Current Issue : April-June Volume : 2026 Issue Number : 2 Articles : 5 Articles
Very-Low Earth Orbit Synthetic Aperture Radar (VLEO SAR) satellites, defined as SAR satellites operating at orbital altitudes 350 km or below, offer distinct technical advantages compared to conventional SAR satellites. Equipped with a high-resolution SAR payload, the Haishao-1 (HS-1) satellite was successfully launched on 4 December 2024. According to publicly available information, the HS-1 satellite represents the world’s first VLEO SAR satellite and has successfully demonstrated 1-m resolution Stripmap mode imaging with continuous azimuth coverage. Through an analysis of the HS-1 satellite’s system parameters and imaging results, this paper comprehensively explores the advantages of VLEO SAR satellites over traditional orbit SAR satellites, particularly in terms of enhanced resolution, reduced payload costs, and improved constellation deployment capabilities. VLEO SAR satellites possess significant advantages, including the potential for higher-resolution imagery and lower-cost payload designs, positioning them for extensive application prospects in fields such as space-based military reconnaissance, natural resource surveying, and natural disaster monitoring....
Hydrogen peroxide (H2O2) is a dense, storable oxidizer, but its suitability for highenergy upper stages is limited. This study evaluates liquid hydrogen–hydrogen peroxide (LH2/H2O2) as an alternate propellant using KSLV-II as the reference vehicle. Propulsion performance was analyzed with NASA CEA and RPA, while staging and MER methods assessed system-level effects. The results show that the specific impulse decreases from 465 s (LH2/LOX) to 372~382 s with H2O2, but structural efficiency improves as the coefficient drops from 0.162 to 0.099~0.102. The payload capacity increases compared with Jet A-1/LOX yet remains below that of LOX. These findings clarify both the advantages and limitations of H2O2 as an upper-stage oxidizer....
In aerospace engineering, structural lightweight remains one of the core design objectives. Here, a design methodology combining topology optimization (TO) with honeycomb materials is proposed to achieve lightweight for a typical aircraft double-lug joint structure (DLJS). The initial DLJS is topologically optimized using the variable density method to identify optimal material distribution. The optimized result is then reconstructed into a regular geometric model using the three dimensional (3D) modeling software SolidWorks 2022. In the reconstructed DLJS, the lower stress regions are replaced with honeycomb materials possessing superior mechanical properties or either removed to further enhance stiffness-to-weight ratio. Numerical strength verifications are performed on the final designed DLJS, demonstrating that the maximum stresses designed DLJS remain below the material yield strength under three typical load cases, meeting both strength requirements and safety margins. The mass of the designed DLJS is 38.44 kg, achieving a weight reduction rate of 59.7% compared to the initial DLJS (95.38 kg). Finally, the fabrication feasibility of the designed DLJS is evaluated, and a scaled-down DLJS specimen is fabricated using 3D printing technology with photopolymer resin. This work demonstrates the effectiveness and potential of TO combined with honeycomb materials in lightweighting complex 3D engineering components, providing valuable insights for the lightweight design of intricate 3D structures....
The International Geomagnetic Reference Field (IGRF) is a spherical harmonic model representing the large-scale Earth’s main magnetic field and its secular variation (SV). In 2024, the International Association of Geomagnetism and Aeronomy (IAGA) V-MOD Working Group called for candidate models for the 14th generation of IGRF (IGRF-14). Inspired by successful launch of the Macau Science Satellite-1 (MSS-1) on May 21, 2023, Macau Institute of Space Technology and Application (MISTA) and the MSS-1 team submitted three candidate models based on newly acquired magnetic data: a main field model for epoch 2020.0, a main field model for epoch 2025.0, and an average SV model for the period 2025.0–2030.0. The 2020.0 model was contributed by Swarm satellite and ground observatory data, while the 2025.0 and SV models incorporated the latest magnetic data from MSS-1, Swarm and global observatories. This paper describes the construction and evaluation of these candidate models. The results of the evaluation show strong consistency between the MISTA candidate models and the officially released IGRF-14 models, confirming the reliability of our candidate models and the high quality of MSS-1 magnetic data. We also assess the unique contribution of MSS-1 data. Our discussion emphasizes the complementary value of combining observations from polarorbiting satellites like Swarm with those from low-inclination missions like MSS-1 to improve the resolution of Earth’s magnetic field model....
The increasing environmental concerns related to aircraft carbon dioxide (CO2) emissions call for efficient fuel-saving strategies. This study proposes an alternative cruising strategy to minimize fuel consumption during the cruise flight phase by introducing a two-phase maneuver consisting of a descent followed by a climb. Constraints related to both passenger comfort and aviator regulatory frameworks are considered to ensure the feasibility of the proposed strategy in real-world operational contexts. Using closed-form formulas of the aircraft’s fuel consumption, this strategy is compared against the conventional constant altitude cruise approach. Numerical simulations using data from a Boeing 767-300ER show that the proposed strategy can achieve reduction in fuel consumption at the cost of an increment in flight time. This can be achieved by repeating the proposed strategy as many times as needed according to the distance to be covered during the cruise flight phase....
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