Journal of Space Safety Engineering最新文献

Approximately 70 % of launches in 2022 resulted in an uncontrolled rocket body reentry, creating an unnecessary casualty risk to people on the ground, at sea, and in aircraft. Rocket bodies have masses ranging from tens of kilograms to 20 tonnes. Using known rocket body masses and correlations between mass and casualty area, we present revised estimates for the expected risk, finding a 20–29 % probability of one or more casualties over the next decade.

Some states use a 1-in-10,000 threshold for accepting an uncontrolled reentry casualty risk when approving a space activity. This threshold, which is not universally agreed upon, represents a risk acceptance by one country, but imposed on the world population. As the use of space expands, with a record 180 successful launches in 2022, states and other launch providers should adopt technologies and mission designs that ensure controlled reentries. Uncontrolled reentries, particularly of large rocket bodies, constitute an unsafe and unnecessary practice.

Resistojet is a thruster based on electrothermal propulsion which uses heating element to increase the temperature of the thruster, so the propellant ionizes and gives out thrust at the nozzle section. Given their high propulsive performance, resistojets are widely used in satellite technology for control, tangential orbit modification, and propulsion. Therefore, numerous experimental and numerical research was carried out to comprehend the performance of a resistojet. The four major elements of a resistojet thruster are the material for the heating element, the cooling system, the type of nozzle and the choice of propellant. The combination of these four major elements matters greatly to design an efficient resistojet thruster. The main objective here is to compare and analyze the existing high performance resistojet thrusters. Therefore, it is critical to comprehend how well the four major elements of a resistojet thruster perform under different conditions. A resistojets’ performance is greatly affected by the design of the thruster. The right choice of propellant plays an important role with respect to the performance of a resistojet thruster. Every propellant type used up to this point has been thoroughly analyzed with respect to its effect on the resistojets’ thrust and specific impulse values. Parallelly, several cooling system and flow channel designs were examined to a great extent keeping the metrics of a resistojet in mind. A thruster's nozzle is a part that enables hot gases to escape at a higher velocity. Hence, version of nozzle types was studied, and their performances are charted in this paper. In addition to the performance characteristics, future aspects of the resistojet in electric propulsion has been discussed.

In recent times, the explosion of digital appliances and radio communication systems has triggered an elevated debate over electromagnetic interference (EMI) in numerous industries, including the aerospace sector. EMI can disrupt verbal exchange systems, navigation gadgets, or even crucial flight controls. This paper aims to explore the need for EMI protection in the context of discussing the techniques and packages of nanocomposites used for effective shielding. It broadly covers the introduction to EMI shielding, strategies for effective shielding, and the utilization of advanced nanocomposites for EMI mitigation in aircraft. The paper also highlights the amplifying dependence on digital devices in the current aircraft and highlights the increasing coercion of EMI that leads to the demand for strong EMI-protecting solutions. Different EMI shielding techniques based on their effectiveness in protecting sensitive digital components from electromagnetic disturbances are discussed. The use of techniques such as EMI filters, shielded cables, and Faraday cages are investigated for applicability in distinctive aerospace appliances. The emerging requirement for slender and flexible EMI shielding materials that has resulted in the development of conductive polymer nanocomposites in recent years and the use of nanocomposites with excellent EMI shielding regardless of their sustaining mechanical properties has been discussed in detail. Different methods like in-situ polymerization, solution blending, layer-by-layer assembly, and electrospinning are also discussed. In conclusion, the importance of EMI protection in ensuring the dependable and stable operation of modern aircraft and the utility of polymer nanocomposites, a promising method to deal with EMI-related challenges in making air travel more secure and greener in the digital age has been impressed upon.

The purpose of the research is to demonstrate an application of the existing methodology for risk assessment Failure Mode and Effect Criticality Analysis (FMECA) in nanosatellite projects together with a risk register proposal elaborated based on a literature review and expert interviews. The paper also elaborates on the integration of FMECA and knowledge capture and transfer technique. Literature evidence and the use case of the VZLUSAT-1 CubeSat show that it is challenging to implement proper project management and especially risk management practices into nanosatellite (or CubeSat) projects. The risks identified are mostly connected with the technical part, design, and operation of the satellite, and personal, financial, stakeholder, or managerial risks are omitted. The mission success rate can be significantly improved when risks are adequately considered at stages preceding the launch and operation of the satellite.

In compliance with ISO 24,113 and ESA Space Debris Mitigation requirements, spacecrafts in Low Earth Orbit (LEO) must be removed from their operational orbit within 25 years and re-enter the Earth's atmosphere having an on-ground casualty risk lower than 1 in 10,000.

To maximize the number of uncontrolled re-entries, which have much less impact on system mass and costs, ESA's Clean Space initiative is investigating design for containment (D4C) techniques and collaborating with European industries and space agencies to assess, model, analyse, and test new concepts through re-entry tools and plasma wind tunnel experiments. The main objectives are to understand the survivability of materials and techniques suitable for different containment concepts, to improve re-entry modelling, and implement effective D4C measures.

This paper shows the results of these activities, that have been the first milestones in the knowledge of D4C, although further investigations are needed.

Among the unmanned launch service providers, the autonomous flight termination concept is no longer an unknown actor around the table. The goal of these systems is to limit the consequences of the potential feared events caused by a launch vehicle malfunction by automatically terminating the flight of the vehicle in a safe manner, replacing the human component on the traditional flight termination decision in case of failure.

Although some public and private players have already designed (and even flown) an autonomous flight termination system, the problem arises when looking into the safety standards that need to be to be applied to launch from different locations, which are highly dependent on the respective safety authorities.

This paper aims at analysing the gap in the current launch safety policies and proposing the guidelines to be followed to widen the range of spaceports capable of hosting a launch vehicle with such a feature.

Over the past 30 years, numerous methods and tools have been developed to simulate spacecraft breakup during atmospheric re-entry, predict the characteristics of the surviving fragments, and estimate the ground casualty risk. With the introduction of the Design for Demise (or simply D4D) concept, these tools have become increasingly vital in designing spacecraft that break up and burn up during re-entry, thus reducing the risk posed by impacting debris. To enhance the accuracy and efficiency of predictions, researchers have made continuous improvements in this field, especially in the last decade, but uncertainties and gaps in knowledge remain. This article provides an overview of the state-of-the-art, with a particular emphasis on tools developed in Europe. It covers the latest advancements and improvements, as well as novel techniques proposed in the field.

All spacecraft use some sort of thermal insulation, or thermal protection system (TPS), in their design. TPS materials vary, ranging from ceramic tiles or phenolic ablators for heatshields to lightweight multi-layer insulation (MLI) blankets. Since TPS is usually placed on the spacecraft's exterior, it is susceptible to impacts by meteoroids and orbital debris. These high-speed impacts can damage the TPS to a point where the protection it offers is below acceptable limits. As such, it is important to be able to characterize expected TPS damage levels stemming from such high-speed impacts. In this paper, we present the results of a study that sought to characterize the high-speed impact damage that would be sustained by two TPS materials that have recently gained attention for possible use in future interplanetary missions. Empirical equations were developed for TPS crater depths, as well as maximum and minimum crater mouth dimensions. In the event of TPS perforations, empirical equations were developed for the maximum and minimum through-hole dimensions. As part of the analyses performed, ballistic limit equations (BLEs) for these TPS configurations were also developed where possible. The validity of the equations developed was assessed by comparing their predictions against test data. In nearly all cases, the empirical equations developed herein were seen to adequately capture the magnitudes of the measured damage parameters.

The population of objects in space has increased dramatically over recent decades. Space debris now represents the majority of objects in space resulting from inactive satellites, breakups, collisions and fragmentations. It has become a concern for institutions all over the world and, as such, it has led to the fostering of several programmes to counter the issues. Among these, the use of ground-based sensors for Space Surveillance Tracking (SST) activities and services and tools for analysing fragmentations play a crucial role.

This work presents the activities carried out by Politecnico di Milano, Italian Space Agency and Italian National Institute of Astrophysics in this framework, using data from SST networks and the observation measurements from Bistatic Radar for LEo Survey (BIRALES), an Italian bistatic radar belonging to the EUropean Space Surveillance and Tracking (EUSST), which contributed most to the monitoring of the cloud of fragments. Exploiting Two-Line Elements (TLEs) of observed fragments, a reverse engineering approach is used to reconstruct a fragmentation in orbit through the use of the software suite PUZZLE developed at Politecnico di Milano. The analyses focus on studying the fragmentation of the Cosmos 1408 satellite, which occurred on November 15th 2021 following an Anti-SATellite (ASAT) missile test. More than 1000 trackable pieces and millions of smaller debris (estimated from numerical analysis) were produced by this event, increasing the population of inactive objects around the Earth, and threatening nearby orbiting objects.

First, the processing method adopted from BIRALES in observing Cosmos debris is presented and discussed and a critical analysis about the derivable information is conducted. Then, these data and those from SST network observations are used to identify the epoch and the location of the fragmentation. In this procedure, the software toolkit PUZZLE, developed by Politecnico di Milano within a project funded by the Italian Space Agency and extended through the European Research Council, is used.

The article provides a thorough characterization of wartime space activity, which has grown and evolved significantly over the past six decades. It is substantiated that the utilization of space under the auspices of several space states has turned into a type of activity in more than 60 countries around the world. Authors carried out a study of trends in the sources of funding for the space industry, as well as identified negative factors that affect the pace of development of the space industry established in previous years, namely: problems in the world economy caused by the introduction of sanctions against the Russian Federation, inflation rates, changes in interest rates and loss Ukraine's export opportunities. We studied the European Space Agency report on changes to funding amounts for space sector projects that fit the definition of projects with rapid development for the years 2019–2022. The impact of the conflict on Ukraine's space industry and strategies for maintaining pre-war accomplishments under novel circumstances are identified. The process via which the government and private businesses fund domestic space activities is examined. The purpose of the article is a thorough analysis of the pre-war and post-war financing of space activities, as well as the formulation of the main models of financing the space industry in the post-war period in order to bring it to a new level of functioning. The research underscores space activity as a major financing priority in developed nations. Pre-war, the space industry showed rapid growth, initially state-funded, later attracting private investments. However, ongoing conflict in Ukraine led to reduced funding for less profitable projects, emphasizing the need for a balanced strategy using state and private investments for post-war reconstruction and maintaining a strong national defense capability in the global space sector.