System Mission Research Articles

Exploratory data analysis (EDA) machine learning approaches for ocean world analog mass spectrometry

Many upcoming and proposed missions to ocean worlds such as Europa, Enceladus, and Titan aim to evaluate their habitability and the existence of potential life on these moons. These missions will suffer from communication challenges and technology limitations. We review and investigate the applicability of data science and unsupervised machine learning (ML) techniques on isotope ratio mass spectrometry data (IRMS) from volatile laboratory analogs of Europa and Enceladus seawaters as a case study for development of new strategies for icy ocean world missions. Our driving science goal is to determine whether the mass spectra of volatile gases could contain information about the composition of the seawater and potential biosignatures. We implement data science and ML techniques to investigate what inherent information the spectra contain and determine whether a data science pipeline could be designed to quickly analyze data from future ocean worlds missions. In this study, we focus on the exploratory data analysis (EDA) step in the analytics pipeline. This is a crucial unsupervised learning step that allows us to understand the data in depth before subsequent steps such as predictive/supervised learning. EDA identifies and characterizes recurring patterns, significant correlation structure, and helps determine which variables are redundant and which contribute to significant variation in the lower dimensional space. In addition, EDA helps to identify irregularities such as outliers that might be due to poor data quality. We compared dimensionality reduction methods Uniform Manifold Approximation and Projection (UMAP) and Principal Component Analysis (PCA) for transforming our data from a high-dimensional space to a lower dimension, and we compared clustering algorithms for identifying data-driven groups (“clusters”) in the ocean worlds analog IRMS data and mapping these clusters to experimental conditions such as seawater composition and CO2 concentration. Such data analysis and characterization efforts are the first steps toward the longer-term science autonomy goal where similar automated ML tools could be used onboard a spacecraft to prioritize data transmissions for bandwidth-limited outer Solar System missions.

African American education in the Global South: tracing the influences of industrial training in early twentieth-century Fiji

ABSTRACT While Fiji was a British colony, in the early twentieth century, education to Indigenous Fijians was delivered by missions including the Methodist Overseas Mission of Australasia. As argued here, education delivery was influenced by policies for African Americans. Policies from Tuskegee Institute in the American South were transposed to Nausori, where i taukei (people of the land) and Indo-Fijians were encouraged into industrial mission schemes, away from traditional communal lifestyles. This article illustrates how contemporary educational philosophies for and by Black men and women were part of a broader education network that acted as a locus of colonial reform. While some in the colonial hierarchy considered his emphasis on agricultural training appropriate to their vision of Native Fijian advancement, concurrently, Fijians themselves – passing through the mission system promoted competing forms of modernisation. They used missionary education, including influences of Washington’s approach, to speak back to British power and authority.

Perfect Preparation.

Perfect Preparation.

Reliability analysis of a BWR plant system at startup stage - analysis by the GO-FLOW methodology with consideration of loop structures and phased mission problem -

A reliability analysis of a boiling water reactor (BWR) system at startup stage has been performed. This paper is a useful attempt at a reliability analysis of a phased mission system (PMS) with loop structures in a real engineering system. The system startup schedule has been set based on typical BWR system. During startup, phased mission problem occurs, and loop structures are formed in the system. The solution of Boolean expression for a reliability of loop structure has been explained. Reliability analysis has been performed by the GO-FLOW methodology; a brief explanation of the GO-FLOW has been given. The system has been modeled on a GO-FLOW chart. The loop structured parts have been modeled corresponding to the solution of the Boolean equations. The chart suggests a way to model logical loop relations in a diagram without loop structure. The PMS of a BWR system has been also modeled on the same GO-FLOW chart by using the phased mission operator. An exact analytical approach for loop structured system has been selected and both the logic of loop structures and the logic of PMS have been modeled on the same GO-FLOW chart. This allows PMS with loop structures to be easily solved. The mission success probabilities of the system have been obtained in a single computation by a single GO-FLOW chart. The proposed modeling method for logical loop structures and phased mission problem is useful in evaluating reliability and/or availability of large complex engineering systems.

The Diurnal Cycle of East Pacific Convection, Moisture, and CYGNSS Wind Speed and Fluxes

AbstractThe far eastern tropical Pacific is one of the rainiest locations on Earth. This region is characterized by a robust diurnal cycle with precipitation initiating over the Andes mountains in Colombia in the late afternoon and moving offshore overnight while organizing into mesoscale convective systems (MCSs). As the MCSs move westward, they can seed tropical easterly waves that develop into tropical cyclones. Novel measurements of near‐surface wind speeds and latent heat flux (LHFLX) from the Cyclone Global Navigation Satellite System (CYGNSS) mission and ERA5 reanalysis are used to evaluate changes to regional flow patterns, moisture, and LHFLX that favor a strong westward propagating diurnal cycle of precipitation in this region. Days with strongly versus weakly westward propagating diurnal precipitation are compared during the extended boreal summer of the CYGNSS era (May–October 2018–2021). Strongly propagating days have a more moist lower troposphere with stronger vertically integrated moisture flux convergence than days with weakly propagating precipitation. The enhanced low‐level moisture is supported by increased wind‐driven LHFLX from stronger regional flows including the Choco and Caribbean Low‐Level Jets and Panama and Papagayo gap winds. Increased offshore convergence and vorticity also help sustain convection during the days with strongly propagating precipitation. Background variations in the physical environment, as opposed to diurnal variations, seem more important for supporting a robust diurnal cycle of precipitation in the region.

A copula‐based reliability model for phased mission systems with dependent components

AbstractRecently, researches on the reliability analysis of phased mission systems (PMSs) are very popular. And most of the existing research on PMSs assumed that all the components are statistically independent on each other, which is not meet the engineering reality. The system structure changes from phase to phase in the PMSs, so the dependency among components may also change in different phases. Meanwhile, the well‐known phase dependency is also existing in the system reliability modeling. To model the varying dependency among components and phase dependency at the same time, a copula‐based method is proposed for the reliability analysis of PMS with correlated components. Firstly, the system reliability of multi‐state PMS with dependent components is evaluated by different copula functions. Then, multiple indicators are used to select the optimal copula functions for different phases. And an engineering case is illustrated to show the proposed copula‐based method.

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.