System Mission Research Articles

Preliminary design of a space debris removal mission in LEO using a solar sail

This paper discusses a space debris removal mission in low Earth orbit in which, for a preliminary design, a solar sail is used as a chaser satellite to reach, capture and de-orbit a debris object. The sail, which exploits the solar radiation pressure as its main source of thrust, is subject to the effects of aerodynamic forces, Earth’s oblateness and eclipse occurrence. Locally-optimal laws are used to control the transfer with the aim of maximizing (or minimizing) the rate of change of a specific orbital element or a suitable combination of them, depending on the transfer phase. When blended control laws are used to target the debris, the optimal weighting factors are calculated with a genetic algorithm to assess the relative importance of each orbital element. Numerical simulations show the effectiveness of locally-optimal laws in driving the sail towards the target even in the presence of the above-mentioned orbital perturbations. In a test-case scenario, a solar sail with a characteristic acceleration of 0.1 mm/s2, departing from 550 km of altitude, is able to reach the debris orbit at 1200 km of height in less than 200 days with a good accuracy level. The same analysis has been repeated for a solar sail with performance characteristics similar to those of NASA’s planned Advanced Composite Solar Sail System (ACS3) mission.

Enhancing Planetary Exploration through Digital Twins: A Tool for Virtual Prototyping and HUMS Design

In recent times, the demand for resilient space rovers has surged, which has been driven by the amplified exploration of celestial bodies such as the Moon and Mars. Recognising the limitations of direct human intervention in such environments, these rovers have gained a great deal of importance. Our proposal introduces a digital twin for space exploration rovers that seamlessly integrates intricate geometric, kinematic, and dynamic models, along with sensor and control systems. It faithfully emulates genuine real-world scenarios, providing an authentic testing ground for rover prototypes and the development of damage detection algorithms. Its flexibility in replicating diverse terrains, environmental conditions, and operational scenarios significantly expedites rover development. The digital twin serves as a valuable tool in the perfecting of damage detection systems, allowing engineers to efficiently craft diagnostic algorithms. This innovative approach not only conserves valuable resources but also ensures the robustness of space mission systems, thus enhancing the overall success and safety of planetary exploration endeavours.

Feasibility study of a Solar Electric Propulsion mission to Mars

Traditionally, space missions to outer planets have relied on large amounts of chemical propellant or flybys to achieve their objectives. This large mass consumption may be significantly reduced using electric propulsion (EP), since it allows for larger specific impulses. However, this improvement is counteracted by the lower thrust per power levels achievable with EP engines compared to chemical thrusters. Here we discuss how to find a balance for a purely solar EP (SEP) uncrewed mission to Mars. We present system engineering and mission analyses focused on the orbital mechanics. The result is the conceptual design of a realistic mission to Mars, in which any target orbit around Mars can be reached using solely present SEP technology. In particular, for a 2000 kg spacecraft propelled with a Hall effect thruster (HET), the interplanetary transfer can be performed in 363 days with less than 400 kg of fuel consumption, provided that the vehicle leaves the Earth orbit with a suitable specific energy that is attainable using current launchers. Subsequently, 300 kg of propellant are sufficient to allow for the planetary capture, plane change, and circularisation manoeuvres, finally inserting the spacecraft into a polar orbit of height between 300 km and 1000 km above the surface of Mars.

Design and experiment of a sea-air heterogeneous unmanned collaborative system for rapid inspection tasks at sea

The incorporation of Unmanned Aerial Vehicles (UAVs) into sea surface inspection and complex water navigation tasks performed by Unmanned Surface Vessels (USVs) enhances the operational capabilities and task efficiency of heterogeneous systems. The autonomous docking of USV by UAV at sea serves as a foundational and vital element for facilitating collaborative tasks among unmanned systems. Faced with the problem that the UAV visual positioning USV deck is susceptible to interference from maritime meteorological conditions and the positioning accuracy of GPS is poor, this paper introduces the UWB positioning system and analyzes and solves the error disturbance term of its positioning array under the influence of sea sway for the first time. At the same time, due to the error problem caused by the small baseline of UWB installed on the deck, an adaptive Kalman filter that combines GPS speed information and UWB positioning data is proposed to reduce error. In light of the destabilizing effects resulting from the swaying of the USV deck during UAV docking, this study proposes a USV roll and pitch stability control strategy that incorporates environmental wind and wave data. Additionally, a UAV docking controller utilizing a fuzzy PID approach has been developed to facilitate secure and stable UAV takeoff and docking operations at sea. The effectiveness of the proposed algorithm was verified through sea docking experiments under various working conditions. Finally, in the context of the multi-target maritime inspection mission of heterogeneous unmanned systems, an exploratory improved VRP algorithm is proposed, allowing UAVs to quickly and efficiently complete sea surface inspection operations.The feasibility and operational efficiency of the cooperative mission system are tested through joint simulation using Simulink and UE4 in a high-fidelity environment. This provides a reference solution for future applications of heterogeneous unmanned systems in real maritime environments.

Synergistic Retrievals of Ice in High Clouds from Elastic Backscatter Lidar, Ku-Band Radar, and Submillimeter Wave Radiometer Observations

Abstract In this study, we investigate the synergy of elastic backscatter lidar, Ku-band radar, and submillimeter-wave radiometer measurements in the retrieval of ice from satellite observations. The synergy is analyzed through the generation of a large dataset of ice water content (IWC) profiles and simulated lidar, radar and radiometer observations. The characteristics of the instruments (frequencies, sensitivities, etc.) are set based on the expected characteristics of instruments of the Atmosphere Observing System (AOS) mission. A hold-out validation methodology is used to assess the accuracy of the IWC profiles retrieved from various combinations of observations from the three instruments. Specifically, the IWC and associated observations are randomly divided into two datasets, one for training and the other for evaluation. The training dataset is used to train the retrieval algorithm, while the evaluation dataset is used to assess the retrieval performance. The dataset of IWC profiles is derived from CloudSat reflectivity and CALIOP lidar observations. The retrieval of the ice water content IWC profiles from the computed observations is achieved in two steps. In the first step, a class, of 18 potential classes characterized by different vertical distribution of IWC, is estimated from the observations. The 18 classes are predetermined based on the k-means clustering algorithm. In the second step, the IWC profile is estimated using an ensemble Kalman smoother algorithm that uses the estimated class as a priori information. The results of the study show that the synergy of lidar, radar, and radiometer observations is significant in the retrieval of the IWC profiles. Nevertheless, it should be mentioned that this synergy was found under idealized conditions, and additional work might be required to materialize it in practice. The inclusion of the lidar backscatter observations in the retrieval process has a larger impact on the retrieval performance than the inclusion of the radar observations. As ice clouds have a significant impact on atmospheric radiative processes, this work is relevant to ongoing efforts to reduce uncertainties in climate analyses and projections.

Concept of operations for the Neptune system mission Arcanum

AbstractThe Arcanum mission is a proposed L-class mother-daughter spacecraft configuration for the Neptunian system, the mass and volume of which have been maximised to highlight the wide-ranging science the next generation of launch vehicles will enable. The spacecraft is designed to address a long-neglected but high-value region of the outer Solar System, showing that current advances make such a mission more feasible than ever before. This paper adds to a series on Arcanum and specifically provides progress on the study of areas identified as critical weaknesses by the 2013–2022 decadal survey and areas relevant to the recently published Voyage 2050 recommendations to the European Space Agency (ESA).

Optimization partial mission abandonment strategy for k-out-of-n multi-state system

This paper studies a system with n multi-state components, when the number of failed components reaches k, the system fails. During system operation, all non-failed components perform all missions simultaneously. A static mission allocation strategy and a partial mission abandonment strategy are explored. Among them, static mission allocation mainly refers to the allocation of system missions in a fixed proportion according to the performance of components, while partial mission abandonment represents the selection of an appropriate time to give up some missions for the mission system that can be classified according to the characteristics of importance. The study adopts the Markov process to deduce the system reliability and mission execution success probability, and explores the balance between them according to a cost-oriented partial mission abandonment strategy. A distributed computer system is taken as an example to show the feasibility of the model application, and an optimal strategy is provided for the optimization of partial mission abandonment strategy for a system characterized by missions can be graded in the analysis.

Motorcycle Police Training and Service Vehicle Development in Hungary


 The history of the police motorcycle service is almost 100 years old, dating back to the Horthy era in the mid-1920s in Hungary. A turbulent history has interrupted his development several times, but he has remained continuous. Staffing levels peaked in the 1990s, and technology has developed rapidly, focused, and strongly since 2017. As a result, effective implementation of the service's mission system will depend on training development that can move at a pace with technical development and deliver systemic results in implementing missions. In this article, the author examined the use of police personnel authorised to drive specialised motorcycles, their main functions and the determination of the seasonal mileage. A questionnaire survey of motorcycle police officers enrolled in the Basic Motorcycle Training and License Renewal Training Programme of the Police Education and Training Centre in 2022. According to aggregated data, the average annual trip of the country's total of 218 service vehicles is 3,599 km. The main patrol category 104 (officer, patrol leader, patrol commander, team commander) is significantly better with 6589 km/year, while the secondary patrol category 114 (event scene and investigation, district officer, patrol commander, driver category) is 2266 km on average in 2022. The results of the survey highlight the low average driving of motorcycle police. This is mainly because more than 50 per cent of trained officers do not have the major task of carrying out their duties on a service motorcycle. However, due to the high quality of their execution, the training system must be restructured to make it more effective.

Detection of inland water bodies under dense biomass by CYGNSS

The reliable detection of inland water bodies under dense biomass is not possible with traditional spaceborne remote sensing systems. In this investigation, we demonstrate the capability of the National Aeronautics and Space Administration (NASA) Cyclone Global Navigation Satellite System (CYGNSS) mission to detect and quantify the extent of small water bodies under dense biomass up to 400 ton/ha in complex heterogenous scenes such as tropical rainforests. A novel inland water body product based on L1 CYGNSS data is developed using a combination of peak surface reflectivity Γp and its spread with respect to time delay and Doppler shift, as characterized by the power ratio Pratio. Only L1 CYGNSS mission data has the potential to study Earth's surface water dynamics because raw Intermediate Frequency (IF) data availability is limited. Several coherence indices are used to verify that the L-band Global Positioning System (GPS) signals are being coherently reflected by surface water bodies and attenuated by the intervening vegetation canopy. These indices include full and computationally fast versions of the entropy associated with Delay Doppler Maps (DDMs), Efull and Efast, as well as the time derivative of the phase φpeak of the reflected GPS signal. The capability to accurately resolve surface water extent under dense vegetation has been shown to improve the estimation by current state-of-art surface water extension datasets used by global methane CH4 emission models in wetlands.

Optimal tasks assignment policy in multi-task multi-attempt missions

Motivated by real-world applications like unmanned reconnaissance aerial vehicles, this paper considers a multi-task multi-attempt mission system, where each task may be attempted multiple times and each attempt may be performed simultaneously by multiple components to enhance the task completion probability. Such an active redundancy, on the other hand, incurs high cost and high risk associated with the failures of the components. To balance the reward and the risk, this paper formulates and solves a new optimization problem, which determines the number of components performing each uncompleted task in each attempt, referred to as the task assignment policy (TAP), minimizing the expected mission cost (EMC). A recursive algorithm is proposed to evaluate the EMC (aggregating the expected operational cost, cost of lost components, and cost associated with uncompleted tasks) for the considered multi-task multi-attempt system under a given TAP. Based on the suggested EMC evaluation algorithm, the genetic algorithm is implemented to solve the optimal TAP problem. A detailed case study of an unmanned reconnaissance aerial vehicle system performing five independent surveillance tasks is conducted to examine the impacts of several model parameters on the EMC, task successful completion probabilities, and the optimal TAP solutions.

Dynamics of the Tongue of Ionizations During the Geomagnetic Storm on 7 September 2015: The Altitudinal Dependences

AbstractUsing the electron density (Ne) observations from the Defense Meteorological Satellite Program, and Constellation Observing Systems for Meteorology, Ionosphere, and Climate mission and simulations from the Thermosphere Ionosphere Electrodynamic General Circulation Model. we investigate the dynamic evolution of the polar tongue of ionization (TOI) from double to single structures at different altitudes during a geomagnetic storm. The modeled Ne depicted that double and single TOIs occurred at altitudes above 300 km, respectively. During the northward turning of interplanetary magnetic field (IMF) Bz, the afternoon TOI disappeared and the morning TOI was reduced. The plasma transport due to neutral winds and ambipolar diffusion facilitated (prevented) the depletion of plasma density of the morning TOI at 300 (500) km, with a relative contribution of 42.8% and 28.6% (−15.4% and −76.9%), respectively. Downward E × B drifts led to an enhancement/reduction of plasma density in the storm enhanced density region in the lower/upper ionosphere. During the duskward turning of IMF By, the morning TOI could be mostly attributed to the anti‐sunward plasma drifts (75.8% at 300 km, 100% at 500 km), with a relatively stronger role of the zonal component than that of meridional E × B drifts. The upward E × B drifts were important/ignorable in the upper/lower ionosphere. Both the neutral winds and ambipolar diffusion resulted in an accumulation of plasma density of the morning TOI at 300 km indirectly (24.2%), however, their roles were minor at 500 km.

Evaluation of Spire GNSS-R reflectivity from multiple GNSS constellations for soil moisture estimation

ABSTRACT Spaceborne Global Navigation Satellite System-Reflectometry (GNSS-R) has emerged as a pivotal tool with different land applications, prominently encompassing soil moisture estimation. In contrast to conventional radiometer satellites commonly used for this purpose, GNSS-R offers higher spatiotemporal coverage while maintaining cost-effectiveness. The potential of using Global Positioning System (GPS) reflections measured by the Cyclone Global Navigation Satellite System (CYGNSS) mission to retrieve soil moisture has been previously demonstrated. In 2019, Spire Global Inc. launched their first GNSS-R satellites, which now comprise a constellation of four CubeSats. These satellites track reflections from multi-constellation, encompassing GPS, Galileo, BeiDou Navigation Satellite System (BDS), and Quasi-Zenith Satellite System (QZSS). In this study, an analysis and validation of Spire GNSS-R L1B surface reflectivity for soil moisture retrieval within east Australia during an eight-month period in 2021 is presented. A comparison of the estimated Spire surface reflectivity to that of CYGNSS is performed, unveiling analogous behavioural patterns and biases across both missions. Soil moisture is estimated using observations from Spire GPS-only, Spire multi-constellation, and CYGNSS. The Soil Moisture Active and Passive (SMAP) retrievals are used as the reference, presuming a linear relationship between changes in soil moisture and changes in reflectivity. Our results indicate that the Spire GNSS-R mission can detect variations in soil moisture with a performance comparable to that of CYGNSS. A median unbiased root-mean-square difference (ubRMSD) of 0.062 m3.m−3 is found for both Spire GPS and multi-constellation when using 9-km products and SMAP as the reference.

Lifecycle mission safety for space nuclear systems

The development of novel space nuclear systems by governments and companies can greatly enhance space exploration, commerce, and defense capabilities. However, the predominant safety framework for space nuclear in soft law and in practice focuses narrowly on launch safety. A Lifecycle Mission Safety Framework provides a new heuristic to guide system designers, mission planners, regulators, and international law for safety across the broad range of space nuclear applications. It expands safety goals beyond protection of the terrestrial population to workers and astronauts, as well as to activities in orbital space and planetary surfaces. By defining mission phases and identifying safety considerations in each, this framework provides for proactive identification and management of risk.

Indigenous Foodways as Persistence in the Alta California Mission System

AbstractThis article investigates Indigenous persistence within Mission Santa Clara de Asís in central California through the analysis of animal food remains. The Spanish colonial mission system within Alta California had a profound social and ecological impact on Indigenous peoples, altering traditional subsistence strategies and foodway patterns. Past research has highlighted the continued use of precolonial foods within the Alta California mission system alongside the daily consumption of colonial-style beef stews. This article expands on that literature to consider how Indigenous and colonial residents differentially acquired ingredients and prepared daily meals within the Alta California colonial mission system. This assessment demonstrates a sharp divergence between Indigenous and colonists’ daily diet, manifested in the continued use of wild food resources by Indigenous people as well as the maintenance of precolonial culinary practices in the preparation of cattle meat for daily stews. These findings complicate our understanding of foodways within the Spanish mission system and expand our understanding of Indigenous autonomy within conditions of colonialism.

Game of Drones: Multi-UAV Pursuit-Evasion Game With Online Motion Planning by Deep Reinforcement Learning.

As one of the tiniest flying objects, unmanned aerial vehicles (UAVs) are often expanded as the ``swarm'' to execute missions. In this article, we investigate the multiquadcopter and target pursuit-evasion game in the obstacles environment. For high-quality simulation of the urban environment, we propose the pursuit-evasion scenario (PES) framework to create the environment with a physics engine, which enables quadcopter agents to take actions and interact with the environment. On this basis, we construct multiagent coronal bidirectionally coordinated with target prediction network (CBC-TP Net) with a vectorized extension of multiagent deep deterministic policy gradient (MADDPG) formulation to ensure the effectiveness of the damaged ``swarm'' system in pursuit-evasion mission. Unlike traditional reinforcement learning, we design a target prediction network (TP Net) innovatively in the common framework to imitate the way of human thinking: situation prediction is always before decision-making. The experiments of the pursuit-evasion game are conducted to verify the state-of-the-art performance of the proposed strategy, both in the normal and antidamaged situations.

Reliability modeling and optimization of K/N phased mission system with backup missions and global redundancy strategy

AbstractThe mission success probability (MSP) is a critical indicator for phased mission systems (PMSs). In the modern aerospace industry, redundancy techniques, including component/phase redundancy, are commonly seen to increase the MSP of the whole system. These component/phase redundancies make the reliability analysis more complex. Meanwhile, one or more components are required for normal working for different subsystems, called the K/N structure. In this article, a Markov‐process method is proposed for PMS with K/N subsystems and different redundancy strategies. Then, a universal system optimization model is proposed to optimize system structure and redundancy strategies for all subsystems at the same time. Then, an improved genetic algorithm (GA) is used to resolve the optimization problem. At last, a propulsion system is used as an engineering case, showing the proposed binary decision diagram‐based method.

The Benefit of NASA’s Atmosphere Observing System (AOS) Mission Lidar and Polarimeter Observations for Health and Air Quality Applications

The Benefit of NASA’s Atmosphere Observing System (AOS) Mission Lidar and Polarimeter Observations for Health and Air Quality Applications

Sample return system of OKEANOS—The solar power sail for Jupiter Trojan exploration

The Japan Aerospace Exploration Agency had planned a sample return from the Jupiter Trojans using a solar power sail in its Oversize Kite-craft for Exploration and AstroNautics in the Outer Solar system (OKEANOS) mission. Solar power sail is an extended concept of solar sail consisting of a sail membrane covered with flexible solar arrays. OKEANOS is capable of generating a large amount of power sufficient to drive high-specific-impulse ion engines in the outer solar system, thus making it possible to perform sample return from the Jupiter Trojans. Various innovative technologies are needed to realize such a challenging mission in the distant space. Specifically, OKEANOS deploys a small lander to ensure the safety and save propellant of the mother spacecraft. The lander collects samples of the asteroid, and separates them into different groups, namely, those for in-situ analysis and those for return. After completing the in-situ analysis, the lander lifts off the asteroid, docks with the mother spacecraft, and delivers the samples to the reentry capsule mounted on the mother spacecraft. The reentry capsule is designed so that it can manage the reentry speed of 15 km/s. Although OKEANOS was proposed as a Japanese large-class mission and advanced to the final selection, it was not selected because of a cost issue. However, its sample return concept is inherited by small- and massive-body explorations coming in the next generations. In this paper, we report the state-of-the-art technologies that enable sample returns from the outer solar system, which were developed through the OKEANOS mission study.

Techno-economic Optimization of an Offshore Hybrid Power System: Argentine Basin Case Study

Ocean observation and monitoring relies on data gathered from multiple sources including gliders, cabled observatories, underwater vehicles, and moored buoys. Moored buoys, augmented by resident autonomous underwater vehicles, are potentially well-suited to long-term oceanographic data collection with the resolution and scope of data collection increased by utilizing in-situ power generation. While power needs could be provided by a single generation source (e.g., diesel generator, solar photovoltaics, or wave energy converter) with battery backup, a hybrid power system can potentially smooth seasonal variations that would otherwise require large generation and storage capacities, and be tailored to a locations’ resource availability. By reducing system size through hybridization, we have the potential to reduce overall system cost. To this end, we developed an optimization model that defines the generator and storage capacities of the cost-optimal hybrid power system for a given location and load profile. The model considers generation by wave energy converters, wind turbines, solar photovoltaics, diesel generators, and current turbines with a battery for energy storage. The model uses the defined load profile and location specific time series of resource availability for a time-domain simulation of the power generated and battery state of charge. Based on the power system size, mooring, and mission specific maintenance schedule, the model calculates capital and operating costs for each potential combination of generation and storage capacities. The optimization model searches the 6-dimensional design space to find the lowest cost system that can satisfy the load requirements. In this paper, we focus on a case study of a hybrid power system serving an ocean observation buoy with a resident autonomous underwater vehicle located at the Mid-Atlantic Shelf Break. Diagnostic metrics such as the cost-breakdown and generator capacity factors are evaluated to understand cost drivers and draw comparisons to the costs of single generation systems. Additionally, the model sensitivity to key assumptions such as battery life, maintenance vessel cost, survival loads, and required persistence are discussed.

Optimising plant form and function for controlled environment agriculture in space and on earth

AbstractPlanned missions to Mars and the moon stress the urgency of developing self‐sustaining food production systems for crewed, long‐term, space exploration. Here we discuss space agriculture (SpaceAg) as a sustainable complete life support system for prolonged space travel and surface missions. The unique challenges and considerations for cultivating crops in space, where radiation, gravity, atmosphere and temperature differ from Earth, are presented. We discuss the selection of suitable crops and approaches to optimise growth traits for the ideal plant form, including the potential of genetic engineering to enhance yield and nutritional content. Plants can serve multiple roles, from providing nutritious foods and wellbeing to acting as biofactories for essential pharmaceuticals. The need for robust and efficient controlled environment agriculture (CEA) systems that are integral to life support is explored. Finally, we discuss promising solutions for sustainable agriculture in controlled environments on Earth, based on SpaceAg research and innovation.