System Mission Research Articles

Of missions and marshes: Stable isotope analysis of Mission-Era Guale oyster harvesting on St. Catherines Island, Georgia

This article presents the results of oxygen stable isotope analysis on eastern oyster (Crassostrea virginica) samples (n = 25) from a Mission-Era (ca. AD 1565–1680) site, Pueblo Santa Catalina de Guale, on St. Catherines Island, GA. Stable isotope analysis was used to assess the seasonality of oyster harvesting on St. Catherines Island during the Mission Era to better understand how Spanish colonization and the Catholic mission system may have impacted Guale foodways. Five eastern oyster left valves were sampled from each known neighborhood of Pueblo Santa Catalina de Guale. Existing data regarding the seasonality of pre-colonial mollusk collection on St. Catherines Island and elsewhere in the coastal Southeast are discussed in conversation with the results of this analysis. This work indicates that Guale residents of St. Catherines Island during the Mission Era were harvesting oysters most intensely during cooler months. This pattern is consistent with estimates of pre-colonial shellfishing seasonality across the region and may even represent a modest increase in the seasonal constriction of shellfishing when compared to data from the preceding period. Salinity estimates based on the isotope data also suggest Guale people during the Mission Era were collecting from a comparatively narrower range of estuarine habitats. We argue that these subtle shifts are a consequence of the reorganization of Guale labor associated with missionization.

Reliability-Oriented Optimal DPWM Strategy for Single-Phase Five-Level T-Type Inverter in PV Systems

Many efforts have been devoted to improving the reliability of PV inverters with a focus on reliability-critical components such as power devices and capacitors. Discontinuous pulsewidth modulation (DPWM) methods are representative of improving the reliability of power devices by decreasing their thermal loadings. However, although the DPWM method affects the ripple current of the DC-link capacitor, prior-art research is only focusing on the power devices. There is a lack of study on the effect of applying the DPWM method on the reliability of the DC-link capacitor. It may have a negative effect on the reliability of the DC-link capacitor and thus affects the reliability of overall PV inverters. In this article, the influence of the DPWM method with different clamping periods on the reliability of power devices and DC-link capacitors of the single-phase five-level T-type inverter is investigated, where a 7-kW PV system and annual mission profile of PV system are considered as a case study. Then, a reliability-oriented optimal DPWM strategy is presented for the target lifetime of the T-type inverter by considering system-level reliability, including the lifetimes of both power devices and DC-link capacitors.

Intervention Strategy for the Development of Specific Competencies in the Care of the Pathological Neonate

<i>Introduction:</i> Neonatology experts affirm that neonatal complications are closely related to the performance of nurses, in such a sense the factual reasons that motivate the present study denoted a high incidence of complications in neonates assisted at the NICU of the National Hospital "Edward Francis Small Teaching Hospital in The Gambia in the period of julio-december 2021, revealed an increase in complications and the number of neonatal deaths. The solution of this assignment has as <i>objective</i>: Implement an intervention strategy for the development of specific competencies in the care of the pathological newborn that contributes to the prevention of complications and impacts on the quality of life of the child population in The Gambia. The intervention strategy implemented is based on the philosophical, sociological, psychological and epistemological ones that, from their contextualization, improvement the <i>development</i> of competencies in the care of the pathological neonate in 26 nurses who participated in the study. As a <i>result</i> of the implementation, it was possible to verify the level of promotion of the competencies to an average of 4.03, which corresponds to high levels of development and its impact on neonatal morbidity and mortality in the NICU. <i>Conclusions:</i> the intervention Strategy is the theoretical methodological concretion that from the scientific point of view emanates from the work in the training of personnel competencies in the NICU, is in correspondence with the social demands and the requirements of the Health System in the Cuban medical mission. The Gambia.

Parameteric Estimation for Reliability Function of Phased Mission Systems with Series Network

In this paper, we consider a phased mission system consisting of [Formula: see text] phases (subsystems) wherein the control flows sequentially. The mission is successful if tasks associated with every phase are successful. Density and reliability functions of the lifetime of such a system are worked out when the lifetimes of components of the subsystems follow exponential distribution. It is assumed that components in different subsystems are in series configuration and function independently. The subsystems are assumed to operate independently. A simulation study is conducted to find bias of the estimates of the parameters and the reliability function. The Root Mean Square Error (RMSE) of the estimates is also calculated.

Redundant BLDC motors control system for scientific uncrewed space missions

Brushless DC (BLDC) motors are widely used in payloads of scientific space missions. To work with this type of motor it’s required to develop a complex control system considering basic technical requirements as well as the demands to reliability linked with the space application of the system. The basic technical requirements and the demands for the reliability of the system were formulated in the article. The block commutation algorithm was selected for the system since it’s simple and it doesn’t require using a high-performance processor and precision rotor position sensors. Based on the selected algorithm and the requirements structural scheme of the control system with redundancy features was designed. Further, schematics for output stages of the system were considered. They allowed connecting one set of motors and Hall sensors to both the main and the redundant control system. To test the structural and schematic solutions a prototype board was developed. The prototype was successfully tested and the solutions were verified.

HERA: A Timepix-based radiation detection system for Exploration-class space missions

The Hybrid Electronic Radiation Assessor (HERA) system is a Timepix-based ionizing radiation detector built for NASA Exploration-class crewed missions. The HERA performs data analysis on-system and generates telemetry messages for ingestion, display, and relay by the spacecraft. Several iterations of the hardware have been flown aboard the International Space Station as payloads to test system operation and gain experience with the hardware in the space radiation environment. The HERA system and its payload operations are described, and data collected by the various HERA systems are presented.

CYGNSS Storm-Centric Tropical Cyclone Gridded Wind Speed Product

Abstract The Cyclone Global Navigation Satellite System (CYGNSS) mission has generated several new ocean surface data products. Because of its high overpass rate and ability to measure surface wind speeds through weather, these data products are typically higher temporal resolution than traditional satellite tropical cyclone (TC) data products. However, the nature of the Global Navigation Satellite Systems reflectometry (GNSS-R) signal, which is essentially a single pixelwide measurement along the CYGNSS specular point (SP) track on the ground, necessitates aggregating the wind speed data over a period of time to accurately characterize TCs in terms of intensity and structure. The standard CYGNSS level 3 (L3) wind products are averaged over 1 h, which typically is not sufficient to produce an accurate characterization. A new L3 storm-centric gridded (SCG) wind speed product is presented here. It has been developed to improve upon the standard L3 algorithm for the purpose of providing better characterization of TC wind fields over their storm life cycle. This paper describes the L3 SCG algorithm, provides examples of L3 SCG wind fields, and discusses the potential uses and limitations of the new data product.

Velocity estimation using a compact correlation velocity log

Unmanned underwater vehicles require bottom-referenced acoustic navigation aids to maintain long-term positional accuracy without surfacing. When these platforms are small, they create new design constraints for acoustic navigation aids because of the limited available space and power. Traditional acoustic navigation techniques, such as Doppler Velocity Logs, are unsuitable for use on small platforms because of the power required to maintain adequate signal to noise ratio when they are scaled in size. A compact correlation velocity log (CVL) is an alternative approach that can meet the power, space, and accuracy requirements for an acoustic navigation aid on such platforms. This device uses a single projector, a sparse receive array, and estimates platform motion using a multi-dimensional fitting algorithm over an ensemble of 3 or more pings. This presentation will discuss the theory of operation, simulation, and experimental results for a 300 kHz compact CVL that is 4 × 8 cm2. [The authors want to acknowledge Lockheed Martin Rotary and Mission Systems for their financial support of this work.]

Harpia: A hybrid system for agricultural UAV missions

The present paper introduces Harpia, a hybrid artificial intelligent planning system for UAVs. Harpia aims to execute tasks for agricultural applications with minimum human intervention. The mission's execution is on-board, running under the Robotic Operating System and executing re-planning for tasks and path planning with obstacle avoidance. The re-planning can happen after mission changes in real-time or unpredictable UAV behavior. It combines Planning Domain Definition Language for task planning, Bayesian Network to evaluate mission execution, and K-Nearest Neighbors algorithm to select a path planner. Thus, Harpia's novelty focuses on robustness for autonomously planning and re-planning the sequence of tasks and trajectories to regions of interest. The main contributions include an autonomous system architecture for planning missions with minimum human intervention, no boundary by specific tasks, and computationally simple for operating within non-convex scenarios. The computational tests report results for 21 simulated scenarios, where Harpia handled all situations properly, e.g., making decisions about task re-planning with 97.57% accuracy based on battery health and choosing the better path-planning for each case with at least 95% of accuracy.

Flight Dynamics Modeling with Multi-Model Estimation Techniques: A Consolidated Framework

In modern era of aviation technology evolution, unmanned aerial vehicles have proved to be crucial in all fields including military and research. The development of robust control system and successful mission accomplishment requires an meticulous UAV model. The aim of this paper is to lay out an elaborate model estimation scheme using various model structure techniques including Auto-regressive Exogenous, Auto-regressive Moving Average exogenous, Box Jenkin’s, Output Error, and state space and non-linear Auto-regressive Exogenous. The obtained models are then analyzed and compared for best model quality parameters like residual analysis, final prediction error and fit percentages. The efficacy of developed model through proposed model is further validated using simulations data for UAV. Results demonstrate the model’s feasibility as it properly predicts system performance over a broad variety of operating situations. To the best of our knowledge, this is the first time in the literature that a model estimation study for UAV platform with such a wide variety of model structures has been presented.

Organization Preference Knowledge Acquisition of Multi-Platform Aircraft Mission System Utilizing Frequent Closed Itemset Mining

Organization preference knowledge is critical to enhancing the intelligence and efficiency of the multi-platform aircraft mission system (MPAMS), particularly the collaboration tactics of task behaviors, platform types, and mount resources. However, it is challenging to extract such knowledge concisely, which is buried in massive historical data. Therefore, this paper proposes an innovative data-driven approach via frequent closed itemset mining (FCIM) algorithm to discover valuable MPAMS organizational knowledge. The proposed approach addresses the limitations of poor effectiveness and low mining efficiency for the previously discovered knowledge. To ensure the knowledge effectiveness, this paper designs a multi-layer knowledge discovery framework from the system-of-systems perspective, allowing to discover more systematic knowledge than traditional frameworks considering an isolated layer. Additionally, the MPAMS’s contextual capability reflecting the decision motivation is integrated into the knowledge representation, making the knowledge more intelligible to decision-makers. Further, to ensure mining efficiency, the knowledge mining process is accelerated by designing an itemset storage structure and three pruning strategies for FCIM. The simulation of 1100 air-to-sea assault scenarios has provided abundant knowledge with high interpretability. The performance superiority of the proposed approach is thoroughly verified by comparative experiments. The approach provides guidance and insights for future MPAMS development and organization optimization.

Space Launch System acoustics: Far-field noise measurements of the Artemis-I launch.

To improve understanding of super heavy-lift rocket acoustics, this letter documents initial findings from noise measurements during liftoff of the Space Launch System's Artemis-I mission. Overall sound pressure levels, waveform characteristics, and spectra are described at distances ranging from 1.5 to 5.2 km. Significant results include: (a) the solid rocket boosters' ignition overpressure is particularly intense in the direction of the pad flame trench exit; (b) post-liftoff maximum overall levels range from 127 to 136 dB, greater than pre-launch predictions; and (c) the average maximum one-third-octave spectral peak occurred at 20 Hz, causing significant deviation between flat and A-weighted levels.

Mercury's Circumsolar Dust Ring as an Imprint of a Recent Impact

A circumsolar dust ring has been recently discovered close to the orbit of Mercury. There are currently no hypotheses for the origin of this ring in the literature, so we explore four different origin scenarios here: the dust originated from (1) the sporadic meteoroid complex that comprises the major portion of the Zodiacal Cloud, (2) recent asteroidal/cometary activity, (3) hypothetical dust-generating bodies locked in mean-motion resonances beyond Mercury, and (4) bodies co-orbiting with Mercury. We find that only scenario (4) reproduces the observed structure and location of Mercury’s dust ring. However, the lifetimes of Mercury’s co-orbitals (<20 Ma) preclude a primordial origin of the co-orbiting source population due to dynamical instabilities and meteoroid bombardment, demanding a recent event feeding the observed dust ring. We find that an impact on Mercury can eject debris into the co-orbital resonance. We estimate the ages of six candidate impacts that formed craters larger than 40 km in diameter using high-resolution spacecraft data from MESSENGER and find two craters with estimated surface ages younger than 50 Ma. We find that the amount of mass transported from Mercury’s surface into the co-orbital resonance from these two impacts is several orders of magnitude smaller than what is needed to explain the magnitude of Mercury’s ring inferred from remote sensing. Therefore we suggest that numerous younger, smaller impacts collectively contributed to the origin of the ring. We conclude that the recent impact hypothesis for the origin of Mercury’s dust ring is a viable scenario, whose validity can be constrained by future inner solar system missions.

Observed Atmospheric Features for the 2022 Hunga Tonga Volcanic Eruption from Joint Polar Satellite System Science Data Products

The Joint Polar Satellite System (JPSS) mission has provided over ten years of high-quality data products for environment forecasting and monitoring through the current Suomi National Polar-orbiting Partnership (S-NPP) and NOAA-20 satellites. Particularly, the sensor data record (SDR) and the derived environmental data record (EDR) products from the Visible Infrared Imaging Radiometer Suite (VIIRS), the Cross-track Infrared Sounder (CrIS), the Advanced Technology Microwave Sounder (ATMS), and the Ozone Mapping and Profiler Suite (OMPS) offer an unprecedented opportunity to observe severe weather and environmental events over the Earth. This paper presents the observations about atmospheric features of the Hunga Tonga Volcanic eruption of January 2022, e.g., the gravity wave, volcanic cloud, and aerosol (sulfate) plume phenomena, by using the ATMS, CrIS, OMPS, and VIIRS SDR and EDR products. Powerful gravity waves ringing through the atmosphere after the eruption of the Hunga Tonga volcano are discovered at two CrIS upper sounding channels (670 cm−1 and 2320 cm−1) in the deviations of the observed brightness temperature (O) from the simulated baseline brightness temperature (B) using the Community Radiative Transfer Model (CRTM), i.e., O—B. A similar pattern is also observed in the ATMS global maps at channel 15, whose peak weighting function is around 40 km, showing the atmospheric disturbance caused by the eruption that reached 40 km above the surface. The Tonga volcanic cloud (plume) was also captured by the OMPS SO2 EDR product. The gravity wave features were also captured in the native resolution image of the S-NPP VIIRS I-5 band nighttime observations. In addition, the VIIRS Aerosol Optical Depth (AOD) captured and tracked the volcanic aerosol (sulfate) plume successfully. These discoveries demonstrate the scientific potential of the JPSS SDR and EDR products in monitoring and tracking the eruption of the Hunga Tonga volcano and its severe environmental impacts. This paper presents the atmospheric features of the Hunga Tonga volcano eruption that is uniquely captured by all four advanced sensors onboard JPSS satellites, with different spectral coverages and spatial resolutions.

SpaceWire-to-UWB Wireless Interface Units for Intra-spacecraft Communication Links.

In the context of the Eu:CROPIS mission requirements, this paper aims to test and validate an intra-spacecraft wireless transmission carried between two SpW-to-UWB Wireless Interface Units (WIUs). The WIUs are designed to replace the on-board SpaceWire (SpW) connections of a spacecraft network. The novelty of this solution resides in prototyping and testing proprietary TRL6 WIUs for the implementation of both PDHU and CDHU units, which constitute a spacecraft network. The validation test scenarios employed in this paper were designed under the Eu:CROPIS mission system requirements as defined by the WiSAT-3 European Space Agency (ESA)-funded project. The SpW-to-UWB WIUs run a custom-built ISA100 over an IEEE 802.15.4 UWB PHY layer communication stack. The WIUs are evaluated based on four mission-specific performance test scenarios: (1) the link setup test, (2) the end-to-end delay test, (3) the maximum data rate test and (4) the housekeeping test. The validation test scenarios of the WIUs are carried out with the use of STAR-Dundee SpW-capable equipment. The test results demonstrate the reliability of the deployed SpW-to-UWB WIUs devices for UWB wireless communications carried out within a space shuttle. The SpW data were successfully transmitted across the intra-spacecraft wireless network in all experimental tests. The technology can be considered to be at the maturity level TRL6 (functionality demonstrated in relevant environment) for LEO missions.

Baptism Between Empires: A Coast Miwok Family in the Pacific World

Scholarship has documented in detail how Spanish colonists forced California Indians to convert to Catholicism, but some Indigenous converts managed to avoid confinement in the mission system, particularly those who resided in the borderlands between Spanish and Russian settlements. This contribution to the roundtable considers the travels of one Coast Miwok family who avoided confinement and preserved local control over tribal homelands by assiduously cultivating links with Catholic and Russian Orthodox churches while holding colonial newcomers at arm's length.

Sustaining a Mars Colony through Integration of Single-Cell Oil in Biological Life Support Systems

Abstract As humanity sets its sights on establishing a sustainable and prosperous colony on Mars, the main challenges to be overcome are ensuring a reliable and nutritious food supply for settlers, feedstock for 3D printing, fuel and pharmaceuticals. While various solutions for production of essential products on Mars have been proposed, there is growing interest in the use of microorganisms as the main production units. This scientific review article proposes a novel concept of using single cell oil (SCO) as a versatile feedstock for various applications in a bioregenerative life support system (BLSS) for space missions. The authors suggest using outputs from autotrophic systems, such as cyanobacteria biomass and oxygen, to cultivate SCO-producing microorganisms from the class Labyrinthulomycetes. The produced SCO can be used for food, fuel, 3D printing materials, and pharmaceuticals. This approach can potentially reduce the importance of carbohydrates in space foods, offering various benefits, including a reduction in food weight, simpler, lightweight, more compact bioreactors, launch cost reduction, potentially improved mental and cognitive performance, and reduced fatigue for the crew. The authors also suggest using SCO as the feedstock for the production of 3D printable filaments and resins and as a supplementary fuel source for space colonies. While the concept is hypothetical, the theoretical foundation is solid, and this approach could potentially become an important element required for the establishment of a successful Mars colony.

Exploiting Frequency-Domain Information of GNSS Reflectometry for Sea Surface Wind Speed Retrieval

Global navigation satellite system reflectometry (GNSS-R) Delay-Doppler map measures the sea surface roughness, which has recently been applied to retrieve sea surface wind speed. However, current studies on GNSS-R wind speed retrieval only use the spatial domain of the delay-Doppler map without considering the variations patterns in the map, which is regarded as frequency domain information of the map. In this study, we propose a joint frequency-spatial-domain wind speed retrieval network (FSNet) based on reflectivity data provided by the Cyclone Global Navigation Satellite System (CyGNSS) mission. We construct a matchup dataset between the CyGNSS satellite data and ECMWF model data from January 1, 2018, to December 31, 2019. The wind speed range is 0–25 m/s. Using the proposed FSNet, frequency and spatial features are simultaneously extracted. The frequency domain feature supplements the spatial-domain information of the mid and high-level features in the neural network. Rather than directly concatenating the frequency-domain features with the spatial-domain features, we designed a feature fusion module to fuse frequency and spatial features for wind speed retrieval adaptively. Experiments show that our FSNet wind speed retrieval has a root mean square error (RMSE) of 1.63 m/s for a wind range of 0-25 m/s. This accuracy is 25.4% better than the operational algorithm provided by the CyGNSS Level 2 wind speed product. For a higher wind range of 16-25m/s, FSNet performed even better, improving the RMSE by 31%.

Model Predictive Framework for Guidance and Control of a Multi-Satellite Assembly in Elliptic Orbit

In this paper, a guidance and control system for multi-satellite assembly missions in proximity operations is proposed. Utilizing the Tschauner-Hempel relative motion equations, the system is developed within the framework of model predictive control. Linear inequality constraints are employed to handle control input saturation of thrusters and to ensure collision avoidance between satellites. Additionally, a new line-of-sight constraint method is introduced to facilitate smooth docking while simplifying the optimization problem. The proposed algorithm aims to minimize a predefined cost function, which is a weighted sum of state errors and control efforts. At each sampling time, an online quadratic optimization problem is solved to determine the optimal control action that satisfies all mission constraints. Nonlinear numerical simulations in MATLAB are used to demonstrate that the proposed guidance and control system achieves the desired performance. The algorithm is tested for various multi-satellite assembly configurations (cubic and hexagonal) in elliptic orbits of arbitrary eccentricity. A comparative study is conducted between the proposed algorithm and a linear model predictive control algorithm based on the Clohessy-Wiltshire linear model. The results show that the proposed algorithm achieves superior performance in terms of constraint satisfaction and control efforts.

MANEUVERABILITY, ONE OF THE MOST IMPORTANT FEATURES OF AIR DEFENCE SYSTEMS

The basic Surface-to-Air Missile System (SAMS) mission is to combat and destroy the aerial threats on the close and direct ways of access to the defended anti-aircraft objectives, before they fulfil their mission. The main features of Air Defence Systems will aim to increase the effectiveness, Electronic Counter-Counter Measures (ECCM), short reaction time, mobility and stability in work during the day or at night regardless of the weather conditions.