ARI, IASJournal of Space Science and Technology2008-456018Special Issue (S1)20250401Cyber Risk Prediction for UAVs in Space-Related Missions Using Deep Reinforcement LearningCyber Risk Prediction for UAVs in Space-Related Missions Using Deep Reinforcement Learning11521646910.22034/jsst.2025.1527ENErfanKhosravianDepartment of Mechanical Engineering, Payame Noor University, Tehran, Iran0000-0002-7239-2985MotaharehDehghanFaculty of Industrial and Systems Engineering, Tarbiat Modares University, Tehran, IranJournal Article20250127Space exploration and satellite deployment drive modern technological advancements. They are crucial for global communication, navigation, and scientific discovery. Satellites form the backbone of interstellar communication, ensuring reliable data transfer in both civilian and defense sectors. However, as space missions grow more complex, maintaining their integrity and security becomes a major challenge.<br />Unmanned Aerial Vehicles (UAVs) play a key role in space missions. They assist in satellite deployment, orbital inspections, and inter-satellite communication. Yet, these cyber-physical systems face evolving cybersecurity threats that could jeopardize mission-critical tasks. Traditional intrusion detection systems struggle to counter the complex and dynamic cyber threats targeting UAVs in harsh space environments.<br />This paper introduces a novel Deep Reinforcement Learning model to predict and mitigate cyber risks in space-related UAV missions. Using a publicly available dataset that combines cyber and physical UAV data, the model predicts multi-step threats such as Denial of Service, Replay, Evil Twin, and False Data Injection. This enables proactive threat mitigation. Compared to traditional machine learning models—Support Vector Machines, Random Forests, and Recurrent Neural Networks—the proposed model achieves superior performance, with 99.34% accuracy and an AUC score of 0.99.Space exploration and satellite deployment drive modern technological advancements. They are crucial for global communication, navigation, and scientific discovery. Satellites form the backbone of interstellar communication, ensuring reliable data transfer in both civilian and defense sectors. However, as space missions grow more complex, maintaining their integrity and security becomes a major challenge.<br />Unmanned Aerial Vehicles (UAVs) play a key role in space missions. They assist in satellite deployment, orbital inspections, and inter-satellite communication. Yet, these cyber-physical systems face evolving cybersecurity threats that could jeopardize mission-critical tasks. Traditional intrusion detection systems struggle to counter the complex and dynamic cyber threats targeting UAVs in harsh space environments.<br />This paper introduces a novel Deep Reinforcement Learning model to predict and mitigate cyber risks in space-related UAV missions. Using a publicly available dataset that combines cyber and physical UAV data, the model predicts multi-step threats such as Denial of Service, Replay, Evil Twin, and False Data Injection. This enables proactive threat mitigation. Compared to traditional machine learning models—Support Vector Machines, Random Forests, and Recurrent Neural Networks—the proposed model achieves superior performance, with 99.34% accuracy and an AUC score of 0.99.https://www.jsstpub.com/article_216469_2a4deae42ba414e75f8025e996766e24.pdfARI, IASJournal of Space Science and Technology2008-456018Special Issue (S1)20250401Plasma-Based Beamforming AntennasPlasma-Based Beamforming Antennas162521391810.22034/jsst.2024.468738.1493ENFatemehSadeghi KiaAerospace Research Institute, Ministry of Science, Research and Technology, Tehran, Iran0000-0003-4665-5566MahmoudTalafi NoghaniAerospace Research Institute, Ministry of Science , Research and Technology, Tehran, Iran0000-0002-4719-6712AliKarami HorestaniAerospace Research Institute, Ministry of Science , Research and Technology, Tehran, Iran0000-0002-7747-2554FatemehZamaniAerospace Research Institute, Ministry of Science, Research and Technology, Tehran, IranJournal Article20240720In this article, beamforming methodologies for antennas are first reviewed, highlighting the pros and cons of each method. It is observed that each method offers unique advantages and limitations. Some of the key technologies used to provide beamforming antennas are also compared with consideration of complexity, beamwidth, price, scanning angle, frequency range, beamforming speed, and accuracy. It is shown that beamforming using plasma offers flexibility compared to other techniques while remaining relatively cost-efficient. Moreover, using plasma components, it is possible to conceal the entire antenna or parts of it. Based on these advantages, this study presents a low-complexity, low-cost plasma-based antenna for beamforming. This novel antenna combines an axial mode helical antenna surrounded by circular arrays of plasma elements, forming plasma cups around the helix. The plasma cups are used to control the direction and width of the radiated beam of the helix. Activation of a plasma cup enhances the beamwidth of the helix, while asymmetrically activated configurations allow for steering the end-fire beam pattern up to ±27°. A prototype of the proposed antenna structure has been fabricated, and measurements for different configurations of the plasma reflectors have been carried out. The concept and computational results have been validated by the strong agreement between the simulation and measurement results. The proposed antenna offers a cost-effective solution for scanning and target acquisition in space communications and radar systems.In this article, beamforming methodologies for antennas are first reviewed, highlighting the pros and cons of each method. It is observed that each method offers unique advantages and limitations. Some of the key technologies used to provide beamforming antennas are also compared with consideration of complexity, beamwidth, price, scanning angle, frequency range, beamforming speed, and accuracy. It is shown that beamforming using plasma offers flexibility compared to other techniques while remaining relatively cost-efficient. Moreover, using plasma components, it is possible to conceal the entire antenna or parts of it. Based on these advantages, this study presents a low-complexity, low-cost plasma-based antenna for beamforming. This novel antenna combines an axial mode helical antenna surrounded by circular arrays of plasma elements, forming plasma cups around the helix. The plasma cups are used to control the direction and width of the radiated beam of the helix. Activation of a plasma cup enhances the beamwidth of the helix, while asymmetrically activated configurations allow for steering the end-fire beam pattern up to ±27°. A prototype of the proposed antenna structure has been fabricated, and measurements for different configurations of the plasma reflectors have been carried out. The concept and computational results have been validated by the strong agreement between the simulation and measurement results. The proposed antenna offers a cost-effective solution for scanning and target acquisition in space communications and radar systems.https://www.jsstpub.com/article_213918_0a15355d706ea26ec504d8863aae9030.pdfARI, IASJournal of Space Science and Technology2008-456018Special Issue (S1)20250421Effectiveness of Multi-Layered Radiation Shields Constructed from Polyethylene and Metal Hydrides Using HZETRN and OLTARIS for Space ApplicationsEffectiveness of Multi-Layered Radiation Shields Constructed from Polyethylene and Metal Hydrides Using HZETRN and OLTARIS for Space Applications263321959110.22034/jsst.2025.1520ENSreedeviVVDepartment of Physics, Malaviya National Institute of Technology Jaipur, India0009-0008-3847-8743KavitaLalwaniDepartment of Physics, Malaviya National Institute of Technology Jaipur, India0000-0002-7294-396XJournal Article20250115A major challenge for extended human spaceflights in deep space is the dangerous exposure to space radiation. These high-energy particles pose significant risks to astronaut health. To mitigate these risks, effective radiation shielding is essential. In previous studies, aluminium has been used as a multilayer shielding material in GCR (Galactic Cosmic Rays) space radiation environment with high dose equivalent. Because of aluminium's secondary particle production, the overall effective dose equivalent for astronauts behind an aluminium shield is higher than for more advanced shielding materials. To further reduce the dose equivalent, the shielding effectiveness of various metal hydrides in GCR free space environment is investigated using HZETRN2015 (High charge (Z) & Energy TRaNsport) and OLTARIS (On-Line Tool for the Assessment of Radiation In Space) in this work. Metal hydride materials are chosen because of their capacity to store hydrogen. Among these materials, lithium hydride has demonstrated superior effectiveness as a radiation shield. Given this, the potential of a multilayer shield composed of polyethylene and lithium hydride is also being explored considering the tensile strength certain varieties of polyethylene like UHMWPE (Ultra High Molecular Weight Poly-Ethylene) can provide. In multilayer shielding, different materials can target different types of radiation, providing more comprehensive protection. The results from HZETRN2015 and OLTARIS transport codes are compared and found in agreement.A major challenge for extended human spaceflight in deep space is the hazardous exposure to space radiation, which consists of high-energy particles that pose significant risks to astronaut health. Effective radiation shielding is essential to mitigate these risks. This study optimizes the shielding performance of a multi-layered structure composed of polyethylene and metal hydrides for space applications. Using two simulation tools: HZETRN and OLTARIS, developed by NASA, we model these structures and evaluate dose equivalent in a Galactic Cosmic Ray (GCR) free-space radiation environment, which is the primary and major contributor to radiation exposure for long-duration space missions. Among the materials studied, lithium hydride exhibits the highest shielding effectiveness. The results on the dose equivalent are compared with aluminum, a conventional shielding material, revealing that the multi-layered structure constructed from polyethylene and lithium hydride provides a 54.9% improvement in shielding effectiveness while maintaining structural stability. Additionally, the dose equivalent contribution of different radiation particles (protons, alpha particles, and heavy ions) and their flux are analyzed for further validation across both tools. Our results highlight the effectiveness of multi-layered shielding in reducing dose equivalent while maintaining structural stability, making it a viable solution for deep-space missions.https://www.jsstpub.com/article_219591_7319e112a7747172aba1a2d735bb6852.pdfARI, IASJournal of Space Science and Technology2008-456018Special Issue (S1)20250421Simultaneous Resolution and Dynamic Range Improvement in Microwave Phase-Variation Displacement SensorsSimultaneous Resolution and Dynamic Range Improvement in Microwave Phase-Variation Displacement Sensors344021959210.22034/jsst.2025.1526ENAmirhosseinKarami HorestaniDepartament d’Enginyeria Electrònica, Universitat Autónoma de Barcelona, Bellaterra, SpainFerranParedesDepartament d’Enginyeria Electrònica, Universitat Autónoma de Barcelona, Bellaterra, Spain0000-0002-7252-1169FerranMartínDepartament d’Enginyeria Electrònica, Universitat Autónoma de Barcelona, Bellaterra, Spain0000-0002-1494-9167Journal Article20250126Abstract: In this paper, a reflective-mode phase-variation microwave moderate range displacement sensor is proposed. It consists of a reader which is a one-port microstrip line terminated with a matched load, and a movable resonator (etched in an independent substrate), which exhibits three different resonance frequencies, two of them in low frequency range and close to each other, and the third one at a higher frequency. The sensing mechanism is based on the motion of the resonator along the microstrip line, with a small airgap in between. The phase of the reflection coefficient at the three resonance frequencies of the resonator is recorded at the input port of the reader. As a result, the motion of the movable resonator can be characterized. The phase of the reflection coefficient at the two lower frequencies is used to enhance the dynamic range, while the phase at the higher frequency improves sensor resolution.<br /><br />Index Terms—microstrip technology, microwave sensor, reflective-mode sensor, displacement sensor, phase-variation sensor.Abstract: In this paper, a reflective-mode phase-variation microwave moderate range displacement sensor is proposed. It consists of a reader which is a one-port microstrip line terminated with a matched load, and a movable resonator (etched in an independent substrate), which exhibits three different resonance frequencies, two of them in low frequency range and close to each other, and the third one at a higher frequency. The sensing mechanism is based on the motion of the resonator along the microstrip line, with a small airgap in between. The phase of the reflection coefficient at the three resonance frequencies of the resonator is recorded at the input port of the reader. As a result, the motion of the movable resonator can be characterized. The phase of the reflection coefficient at the two lower frequencies is used to enhance the dynamic range, while the phase at the higher frequency improves sensor resolution.https://www.jsstpub.com/article_219592_5baa10af508ac14d8a57b75c43d4fadc.pdfARI, IASJournal of Space Science and Technology2008-456018Special Issue (S1)20250401Numerical Study of V-Shaped Microgrooves Location on an Aerodynamic Surface for Drag ReductionNumerical Study of V-Shaped Microgrooves Location on an Aerodynamic Surface for Drag Reduction415121608310.22034/JSST.2025.1521ENMohammad JavadKahalianAerospace Research Institute, Ministry of Science, Research and Technology, Tehran, Iran.RaminKamalimoghadamAerospace Research Institute, Ministry of Science, Research and Technology, Tehran, Iran0000-0002-0780-7689ImanBahman JahromiAerospace Research Institute, Ministry of Science, Research and Technology, Tehran, Iran0000-0002-6411-3800MahmoudNajafiMathematical Science Department, Kent State University, USAJournal Article20250117One important passive technique for drag reduction is the use of microstructured surfaces. In recent years, the advantages of this method have led some airlines to reduce their fuel consumption by installing microstructured films on aircraft. To understand the physics governing microstructures, this article investigates the effect of V-shaped transverse microgrooves on the NACA 8-H-12 airfoil. For this purpose, grooves with a base and height of 150 μm are placed transversely at eight different locations on the airfoil surface and their effects are investigated at zero angle of attack (AoA) and at velocities of 35, 65, and 100 m/s. The results show that vortices trapped within the transverse microgrooves reduce viscous drag by decreasing shear stress magnitude near the peaks and reversing its direction within the valleys. However, the microgrooves also generate pressure drag due to pressure gradients created within and around the structures. The combined effects of these changes in viscous and pressure drag determine the overall change in total drag. Total drag can either increase or decrease depending on the microgrooved surface area, its location on the airfoil, and the freestream velocity. The maximum drag reduction observed in this study was approximately 6%, achieved with two 200 mm microgrooved surfaces located mid-chord on both the suction and pressure sides at 35 m/s.One important passive technique for drag reduction is the use of microstructured surfaces. In recent years, the advantages of this method have led some airlines to reduce their fuel consumption by installing microstructured films on aircraft. To understand the physics governing microstructures, this article investigates the effect of V-shaped transverse microgrooves on the NACA 8-H-12 airfoil. For this purpose, grooves with a base and height of 150 μm are placed transversely at eight different locations on the airfoil surface and their effects are investigated at zero angle of attack (AoA) and at velocities of 35, 65, and 100 m/s. The results show that vortices trapped within the transverse microgrooves reduce viscous drag by decreasing shear stress magnitude near the peaks and reversing its direction within the valleys. However, the microgrooves also generate pressure drag due to pressure gradients created within and around the structures. The combined effects of these changes in viscous and pressure drag determine the overall change in total drag. Total drag can either increase or decrease depending on the microgrooved surface area, its location on the airfoil, and the freestream velocity. The maximum drag reduction observed in this study was approximately 6%, achieved with two 200 mm microgrooved surfaces located mid-chord on both the suction and pressure sides at 35 m/s.https://www.jsstpub.com/article_216083_b18626a498f5e549beeef4c6afb830bb.pdfARI, IASJournal of Space Science and Technology2008-456018Special Issue (S1)20250401Boundary Layer Transition and Re-Laminarization in the Nozzle of a Shock Tunnel – a Numerical StudyBoundary Layer Transition and Re-Laminarization in the Nozzle of a Shock Tunnel – a Numerical Study525921608410.22034/JSST.2025.1525ENShahedMalekipourAerospace Research Institute, Ministry of Science, Research and Technology, Tehran, IranImanBahman JahromiAerospace Research Institute, Ministry of Science, Research and Technology, Tehran, Iran0000-0002-6411-3800MeisamMohammadi AminTechnical University of Denmark, Lyngby, DenmarkJournal Article20250121The boundary layer behavior in hypersonic nozzle of a shock tunnel has been investigated by means of the computational fluid dynamics simulations. The state of boundary layer at the nozzle outlet can highly affect the downstream flow passing around the test model in the shock tunnel test section. The formation of shock and expansion wave systems towards the downstream diaphragm and the reflection and expansion waves towards the upstream shock tube were well-simulated after the diaphragm rupture. Focusing on the transitional boundary layer simulation, results of the optimal nozzle's steady-state flow indicate that the boundary layer enters the throat region, undergoes a phase transition, and then returns to a laminar state due to re-acceleration. The turbulence intensity in this region, coupled with the width of the transition zone, increases with higher upstream stagnation pressure. Furthermore, simulation of the unsteady starting flow shows that the passage time of unsteady waves and the quasi-steady region, have good agreement with the experimental results.The boundary layer behavior in hypersonic nozzle of a shock tunnel has been investigated by means of the computational fluid dynamics simulations. The state of boundary layer at the nozzle outlet can highly affect the downstream flow passing around the test model in the shock tunnel test section. The formation of shock and expansion wave systems towards the downstream diaphragm and the reflection and expansion waves towards the upstream shock tube were well-simulated after the diaphragm rupture. Focusing on the transitional boundary layer simulation, results of the optimal nozzle's steady-state flow indicate that the boundary layer enters the throat region, undergoes a phase transition, and then returns to a laminar state due to re-acceleration. The turbulence intensity in this region, coupled with the width of the transition zone, increases with higher upstream stagnation pressure. Furthermore, simulation of the unsteady starting flow shows that the passage time of unsteady waves and the quasi-steady region, have good agreement with the experimental results.https://www.jsstpub.com/article_216084_fcb338002b2026e25332708450331346.pdf