Satellite Tracking Research Articles

Natural and Artificial Structures Influence the Movement and Habitat Connectivity of Whale Sharks (Rhincodon typus) Across Seascapes

ABSTRACTAimTo understand how natural geomorphological features and oil and gas platforms (OG platforms) influence the habitat use and seascape connectivity of the whale shark (Rhincodon typus).LocationEast‐Indian Ocean and North‐West Australia.MethodsWe compiled a satellite tracking dataset of 78 whale sharks tagged across a 14‐year period at Ningaloo Reef and Shark Bay World Heritage Areas in Western Australia to develop spatial networks for the regions of the East‐Indian Ocean and North‐West Australia. We then applied a Bayesian modelling framework to assess the effects of natural features and OG platforms on spatial patterns and habitat connectivity.ResultsGeomorphological features such as pinnacles, canyons, and seamounts promoted habitat connectivity and strongly influenced the habitat use of whale sharks across both regional (1000's km; East‐Indian Ocean) and local (100's km; North‐West Australia) spatial scales. In the North‐West of Australia, OG platforms had similar effects on habitat use as natural feature types and also enhanced habitat connectivity. The OG platforms most visited by whale sharks were situated close to the edge of the continental shelf and near natural geomorphological features that likely enhance productivity.Main ConclusionOur work identified natural geomorphological features that promoted habitat use and connectivity for whale sharks across oceanic and coastal seascapes. Sharks routinely visited OG platforms, which acted as migratory stepping stones that further enhanced habitat connectivity. Protection of natural feature types that promote habitat use and connectivity could assist conservation management of whale sharks. We suggest that the influence of OG platforms on their movement and habitat use beyond individual structures, should be considered in environmental impact assessments during operation and decommissioning phases.

Satellite tracking reveals critical habitats and migratory pathways for green and hawksbill turtles nesting in Montserrat, Eastern Caribbean

The United Kingdom Overseas Territory of Montserrat supports modest but regionally important nesting populations of green and hawksbill turtles. However, knowledge of the spatial ecology and regional connectivity of these populations is limited. Here, we provide the first detailed description of the spatial distribution, migratory connectivity, and habitat use of 9 adult female green turtles Chelonia mydas and 1 adult female hawksbill turtle Eretmochelys imbricata tagged with satellite transmitters at 4 nesting beaches in Montserrat. Two critical aggregation areas for inter-nesting green turtles were identified along the western coast of Montserrat which could act as focal points for spatial protection. Nine individuals, including the hawksbill turtle, performed transboundary post-nesting migrations, covering distances from 45 to 1013 km, and crossing 10 different national jurisdictions. Green turtles migrated to foraging grounds in Antigua and Barbuda (n = 4), United States Virgin Islands (n = 2), Puerto Rico (n = 1), and Dominican Republic (n = 1), whereas the hawksbill turtle migrated to a foraging ground in Guadeloupe. One green turtle remained resident in Montserrat. Within foraging grounds, green turtles primarily occupied sand, seagrass, and hardbottom algal habitats located in shallow (<25 m) coastal waters. On average, turtles spent 22 and 24% of their time within Marine Protected Areas during migration and foraging periods, respectively. Our results provide novel insights into the ecology of individuals nesting at a previously understudied rookery that can be used to inform local and regional management.

Satellite Altimetry and Seasonal Circulation in the Ligurian Sea

Satellite altimetry observations are checked against in situ measurements to assess the capability of this remote sensing technique to describe the surface circulation in the Ligurian Sea. CTD profiles were collected during five oceanographic campaigns from 2017 and 2024 along the satellite track Jason 044, crossing the Ligurian Sea from the Corsica Channel to the coast close to Genoa. Eight months of ADCP surface currents from a fixed mooring were also used for the comparison with altimetric-derived geostrophic currents. Moreover, the possible contribution of ICESat-2 to oceanographic studies in the area is investigated. Altimetric measurements successfully reproduce the basic circulation features of the region and their seasonal variation and, despite the different nature of the used systems, can be well integrated with in situ observations. The results from the direct comparison with daily mean values of ADCP surface currents reported an RMSD of the same order as the standard deviation, which is consistent with similar investigations in other areas but evidences the need to define more appropriate metrics and methods.

Arctic migrating barnacle geese utilize accommodation fields in a new agricultural staging area

Abstract The recovery of threatened species after conservation measures can lead to human–wildlife conflicts. One example of such is the recent population growth of the Barnacle Goose Branta leucopsis, a large herbivorous bird. During migration, geese stage in large numbers on agricultural fields in range countries and cause substantial damage to farms. A combination of repelling fields, where geese were chased off by humans, and accommodation fields, which provide refuge sites for foraging geese, has been suggested as an effective management tool to mitigate conflicts. Using high‐resolution satellite tracking data, we investigated habitat selection of 41 barnacle geese staging in Northern Karelia, Finland, during spring 2021. We estimated relative habitat use by these geese and conducted a fine‐scale analysis of their use of different fields by employing Hidden Markov Models and integrated step‐selection analysis. Fields included normal crop (no goose management), project and other (private and Nature 2000 area) accommodation fields and repelling fields. Project accommodation and repelling fields were established on areas known to have a long history of high grazing pressure by barnacle geese. We found that behavioural data of geese can be categorized into three different states (static, slow and fast movement). Static and slow states were used for local field selection, fast state for field selection in the regional area, and all states for field selection after leaving a repelling field. Overall, relative habitat use indicated that geese utilize accommodation fields more than expected by their availability. Integrated step‐selection analyses revealed that geese avoided normal and repelling versus project accommodation fields at the regional scale. At the local scale, they preferred project accommodation fields over all other fields. After leaving a repelling field, geese did not show preference for any accommodation over repelling fields. Synthesis and application. Geese show individual selection for accommodation fields compared to normal or repelling fields across several scales. Our results suggest that the accommodation field concept—consisting of refuge areas and no‐go areas where geese are repelled from—can help to mitigate the human–wildlife conflict using local stakeholders' knowledge.

Operational field trialling of Felixer™ grooming traps for the control of feral cats in the Strzelecki Desert, Australia

Context Feral cats (Felis catus) have an impact on native wildlife populations around the world but are difficult to control because of their neophobic behaviours and preference for live prey over scavenging poisoned baits. Felixers™ address these challenges by squirting poison-gel directly onto feral cats, exploiting their fastidious oral grooming tendencies to facilitate poison ingestion. Aims This study trialled Felixers in a landscape-scale arid-ecosystem site to assess their capacity to sustainably manage cat populations in a semi-bounded in situ predator training area and to eradicate cat incursions into a feral-free safe haven. Specifically, the aims were to determine target specificity and firing rates; optimise installation sites to exploit cat behaviour and landscape features; assess the fate of individuals following Felixer interaction; and assess the overall cost, performance and efficacy of Felixers compared with conventional cat control methods. Methods Up to nine Felixers were simultaneously deployed across three trial periods, spanning 30 months (4,642 trap nights) in Sturt National Park in the Strzelecki Desert dunefields of Australia. Felixers were deployed within and outside of feral-free safe havens, at varying cat densities, with populations monitored through camera-trap activity indices and individual behaviour monitored through satellite tracking. Key results Felixers fired at 20.3–43.9% of cats that passed in front (292 of 1,144 cats), with the remainder failing to satisfy the discriminatory algorithm’s target criteria. The devices had 99.93% target specificity from 17,425 interactions with moving animals and objects. Overall cat activity was lower in a semi-bounded 10,400 ha landscape-scale area where Felixers were intensively used, relative to an adjacent unbounded area where no cat control was occurring, over a 12-month subset of the 30-month trial. Felixers also resolved one of two incursions by cats into a 2,000 ha safe haven. Optimisation of Felixer placement and upgrading of software drove improvements in technical reliability and target identification during the trial. Shortcomings included cost and high incidence of technical faults, causing significant downtime and requiring regular investment of field staff time for monitoring and resolution. Conclusions Felixers provide a safe tool for cat management and eradication at intensively managed conservation sites. Efficacy could be improved through reductions in cost and improvements in reliability. Implications Overall Felixers appear to be an effective tool for cat management, when used in an integrated approach.

Post-nesting migrations of green turtles from Aldabra Atoll, Seychelles: satellite tracking, flipper tag returns and marine protected areas

To effectively implement protective measures for migratory species such as marine turtles, knowledge of their breeding grounds, foraging areas, migratory pathways and possible threats encountered is required. Aldabra Atoll, a UNESCO World Heritage site in Seychelles, hosts and protects one of the largest nesting populations of green turtles Chelonia mydas in the Western Indian Ocean. We satellite tracked 21 post-nesting green turtles during 2011-2014 (n = 8) and in 2022 (n = 13). Nineteen turtles were tracked beyond Aldabra and took 8-49 d to reach their final recorded locations, travelling 743-2552 km along distinct routes, each taking a unique path to widely dispersed coastal sites in Tanzania, Madagascar, Somalia, Kenya, Mozambique and Seychelles, highlighting the connectivity of the region through one large rookery. When compared to the locations of 54 international flipper tag returns from Aldabra females recorded since the 1980s, there was consistency in the use of Tanzania, Kenya, Mozambique, Somalia and Madagascar as foraging destination countries for Aldabra turtles. However, satellite tracking expanded the countries used as foraging sites to include Seychelles and elevated the relative importance of remote sites for which fishermen were unlikely to report intercepted flipper tags—especially Somalia, northern Madagascar and distant offshore foraging habitat within Seychelles. The end points for >40% of the turtles were within or nearby marine protected areas (MPAs) in Madagascar, Mozambique, Tanzania and Seychelles, 5 (26.3%) within MPAs and 3 (15.8%) <25 km away from MPAs. Eleven (57.9%) turtles travelled through MPAs after leaving the Aldabra protected zone. There is further opportunity to increase the protection and connectivity of foraging areas by expanding existing MPAs. Identifying foraging hot spots within the region by pooling data from other important breeding grounds should be a priority to focus conservation efforts on migratory corridors and the status and state of those foraging areas.

Habitat suitability modeling of loggerhead sea turtles in the Central-Eastern Mediterranean Sea: a machine learning approach using satellite tracking data

Understanding how sea turtle species move through the environment and respond to environmental features is fundamental for sustainable ecosystem management and effective conservation. This study investigates the habitat suitability of the loggerhead sea turtle (Caretta caretta) in the Adriatic and Northern Ionian Seas (Central-Eastern Mediterranean) by developing and validating a multidisciplinary framework that leverages machine learning to investigate movement patterns collected by satellite tags Argos satellite tags. Satellite tracking data, enriched with sixteen environmental variables from the Copernicus Marine Service and EMODnet-bathymetry, were analyzed using Random Forest models, obtaining an accuracy of 80.9% when classifying presence versus pseudo-absence of loggerhead sea turtles. As main findings, sea bottom depth, surface chlorophyll (chl-a), and mixed layer depth (MLD) were identified as the most influential features in the habitat suitability of these specimens. Moreover, statistically significant differences, evaluated using t-test statistics, were found between coastal and pelagic locations, for the different seasons, in mixed layer depth, chl-a, 3D-clorophyll, salinity and phosphate. Although based on a limited sample of tagged animals, this study demonstrates that the distribution patterns of loggerhead sea turtles in Mediterranean coastal and pelagic areas are primarily influenced by sea water features linked to productivity and, consequently, to potential prey abundance. Additionally, this multidisciplinary framework presents a replicable approach that can be adapted for various species and regions.

Projected expansion in two influenza-susceptible birds' distribution under climate and land-cover changes on the Qinghai-Tibetan Plateau

Avian influenza is a global zoonotic disease influencing bird conservation and public health. Climate and land-cover changes can significantly impact influenza-susceptible species' distribution, thereby influencing avian influenza outbreaks. The Qinghai-Tibetan Plateau (QTP) plays a crucial role in avian influenza virus transmission and is susceptible to environmental changes. Here, we focused on two influenza-susceptible birds, the bar-headed goose (Anser indicus) and brown-headed gull (Chroicocephalus brunnicephalus), to predict their distribution on the QTP under climate and land-cover change scenarios. We integrated satellite tracking, field surveys, and publicly available datasets to collect species occurrence. Then, we utilized Biomod models to predict bird distribution under current and future scenarios. Our results indicated that the distance to water bodies (DW) and the mean temperature of the wettest quarter (BIO 8) significantly influenced the distribution of bar-headed geese and brown-headed gulls. The highly suitable distributions of both species are concentrated in the northeastern QTP and the Changtang Plateau, with only the Qaidam Basin showing a decrease in the future. Their future distribution has roughly doubled, with expansions toward western and higher elevations. We highlighted the influence of climate and land cover changes on bird distribution, and identified key areas of bird distribution, which are also critical areas for future avian influenza monitoring and prevention.

New Astronomical Observatory Design for the Detection and Tracking of Satellite Objects: The Satellite Robotic Observatory (SRO)

Robotic Astronomical Observatories (RAOs) have provided very good results in different research projects in astrophysics/astronomy. Their applications in the detection, tracking, and identification of near-Earth objects have contributed to the identification of potentially dangerous objects for our security, such as near-Earth Objects (NEOs), near-Earth Asteroids (NEAs), meteors, and comets, whose trajectory changes can cause an impact on our planet. If advances in astrometry techniques (measuring the position and trajectory of Earth-orbiting objects) and photometry (variation in light curves) are considered together with the new sensors that work in the optical and near-infrared spectral ranges, a new observatory system that allows for the detection of nearby satellite objects in different spectral ranges and with better-defined optics can be developed. The present paper describes the design of a new observatory applied to the surveillance and tracking of satellites and other debris objects, the Satellite Robotic Observatory (SRO). Starting from general constraints from astronomy observatories, the design process has been determined, considering the main objectives, the necessary sensors, and several technical improvements that have contributed to a final configuration proposed for the SRO. The result is the design of a portable observatory model that can host at least two sensors to track and monitor satellite objects simultaneously.

Stopover habitat use of coastal Pied Avocet revealed by satellite tracking and remote sensing technology

Stopover sites identification for migratory waterbirds is important in China’s coastal wetlands, which have experienced a massive loss of natural wetlands in recent decades. Taking the Pied Avocet (Recurvirostra avosetta), a common waterbird in China’s coastal zone as an example, our research focused on their stopover habitat use based on satellite tracking and remote sensing technology. Along the coast, a total of 6 critical stopover sites, duration of stay more than 14 days, were recognized during their 2022–2023 autumn and spring migrations of the 4 tagged individuals. The results showed that Pied Avocets used habitats close to the coastline and water source, at low elevation, and with sparse vegetation. They also had a certain tolerance for human interference. From the perspective of the land use and land cover type, the proportion (33.01 %) of artificial wetlands including paddy, salt pan, and mariculture has exceeded that (27.97 %) of natural wetlands such as bottomland, tidal flat, estuarine waters, and shallow water in the home ranges of the 6 stopover areas. The study emphasized that the habitat function of artificial wetland should be paid enough attention to while maintaining the natural wetland without further loss. In addition, habitat-oriented management suggestions were put forward for artificial wetlands. This study can provide data and technical support for the conservation and management of waterbirds stopovers, also having reference value for other species.

Interannual Variability and Trend of the Bering Strait Throughflow Gleaned from Satellite Altimeters

Abstract Beginning with the TOPEX/Poseidon altimetry mission in 1992, along-track satellite sea surface height (SSH) estimates have been taken every 6–7 km at 10-day intervals at a cluster of satellite tracks across the Bering Strait near 66°N where the satellite tracks turn. Year-to-year geostrophic SSH estimates of the Bering Strait flow show that the flow in the warmer months is almost entirely confined to a 50-m-depth channel rather than the whole cross-sectional area and that the peak-to-peak transport change is comparable to the approximate 0.8 Sverdrup mean (Sv; 1 Sv ≡ 106 m3 s−1). Energy flux calculations using the high-resolution SSH across the Bering Strait, as well as an analysis of historical coastal Russian sea levels and wind stress along the Russian Arctic and Bering Sea shelves, suggest that the interannual Bering Strait transport in the warmer water months can be described using wind-forced arrested topographic waves (ATWs) driven by along-shelf wind stress on both the Russian Arctic and Bering Sea shelves. Most of the Bering Strait transport is barotropic and in the 50-m-depth channel, but analysis of SSH and in situ Alaskan coastal sea level shows that interannual transport variations in the narrow baroclinic Alaskan Coastal Current are not negligible. In disagreement with previous transport estimates, the satellite SSH analysis and almost all of the in situ current measurements do not indicate a significant long-term trend in the barotropic Bering Strait northward transport in the warmer water late summer/fall months. Significance Statement The shallow, narrow Bering Strait between eastern Siberia and Alaska is a key climate pathway linking the Pacific Ocean and the Bering Sea to the Arctic Ocean. By utilizing nearly three decades of satellite sea surface height, we found that warmer water month volume transport through the Bering Strait in this remote, harsh environment can be monitored by satellite. Analysis suggests that the average warmer month interannual flows are remotely driven by interannual along-shelf winds on the Russian Arctic and Bering Sea shelves and that the warmer month flow has not increased over the last three decades. As the Arctic continues to warm, more ice-free data will only enhance the utility of this remote Bering Strait transport monitoring.

Comprehensive analysis of different GNSS receivers performance based on PPP-AR and positioning accuracy during 22 geomagnetic storms in 2023

Geomagnetic storms induced ionospheric disturbances can degrade the positioning accuracy and Ambiguity Resolution (PPP-AR) of GPS Precise Point Positioning (PPP), and this negative effect varies among different GNSS receivers. Under current conditions with frequent geomagnetic storms occurrences during the peak of solar cycle 25, selecting GNSS receivers with strong resistance to ionospheric disturbances is meaningful for precise GNSS positioning and ionospheric research. Therefore, it is necessary to conduct a comprehensive comparison and evaluation of the performance for different GNSS receivers under geomagnetic storms. Based on 22 geomagnetic storms in 2023, we investigated the three-dimensional root mean square error (3D RMS) and ambiguity resolved percentage (ARP), which is defined as the ratio of the number of carrier-phase observations with fixed ambiguities to the total number of phase measurements of GPS kinematic PPP, across ten groups of collocated stations around the world. For the groups using different receiver brands, the performance ranking for positioning accuracy and PPP-AR during geomagnetic storms are as follows: TPS > JVAVD > SEPTENTRIO > TRIMBLE. The station with a larger average ARP generally has a smaller average 3D RMS error than the another GNSS station. The average 3D RMS error between collocated stations using different receiver brands is typically greater than 0.010 m and even larger. The largest 3D RMS error difference is observed between collocated stations with SEPTENTRIO and JAVAD receivers, with 3D RMS errors of 0.089 m and 0.019 m, respectively. These identical-brand receivers with different types are as follows: TPS NET-G5 > TPS NET-G3A, TRIMBLE ALLOY > TRIMBLE NETRS, SEPT POLARX5TR > SEPT POLARX5S, and LEICA GR10 > LEICA GR30, respectively. The average differences in 3D RMS and ARP can reach up to 0.021 m and 6.0%, respectively. We found that the choice of antennas does not significantly affect PPP positioning performance during storms, with differences in average 3D RMS below 0.005 m and ARP differences below 0.2%.. Higher latitudes have more satellites affected by ionospheric disturbances, while this effect is typically only observed during strong storms (Dstmin≤-100nT) in mid-latitudes. Adequate available GPS satellites are crucial for achieving high PPP-AR and positioning accuracy during storms. The variations of disturbed satellites and the average Rate of Total Electron Content Index (ROTI) for collocated stations are generally consistent. However, there are differences in the average of ROTI values for different receivers under geomagnetic storms. The differences in PPP-AR performance and ROTI values among different receivers under geomagnetic storms can be attributed to the variations in satellite tracking algorithms, tracking loop designs, firmware, and multipath mitigation methods used by different receivers. These findings can provide a reference value and future research direction for selection, application and enhancement for different receivers to achieve GNSS high precision positioning under complex space weather conditions.

Green turtle tracking leads the discovery of seagrass blue carbon resources.

Seagrass meadows are natural carbon sinks, and their conservation and restoration play a crucial role in climate change mitigation and adaptation. However, blue carbon projects are hindered, in most nations, by major gaps in understanding the distribution and extent of seagrasses. Here, we show how satellite tracking of green turtles (Chelonia mydas) provided a major advance in identifying novel seagrass blue carbon resources in the Red Sea. By tracking 53 nesting green turtles, we identified 38 distinctive foraging sites. All ground-truthed foraging sites (100%) identified a seagrass meadow, surpassing the 40% (n = 30) accuracy of satellite imagery-based inferences. Sampling from these turtle-derived locations represents a greater range of depths than previously sampled in the Red Sea providing a carbon stock estimate of 4.89 ± 0.83 kg Corg (organic carbon) m-2. By improving estimates of seagrass extent and associated blue carbon, our approach can support the conservation of blue carbon resources in data-deficient regions worldwide.

Integrated Assessment of Survival, Movement, and Reproduction in Migratory Birds: A Study on Evaluating Reinforcement Success.

Conservation managers increasingly employ reinforcement techniques to bolster declining populations by reintroducing non-wild individuals born in captivity into natural habitats, but success rates remain modest. In this study, the success is evaluated of reinforcement efforts using satellite tracking and field observation data collected between 2010 and 2021. It focuses on 13 non-wild individuals, as follows: seven red-crowned cranes Grus japonensis, two white-naped cranes Antigone vipio, and four demoiselle cranes Anthropoides virgo, as well as five wild individuals including two red-crowned cranes and three white-naped cranes. The assessment criteria included survival, movement, and reproduction, utilizing a comprehensive scoring method. The scoring process indicates that more timely field observation records and the movement pattern scoring combining models and trajectories can improve the accuracy of estimation. From the results, although wild individuals generally achieve higher scores across these metrics, statistical differences were not significant possibly due to limited sample size. Notably, non-wild individuals frequently displayed residence, nomadic, or abnormal migration. In addition, field observations underscored the benefits of pairing non-wild individuals with their wild counterparts to enhance migration success. So in order to enhance migration success, it is advisable to release non-wild individuals approaching sexual maturity in proximity to wild subadult flocks during the breeding or summering periods. Additionally, during the overwintering phase, these individuals should be released in areas where wild populations are concentrated.

Mathematical approaches to fisheries quota management: ensuring sustainable practices in U.S. commercial fishing

Fisheries quota management plays a critical role in ensuring the sustainability of commercial fishing practices, particularly in the United States, where overfishing and resource depletion pose significant challenges to marine ecosystems. This review explores the mathematical approaches utilized to manage fisheries quotas effectively and sustainably. The paper examines key mathematical models, including population dynamics, bioeconomic models, game theory, and Catch-per-Unit-Effort (CPUE) models, highlighting their role in maintaining fish stock levels and regulating fishing activities. Through case studies from U.S. fisheries, such as the New England groundfish and Alaska pollock fisheries, the review assesses the effectiveness of these models in real-world applications. Additionally, it explores how advances in technology, such as satellite tracking, big data, and artificial intelligence, are enhancing the accuracy and adaptability of fisheries management models. The review concludes with insights into future directions for mathematical approaches in fisheries management, emphasizing the need for continuous innovation to support sustainable commercial fishing practices. By integrating advanced mathematical techniques and data-driven models, this paper aims to provide a pathway for policymakers and fisheries managers to achieve long-term sustainability in U.S. commercial fisheries.

Using satellite tracking to assess the use of protected areas and alternative roosts by Whooper and Bewick's Swans

Protected areas are one of the major tools used in the conservation of biodiversity, but animals are unlikely always to remain within these human‐made boundaries. Understanding when and why species choose to leave protected areas can help us to improve the effectiveness of these management tools. Here, we investigate the use of protected and non‐protected areas by two migratory species undergoing rapid wintering population changes in northwest Europe: Whooper Swans Cygnus cygnus and Bewick's Swans Cygnus columbianus bewickii. Global positioning system tags were fitted to 15 Whooper Swans in winter 2008/09 and to 18 Bewick's Swans from winter 2013/14 to 2014/15 at the Ouse Washes Special Protection Area (an internationally important roost for wintering waterbirds) and on adjacent fields in southeast England. Here, swans feed on farmland during the day but return to designated reserves to roost at night, where they receive protection from predators and disturbance within managed roost habitats. When swans roost elsewhere at alternative sites, they may face more adverse conditions, and so understanding the extent and causes of the use of alternative roosts is important for swan conservation efforts. The alternative roosting proportion, defined as the proportion of nights spent outside protected reserves, was 0.237 for Bewick's Swans and challenging to quantify accurately for Whooper Swans. A generalized additive mixed model to model repeated measurements on individuals showed that the proportion of time that Bewick's Swans spent at alternative roosts correlated positively with river level and negatively with temperature. Competition and foraging flight distances are thought to drive these relationships, as swans seek access both to roost space and to nearby feeding habitats. Our findings improve our understanding of the environmental conditions under which migratory waterbirds may choose to roost outside protected areas.

Control system design for azimuth position of earth station antennas

Smart earth station antennas have been used for several decades in many applications, from satellite communications to space object detection and tracking. The accuracy of the azimuth position for such antennas plays a crucial role in most steerable ground station antennas. Satellite tracking and space object detection demand precise tracking capabilities from the Earth. Several methods and techniques have been developed and used in industry to control the directions of ground station antennas, including the azimuth position. The challenge of azimuth tracking is increasing with the demand for full-sky coverage and with the exponential increase in space objects, including man-made satellites and operational and nonoperational objects; thus, providing accurate tracking is a key technology that demands continuous enhancement and development. This article presents the use of a PID-proportional-integral-derivative controller, a slide mode controller and a fractional order PID controller. It also introduces a new methodology based on model predictive control (MPC). The manuscript provides the core design for each of these controllers and provides insight into the performance of each controller even in the presence of disturbance. The camel optimization algorithm (COA) was used to obtain the optimal design parameters of each controller in the considered scenarios.

Developing small satellite ground support software for orbit tracking and target acquisition of the HARP cubesat

Developing small satellite ground support software for orbit tracking and target acquisition of the HARP cubesat

Deep neural network-based robotic visual servoing for satellite target tracking.

In response to the costly and error-prone manual satellite tracking on the International Space Station (ISS), this paper presents a deep neural network (DNN)-based robotic visual servoing solution to the automated tracking operation. This innovative approach directly addresses the critical issue of motion decoupling, which poses a significant challenge in current image moment-based visual servoing. The proposed method uses DNNs to estimate the manipulator's pose, resulting in a significant reduction of coupling effects, which enhances control performance and increases tracking precision. Real-time experimental tests are carried out using a 6-DOF Denso manipulator equipped with an RGB camera and an object, mimicking the targeting pin. The test results demonstrate a 32.04% reduction in pose error and a 21.67% improvement in velocity precision compared to conventional methods. These findings demonstrate that the method has the potential to improve efficiency and accuracy significantly in satellite target tracking and capturing.

Global-scale gravity wave analysis methodology for the ESA Earth Explorer 11 candidate CAIRT

Abstract. In the past, satellite climatologies of gravity waves (GWs) have initiated progress in their representation in global models. However, these could not provide the phase speed and direction distributions needed for a better understanding of the interaction between GWs and the large-scale winds directly. The ESA Earth Explorer 11 candidate CAIRT could provide such observations. CAIRT would use a limb-imaging Michelson interferometer resolving a wide spectral range, allowing temperature and trace gas mixing ratio measurements. With the proposed instrument design, a vertical resolution of 1 km, along-track sampling of 50 km, and across-track sampling of 25 km in a 400 km wide swath will be achieved. In particular, this allows for the observation of three-dimensional (3D), GW-resolving temperature fields throughout the middle atmosphere. In this work, we present the methodology for the GW analysis of CAIRT observations using a limited-volume 3D sinusoidal fit (S3D) wave analysis technique. We assess the capability of CAIRT to provide high-quality GW fields by the generation of synthetic satellite observations from high-resolution model data and comparison of the synthetic observations to the original model fields. For the assessment, wavelength spectra, phase speed spectra, horizontal distributions, and zonal means of GW momentum flux (GWMF) are considered. The atmospheric events we use to exemplify the capabilities of CAIRT are the 2006 sudden stratospheric warming (SSW) event, the quasi-biennial oscillation (QBO) in the tropics, and the mesospheric preconditioning phase of the 2019 SSW event. Our findings indicate that CAIRT would provide highly reliable observations not only of global-scale GW distributions and drag patterns but also of specific wave events and their associated wave parameters. Even under worse-than-expected noise levels of the instrument, the resulting GW measurements are highly consistent with the original model data. Furthermore, we demonstrate that the estimated GW parameters can be used for ray tracing, which physically extends the horizontal coverage of the observations beyond the orbit tracks.