 Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
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- Augmented Illumination of Resident Space Objects in Selected
Lagrange-Point Orbits via Space-Based Mirrors Conducting Proximity
Operations-
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Abstract: The means to repair/refuel spacecraft and de-orbit objects to reduce orbital debris directly supports the increasingly important mission areas of Space Situational Awareness (SSA) and Space Traffic Management. However, natural lighting conditions are not always advantageous for missions to image/inspect or repair/refuel spacecraft due to eclipse conditions or shadowing due to spacecraft geometry relative to incident solar illumination. The primary objective of this paper is to investigate the use of space-based reflectors to illuminate resident space objects in cislunar space. A concept of proximity operations, visual magnitude model, and associated algorithm for the prediction of augmented illumination of objects near the Earth–Moon $$L_1$$, $$L_2$$, and $$L_4$$ Lagrange points is presented. The research advances the ongoing development of cislunar SSA missions and could enable unique lighting opportunities to improve characterization of both natural and artificial objects in the Earth–Moon system. Preliminary analysis indicates that in-track motion yields the highest potential for illumination, while cross-track motion provides only minimal illumination potential. Of the scenarios examined, in-track motion relative to a resident space object in a $$L_2$$ halo orbit provides the greatest illumination for both in- and cross-track proximity operations.
PubDate: 2025-04-04
- Establishment and Development of an Incremental Constitutive Model for
CFRP Considering the Impact Adiabatic Effect-
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Abstract: At any time, the pace of space exploration has never stopped. In recent years, thanks to the rapid progress of space science and technology, satellites, probes, stations and other man-made equipment have been launched into space one after another, and manned space activities have become frequent. It is important to note that lightweight is still a major requirement for these equipment, as a lower launch weight allows more loads to be carried. Carbon fiber reinforced plastic (CFRP) is one of the lightweight, high strength materials commonly used in space. As a key component of spacecraft, it will inevitably experience high-speed collision events with space debris and waste recycling during operation in space, leading to more complex thermodynamic problems. In this study, a method to construct the CFRP constitutive under high strain rate impact was reported by identifying the strain rate state, generating the adiabatic temperature and modifying the (secant) stiffness matrix. In the low strain rate compression state, the initial nonlinearity caused by material defects was described by introducing the initial nonlinear modulus increasing factor. In the high strain rate impact state, the nonlinear high strain rate strengthening effect was described by introducing the dynamic strengthening factors of stress and strain based on the mechanical behavior under the reference strain rate. Based on the instantaneous temperature rise obtained from the impact adiabatic equation, the mechanical-thermal coupling effect was described by considering the influence of temperature on modulus and strength. Using incremental constitutive logic, a user-defined material subroutine was developed and feasibility verification was performed in conjunction with the experiment. This research work includes the establishment method of the constitutive of CFRP under high and low strain rate states, which provides a design reference for some extreme space collision events.
PubDate: 2025-04-03
- Correction: Imaging Performance of Laue Lenses Made of Ge and Si Bent
Crystals for Future Gamma-Ray Astrophysics Telescopes-
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PubDate: 2025-04-01
- Passive Fault-Tolerant Control of Dual-System UAV Transition Flight Under
Partial Loss of Propellers-
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Abstract: A novel passive fault-tolerant control system for the transition flight of a dual-system unmanned aerial vehicle (UAV) is proposed in this paper. The nominal control synthesis is first conducted without considering the occurrence of actuator fault. Stability evaluation using $$\mu$$-analysis and performance analysis based on a multi-model approach, by assuming the existence of actuator fault, are subsequently carried out, which suggests the nominal control system can maintain stability and performance under partial loss of propellers. To further illustrate the effectiveness of passive fault tolerance and the robustness to modeling uncertainty of the proposed control system, validation on the nonlinear six-degree-of-freedom simulator is carried out. The simulation results show that the developed control system using structured $$H_{\infty }$$ is able to overcome the partial loss of both a single and two propellers as well as modeling uncertainty during transition flight, which improves the safety and reliability of the flight of the dual-system UAV.
PubDate: 2025-03-24
- Imaging Performance of Laue Lenses Made of Ge and Si Bent Crystals for
Future Gamma-Ray Astrophysics Telescopes-
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Abstract: Forthcoming hard X-ray (50–700 keV) telescopes designed for high-energy astrophysics will rely on concentrating radiation through diffractive systems utilising crystals and solid-state detectors at focal plane. Our current focus involves exploring the feasibility of employing Laue lenses made from curved crystals. In this study, we estimate the imaging performance of an X-ray Laue lens made of bent germanium and silicon crystals, arranged in concentric rings on a disc of 2.5 m diameter for incident X-rays arriving on the lens off axis. In each ring, the crystals are pre-oriented in order to diffract a parallel X-ray beam in a focus positioned at 20 m from the lens. Each crystal is a 3 × 1 cm2 tile whose longer edge oriented towards the centre of the lens. Thanks to the 40 m curvature of the crystal tiles, each crystal produces a spot around 1.5 × 10 mm2 at the focus plane. The overlap of diffracted beams from all the tiles produces a spot with a point spread function of a few millimetre in diameter corresponding to only 40 arcsec when the incident rays are parallel to the axis of the lens. To evaluate the imaging performance of Laue lenses made of bent crystals, simulation of diffraction from on-axis and off-axis X-ray sources are reported, also permitting to estimate the amount of optical aberration.
PubDate: 2025-03-20
- Numerical and Experimental Study of Effects of Triangular Cross-Section
Riblets on DU89-134 Airfoil-
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Abstract: The research investigates the effects of triangular cross-section transverse riblets on the aerodynamic performance of the DU89-134 airfoil. The free-stream conditions are Reynolds number 500,000 and angle of attack $${5}^\circ$$, and the riblets are positioned on the suction side at the following chordwise locations $${\textbf {[0.3,0.4,0.5,0.6,0.7]}}$$. A comprehensive three-pronged approach includes experimental methods, RANS simulations, and implicit LES. The implicit LES method used in this study is relatively novel and demonstrates consistency with the findings from both the RANS simulations and the experimental results. Despite this alignment, no significant improvement in overall aerodynamic performance has been observed for the tested configurations.
PubDate: 2025-03-16
- Multi-plateau Auxetic Metamaterials with Intra- and Inter-cellular
Gradients for Energy Absorption-
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Abstract: With the rapid development of related aerospace endeavors, such as near-Earth space development and deep space exploration, many ground technologies have begun to be transferred to space. This transition is not without its challenges, particularly in managing collisions during spacecraft operations, such as landing and docking. The critical need for advanced buffering, energy absorption and protective materials has sparked interest in mechanical metamaterials, which are characterized by their capability to handle multiple loading conditions and exhibit various deformation modes. Traditional single-plateau energy absorbers are proving inadequate for the diverse and unpredictable loads encountered in the harsh space environment, underscoring the necessity for mechanical metamaterials with enhanced load-bearing and deformation adaptability. This study advances the field by integrating intra-cellular multi-level gradients and inter-cellular layered gradients within a classical re-entrant configuration to develop a novel multi-plateau auxetic metamaterial. Empirical insights into the compressive mechanical behavior of both single-cell and multi-cell metamaterial configurations were obtained through quasi-static compression testing of 3D-printed samples. The results illustrate that the designed intra-cellular multi-level gradient auxetic metamaterial is not able to generate multiple load plateaus due to the unexpected fracture caused by the brittle nylon material, but multiple load peaks and the exceptional auxetic effect is realized. However, the inter-cellular layered gradient metamaterial exhibits multiple load plateaus under a complex interplay between inter- and intra-cellular deformation modes. The development of programmable multi-plateau auxetic metamaterials represents a significant step forward in addressing the multifaceted energy absorption and protection requirements of space equipment. By offering superior performance in managing multiple energy absorption scenarios and enhancing efficiency, these materials open new avenues for the development of multi-level crashworthiness and multi-functional impact resistance solutions tailored to the rigorous demands of space exploration.
PubDate: 2025-03-09
- Thermal Analysis of Space Station Windows in Low Earth Orbit:
Intermaterial Comparison of Fused Silica and Acrylic Glass-
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Abstract: Calculating the temperatures of windows of space stations in Low Earth Orbit (LEO) is crucial for ensuring their structural integrity. We present a comprehensive thermal analysis that considers direct solar radiation, Earth’s albedo effect, infrared radiation from the Earth and convective heat exchange with the internal environment. The thermal balance equation incorporates the time variation of these contributions due to orbital motion for windows with different orientations, to determine the temperature of the materials, factoring in key parameters, such as absorptivity, transmissivity, reflectivity, and their dependence on the radiation wavelength spectrum. Referring to the conditions of the Cupola of the International Space Station as a paradigmatic example, we compare the thermal performance of two common window materials: fused silica and acrylic glass. Our results indicate that the higher transmissivity of fused silica makes it insensitive to solar and albedo radiation, reducing temperature values and their dependence on plate thickness and exposure variability due to orbital motion. In contrast, the higher absorptivity of acrylic glass results in much higher temperatures, proportional to the thickness, with a cyclical dependence on the orbital period. This analysis provides insights for the design and selection of window materials in space station construction, ensuring their durability and functionality in the conditions of LEO.
PubDate: 2025-02-26
- A Low-Cost Supercapacitor Battery Design for Cube Satellite Application
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Abstract: The reliable operation of satellites and their payloads hinges on a robust power system and an efficient energy storage unit capable of consistently meeting energy demands throughout a satellite’s lifecycle. This paper explores the development of an economical supercapacitor-based battery system tailored for CubeSat applications. It presents a highly efficient design that leverages readily available commercial off the-shelf (COTS) supercapacitors. In recent years, small satellites, particularly CubeSats, have demonstrated impressive performance levels akin to their larger counterparts. They have become instrumental in pioneering new technologies, clean energy solutions, and environmentally friendly materials for sustainable energy storage systems, particularly in the realm of power systems, energy storage, and high-power consumption requirements. As a result, there is a growing interest in storage systems that rely either entirely on supercapacitors or incorporate them in a hybrid fashion. Supercapacitors are favoured for their ability to deliver high power rapidly, quick recharge capabilities, and compact form factors. The designed supercapacitor-based battery system employs a series connection of two 2.7 V 500 F supercapacitors, equipped with a DC–DC converter, charge and discharge control system, as well as mechanisms for balancing and overvoltage protection. This innovative configuration empowers the CubeSat with a tailored energy supply for specific mission objectives and stands as a potential solution to address power supply interruptions.
PubDate: 2025-02-23
- AIDAA News #26
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PubDate: 2025-02-20
- The Political Issues of Satellite Networks for Telecommunications
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PubDate: 2025-02-20
- Spacecraft Trajectory Optimisation Using Differential Dynamic Programming
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Abstract: Spacecraft trajectory optimisation represents a pillar for space mission development, as it allows the design of more cost-effective and high-performance operational concepts. In this context, the Mars exploration race, best epitomised by the Mars Sample Return mission (MSR), has highlighted the need to optimise not only the Keplerian phase trajectory, but also the proximity dynamics and the atmosphere environment one. In this paper, the Differential Dynamic Programming (DDP) optimisation algorithm is initially introduced as a proven second-order technique that relies on Bellman’s Principle of Optimality and successive minimisation of quadratic approximations. Then, a collection of modified DDP methods is presented for the purpose of enhancing the classic DDP weaknesses. Subsequently, a constrained DDP algorithm is implemented and applied to two case studies: a deep-space rendez-vous and a martian soil landing manoeuvre. The choice is to test the algorithm in different environments, showing the influence of gravity and atmosphere on the convergence properties. For both problems, a parametric and a convergence analysis is carried out to identify the best input parameters and the resulting trajectory optimisation process is displayed. Satisfactory results are achieved, proving the validity of the algorithm: order of few centimetres for position and some decimetres per second for velocity errors are reached. Furthermore, its adaptability allows to satisfy diverse requirements depending on the type of manoeuvre performed, extending its application field. Finally, some algorithm’s features are pointed out, investigating the influence of regularisation parameters and time of flight on the convergence process.
PubDate: 2025-02-19
- Hybrid Air Data System Architecture: Accuracy Improvement on an Existing
Ads Architecture-
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Abstract: An aircraft's Air Data System (ADS) is essential for a number of reasons, such as situational awareness and safety. To compute the primary air data, namely pressures and flow angles, the ADS architecture has historically relied on physical sensors mounted on the aircraft's exterior. A lot of research has been done on the possibility of using synthetic reconstruction of air data as a substitute for these sensors. Only a small number of those examples, nevertheless, made it to the certification stage to be incorporated into an aircraft. This paper provides an overview of the design, integration and test of a Hybrid ADS architecture that relies on both sensors and synthetic estimator specifically designed to solve a calibration problem occurring during high AOA maneuvers on an already existing architecture. The avionics, safety, flight control, and aerodynamics departments worked collectively to implement this system in a multidisciplinary framework. In a laboratory environment, the suggested design and integration solution have been verified. Flight testing has been utilized to confirm the ADS's functionality, validate the systems and yield data for future enhancements. The goal of the entire procedure is to give the certification authority the compliance proof and to attain the required accuracy throughout the envelope.
PubDate: 2025-02-15
- Unmanned F/A-18 Aircraft Landing Control on Aircraft Carrier in Adverse
Conditions-
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Abstract: Carrier landing of aircrafts is a challenge for control due to the existence of nonlinear wind disturbances and the requirements of changing reference trajectories. In this paper, a robust landing control system is presented for carrier landing of unmanned F/A-18 aircraft. In the control system, an augmented observer is applied to estimate the combined disturbances in the pitch dynamics of F/A-18 aircraft during carrier landing. Therefore, the control performance is improved through the control compensations from these estimations. Additionally, the controllers are designed to regulate the velocity, rate of descent and vertical position. A full model, including the nonlinear flight dynamics, controller, carrier deck motion, wind and measurement noise, is constructed numerically and implemented in software. Combining the observer with a proportional-derivative (PD) control, the proposed pitch control shows the better transient characteristics and stronger robustness than a proportional-integral-derivative (PID) controller. The simulations verify that the designed control system can make the aircraft quickly track a time-varying reference despite the existence of nonlinear disturbances and noise.
PubDate: 2025-02-12
- Publisher Correction: Feasibility Analysis of a CubeSat Mission for Space
Rider Observation and Docking-
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PubDate: 2025-01-25
- Autonomous Docking Manoeuvre Testing in the Framework of the ERMES
Experiment-
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Abstract: The rise of the “New Space Economy” has expanded access to low-Earth orbits for commercial, non-profit, and educational entities. This has driven significant growth in the small satellite market, offering a low-cost solution for various missions. Autonomous proximity operation systems for small satellites are actively studied for their wide-ranging applications. Experimental Rendezvous in Microgravity Environment Study (ERMES) is a student project, which aimed at testing an autonomous docking manoeuvre between two free-flying CubeSats mock-ups in a reduced gravity environment. The manoeuvre is characterized by an active Chaser and cooperative Target approach. In particular, the Chaser is equipped with a cold gas propulsive system based on expendable $$\hbox {CO}_{2}$$ cartridges for three-dimensional manoeuvering, whereas the Target has a set of reaction wheels for attitude control. The magnetic post-manoeuvre connection is achieved thanks to a dedicated miniaturized docking interface. Moreover, the reduced gravity conditions have been achieved by participating in the European Space Agency (ESA) $$79^{th}$$ Parabolic Flight Campaign thanks to the selection in the ESA Fly Your Thesis! Programme 2022 (FYT).This article provides an overview of the ERMES experiment, discussing its main objectives and key design solutions. It first describes the design of the Guidance Navigation and Control subsystems of the two mock-ups, then discusses the results of the parabolic flight campaign, and finally focuses on the analysis of a specific parabolic test, where the Chaser was able to dock by recovering a high overall misalignment.
PubDate: 2025-01-24
- Comparison of Data-Driven Approach and MAT224 Material Model: A Numerical
Study on the Ballistic Impact Behavior of 2024-T351 Aluminum Plates-
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Abstract: Numerical simulation is a feasible and effective way to investigate the ballistic impact behavior of material. In this research, the numerical simulations of ballistic impact behavior of 2024-T351 Aluminum plates with different thicknesses struck by blunt projectiles are conducted via two numerical approaches, including a data-driven approach using the commercial software ABAQUS/Explicit and MAT224 material model using the commercial software LS-DYNA, are employed to analyze the impact response of 2024-T351 Aluminum plates, respectively. Within the data-driven approach, an enhanced rate-dependent data-driven constitutive model is utilized to describe the mechanical response, where the classical Johnson–Cook fracture criterion is employed to characterize the fracture behavior of the materials during impact simulations. Finally, the relationship between residual velocity and impact velocity, ballistic limit velocities, strain, local displacement, and penetration process are comprehensively investigated to make a detailed comparison between these two numerical approaches. It is found that the data-driven approach provides better accuracy in predicting ballistic limit velocities. Additionally, the data-driven approach differs from the MAT224 material model in the numerical simulation of target plate penetration. This research is to provide instructions for the choice of a numerical approach to the impact simulation of 2024-T351 aluminum.
PubDate: 2025-01-15
- Shooting Scheme for Perturbations in Optimised Solution of the Orbital
Boundary Value Problem-
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Abstract: Monitoring of the near-Earth space environment has become more and more important in recent times. The constantly increasing amount of space debris is a major threat for space activities and an exhaustive knowledge about the space objects population is of primary importance for civil and military applications. The surveillance of the space surrounding the Earth is achieved by means of sensors based on different technologies. Passive optical observations using ground telescopes are usually employed to track space objects in high altitude orbits. The obtained measurements are sparse, and their arcs are very short. The computation of the orbit based on these observations is challenging and several methods have been proposed. One of the known approaches relies on an optimization scheme of the classical boundary value problem. However, in the latter, the object motion is described by a Keplerian orbit without considering additional perturbations. In this novel approach, orbital perturbations are introduced in the computation procedure using a shooting model. The improved algorithm is applied to simulated observations of objects in the geostationary region under the influence of solar radiation pressure. The measured arcs are separated by intervals of one or more orbit revolutions. The performance of the proposed method is evaluated in terms of accuracy considering different levels of perturbation.
PubDate: 2025-01-07
- AIDAA News #25
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PubDate: 2024-12-23
- Mechanical Assessment of Sun Sensors for Launch Environment
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Abstract: Sun sensors are widely utilized in satellite attitude determination, particularly within Attitude Determination and Control Systems (ADCS), where accurate characterization of the satellite’s orientation stability is crucial. This study aims to qualify sun sensors for new applications, focusing on their positioning and inclination to satisfy mission-specific requirements. The operational environment involves a Polar Satellite Launch Vehicle (PSLV) launcher, with dynamic loads from random vibrations being the predominant stress factor. To align with the ADCS mission requirements of ALSAT 1B observation satellite, the position and inclination angle of the sun sensors were modified, ranging from 70° to 50°. Through a combination of simulations and experimental validation, it was observed that the sun sensors exhibited significant responses due to their location on the satellite. However, subsequent verification procedures revealed no damage to the sensor modules, demonstrating their robustness under these conditions. The results confirm that the sun sensors are adequately qualified for flight, ensuring reliable performance without the risk of failure.
PubDate: 2024-12-11
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