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1.
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2.
  • Albers, Roland, et al. (författare)
  • Magnetospheric Venus Space Explorers (MVSE) mission : a proposal for understanding the dynamics of induced magnetospheres
  • 2024
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 221, s. 194-205
  • Tidskriftsartikel (refereegranskat)abstract
    • Induced magnetospheres form around planetary bodies with atmospheres through the interaction of the solar wind with their ionosphere. Induced magnetospheres are highly dependent on the solar wind conditions and have only been studied with single spacecraft missions in the past. Without simultaneous measurements of solar wind variations and phenomena in the magnetosphere, establishing a link between both can only be done indirectly, using statistics over a large set of measurements. This gap in knowledge could be addressed by a multi-spacecraft plasma mission, optimized for studying global spatial and temporal variations in the magnetospheric system around Venus, which hosts the most prominent example of an induced magnetosphere in our solar system. The MVSE mission comprises four satellites, of which three are identical scientific spacecraft, carrying the same suite of instruments probing different regions of the induced magnetosphere and the solar wind simultaneously. The fourth spacecraft is the transfer vehicle which acts as a relay satellite for communications at Venus. In this way, changes in the solar wind conditions and extreme solar events can be observed, and their effects can be quantified as they propagate through the Venusian induced magnetosphere. Additionally, energy transfer in the Venusian induced magnetosphere can be investigated. The scientific payload includes instrumentation to measure the magnetic field, electric field, and ion–electron velocity distributions. This study presents the scientific motivation for the mission as well as requirements and the resulting mission design. Concretely, a mission timeline along with a complete spacecraft design, including mass, power, communication, propulsion and thermal budgets are given. This mission was initially conceived at the Alpbach Summer School 2022 and refined during a week-long study at ESA's Concurrent Design Facility in Redu, Belgium.
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3.
  • Amini, Kasra, et al. (författare)
  • Lighting and illumination investigation of long-term residence on Mars for the case of a set of designed Martian Habitat Units (MHUs)
  • 2022
  • Ingår i: Acta Astronautica. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0094-5765 .- 1879-2030. ; 192, s. 210-232
  • Tidskriftsartikel (refereegranskat)abstract
    • Addressing the subject matter of human missions on Mars, the Martian Habitat Units (MHUs) are presented as a comprehensive solution. MHUs are designed in clusters of 10 units, each capable of serving as long-term habitats for 9 scientific crew members. The life-style requirements of the units are targeted at an imitation of cultural thriving life we all know of, and not a mere survival-type shelter expecting the first people to step foot on Mars. One aspect of many challenging issues to be addressed in such complex settings is the lighting and illuminance condition of the said habitats, which in the context of Mars, and generally deep space missions being far from the sun will certainly lead to an arduous task. To check the validity of the argument and assess the extent to which the natural light level available on the surface of Mars will be sufficient for the daily requirements of the crew and mission in terms of illuminance, the current manuscript presents thorough and detailed simulations and analyses on the availability evaluation of natural lighting in the site location of MHUs, namely Valles Marineris, Melas Chasma. In this paper solar irradiation parameters on Mars are calculated based on the previous research which resulted in global, direct and diffuse irradiance at 12 different Martian solar times. The simulations are distributed over the Martian year and its day-time, and for two extreme orientations of MHUs in their circular surrounding cluster, namely East/West and South/North units. The distribution of illuminance for each case, and trend comparison studies are then accompanied by numerical values and analyses on the percentage to which the natural lighting conditions on Mars have been shown to be sufficient as a fraction of the whole lighting load of the habitats, which is to be compensated using artificial sources. The corresponding values are shown to fall well in the range of 35-45% of the total lighting loads. Also, as the results of the simulations show, due to the consistency of the glazed parts of the designed facade through all exterior surface of the MHU, natural lighting sufficiency percentage does not show a significant difference between two simulated orientations. This fact further approves the circular orientation premise of the MHUs in their cluster.
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5.
  • Anthony, Niklas, et al. (författare)
  • Laboratory experiments with a laser-based attachment mechanism for spacecraft at small bodies
  • 2021
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 189, s. 391-397
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the results of two sets of experiments that investigate laser-based metal-to-rock attachment techniques. Asteroids and comets have low surface gravity which pose a challenge to landers with moving parts. Such parts can generate torques and forces which may tip the lander over or launch it into deep space. Thus, if a lander on a small body is to have moving parts, the spacecraft must be equipped with an anchoring mechanism. To this end, we sought to use a laser to melt and bind a piece of metal mimicking a part of a spacecraft to a rock mimicking the surface of a typical asteroid. In the first set of experiments, extra material was not fed in during the processing. The second set were performed using a standard wire feeder used in laser welding, which added metal to the experiment during processing. During the first experiments, we discovered that a traditional weld, where two melt pools mix and solidify to form a strong bond, was not possible—the melt pools would not mix, and when they did, the resulting weld was extremely brittle. The second set of experiments resulted in a physico-mechanical bond, where a hole was drilled with a laser, and a wire was melted and fed into the hole. These latter experiments were successful in forming bonds as strong as 115 N. Such an attachment mechanism can also be used to maneuver small boulders on asteroid surfaces, to redirect small, monolithic asteroids, or in space-debris removal.
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6.
  • Anthony, Niklas, et al. (författare)
  • Laser-induced spallation of minerals common on asteroids
  • 2021
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 182, s. 325-331
  • Tidskriftsartikel (refereegranskat)abstract
    • The ability to deflect dangerous small bodies in the Solar System or redirect profitable ones is a necessary and worthwhile challenge. One well-studied method to accomplish this is laser ablation, where solid surface material sublimates, and the escaping gas creates a momentum exchange. Alternatively, laser-induced spallation and sputtering could be a more efficient means of deflection, yet little research has studied these processes in detail. We used a 15-kW Ytterbium fiber laser on samples of olivine, pyroxene, and serpentine (minerals commonly found on asteroids) to induce spallation. We observed the process with a high-speed camera and illumination laser, and used X-ray micro-tomography to measure the size of the holes produced by the laser to determine material removal efficiency. We found that pyroxene will spallate at power densities between 1.5 and 6.0 kW cm−2, serpentine will also spallate at 13.7 kW cm−2, but olivine does not spallate at 1.5 kW cm−2 and higher power densities melt the sample. Laser-induced spallation of pyroxene and serpentine can be two- to three-times more energy efficient (volume removed per unit of absorbed energy) than laser-induced spattering, and over 40x more efficient than laser ablation.
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7.
  • Bae, Sangjun, 1986, et al. (författare)
  • Multi-objective suborbit/orbit trajectory optimisation for spaceplanes
  • 2020
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 170, s. 431-442
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, a suborbit to orbit mission profile is analysed for spaceplanes. The proposed mission profile for spaceplanes is currently being considered for multiple earth observation missions and is considered as an extension of the skip re-entry problem which is a highly coupled and nonlinear problem. To solve the problem, we utilise both the Fuzzy Satisfactory Goal Programming (FSGP) method and the Radau Pseudospectral Method (RPM) as the problem includes more than two objective functions conflicting with each other, and needs to be optimised with pre-emptive priorities. A realistic spaceplane model is used with equality and inequality constraints, to demonstrate the feasibility of suborbit-orbit-suborbit manoeuvres through numerical simulations. The simulation results generated by the proposed methodology show that significant propellant savings can be made using multi-objective trajectory optimisation for spaceplanes for future theatre observation missions.
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8.
  • Bannova, Olga, 1964, et al. (författare)
  • Designing From Minimum to Optimum Functionality.
  • 2011
  • Ingår i: Acta Astronautica. - 0094-5765. ; 68:7-8, s. 760-769
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper discusses a multifaceted strategy to link NASA Minimal Functionality Habitable Element (MFHE) requirements to a compatible growth plan; leading forward to evolutionary, deployable habitats including outpost development stages. The discussion begins by reviewing fundamental geometric features inherent in small scale, vertical and horizontal, pressurized module configuration options to characterize applicability to meet stringent MFHE constraints.A proposed scenario to incorporate a vertical core MFHE concept into an expanded architecture to provide continuity of structural form and geometric logic bridging between “minimum” and “optimum”.The paper describes how habitation and logistics accommodations could be pre-integrated into a common Hab/Log Module that serves both habitation and logistics functions. This is offered as a means to reduce unnecessary redundant development costs and to avoid EVA-intensive on-site adaptation and retrofitting requirements for augmented crew capacity. An evolutionary version of the hard shell Hab/Log design would have an expandable middle section to afford larger living and working accommodations.In conclusion, the paper illustrates that a number of cargo missions referenced for NASA’s 4.0.0 Lunar Campaign Scenario could be eliminated altogether to expedite progress and reduce budgets. The plan concludes with a vertical growth geometry that provides versatile and efficient site development opportunities using a combination of hard Hab/Log modules and a hybrid expandable “CLAM” element.
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9.
  • Bannova, Olga, 1964, et al. (författare)
  • Space Architecture Education as Part of Aerospace Engineering Curriculum
  • 2011
  • Ingår i: Acta Astronautica. - 0094-5765. ; 69:11-12, s. 1143-1147
  • Tidskriftsartikel (refereegranskat)abstract
    • Education is particularly important for new fields. In the case of Space Architecture, there are two core needs: 1.educating the aerospace community about the architect’s process and role within the enterprise; 2.educating space architects and associated specialists about constraints, conditions, and priorities unique to human space systems.These needs can be addressed, respectively, by two key educational tools for the 21st century: 1.introducing the Space Architecture discipline into space system engineering curricula;2.developing Space Architecture as a distinct, complete training curriculum. New generations of professionals with a Space Architecture background, by offering their inherently integrative design approach to all types of space structures and facilities, can help shift professional focus from just engineering-driven transportation systems and “sortie” missions to permanent offworld human presence. Although architectural and engineering approaches share some similarities in solving problems, they also have significant differences. Architectural training teaches young professionals to operate at all scales from the “overall picture” down to the smallest details; to provide directive intention – not just analysis – to design opportunities, to address the relationship between human behavior and the built environment, and to interact with many diverse fields and disciplines throughout the project lifecycle.
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10.
  • Barabash, Victoria, Dr, et al. (författare)
  • Development of a competence ecosystem for the future space workforce: strategies, practices and recommendations from international master programs in northern Sweden
  • 2022
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 197, s. 46-52
  • Tidskriftsartikel (refereegranskat)abstract
    • Requirements from the global labor market have substantially changed in recent years. Graduate and post-graduate students with excellent subject knowledge, deep understanding of modern working methods, technicaland higher-order thinking, engineering intuition and problem-solving skills are in great demand. They should also have professional skills such as well-developed abilities in communication and teamwork, usually in an international work environment. This review discusses the advantages of multidisciplinary study environment, educational strategies such as student-oriented teaching, project-based learning with its applicability to a“real-world” setting, active learning techniques, development of entrepreneurial skills, lessons learned and best practices from the international Master Program in Spacecraft Design and the Joint Master Program in SpaceScience and Technology – SpaceMaster at Luleå University of Technology in northern Sweden. The importance of complementarity between formal, informal and non-formal learning methods for science and engineering studentshas been specifically highlighted. Connections to the world of work, through active industry involvementin the education in a systematic way, e.g. External Advisory Board, shared services and facilities, joint projectsand supervision of Master and PhD students, is recognised as a key success factor for professional training. A structural combination of modern pedagogical tools, strategic partnership with industry, business entities, academic partners and up-to-date multidisciplinary labs creates the conceptual framework for a CompetenceEcosystem for fostering a new generation of space scientists and engineers.
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11.
  • Bazzocchi, Michael C.F., et al. (författare)
  • Comparative analysis of redirection methods for asteroid resource exploitation
  • 2016
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 120, s. 1-19
  • Tidskriftsartikel (refereegranskat)abstract
    • An in-depth analysis and systematic comparison of asteroid redirection methods is performed within a resource exploitation framework using different assessment mechanisms. Through this framework, mission objectives and constraints are specified for the redirection of an asteroid from a near-Earth orbit to a stable orbit in the Earth-Moon system. The paper provides a detailed investigation of five redirection methods, i.e., ion beam, tugboat, gravity tractor, laser sublimation, and mass ejector, with respect to their capabilities for a redirection mission. A set of mission level criteria are utilized to assess the performance of each redirection method, and the means of assigning attributes to each criterion is discussed in detail. In addition, the uncertainty in physical characteristics of the asteroid population is quantified through the use of Monte Carlo analysis. The Monte Carlo simulation provides insight into the performance robustness of the redirection methods with respect to the targeted asteroid range. Lastly, the attributes for each redirection method are aggregated using three different multicriteria assessment approaches, i.e., the analytical hierarchy process, a utility-based approach, and a fuzzy aggregation mechanism. The results of each assessment approach as well as recommendations for further studies are discussed in detail.
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12.
  • Bazzocchi, Michael C.F., et al. (författare)
  • Stochastic optimization of asteroid three-dimensional trajectory transfer
  • 2018
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 152, s. 705-718
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work, an approach to designing near-optimal nonplanar transfer trajectories for asteroids is introduced, taking into account the uncertainty in asteroid parameters. The approach is demonstrated using a specific known Near-Earth Asteroid (NEA) as a model for the transfer scenario. The designed trajectory redirects the NEA from its current orbit about the Sun to a new orbit in the Earth-Moon system. The approach utilizes a low-thrust redirection method, namely the ion beam method, to execute the transfer; however, the work can be extrapolated to most low-thrust redirection methods. Asteroid parameters, such as absolute magnitude, albedo and density, are modelled, and a Monte Carlo analysis is employed to investigate the redirection maneuver in light of the expected variation in parameters. The trajectory transfer is modelled in three dimensions through the use of pseudo-equinoctial shaping, and is subsequently optimized. Due to the large design space created by the 21 decision variables, the optimization is parsed into two main steps; first, a global optimization that employs a genetic algorithm, followed by a local optimization that utilizes sequential quadratic programming to refine the result from the global optimization. Lastly, the results of the Monte Carlo analysis for the near-optimal trajectory transfer of the NEA are discussed.
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13.
  • Bodin, Per, et al. (författare)
  • System test results from the GNC experiments on the PRISMA in-orbit test bed
  • 2011
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 68:7, s. 862-872
  • Tidskriftsartikel (refereegranskat)abstract
    • The PRISMA in-orbit test bed will demonstrate guidance, navigation, and control strategies for spacecraft formation flying and rendezvous. The project is funded by the Swedish National Space Board and the prime contractor is the Swedish Space Corporation. The project is further supported by the German Aerospace Center, the Technical University of Denmark, and the French Space Agency. PRISMA was launched on June 15, 2010 and after three weeks of operations, all on-board systems and units have passed an initial commissioning phase. Separation of the two PRISMA satellites from each other is expected by mid-August 2010. PRISMA consists of two spacecraft: MAIN and TARGET. The MAIN spacecraft has full orbit control capability while TARGET is attitude controlled only. The Swedish Space Corporation is responsible for three groups of guidance, navigation, and control experiments. These experiments include GPS- and vision-based formation flying during which the spacecraft will fly in passive as well as forced motion. The three experiments are: autonomous formation flying, proximity operations with final approach/recede maneuvers, and autonomous rendezvous. This paper presents system test results from two of these experiments as obtained with the flight-ready system. The system tests consist of a series of simulations performed on the flight model spacecraft with a large amount of hardware in the loop.
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14.
  • Bruhn, Fredrik, et al. (författare)
  • A Preliminary Design for a Spherical Inflatable Microrover for Planetary Exploration
  • 2008
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 63:5-6, s. 618-631
  • Tidskriftsartikel (refereegranskat)abstract
    • The Spherical Mobile Investigator for Planetary Surface (SMIPS) concept aims at making use of the latest developments within extreme miniaturization of space systems. The introduction of Microelectromechanical Systems (MEMSs) and higher level Multifunctional Microsystems (MMSs) design solutions gives the robot high performance per weight unit. The untraditional spherical shape makes it easily maneuverable and thus provides a platform for scientific investigations of interplanetary bodies. Preliminary investigations of the SMIPS concept show several advantages over conventional robots and rovers in maneuverability, coverage, size, and mass. A locomotion proof-of-concept has been Studied together with a new distributed on-board data system configuration. This paper discusses theoretical robot analysis, an overall concept, possible science, enabling technologies, and how to perform scientific investigations. A preliminary design of an inflatable multifunctional shell is proposed.
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15.
  • Cai, Zun, et al. (författare)
  • Effect of combustor geometry and fuel injection scheme on the combustion process in a supersonic flow
  • 2016
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 129, s. 44-51
  • Tidskriftsartikel (refereegranskat)abstract
    • The combustion process in a hydrogen fueled scramjet combustor with a rearwall-expansion cavity was investigated numerically under inflow conditions of Ma=2.52 with stagnation pressure P0=1.6 Mpa and stagnation temperature T0=1486 K. The numerical solver was first evaluated for supersonic reactive flows in a similar combustor configuration where experimental data is available. Wall-pressure distribution was compared with the experiments, and grid independency analysis and chemical mechanism comparison were conducted. The numerical results showed fairly good agreements with the available experimental data under supersonic combustion conditions. Then the numerical solver was used to study the effects of combustor geometry, fuel injection scheme and injection equivalence ratio on the combustion process. It was found that under the same fuel injection condition, the combustor configuration with a rearwall-expansion cavity is in favor of the supersonic combustion mode and present better ability of thermal choking prevention than the other combustor configurations. For the rearwall-expansion cavity combustor, the supersonic flow field was found to be sensitive to the injector position and injection scheme, but not highly sensitive to the injection pressure. Besides, rearwall-expansion cavity with the combined fuel injection scheme (with an injection upstream the cavity and a direct injection on the rear wall) is an optimized injection scheme during the flame stabilization process.
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16.
  • Cai, Zun, et al. (författare)
  • Large Eddy Simulation of the fuel transport and mixing process in a scramjet combustor with rearwall-expansion cavity
  • 2016
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 126, s. 375-381
  • Tidskriftsartikel (refereegranskat)abstract
    • Large Eddy Simulation (LES) was employed to investigate the fuel/oxidizer mixing process in an ethylene fueled scramjet combustor with a rearwall-expansion cavity. The numerical solver was first validated for an experimental flow, the DLR strut-based scramjet combustor case. Shock wave structures and wall-pressure distribution from the numerical simulations were compared with experimental data and the numerical results were shown in good agreement with the available experimental data. Effects of the injection location on the flow and mixing process were then studied. It was found that with a long injection distance upstream the cavity, the fuel is transported much further into the main flow and a smaller subsonic zone is formed inside the cavity. Conversely, with a short injection distance, the fuel is entrained more into the cavity and a larger subsonic zone is formed inside the cavity, which is favorable for ignition in the cavity. For the rearwall-expansion cavity, it is suggested that the optimized ignition location with a long upstream injection distance should be in the bottom wall in the middle part of the cavity, while the optimized ignition location with a short upstream injection distance should be in the bottom wall in the front side of the cavity. By employing a cavity direct injection on the rear wall, the fuel mass fraction inside the cavity and the local turbulent intensity will both be increased due to this fueling, and it will also enhance the mixing process which will also lead to increased mixing efficiency. For the rearwall-expansion cavity, the combined injection scheme is expected to be an optimized injection scheme.
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17.
  • Cakir, Bora O., et al. (författare)
  • Reduced order design and investigation of intakes for high speed propulsion systems
  • 2022
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 199, s. 259-276
  • Tidskriftsartikel (refereegranskat)abstract
    • Ramjet propulsion is commonly preferred to power supersonic and hypersonic vehicles for cruising faster than Mach 3. This is an elegant solution owing to the lean architecture which does not embody any rotating parts. Although the geometry of the engine is simple as compared to turbine based configurations, the flow physics through the engine duct is quite complex and the flow speeds modulate between the supersonic and subsonic regimes multiple times. The design and performance analysis of ramjet engines are vital to ensure that propulsion system can satisfy the flight trajectory requirements. Therefore, this study introduces a reduced order holistic approach for design and assessment of the flow development in high-speed propulsion systems composed of generic elements of ramjet/scramjet engine configurations. Accordingly, the intakes designed based on axisymmetric flow templates are used to provide the necessary freestream flow modulation prior to the isolator through which a normal shock assumption is applied. The resultant flow properties are utilized for the combustion module where the flow expansion within the combustor and nozzle components are computed based on 1D steady inviscid flow equations coupled with detailed chemistry approach and JANAF tables. The module was validated and verified with the experimental and numerical data obtained for a dual-mode ramjet/scramjet combustor. Consequently, the parameters such as thrust, fuel consumption and specific impulse are calculated to quantify the engine performance for each design. Finally, the employment of the low fidelity model is demonstrated over a family of ramjet flow paths where the design space is confined based on the requirements of a high-supersonic cruise vehicle.
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18.
  • Conte, Davide, et al. (författare)
  • Advanced concept for a crewed mission to the martian moons
  • 2017
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 139, s. 545-563
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the conceptual design of the IMaGInE (Innovative Mars Global International Exploration) Mission. The mission's objectives are to deliver a crew of four astronauts to the surface of Deimos and perform a robotic exploration mission to Phobos. Over the course of the 343 day mission during the years 2031 and 2032, the crew will perform surface excursions, technology demonstrations, In Situ Resource Utilization (ISRU) of the Martian moons, as well as site reconnaissance for future human exploration of Mars. This mission design makes use of an innovative hybrid propulsion concept (chemical and electric) to deliver a relatively low-mass reusable crewed spacecraft (approximately 100 mt) to cis-martian space. The crew makes use of torpor which minimizes launch payload mass. Green technologies are proposed as a stepping stone towards minimum environmental impact space access. The usage of beamed energy to power a grid of decentralized science stations is introduced, allowing for large scale characterization of the Martian environment. The low-thrust outbound and inbound trajectories are computed through the use of a direct method and a multiple shooting algorithm that considers various thrust and coast sequences to arrive at the final body with zero relative velocity. It is shown that the entire mission is rooted within the current NASA technology roadmap, ongoing scientific investments and feasible with an extrapolated NASA Budget. The presented mission won the 2016 Revolutionary Aerospace Systems Concepts - Academic Linkage (RASC-AL) competition.
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19.
  • Delpech, M, et al. (författare)
  • Flight demonstration of formation flying capabilities for future missions (NEAT Pathfinder)
  • 2014
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 105:1, s. 82-94
  • Tidskriftsartikel (refereegranskat)abstract
    • PRISMA is a demonstration mission for formation-flying and on-orbit-servicing critical technologies that involves two spacecraft launched in low Earth orbit in June 2010 and still in operation. Funded by the Swedish National Space Board, PRISMA mission has been developed by OHB-Sweden (formerly Swedish Space Corporation) with important contributions from the German Aerospace Centre (DLR/GSOC), the French Space Agency (CNES), and the Technical University of Denmark (DTU). The paper focuses on the last CNES experiment achieved in September 2012 that was devoted to the preparation of future astrometry missions illustrated by the NEAT and mu-NEAT mission concepts. The experiment consisted of performing the type of formation maneuvers required to point the two-satellite axis to a celestial target and maintain it fixed during the observation period. Achieving inertial pointing for a LEO formation represented a new challenge given the numerous constraints from propellant usage to star tracker blinding. The paper presents the experiment objectives in relation with the NEAT/mu-NEAT mission concept, describes its main design features along with the guidance and control algorithms evolutions and discusses the results in terms of performances achieved during the two rehearsals.
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20.
  • Felicetti, Leonard, et al. (författare)
  • A multi-spacecraft formation approach to space debris surveillance
  • 2016
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 127, s. 491-504
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper proposes a new mission concept devoted to the identification and tracking of space debris through observations made by multiple spacecraft. Specifically, a formation of spacecraft has been designed taking into account the characteristics and requirements of the utilized optical sensors as well as the constraints imposed by sun illumination and visibility conditions. The debris observations are then shared among the team of spacecraft, and processed onboard of a “hosting leader” to estimate the debris motion by means of Kalman filtering techniques. The primary contribution of this paper resides on the application of a distributed coordination architecture, which provides an autonomous and robust ability to dynamically form spacecraft teams once the target has been detected, and to dynamically build a processing network for the orbit determination of space debris. The team performance, in terms of accuracy, readiness and number of the detected objects, is discussed through numerical simulations.
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21.
  • Felicetti, Leonard, et al. (författare)
  • Analytical and numerical investigations on spacecraft formation control by using electrostatic forces
  • 2016
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 123, s. 455-469
  • Tidskriftsartikel (refereegranskat)abstract
    • The paper investigates some analytical and numerical aspects of the formation control exploited by means of inter-spacecraft electrostatic actions. The analysis is based on the evaluation and check of the stability issues by using a sequence of purposely defined Lyapunov functions. The same Lyapunov approach can also define a specific under-actuate control strategy for controlling selected “virtual links” of the formation. Two different selection criteria for these links are then discussed, showing the implications on the control chain. An optimal charge distribution strategy, which assigns univocally the charges to all the spacecraft starting from the charge products computed by the control, is also presented and discussed. Numerical simulations prove the suitability of the proposed approach to a formation of 4 satellites.
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22.
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23.
  • Filgas, Robert, et al. (författare)
  • Miniature semiconductor neutron spectrometer HardPix for surface mapping of lunar water
  • 2022
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 200, s. 620-625
  • Tidskriftsartikel (refereegranskat)abstract
    • A current renaissance of lunar exploration enables to search for lunar water deposits directly on the surface of the Moon with robotic rovers. We present a novel miniature semiconductor neutron spectrometer capable of mapping the water deposits using non-invasive detection of neutrons created underground by cosmic rays and thermalized by hydrogen. This prospecting package consists of a radiation detector to monitor the cosmic rays background, a thermal/epithermal neutron detector to measure flux of neutrons moderated by water, and a gamma spectrometer suitable for monitoring local changes of major elemental components of the lunar regolith. Using miniature semiconductor detectors allows to deploy them even on small commercial rovers where resources are extremely limited. The prospecting package is being developed for ispace lunar rover and studied for ESA EL3 rover. It is based on Timepix pixel sensors, with space heritage onboard NASA, ESA and JAXA vessels.
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24.
  • Fuglesang, Christer, 1957-, et al. (författare)
  • Realistic sunshade system at L-1 for global temperature control
  • 2021
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 186, s. 269-279
  • Tidskriftsartikel (refereegranskat)abstract
    • So far, space-based geoengineering has rarely been studied from a practical point of view, considered unrealistic as a near-future alternative to fight climate change. This paper evaluates the feasibility of implementing a space sunshade in the vicinity of the first Lagrange point of the Sun-Earth system by the middle of the century. The analysis considers the necessary technological development, the possible trajectories for the shades, and an approximation of the size and cost of the system. It is strongly dependent on the possible optical properties of future solar sails, so an optimal and a more conservative alternative have been studied. With the latter, the shade will be formed by 1.5 x 10(9) sailcraft with a sail area of 2500 m(2) and a total mass of 8.3 x 10(10) kg. In the optimal case, the total mass is 3.4 x 10(10) kg. Each one of these sails will be launched to a 2000 km orbit, from where they will travel for about 600 days to the equilibrium point using solar radiation pressure. The total cost of the mission is estimated to be five to ten trillion dollars, based on a launch cost of US$50/kg. There are two main technological challenges for this to become a reality: the low TRL of the solar sails proposed and the necessary development in the launch vehicle industry given the dimensions of the mission.
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25.
  • Gassot, Oriane, et al. (författare)
  • Calathus : A sample-return mission to Ceres
  • 2021
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 181, s. 112-129
  • Tidskriftsartikel (refereegranskat)abstract
    • Ceres, as revealed by NASA's Dawn spacecraft, is an ancient, crater-saturated body dominated by low-albedo clays. Yet, localised sites display a bright, carbonate mineralogy that may be as young as 2 Myr. The largest of these bright regions (faculae) are found in the 92 km Occator Crater, and would have formed by the eruption of alkaline brines from a subsurface reservoir of fluids. The internal structure and surface chemistry suggest that Ceres is an extant host for a number of the known prerequisites for terrestrial biota, and as such, represents an accessible insight into a potentially habitable "ocean world". In this paper, the case and the means for a return mission to Ceres are outlined, presenting the Calathus mission to return to Earth a sample of the Occator Crater faculae for high-precision laboratory analyses. Calathus consists of an orbiter and a lander with an ascent module: the orbiter is equipped with a high-resolution camera, a thermal imager, and a radar; the lander contains a sampling arm, a camera, and an on-board gas chromatograph mass spectrometer; and the ascent module contains vessels for four cerean samples, collectively amounting to a maximum 40 g. Upon return to Earth, the samples would be characterised via high-precision analyses to understand the salt and organic composition of the Occator faculae, and from there to assess both the habitability and the evolution of a relict ocean world from the dawn of the Solar System.
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26.
  • Gurvits,, et al. (författare)
  • The science case and challenges of space-borne sub-millimeter interferometry
  • 2022
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 196, s. 314-333
  • Tidskriftsartikel (refereegranskat)abstract
    • Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results in direct imaging of the vicinity of the supermassive black hole in the nucleus of the radio galaxy M87 by the millimeter VLBI system Event Horizon Telescope and various pioneering results of the Space VLBI mission RadioAstron provided new momentum in high angular resolution astrophysics. In both mentioned cases, the angular resolution reached the values of about 10???20 microarcseconds (0.05???0.1 nanoradian). Further developments towards at least an order of magnitude ???sharper???values, at the level of 1 microarcsecond are dictated by the needs of advanced astrophysical studies. The paper emphasis that these higher values can only be achieved by placing millimeter and submillimeter wavelength interferometric systems in space. A concept of such the system, called Terahertz Exploration and Zooming-in for Astrophysics, has been proposed in the framework of the ESA Call for White Papers for the Voyage 2050 long term plan in 2019. In the current paper we present new science objectives for such the concept based on recent results in studies of active galactic nuclei and supermassive black holes. We also discuss several approaches for addressing technological challenges of creating a millimeter/sub-millimeter wavelength interferometric system in space. In particular, we consider a novel configuration of a space-borne millimeter/sub-millimeter antenna which might resolve several bottlenecks in creating large precise mechanical structures. The paper also presents an overview of prospective space-qualified technologies of low-noise analogue front-end instrumentation for millimeter/sub-millimeter telescopes. Data handling and processing instrumentation is another key technological component of a sub-millimeter Space VLBI system. Requirements and possible implementation options for this instrumentation are described as an extrapolation of the current state-of-the-art Earth-based VLBI data transport and processing instrumentation. The paper also briefly discusses approaches to the interferometric baseline state vector determination and synchronisation and heterodyning system. The technology-oriented sections of the paper do not aim at presenting a complete set of technological solutions for sub-millimeter (terahertz) space-borne interferometers. Rather, in combination with the original ESA Voyage 2050 White Paper, it sharpens the case for the next generation microarcsecond-level imaging instruments and provides starting points for further in-depth technology trade-off studies.
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27.
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28.
  • Hakima, Houman, et al. (författare)
  • Assessment of active methods for removal of LEO debris
  • 2018
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 144, s. 225-243
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper investigates the applicability of five active methods for removal of large low Earth orbit debris. The removal methods, namely net, laser, electrodynamic tether, ion beam shepherd, and robotic arm, are selected based on a set of high-level space mission constraints. Mission level criteria are then utilized to assess the performance of each redirection method in light of the results obtained from a Monte Carlo simulation. The simulation provides an insight into the removal time, performance robustness, and propellant mass criteria for the targeted debris range. The remaining attributes are quantified based on the models provided in the literature, which take into account several important parameters pertaining to each removal method. The means of assigning attributes to each assessment criterion is discussed in detail. A systematic comparison is performed using two different assessment schemes: Analytical Hierarchy Process and utility-based approach. A third assessment technique, namely the potential-loss analysis, is utilized to highlight the effect of risks in each removal methods
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29.
  • Heldens, Jules C., et al. (författare)
  • On the characterization of methane in rocket nozzle cooling channels
  • 2021
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 186, s. 337-346
  • Tidskriftsartikel (refereegranskat)abstract
    • In recent years there has been a growing interest in methane as an alternative rocket fuel due to its favourable specific gravity, storage temperature and thermal stability, in addition to its ability to support In-Situ Resource Utilization. Due to these properties methane supports the ongoing design trend of strategic reduction in system complexity and increase of reusability. The current work presents a first step in addressing the lack of information in open literature on the characteristics of methane under conditions found in rocket nozzle cooling channels, i.e. elevated inflow temperature and a high single sided heat load. A new experimental facility has been established at KTH Royal Institute of Technology in cooperation with GKN Aerospace, and as part of ESA's Future Launcher Preparatory Programme. This facility is shown to enable direct measurement of the Heat Transfer Coefficient (HTC) of methane under a range of conditions, with a limited uncertainty and good repeatability. For inflow temperatures of around 400 K, mass flows up to 15 g/s and pressures up to 3 MPa, it has been observed that the effect of single sided heating results in a significant development of the flow field, which influences the heat transfer in second half of the test section. This development results in an increase of the HTC towards the end of the cooling channel. No significant effect of the pressure on the HTC has been observed under the current experimental conditions.
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30.
  • Holmlid, Leif, 1942, et al. (författare)
  • Future interstellar rockets may use laser-induced annihilation reactions for relativistic drive
  • 2020
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 175, s. 32-6
  • Tidskriftsartikel (refereegranskat)abstract
    • Interstellar probes and future interstellar travel will require relativistic rockets. The problem is that such a rocket drive requires that the rocket exhaust velocity from the fuel also is relativistic, since otherwise the rocket thrust is much too small: the total mass of the fuel will be so large that relativistic speeds cannot be reached in a rea- sonable time and the total mass of the rocket will be extremely large. Until now, no technology was known that would be able to give rocket exhaust at relativistic speed and a high enough momentum for relativistic travel. Here, a useful method for relativistic interstellar propulsion is described for the first time. This method gives ex- haust at relativistic speeds and is a factor of at least one hundred better than normal fusion due to its increased energy output from the annihilation-like meson formation processes. It uses ordinary hydrogen as fuel so a re- turn travel is possible after refuelling almost anywhere in space. The central nuclear processes have been studied in around 20 publications, which is considered to be sufficient evidence for the general properties. The nuclear processes give relativistic particles (kaons, pions and muons) by laser-induced annihilation-like processes in ul- tra-dense hydrogen H(0). The kinetic energy of the mesons is 1300 times larger than the energy of the laser pulse. This method is superior to the laser-sail method by several orders of magnitude and is suitable for large space- ships.
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31.
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32.
  • Ispir, Ali Can, et al. (författare)
  • Design space investigations of scramjet engines using reduced-order modeling
  • 2024
  • Ingår i: Acta Astronautica. - 0094-5765. ; 217, s. 349-362
  • Tidskriftsartikel (refereegranskat)abstract
    • Conceptual design studies performed with reduced-order approaches allow feasibility and sizing considerations of air-breathing engines to be configured at an affordable computational cost. The present study is devoted to exploring the design space of a dual-mode ramjet engine operating in scramjet mode by means of reduced-order analysis to assess the effects of propulsive system design configurations on component level and overall performance characteristics. The approach proposed in this work combines axisymmetric flow configuration used for the design of supersonic/hypersonic intakes and solutions of one-dimensional flow governing equations coupled with finite-rate chemistry and thermophysical properties tables in the numerical domains of the combustor and nozzle components. The scramjet design space is generated by varying parameters which are flight Mach number and altitude, intake truncation angle, intake exit Mach number and equivalence ratio. Performance outputs of total pressure recovery factor, compression ratio, captured air mass flow rate, intake startability index, thrust, specific impulse, fuel consumption and overall efficiency are computed for each design scenario. The generated database is visualized via performance maps and analyzed in terms of propulsive characteristics. A feature importance study is also conducted to quantify the effects of design parameters on the propulsive performance.
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33.
  • Israel Nazarious, Miracle, et al. (författare)
  • Calibration and preliminary tests of the Brine Observation Transition To Liquid Experiment on HABIT/ExoMars 2020 for demonstration of liquid water stability on Mars
  • 2019
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 162, s. 497-510
  • Tidskriftsartikel (refereegranskat)abstract
    • The search for unequivocal proofs of liquid water on present day Mars is a prominent domain of research with implications on habitability and future Mars exploration. The HABIT (Habitability: Brines, Irradiation, and Temperature) instrument that will be on-board the ExoMars 2020 Surface Platform (ESA-IKI Roscosmos) will investigate the habitability of present day Mars, monitoring temperature, winds, dust conductivity, ultraviolet radiation and liquid water formation. One of the components of HABIT is the experiment BOTTLE (Brine Observation Transition To Liquid Experiment). The purposes of BOTTLE are to: (1) quantify the formation of transient liquid brines; (2) observe their stability over time under non-equilibrium conditions; and (3) serve as an In-Situ Resource Utilization (ISRU) technology demonstrator for water moisture capture. In this manuscript, we describe the calibration procedure of BOTTLE with standard concentrations of brines, the calibration function and the coefficients needed to interpret the observations on Mars.BOTTLE consists of six containers: four of them are filled with different deliquescent salts that have been found on Mars (calcium-perchlorate, magnesium-perchlorate, calcium-chloride, and sodium-perchlorate); and two containers that are open to the air, to collect atmospheric dust. The salts are exposed to the Martian environment through a high efficiency particulate air (HEPA) filter (to comply with planetary protection protocols). The deliquescence process will be monitored by observing the changes in electrical conductivity (EC) in each container: dehydrated salts show low EC, hydrated salts show medium EC and, liquid brines show high EC values. We report and interpret the preliminary test results using the BOTTLE engineering model in representative conditions; and we discuss how this concept can be adapted to other exploration missions.Our laboratory observations show that 1.2 g of anhydrous calcium-chloride captures about 3.7 g of liquid water as brine passing through various possible hydrate forms. This ISRU technology could potentially be the first attempt to understand the formation of transient liquid water on Mars and to develop self-sustaining in-situ water harvesting on Mars for future human and robotic missions.
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34.
  • Jonsson, Jonas, et al. (författare)
  • Instrumentation and vehicle platform of a miniaturized submersible for exploration of terrestrial and extraterrestrial aqueous environments
  • 2012
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 79, s. 203-211
  • Tidskriftsartikel (refereegranskat)abstract
    • An example of an extraterrestrial environment likely to support life is the vast liquid body believed to hide underneath the frozen crust of Jupiter's moon Europa. The hypothetical exploration of this, as well as the more accessible subglacial lakes on Earth, has been used as model applications for the development of a heavily miniaturized, yet qualified, submersible with the potential to be deployable either in itself through a long and narrow borehole or as the daughter craft of an ice-penetrating cryobot.Onboard the submersible, which is only 20 cm in length and 5 cm in diameter, accommodation of a versatile set of sensors and instruments capable of characterizing and imaging the surroundings, and even collecting water samples with microorganisms for return, is facilitated through the use of miniaturization technologies. For instance, together with a small camera, a laser-based, microoptic device enables the 3-D reconstruction of imaged objects for topographical measurements. As a complement, when the water is turbid or a longer range is wanted, the world's smallest side-scanning sonar, exhibiting centimeter resolution and a range of over 30 m, has been developed. The work on miniaturizing a CTD, which is a widely employed oceanographic instrument used to measure and correlate conductivity, temperature, and depth, has commenced. Furthermore, a device employing acoustics to trap microscopic particles and organisms, and, by this, enrich water samples, is under development. To ensure that the gathered samples are pristine until analyzed at the end of a mission, the device is equipped with high-pressure, latchable valves.Remote operation and transfer of measurement data and images, or even live streaming of video, is made possible through a kilometer-long fiber optic cable being reeled out from the vehicle underway and tethering it to a terminal. To extend the missions, the same fiber shall also be capable of charging the onboard batteries.In this paper, the vehicle and its subsystems are summarized. Subsystems essential for the vehicle's operation, e.g., hull structure, communication and power management, are treated separately from those of more mission-specific nature, like the instruments mentioned above.
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35.
  • Kastinen, Daniel, et al. (författare)
  • Using radar beam-parks to characterize the Kosmos-1408 fragmentation event
  • 2023
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 202, s. 341-359
  • Tidskriftsartikel (refereegranskat)abstract
    • We describe the use of radar beam-park experiments to characterize the space debris resulting from a recent fragmentation event, the deliberate demolition of the defunct Kosmos-1408 satellite. We identify the Kosmos-1408 fragments and present distribution of measurement parameters as well as proxy orbit parameters. We present and apply a novel technique to estimate the size of objects by matching the signal to noise ratio of the detection to the radiation pattern of the radar. With this method we estimate the size distribution of the debris cloud. We also demonstrate how a pair of beam-park observations can be used to perform a crude, yet seemingly reliable, initial orbit determination. Finally, we present followup observations ∼5 months after the fragmentation that show a still compact cloud of debris.
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36.
  • Kozynchenko, Alexander (författare)
  • Analysis of predictive entry guidance for a Mars lander under high model uncertainties
  • 2011
  • Ingår i: Acta Astronautica. - : Elsevier Ltd.. - 0094-5765. ; 68
  • Tidskriftsartikel (refereegranskat)abstract
    • The problem of precision landing on Mars is now considered to be an essential challenge in the planned Mars missions. The paper focused on the guided atmospheric entry as a predominant phase in achieving a desired target state, as compared with the following parachute and powered descent. The predictive algorithms for the longitudinal guidance of a low-lift entry vehicle are treated. The purpose is to investigate applicability of the predictive strategy under possible high discrepancies between the on-board dynamic model and real environment while in entry trajectory. The comparative performance analysis based on computer simulation has been made between the standard one-parametric “shooting” predictive algorithm and a more complex two-parametric algorithm providing lower final velocity and, thus, expanding the interval of admissible downrange. However, both algorithms display considerable degradation of downrange accuracy in the cases when the actual drag force is larger than the modelled one. An acceptable solution has been found by including to both predictive guidance schemes an identification algorithm that repeatedly adapts the on-board model to varied environment in real time scale.
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37.
  • Kozynchenko, Alexander I (författare)
  • Predictive guidance algorithms for maximal downrange maneuvrability with application to low-lift re-entry
  • 2009
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 64:7-8, s. 770-777
  • Tidskriftsartikel (refereegranskat)abstract
    • The paper concerns the general problem of a bounded final state control of non-linear dynamic systems with reference to near-optimal predictive guidance for low lift-to-drag ratio re-entry vehicles. More specifically, it addresses deriving guidance strategies capable to provide a maximal downrange maneuvrability for a maximal remaining flight time. Such robust, “guaranteed”, or assured, guidance keeps the remaining range-to-go to be coincident with the center of instant attainability domain. The paper discusses the existing guaranteed guidance strategy, and presents more general approach that provides an on-board planning of the entry trajectory, thus giving future state and control profiles. As a consequence the proposed guidance law is able to satisfy not only specified terminal conditions but also typical inequality constraints such as the maximal load factor and heat load. Computer simulations show that the algorithm can generate the feasible trajectories with equal downrange margins, using simple two-parametric families of control functions.
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38.
  • Lehner, B.A.E., et al. (författare)
  • End-to-end mission design for microbial ISRU activities as preparation for a moon village
  • 2019
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 162, s. 216-226
  • Tidskriftsartikel (refereegranskat)abstract
    • In situ resource utilization (ISRU) increasingly features as an element of human long-term exploration and settlement missions to the lunar surface. In this study, all requirements to test a novel, biological approach for ISRU are validated, and an end-to-end mission architecture is proposed. The general mission consists of a lander with a fully autonomous bioreactor able to process lunar regolith and extract elemental iron. The elemental iron could either be stored or directly utilized to generate iron wires or construction material. To maximize the success rate of this mission, potential landing sites for future missions are studied, and technical details (thermal radiation, shielding, power-supply) are analyzed. The final section will assess the potential mission architecture (orbit, rocket, lander, timeframe). This design might not only be one step further towards an international “Moon Village”, but may also enable similar missions to ultimately colonize Mars and further explore our solar system.
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39.
  • Lehnert, Christopher, et al. (författare)
  • Global risk and global challenges – Space as a game changer for socioeconomic sustainable development
  • 2017
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 140, s. 59-65
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2017 IAA The world's societies at the beginning of the 21st century are better off than ever before. (Gapminder, 2015) At the same time, the world is also threatened by global challenges where space as a tool has and can play a pivotal role in meeting those challenges. The challenges range from climate change, over mass unemployment, to terrorism or migration – to name but a few. Space activities have started to respond to this changing world, not only by providing a deeper understanding of our universe, but by using space as an additional sphere and sector, through which humankind can increase and secure its wealth – it is thus game changing in the way we sustain humanity's existence. This paper is meant to capture this development. In the first part, an overview is given on the risks that humankind is facing. The second part describes the way that space can be used as a tool to prevent and manage these risks. The overview in the first part is based on the examination of the most recent reports and overall strategies of key International Governmental Organisations and Non-Governmental Organisations that are involved in agenda-setting, policy formulation and implementation. The second part includes an overview on current activities of the European Space Agency (ESA) that play a role in responding to these risks. To better understand ESA's activities that contain humanity's risks, a standard classification for risks management is used, which distinguishes between four components: Identification, Assessment, Management and Communication (Renn, 2005). The analysis reveals how space activities already today play a pivotal role in all four types of risk management. Space activities contribute very tangible to the management of risks through its space mission, but also in a more indirect way, as providing the technical backbone for stable and reliable cooperation in the international governance arena, and serve as crucial economic stimulator. The overall results show that space activities touch upon every aspect of responding to the humanity's risks. Especially in the identification and the preventive management of humanity's risks, space systems are a crucial enabler. They are also an important part in dealing with risks related to scarcity of resources. It is thus important that current levels of investments into space infrastructure are maintained, as the benefits of space activities is essential to humankind's existence and that upon further programmatic decisions, stakeholders involved with the management of risks are being consulted.
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40.
  • Lehtinen, Tuomas, et al. (författare)
  • Icarus : In-situ monitoring of the surface degradation on a near-Sun asteroid
  • 2021
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 186, s. 98-108
  • Tidskriftsartikel (refereegranskat)abstract
    • Icarus is a mission concept designed to record the activity of an asteroid during a close encounter with the Sun. The primary science goal of the mission is to unravel the nontrivial mechanism(s) that destroy asteroids on orbits with small perihelion distances. Understanding the destruction mechanism(s) allows us to constrain the bulk composition and interior structure of asteroids in general. The Icarus mission does not only aim to achieve its science goals but also functions as a technical demonstration of what a low-cost space mission can do. The proposed space segment will include a single spacecraft capable of surviving and operating in the harsh environment near the Sun. The spacecraft design relies on the heritage of missions such as Rosetta, MESSENGER, Parker Solar Probe, BepiColombo, and Solar Orbiter. The spacecraft will rendezvous with an asteroid during its perihelion passage and records the changes taking place on the asteroid’s surface. The primary scientific payload has to be capable of imaging the asteroid’s surface in high resolution using visual and near-infrared channels as well as collecting and analyzing particles that are ejected from the asteroid. The payload bay also allows for additional payloads relating to, for example, solar research. The Icarus spacecraft and the planned payloads have high technology readiness levels and the mission is aimed to fit the programmatic and cost constraints of the F1 mission (Comet Interceptor) by the European Space Agency. Considering the challenging nature of the Icarus trajectory and the fact that the next F-class mission opportunity (F2) is yet to be announced, we conclude that Icarus is feasible as an F-class mission when certain constraints such as a suitable launch configuration are met. A larger mission class, such as the M class by the European Space Agency, would be feasible in all circumstances.
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41.
  • Liberman, M. A., et al. (författare)
  • Deflagration-to-detonation transition in highly reactive combustible mixtures
  • 2010
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 67:7-8, s. 688-701
  • Tidskriftsartikel (refereegranskat)abstract
    • The paper presents experimental, theoretical, and numerical studies of deflagration-to-detonation transition (DDT) in highly reactive hydrogen-oxygen and ethylene-oxygen mixtures. Two-dimensional reactive Navier-Stokes equations for a hydrogen-oxygen gaseous mixture including the effects of viscosity, thermal conduction, molecular diffusion, and a detailed chemical reaction mechanism are solved numerically. It is found that mechanism of DDT is entirely determined by the features of the flame acceleration in tubes with no-slip walls. The experiments and computations show three distinct stages of the process: (1) the flame accelerates exponentially producing shock waves far ahead from the flame, (2) the flame acceleration decreases and shocks are formed directly on the flame surface, and (3) the final third stage of the actual transition to a detonation. During the second stage a compressed and heated pocket of unreacted gas adjacent ahead to the flame the preheat zone is forming and the compressed unreacted mixture entering the flame produces large amplitude pressure pulse. The increase of pressure enhances reaction rate and due to a positive feedback between the pressure peak and the reaction the pressure peak grows exponentially, steepens into a strong shock that is coupled with the reaction zone forming the overdriven detonation wave. The proposed new physical mechanism of DDT highlights the features of flame acceleration in tubes with no-slip walls, which is the key factor of the DDT origin.
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42.
  • Liberman, Michael A., et al. (författare)
  • Radiation heat transfer in particle-laden gaseous flame : Flame acceleration and triggering detonation
  • 2015
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 115, s. 82-93
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study we examine influence of the radiation heat transfer on the combustion regimes in the mixture, formed by suspension of fine inert particles in hydrogen gas. The gaseous phase is assumed to be transparent for the thermal radiation, while the radiant heat absorbed by the particles is then lost by conduction to the surrounding gas. The particles and gas ahead of the flame is assumed to be heated by radiation from the original flame. It is shown that the maximum temperature increase due to the radiation preheating becomes larger for a flame with lower velocity. For a flame with small enough velocity temperature of the radiation preheating may exceed the crossover temperature, so that the radiation heat transfer may become a dominant mechanism of the flame propagation. In the case of non-uniform distribution of particles, the temperature gradient formed due to the radiation preheating can initiate either deflagration or detonation ahead of the original flame via the Zel'dovich's gradient mechanism. The initiated combustion regime ignited in the preheat zone ahead of the flame depends on the radiation absorption length and on the steepness of the formed temperature gradient. Scenario of the detonation triggering via the temperature gradient mechanism formed due to the radiation preheating is plausible explanation of the transition to detonation in Supernovae Type la explosion. (C) 2015 IAA. Published by Elsevier Ltd. All rights reserved.
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43.
  • Liu, Xiao, et al. (författare)
  • Investigation of transient ignition process in a cavity based scramjet combustor using combined ethylene injectors
  • 2017
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 137, s. 1-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Large Eddy Simulation (LES) and experiment were employed to investigate the transient ignition and flame propagation process in a rearwall-expansion cavity scramjet combustor using combined fuel injection schemes. The compressible supersonic solver and three ethylene combustion mechanisms were first validated against experimental data and results show in reasonably good agreement. Fuel injection scheme combining transverse and direct injectors in the cavity provides a benefit mixture distribution and could achieve a successful ignition. Four stages are illustrated in detail from both experiment and LES. After forced ignition in the cavity, initial flame kernel propagates upstream towards the cavity front edge and ignites the mixture, which acts as a continuous pilot flame, and then propagates downstream along the cavity shear layer rapidly to the combustor exit. Cavity shear layer flame stabilization mode can be concluded from the heat release rate and local high temperature distribution during the combustion process.
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44.
  • Mao, Huina, et al. (författare)
  • Post-launch analysis of the deployment dynamics of a space web sounding rocket experiment
  • 2016
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 127, s. 345-358
  • Tidskriftsartikel (refereegranskat)abstract
    • Lightweight deployable space webs have been proposed as platforms or frames for a construction of structures in space where centrifugal forces enable deployment and stabilization. The Suaineadh project was aimed to deploy a 2 x 2 m2 space web by centrifugal forces in milli-gravity conditions and act as a test bed for the space web technology. Data from former sounding rocket experiments, ground tests and simulations were used to design the structure, the folding pattern and control parameters. A developed control law and a reaction wheel were used to control the deployment. After ejection from the rocket, the web was deployed but entanglements occurred since the web did not start to deploy at the specified angular velocity. The deployment dynamics was reconstructed from the information recorded in inertial measurement units and cameras. The nonlinear torque of the motor used to drive the reaction wheel was calculated from the results. Simulations show that if the Suaineadh started to deploy at the specified angular velocity, the web would most likely have been deployed and stabilized in space by the motor, reaction wheel and controller used in the experiment.
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45.
  • Matelli, José Alexandre, et al. (författare)
  • Resilience evaluation of the environmental control and life support system of a spacecraft for deep space travel
  • 2018
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 152, s. 360-369
  • Tidskriftsartikel (refereegranskat)abstract
    • In deep space manned travels, the crew life will be totally dependent on the environment control and life support system of the spacecraft. A life-support system for manned missions is a set of technologies to regenerate the basic life-support elements, such as oxygen and water, which makes resilience a paramount feature of this system. The resilience of a complex engineered system is the ability of the system to withstand failures, continue operating and recover from those failures with minimum disruption. Resilient design is a new design framework on which the main goal is to quantify system resilience upfront in order to guide the design team during the conceptual design stage. In this article, we present a tool that combines a rule-based approach with a Monte Carlo-based approach to evaluate the resilience of a proposed environment control and life support system designed for deep space travel. Based on the results found, we explore a few design alternatives in order to increase system resilience.
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46.
  • Mathanlal, Thasshwin, et al. (författare)
  • Implementing bioburden reduction and control on the deliquescent hydrogel of the HABIT/ExoMars 2020 instrument
  • 2020
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 173, s. 232-239
  • Tidskriftsartikel (refereegranskat)abstract
    • The HabitAbility: Brines, Irradiation and Temperature (HABIT) instrument will be part of the ExoMars 2020 mission (ESA/Roscosmos) and will be the first European In-situ Resource Utilization (ISRU) instrument capable of producing liquid water on Mars. HABIT is composed by two modules: Environmental Package (EnvPack) and Brine Observation Transition To Liquid Experiment (BOTTLE). EnvPack will help to study the current habitability conditions on Mars investigating the air and surface thermal ranges and Ultraviolet (UV) irradiance; and BOTTLE is a container with four independent vessels housing deliquescent salts, which are known to be present on Mars, where the liquid water will be produced after deliquescence. In order to prevent capillarity of deliquescent or hydrated salts, a mixture of deliquescent salts with Super Absorbent Polymer (SAP) based on polyacrylamide is utilized. This mixture has deliquescent and hydrogel properties and can be reused by applying a thermal cycle, complying thus with the purpose of the instrument. A High Efficiency Particulate Air (HEPA) grade filter made of polytetrafluroethylene (PTFE) porous membrane sandwiched between spunbounded non-woven fabric stands as a physical barrier allowing interaction between the gaseous molecules of the Martian atmosphere and the salt mixtures, and at the same time preventing the passage of any potential biological contamination from the cells to the outside or vice-versa. In addition to the physical barrier, a strict bioburden reduction and analysis procedure is applied to the hardware and the contained salt mixtures adhering to the European Cooperation for Space Standardization protocol of microbial examination of flight hardware (ECSS-Q-ST-70-55C). The deliquescent salts and the SAP products need to be properly treated independently to adhere to the planetary protection protocols. In this manuscript, we describe the bioburden reduction process utilized to sterilize the salt mixtures in BOTTLE and the assays adopted to validate the sterilization. We also describe the construction of a low-cost, portable ISO 7 cleanroom tent, exclusively designed for planetary protection tests. The sterilization process involves Dry Heat Microbial Reduction (DHMR) of the deliquescent salts and the SAP mixtures. The performance of SAP after DHMR is validated to ensure its working efficiency after sterilization. A slightly modified version of the standard swab assay is used in the validation process and a comparison is made between samples exposed to a thermal shock treatment and those without thermal shock, to determine the best assay to be applied for future space hardware utilizing such salt mixtures for planetary investigation and In-Situ Resource Utilization (ISRU). The demonstration of the compatibility of these products with the processes commonly required for space applications has implications for the future exploration of Mars.
  •  
47.
  • Mayorova, V. I., et al. (författare)
  • Importance of joint efforts for balanced process of designing and education
  • 2015
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 111, s. 249-256
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper discusses importance of a strategic planning and design process when developing long-term space exploration missions both robotic and manned. The discussion begins with reviewing current and/or traditional international perspectives on space development at the American, Russian and European space agencies. Some analogies and comparisons will be drawn upon analysis of several international student collaborative programs: Summer International workshops at the Bauman Moscow State Technical University, International European Summer Space School "Future Space Technologies and Experiments in Space", Summer school at Stuttgart University in Germany. The paper will focus on discussion about optimization of design and planning processes for successful space exploration missions and will highlight importance of the following: understanding connectivity between different levels of human being and machinery; simultaneous mission planning approach; reflections and correlations between disciplines involved in planning and executing space exploration missions; knowledge gained from different disciplines and through cross-applying and re-applying design approaches between variable space related fields of study and research. The conclusions will summarize benefits and complications of applying balanced design approach at all levels of the design process. Analysis of successes and failures of organizational efforts in space endeavors is used as a methodological approach to identify key questions to be researched as they often cause many planning and design processing problems. (C) 2015 IAA. Published by Elsevier Ltd. All rights reserved.
  •  
48.
  • Mège, Daniel, et al. (författare)
  • The Highland Terrain Hopper (HOPTER) : Concept and use cases of a new locomotion system for the exploration of low gravity Solar System bodies
  • 2016
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 121, s. 200-220
  • Tidskriftsartikel (refereegranskat)abstract
    • Comprehensive understanding of the principles governing the geological activity of the Earth was obtained in continental and oceanic mountains. It is not expected that the principles governing the overall geologic activity and evolution of other planetary bodies such as Mars will be understood if exploration is limited to nearly flat terrains, either imposed by the used exploration platform capabilities, the risk of getting stuck, or by the time required to cross the border of a landing ellipse. Surface exploration of mountains is additionally to be coupled to two- or three-dimensional geophysical surveys to correlate the surface observations with deeper processes. On the small bodies where ultra-low gravity prevails, the weight of wheel-driven platforms is not sufficient to generate the friction at the contact with the ground that is required to trigger motion of the rover relative to the ground. Under such circumstances, hopping is one of the mobility solutions. We present a new locomotion system, the hopter platform, which is adapted to these challenges on Solar System bodies having a gravity field lower than on Earth. The hopter is a robust, versatile and highly manoeuvrable platform based on simple mechanical concepts that accurately jumps to distances of metres to tens of metres and more, depending on the gravity field of the studied body. Its low mass of 10 kg (including up to 3 kg of miniaturised payload), makes it possible to simultaneously launch several hopters to work as a fractionated explorer at a very competitive cost. After reviewing the payload that may be placed onboard hopters, we illustrate the scientific capabilities of hopters and hopter networks in performing basic geologic observations at distinct study sites in a variety of geological environments, obtaining data along steep geological cross sections, surveying geophysical anomalies in the subsurface, prospecting resources, monitoring micro environments, meteorological events, and geodetic deformation, or characterizing dust activity on Mars, the Moon, and Phobos.
  •  
49.
  • Mege, Daniel, et al. (författare)
  • The Highland Terrain Hopper (HOPTER): Concept and usecases of a new locomotion system for the exploration of lowgravity Solar System bodies
  • 2016
  • Ingår i: Acta Astronautica. - 0094-5765 .- 1879-2030. ; 121, s. 200-220
  • Tidskriftsartikel (refereegranskat)abstract
    • Comprehensive understanding of the principles governing the geological activity of theEarth was obtained in continental and oceanic mountains. It is not expected that theprinciples governing the overall geologic activity and evolution of other planetary bodiessuch as Mars will be understood if exploration is limited to nearlyflat terrains, eitherimposed by the used exploration platform capabilities, the risk of getting stuck, or by thetime required to cross the border of a landing ellipse. Surface exploration of mountains isadditionally to be coupled to two- or three-dimensional geophysical surveys to correlatethe surface observations with deeper processes. On the small bodies where ultra-lowgravity prevails, the weight of wheel-driven platforms is not sufficient to generate thefriction at the contact with the ground that is required to trigger motion of the roverrelative to the ground. Under such circumstances, hopping is one of the mobility solutions.We present a new locomotion system, the hopter platform, which is adapted to thesechallenges on Solar System bodies having a gravityfield lower than on Earth. The hopter isa robust, versatile and highly manoeuvrable platform based on simple mechanical con-cepts that accurately jumps to distances of metres to tens of metres and more, dependingon the gravityfield of the studied body. Its low mass of 10 kg (including up to 3 kg ofminiaturised payload), makes it possible to simultaneously launch several hopters to workas a fractionated explorer at a very competitive cost. After reviewing the payload that maybe placed onboard hopters, we illustrate the scientific capabilities of hopters and hopternetworks in performing basic geologic observations at distinct study sites in a variety ofgeological environments, obtaining data along steep geological cross sections, surveyinggeophysical anomalies in the subsurface, prospecting resources, monitoring micro-environments, meteorological events, and geodetic deformation, or characterizing dustactivity on Mars, the Moon, and Phobos.
  •  
50.
  • Muralidharan, Vijay, et al. (författare)
  • Concurrent rendezvous control of underactuated spacecraft
  • 2017
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 138, s. 28-42
  • Tidskriftsartikel (refereegranskat)abstract
    • The concurrent control of spacecraft equipped with one-axis unilateral thruster and three-axis attitude actuator is considered in this paper. The proposed control law utilizes attitude control channels along with the single thrust force concurrently, for three-dimensional trajectory tracking and rendezvous with a target object. The concurrent controller also achieves orbital transfer to low Earth orbits with long range separation. To demonstrate the orbit transfer capabilities of the concurrent controller, a smooth elliptical orbit transfer trajectory for co-planar circular orbits is designed. The velocity change and energy consumption of the designed orbit transfer trajectory is observed to be equivalent to that of Hohmann transfer.
  •  
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