ZBLAN (ZrF4–BaF2–LaF3–AlF3–NaF) is a heavy metal fluoride glass with a theoretical minimum optical attenuation of approximately 0.001–0.01 dB/km near 2.5 m two to three orders of magnitude below the intrinsic limit of silica optical fiber. Despite five decades of concentrated research, terrestrial manufacturing has never approached these theoretical limits, owing primarily to microcrystallite formation driven by buoyancy-induced convection, compositional sedimentation and shear-thinning-mediated viscosity reduction during the fiber drawing process. Microgravity environments suppress these gravity-dependent phenomena. Experiments spanning NASA KC-135 parabolic flights (1994), sounding rockets and multiple International Space Station (ISS) campaigns (2017–2024) have consistently demonstrated reduced crystallisation in undercooled ZBLAN melts processed under reduced gravity. The most significant milestone to date was achieved by Flawless Photonics, which produced 11.9 km of ZBLAN fiber aboard the ISS in a single month in early 2024 surpassing all previous records by two orders of magnitude. In parallel, terrestrial approaches including rapid electrothermal processing achieving 4000 K/min cooling rates and magnetic-field crystallisation suppression represent credible alternatives. This paper provides a review of the fundamental physics of ZBLAN glass, the mechanisms by which gravity drives manufacturing defects, the experimental history and current state of microgravity fiber production, a comparative quality analysis, the commercial landscape and the open challenges that will determine whether ZBLAN fiber manufacturing in space becomes a sustainable industry.
The transition toward electrified aviation is driven by the need to reduce the environmental impact of air transport. This study evaluates the suitability of electrical energy storage systems (EESSs), including batteries, flywheels, and supercapacitors, for powering aircraft subsystems in more electric aircraft (MEA). A multi-criteria assessment considering performance, integration, safety, and sustainability identifies supercapacitors as the most suitable option for short-duration applications, batteries for long-duration applications, and both technologies as similarly suitable for medium-duration operations. Flywheels are found to have limited applicability due to safety concerns and integration challenges. A system sizing for representative use cases indicates that fuel-saving potential is highly dependent on the specific energy of the EESS. For a 1500 km mission, a battery system with a specific energy of 0.5 kWh/kg could reduce subsystem fuel consumption by approximately 30
The rapid development of the Internet of Things (IoT) and the increasing demand for communication coverage have made low-cost CubeSat constellations a promising solution for regional satellite communications. This study presents the design and simulation of a CubeSat constellation to provide IoT services over Iran. The proposed system aims to achieve continuous regional coverage for communication and tracking applications in the transportation and industrial sectors. Thirteen constellation configurations with different orbital altitudes, inclination angles, and satellite distributions were designed and evaluated using AGI Systems Tool Kit (STK). The simulation results show that Model No. 2, consisting of 30 satellites distributed in 10 orbital planes at an altitude of 750 km and an inclination of 40°, provides the most efficient solution by achieving continuous regional coverage while minimizing revisit time, constellation size, and the number of inter-satellite links. A three-year perturbation analysis, considering the Earth’s gravity field, solar radiation pressure, the Van Allen belts, and the Earth’s magnetic field, indicates that these effects do not significantly alter the constellation’s orbital characteristics. The electrical power, attitude control, and IoT payload subsystems were designed using commercially available components. The proposed CubeSat has a maximum instantaneous power consumption of 35.86 W under peak operating conditions, which represents the peak electrical load considered in the electrical power subsystem design. The results demonstrate that the proposed CubeSat constellation provides a practical and cost-effective solution for regional IoT services.
Ground station’s antenna angles (azimuth and elevation angles) is a crucial input for the precise tracking of satellite and launch vehicle during the launch. Antenna’s angle data calibration is an important activity where Telemetry Tracking Commanding (TTC) stations antenna error coefficients are estimated and used for precise targeting of the space objects. The calibrated coefficients are also used for the initial orbit determination using range and angles data immediately after the launch to enhance the orbit determination accuracy. In this paper, we describe the angles data calibration computational process which is carried out periodically for ISRO Telemetry Tracking and Command Network (ISTRAC) S-band ground station antenna. The in-house developed satellite precise orbit propagator (SPOP) is incorporated for the precise ephemeris generation in the angles data calibration process to compute the predicted antenna angles corresponding to the measured one tracked through the auto mode tracking. The developed angles data calibration package estimates the antenna error coefficients and azimuth and elevation mean errors using the linear least squares in the batch processing mode. The error coefficients are estimated making use of Indian Remote Sensing-Low Earth Orbiting (IRS-LEO) satellite auto tracking and its operational orbit determination. Systematic errors of each ground station antenna are estimated by conducting tracking campaigns designed to collect data spread evenly in the azimuth-elevation domain.
The present work investigates the low-velocity impact response of composite laminate plates using the Carrera Unified Formulation for structural modelling, the 3D Hashin failure criterion for damage evaluation, and cohesive elements. 2D structural theories are employed, based on a layer-wise approach, capable of accurate modeling of transverse stresses and delamination. The numerical examples consider three cases, and the results are verified and validated with numerical models and experiments retrieved from the literature. The results show the advantages of the present formulation in reducing computational costs compared to 3D finite elements; the need for parabolic displacement fields within each layer for good accuracy; improvements in the oscillatory behavior of the time response; and the proper detection of damage distributions over the 3D domain.
