding this relationship can aid in extraterrestrial material behavior for detection and analysis efforts. The study investigated the patterns of heat generation and the distribution of temperature on the surface of a projectile as it penetrates lunar regolith. For discrete medium penetration, large deviations appear in temperature prediction due to particle extrusion flow. Thus, a heat flux density model on the projectile surface by introducing a relative velocity factor (RVF) for correction was established. The particle flow characteristics simulation and fitting model of the introduced factor were also obtained. We constructed a theoretical relationship between the resistance and stress model parameters using dynamic modeling. Experimental projectiles recording penetration acceleration and temperature at the points of interest on the projectile surface were designed and tested to obtain recorded data. The temperature field in this process was simulated in COMSOL software to calculate the projectile surface's heat flux density and temperature distribution. The results indicate that the developed model is effective. This research infers the physical characteristics of the penetrating target under specified penetration conditions and provides more dimensional information for lunar regolith exploration.</p></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272262","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":"Stochastic monitoring of the space environment with femtosatellite swarms","authors":"","doi":"10.1016/j.actaastro.2024.09.026","DOIUrl":"10.1016/j.actaastro.2024.09.026","url":null,"abstract":"<div><div>This paper is an exploration of how massively distributed femtosatellite networks can be implemented in space missions aimed at modelling the space environment for variables that show both time and space dependence. A theory of distributed sensing for space-time deconvolution is presented and performance parameters for system evaluation are described. Measurement of the magnetic field in low Earth orbit, in the presence of field perturbations, is selected as a case study for demonstrating the concept in simulation. A femtosatellite swarm, designed for the simulated space environment, shows the capability of space-time deconvolution in sensing. From the simulated mission, challenges in the design and deployment of free-flying sensor swarms, especially in the femtosatellite mass range, are identified and discussed.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0094576524005290/pdfft?md5=4ba28a42dc542f704cb4eb77eec8cd77&pid=1-s2.0-S0094576524005290-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A deep learning framework for supersonic turbulent combustion","authors":"","doi":"10.1016/j.actaastro.2024.09.027","DOIUrl":"10.1016/j.actaastro.2024.09.027","url":null,"abstract":"<div><div>The rapid simulation of supersonic turbulent combustion is a significant demand in scientific research and engineering applications for hypersonic vehicles. This paper proposes a deep learning framework for fast predicting unsteady turbulent combustion flow fields within the combustor of hypersonic vehicles. Based on convolutional neural networks and recurrent neural networks, this framework extracts spatial distribution characteristics of the flow fields and temporal evolution rules. And we enhance the traditional mean square error loss function by assigning loss weights to different channel data. Numerical simulations are conducted on the model scramjet combustor with various geometric structures to generate the dataset for training, and part of the untrained cases are used to verify the effectiveness. The results show that the proposed model, under different geometric structures, achieves high computational accuracy, with a correlation coefficient between the predicted results and the true values above 0.99. Considering the time cost of data transferring between heterogeneous systems, the model takes only 30 s to complete the calculation, representing an acceleration of at least two orders of magnitude compared to computational fluid dynamics. In the future, it can be applied to the rapid prediction of hypersonic vehicle performance and efficiently guide the optimal design of aircraft.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314597","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":"Flow field explorations and design improvements of a hybrid rocket motor LOx feed line","authors":"","doi":"10.1016/j.actaastro.2024.09.023","DOIUrl":"10.1016/j.actaastro.2024.09.023","url":null,"abstract":"<div><p>The oxidizer system in a hybrid rocket motor needs to deliver the flow from a pressurized storage tank to multiple combustor ports. Pressure losses in the oxidizer system directly impacts combustor pressure and consequently the vehicle performance. However, oxidizer feed line designs till date have been done using simple 1D tools. Higher fidelity flow analysis methods have not been reported in the literature to identify loss generating features. Therefore, a design improvement study was carried out to identify and alleviate the impact of undesirable flow features in a typical oxidizer system design. An experimentally calibrated 3D RANS approach is applied to a typical LOx feed system which includes steps, splitters, ports, and pipes with multiple bends. These design features result in varying degrees of flow separation, secondary flows and vortical flow features and result in total pressure losses of up to 7 %. This loss means that the storage tank needs to be pressurized further to accommodate such losses and ensure combustor performance. A targeted design improvement approach that features simple, alternative, implementable solutions in the loss-generating regions is discussed. The best of these design improvements can reduce the total pressure loss to 4 %, indicating a 43 % reduction in the losses and reduced impact on storage tank design and combustor performance. Therefore, this paper demonstrates that a higher fidelity design enhancement process of the oxidizer feed system, which is often neglected in such detailed studies, can result in overall vehicle level design improvements to ensure mission targets are met effectively.</p></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0094576524005253/pdfft?md5=55ab848b133f3e6b330923ed9fee2255&pid=1-s2.0-S0094576524005253-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolving governance in the space sector: From Legacy Space to New Space models","authors":"","doi":"10.1016/j.actaastro.2024.09.005","DOIUrl":"10.1016/j.actaastro.2024.09.005","url":null,"abstract":"<div><div>The space sector is evolving from the “Legacy Space” to the “New Space”. Along with the space sector, space program governance is transitioning to support an environment where legacy and New Space actors co-exist. The aforementioned transitions and the entry of New Space players result in new governance models, as space agencies aim to exploit contributions from non-space sectors, leveraging on collaborative opportunities.</div><div>Public-private partnerships (PPPs) become a new golden rule, disclosing unprecedented achievements.</div><div>However, the existing body of knowledge lacks a framing of models of space program governance, covering both Legacy Space programs and New Space ones. It is not clear how the roles and responsibilities of stakeholders change from the Legacy Space to the New Space, alongside the related changes in contract structures and the practices space agencies favour in current space programs and projects. Therefore, our paper aims to investigate how space program governance evolved.</div><div>We performed a single-case study on NASA-led space exploration programs to investigate the transition of space program governance and its actual state-of-the-art. We co-developed and validated three governance models for space programs through semi-structured interviews with senior experts. Furthermore, we present key drivers and barriers behind the evolution towards New Space governance models.</div><div>We found and discussed three program governance models corresponding to the evolutionary stages of space exploration programs. In the Legacy Space model, the government owns space infrastructures to demonstrate technological supremacy. In the Transitional model, lumpsum contracts, transitioning between cost-plus and fixed-price, replace the legacy EPC (Engineering, Production, Construction) ones. In the New Space model, collaborative efforts and PPPs enable alignment between public and private expertise. Finally, we examine the factors that promote and impede the evolution of space governance, leading to the emergence of a polycentric governance structure observed in current space programs.</div><div>The three models enable managers to visualize space programs from a governance perspective, where stakeholders’ roles and responsibilities in PPPs are clearly identified. Moreover, managers can leverage and innovate existing practices for transitioning across different models of governance in space programs and projects.</div><div>We contribute to research by introducing a transitional governance model that enables the smooth transition between the Legacy Space and the New Space paradigms. We justify the concurrent adoption of multiple governance models within the same space program, as in the current Artemis program.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0094576524005010/pdfft?md5=3dcb076b01bfbf5b9cd5a5d8726b56b2&pid=1-s2.0-S0094576524005010-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Space tourism: Legal and policy aspects (Editor Sandeepa Bhat B.). First Edition. London: Routledge. 2024. 242 pp., £29.59, ISBN 978 1 032 61795-4","authors":"","doi":"10.1016/j.actaastro.2024.09.028","DOIUrl":"10.1016/j.actaastro.2024.09.028","url":null,"abstract":"","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272280","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":"A common law in space for public health","authors":"","doi":"10.1016/j.actaastro.2024.09.006","DOIUrl":"10.1016/j.actaastro.2024.09.006","url":null,"abstract":"<div><p>Beyond the gravitational pull of Earth, space travel poses substantial public health hazards pertaining to the physical and mental well-being of astronauts and passengers, in addition to a possible threat to the populace of Earth upon re-entry. Exposure to cosmic radiation, cranial pressure from microgravity, weakened immunity to contagion, and the potential for depression and psychosis are all risks. Public health crises of this nature are to be expected as the duration of missions extends, as is the case with Mars settlement. In contrast to national space programmes, which have regarded these obstacles as human factors effecting the mission, public health law in common law British nations approaches them from the perspective of social justice and the preservation of human life and societal welfare. Countries including Australia, Canada, the United States, and the United Kingdom continue to apply traditional common law principles of public health law, which provide a sensible and enduring method for reconciling competing public and private interests. Common law permits the violation of civil liberties through the use of force in public health restraint, forced medication, and quarantine, but only if necessary, reasonable, and equitable. While the understanding of the health challenges associated with long-duration spaceflight may be in its infancy for national space programmes and civilian space ventures, the application of common law public health principles could aid in the establishment of health and safety protocols in which human reactions to crises in space resemble those observed on Earth. This may, nevertheless, necessitate the enactment of a more comprehensive federal public health statute. Embedded in both public health common law and international space law, the pre-eminence of preserving and respecting human life and well-being continues to be a cornerstone of humane justice despite the perilous conditions of space.</p></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142231682","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":"Laser hardening of aerospace structural materials","authors":"","doi":"10.1016/j.actaastro.2024.09.014","DOIUrl":"10.1016/j.actaastro.2024.09.014","url":null,"abstract":"<div><p>The work is devoted to the study of laser shock treatment of structural materials used in aviation and space technology with powerful nanosecond pulses in order to reduce surface damage, as well as resistance to crack growth. The hardening effect is achieved due to the mechanical deformation produced by the shock wave from the laser pulse due to the rapidly expanding plasma in the area of the irradiation spot. In this work, laser parameters for processing structural materials are calculated to ensure the required laser radiation power density. The results of laser processing with high-power nanosecond pulses of materials such as oxygen-free copper, aluminum alloy and germanium at various energy densities, with and without a protective coating and a water layer are shown.</p></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244239","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}