scholarly journals Analysis of the Quality of SLR Station Coordinates Determined from Laser Ranging to the LARES Satellite

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 737
Author(s):  
Stanisław Schillak ◽  
Paweł Lejba ◽  
Piotr Michałek
Keyword(s):  
Data Center ◽  
European Space Agency ◽  
Laser Ranging ◽  
Space Agency ◽  
Station Coordinates ◽  
Italian Space Agency ◽  
The Stability ◽  
Better Than ◽  
Observation Results

The LARES (LAser RElativity Satellite) was built by the Italian Space Agency (ASI) and launched on 13 February 2012 by the European Space Agency. It is intended for studying the Lense–Thirring effect resulting from general relativity as well as for geodynamic studies and satellite geodesy. The satellite is observed by most ground laser stations. The task of this work is to determine the station coordinates and to assess the quality of their determination by comparison with the results from the LAGEOS-1 and LAGEOS-2 satellites. Observation results in the form of normal points (396,105 normal points in total) were downloaded from the EUROLAS Data Center for the period from 29 February 2012 to 31 December 2015. Seven-day orbital arcs were computed by the NASA GSFC GEODYN-II software, determining the coordinates of seventeen selected measuring stations. The average Root Mean Square (RMS) (15.1 mm) of the determined orbits is nearly the same as for LAGEOS (15.2 mm). The stability of the coordinates of each station (3DRMS) is from 9 mm to 46 mm (for LAGEOS, from 5 mm to 15 mm) with the uncertainty of determining the coordinates of 3–11 mm (LAGEOS 2–7 mm). The combined positioning for the LARES + LAGEOS-1 + LAGEOS-2 satellites allows for the stability of 5–18 mm with an uncertainty of 2–6 mm. For most stations, this solution is slightly better than the LAGEOS-only one.

scholarly journals GPS Time and Frequency Transfer: PPP and Phase-Only Analysis

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Pascale Defraigne ◽  
Nicolas Guyennon ◽  
Carine Bruyninx
Keyword(s):  
Precise Point Positioning ◽  
Gps Receiver ◽  
Time Transfer ◽  
Phase Measurements ◽  
Royal Observatory ◽  
Station Coordinates ◽  
Analysis Strategy ◽  
The Stability ◽  
Precise Time ◽  
Better Than

To compute precise point positioning (PPP) and precise time transfer using GPS code and phase measurements, a new software named Atomium was developed by the Royal Observatory of Belgium. Atomium was also adapted to perform a phase-only analysis with the goal to obtain a continuous clock solution which is independent of the GPS codes. In this paper, the analysis strategy used in Atomium is described and the clock solutions obtained through the phase-only approach are compared to the results from the PPP mode. It is shown that the phase-only solution improves the stability of the time link for averaging times smaller than 7 days and that the phase-only solution is very sensitive to the station coordinates used. The method is, however, shown to perform better than the IGS clock solution in case of changes in the GPS receiver hardware delays which affects the code measurements.

scholarly journals Multi-Sensor Satellite Data Processing for Marine Traffic Understanding

Electronics ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 152 ◽  
Author(s):  
Marco Reggiannini ◽  
Luigi Bedini
Keyword(s):  
Optical Sensors ◽  
European Space Agency ◽  
Observation System ◽  
Surveillance Systems ◽  
Space Agency ◽  
Novel Approach ◽  
Imaging Results ◽  
Early Processing ◽  
Wake Detection ◽  
Italian Space Agency

The work described in this document concerns the estimation of the kinematics of a navigating vessel. This task can be accomplished through the exploitation of satellite-borne systems for Earth observation. Indeed, Synthetic Aperture Radar (SAR) and optical sensors installed aboard satellites (European Space Agency Sentinel, ImageSat International Earth Remote Observation System, Italian Space Agency Constellation of Small Satellites for Mediterranean basin Observation) return multi-resolution maps providing information about the marine surface. A moving ship represented through satellite imaging results in a bright oblong object, with a peculiar wake pattern generated by the ship’s passage throughout the water. By employing specifically tailored computer vision methods, these vessel features can be identified and individually analyzed for what concerns geometrical and radiometric properties, backscatterers spatial distribution and the spectral content of the wake components. This paper proposes a method for the automatic detection of the vessel’s motion-related features and their exploitation to provide an estimation of the vessel velocity vector. In particular, the ship’s related wake pattern is considered as a crucial target of interest for the purposes mentioned. The corresponding wake detection module has been implemented adopting a novel approach, i.e., by introducing a specifically tailored gradient estimator in the early processing stages. This results in the enhancement of the turbulent wake detection performance. The resulting overall procedure may also be included in marine surveillance systems in charge of detecting illegal maritime traffic, combating unauthorized fishing, irregular migration and related smuggling activities.

scholarly journals Quality of tiger shrimp artificial feed using various dosages of seaweed (Gracilaria gigas) meal as binder

2011 ◽  
Vol 10 (1) ◽  
pp. 59 ◽  
Author(s):  
Edison Saade ◽  
Siti Aslamyah ◽  
Nur Insana Salam
Keyword(s):  
Physical Parameters ◽  
Water Stability ◽  
Sinking Rate ◽  
Hardness Level ◽  
Randomized Design ◽  
Commercial Feed ◽  
Binding Agents ◽  
The Stability ◽  
Better Than

<p>The quality of an artificial feed particularly the stability of the feed in the water is highly determined by binding agents. The objective of this study was to determine the optimum dosage of seaweed, <em>Gracilaria gigas</em> meal as binder.  Completely randomized design was used in this study, with three dosages of sea weed meal as treatment feeds, i.e. 3, 6, and 9%, with three replications. The control feed was a commercial feed. The physical parameters measured were water stability, hardness level, homogeneity level, sinking rate, attractiveness, and palatability of the feed, and the chemical parameters were protein and lipid dispersion. Based on parameters of hardness level, homogeneity level, protein and lipid dispersion, feed used <em>G. gigas</em> meal of 9% was better than the commercial feed; parameters of sinking rate, attractiveness, and palatability with <em>G. gigas</em> of 9% was equal to the commercial feed; and based on parameters of water stability, the commercial feed was better than treatment feeds. However, when the three treatment feeds were compared, the 9% dosage of <em>G. gigas </em>meal was better than the other two dosages. Based on the results, the feed using seaweed, <em>G. gigas</em> meal of 9% was the best feed.</p> <p>Key words:  Artificial feed, binder, feed quality, G. gigas meal</p> <p> </p> <p>ABSTRAK</p> <p>Bahan perekat sangat menentukan kualitas pakan buatan, terutama stabilitas dalam air.  Tujuan penelitian ini adalah untuk menentukan dosis tepung rumput laut, <em>Gracilaria gigas</em> yang terbaik sebagai bahan perekat. Penelitian didesain menggunakan rancangan acak lengkap, dengan tiga dosis tepung <em>G.gigas</em>, yaitu 3, 6, dan 9% yang diulang tiga kali.  Pakan komersial digunakan sebagai pakan kontrol.  Parameter fisik yang diukur adalah <em>water stability</em> (kecepatan pecah dan dispersi padatan), tingkat kekerasan, tingkat homogenitas, kecepatan tenggelam, daya pikat dan daya lezat pelet, sedangkan parameter kimiawi adalah dispersi protein dan lemak.  Berdasarkan parameter tingkat kekerasan, tingkat homogenitas, dispersi potein dan dispersi lemak pakan yang menggunakan <em>binder </em>tepung <em>G. gigas</em> 9% lebih baik dibanding dengan pakan komersial; parameter kecepatan tenggelam, daya pikat dan daya lezat pakan yang mengandung <em>binder</em> <em>G. gigas</em> 9% sama dengan pakan komersial; dan berdasarkan <em>water stability</em>, pakan komersial lebih baik dibanding dengan pakan yang menggunakan <em>binder </em>tepung rumput laut <em>G. gigas</em>. Namun bila ketiga pakan perlakuan dibandingkan, pakan dengan <em>binder</em> <em>G. gigas</em> 9% masih lebih baik dibanding dengan kedua pakan perlakuan lainnya.  Sesuai hasil penelitian ini, pakan yang menggunakan <em>binder</em> tepung rumput laut, G. <em>gigas</em> dengan dosis 9% adalah pakan terbaik.</p> <p>Kata kunci:  kualitas pakan, <em>binder</em>, tepung <em>G. gigas</em>, pakan buatan</p>

General approaches to assessing the resistance to the effects of ionizing radiation of outer space for foreign electronic component base of development enterprises

2022 ◽  
Vol 14 (4) ◽  
pp. 58-66
Author(s):  
Aleksandr Kozyukov ◽  
N. Gamzatov ◽  
Sergey Grechanyy ◽  
Konstantin Zolnikov ◽  
I. Strukov ◽  
...  
Keyword(s):  
Radiation Resistance ◽  
Outer Space ◽  
European Space Agency ◽  
Electronic Component ◽  
Space Technology ◽  
Space Agency ◽  
Urgent Task ◽  
The Stability ◽  
Main Components ◽  
Selection Of

The analysis of information on the stability of the electronic component base (ECB) in the development of radio-electronic equipment (REE) of spacecraft (spacecraft) is an important and urgent task. The paper considers the main components of the approaches of foreign organizations developing radio space technology to ensure its radiation resistance. The design approaches of Thales Alenia Space, Airbus Defense and Space, and the European Space Agency are presented. The article outlines the main directions for optimizing the procedures for the preliminary selection of ECB, which consist in ensuring the required resistance of REE SC at the ECB level with ensuring the reliability of data on durability, in minimizing the costs of applying resistance enhancement measures (through the use of a promising ECB with increased resistance characteristics), to replace ECB.

scholarly journals Combining satellite observations to develop a global soil moisture product for near-real-time applications

2016 ◽  
Vol 20 (10) ◽  
pp. 4191-4208 ◽  
Author(s):  
Markus Enenkel ◽  
Christoph Reimer ◽  
Wouter Dorigo ◽  
Wolfgang Wagner ◽  
Isabella Pfeil ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Real Time ◽  
Weather Forecasting ◽  
European Space Agency ◽  
Space Agency ◽  
Global Correlation ◽  
Global Soil ◽  
The Individual

Abstract. The soil moisture dataset that is generated via the Climate Change Initiative (CCI) of the European Space Agency (ESA) (ESA CCI SM) is a popular research product. It is composed of observations from 10 different satellites and aims to exploit the individual strengths of active (radar) and passive (radiometer) sensors, thereby providing surface soil moisture estimates at a spatial resolution of 0.25°. However, the annual updating cycle limits the use of the ESA CCI SM dataset for operational applications. Therefore, this study proposes an adaptation of the ESA CCI product for daily global updates via satellite-derived near-real-time (NRT) soil moisture observations. In order to extend the ESA CCI SM dataset from 1978 to present we use NRT observations from the Advanced Scatterometer on-board the two MetOp satellites and the Advanced Microwave Scanning Radiometer 2 on-board GCOM-W. Since these NRT observations do not incorporate the latest algorithmic updates, parameter databases and intercalibration efforts, by nature they offer a lower quality than reprocessed offline datasets. In addition to adaptations of the ESA CCI SM processing chain for NRT datasets, the quality of the NRT datasets is a main source of uncertainty. Our findings indicate that, despite issues in arid regions, the new CCI NRT dataset shows a good correlation with ESA CCI SM. The average global correlation coefficient between CCI NRT and ESA CCI SM (Pearson's R) is 0.80. An initial validation with 40 in situ observations in France, Spain, Senegal and Kenya yields an average R of 0.58 and 0.49 for ESA CCI SM and CCI NRT, respectively. In summary, the CCI NRT product is nearly as accurate as the existing ESA CCI SM product and, therefore, of significant value for operational applications such as drought and flood forecasting, agricultural index insurance or weather forecasting.

scholarly journals Copernicus Sentinel-2 Calibration and Products Validation Status

2016 ◽  
Author(s):  
Ferran Gascon ◽  
Olivier Thépaut ◽  
Mathieu Jung ◽  
Benjamin Francesconi ◽  
Jérôme Louis ◽  
...  
Keyword(s):  
European Union ◽  
High Spatial Resolution ◽  
European Space Agency ◽  
Current Status ◽  
The European Union ◽  
Space Agency ◽  
Quality Aspects ◽  
Optical Imagery ◽  
Sentinel 2

As part of the Copernicus programme of the European Union (EU), the European Space Agency (ESA) has developed and is currently operating the Sentinel-2 mission that is acquiring high spatial resolution optical imagery. This paper provides a description of the calibration activities and the current status of the mission products validation activities. Measured performances, from the validation activities, cover both Top-Of-Atmosphere (TOA) and Bottom-Of-Atmosphere (BOA) products. Results presented in this paper show the good quality of the mission products both in terms of radiometry and geometry and provide an overview on next mission steps related to data quality aspects.

scholarly journals Air Quality During COVID-19: Analysis of Particulate Matter for a Coastal Urban Station Visakhapatnam(India)

2020 ◽  
Vol 10 (1) ◽  
pp. 1925-1935
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
European Space Agency ◽  
World Population ◽  
Urban Station ◽  
Space Agency ◽  
The World ◽  
Before And After ◽  
Pm2.5 And Pm10

The last day of the year 2019 (December 31st), a new infection, coronavirus, was reported from Wuhan (China) to WHO. Subsequently, it was named COVID-19 disease and being declared pandemic on the 11thof March 2020. It was one of the ever faced challenges, and 40 to 60 percent of the world population was estimated to be affected by this virus. This led to severe crises in all countries in terms of economic, social, and environment, emphasizing health. To avoid transmission of this virus worldwide, the lockdown was implemented. This lockdown started on 23rd January 2020 in some parts of the world that impacted the environment and air quality of various cities, depending on their socio-economic conditions. As per the ESA (European Space Agency) and NASA (National Aeronautics and Space Administration), Wuhan experienced a 30% reduction in air pollution. It is a known fact that air pollution has a major impact on human health; the effect of lockdown in various cities and its impact on air pollution prompt us to review some of the recent results published in a nutshell. This paper presented some of the results related to air pollution before and after the announcement of lockdown in various cities around the globe, including Visakhapatnam (India) a polluted coastal urban station with more emphasis on PM2.5 and PM10 concentrations along with air pollutants like NO2, SO2, NO, CO and Relative Humidity.

scholarly journals IDENTIFYING SURFACE CHANGES ON HRSC IMAGES OF THE MARS SOUTH POLAR RESIDUAL CAP (SPRC)

2016 ◽  
Vol XLI-B4 ◽  
pp. 463-469
Author(s):  
Alfiah Rizky Diana Putri ◽  
Panagiotis Sidiropoulos ◽  
Jan-Peter Muller
Keyword(s):  
High Resolution ◽  
European Space Agency ◽  
Martian Surface ◽  
Mars Global Surveyor ◽  
Space Agency ◽  
Imaging Science ◽  
Resolution Imaging ◽  
Visual Imaging ◽  
Better Than ◽  
Surface Changes

The surface of Mars has been an object of interest for planetary research since the launch of Mariner 4 in 1964. Since then different cameras such as the Viking Visual Imaging Subsystem (VIS), Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), and Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) have been imaging its surface at ever higher resolution. The High Resolution Stereo Camera (HRSC) on board of the European Space Agency (ESA) Mars Express, has been imaging the Martian surface, since 25th December 2003 until the present-day. HRSC has covered 100&thinsp;% of the surface of Mars, about 70&thinsp;% of the surface with panchromatic images at 10-20&thinsp;m/pixel, and about 98&thinsp;% at better than 100&thinsp;

scholarly journals Radio Wave Satellite Propagation in Ka/Q Band

2018 ◽  
Vol 62 (2) ◽  
pp. 38-46 ◽  
Author(s):  
László Csurgai-Horváth ◽  
Bernard Adjei-Frimpong ◽  
Carlo Riva ◽  
Lorenzo Luini
Keyword(s):  
European Space Agency ◽  
Atmospheric Effects ◽  
Radio Communication ◽  
Scientific Experiment ◽  
Ground Station ◽  
Atmospheric Propagation ◽  
Space Agency ◽  
University Of Technology ◽  
Communication Experiment ◽  
Italian Space Agency

In 2013 the European Space Agency, in cooperation with Inmarsat, launched the Alphasat communication satellite hosting four Technology Demonstration Payloads (TDPs). One of them is the Aldo Paraboni payload, supported by the Italian Space Agency (ASI) and executed by ESA in the framework of the Advanced Research in Telecommunications Systems (ARTES) 8 Telecom program. In addition to the Communication experiment, it includes the Alphasat Scientific Experiment transmitting coherent beacon signals at Ka-band (19.701 GHz) and Q-band (39.402 GHz). The satellite supports a Europe-wide experiment to investigate the atmospheric propagation effects occurring in Ka and Q bands. The demand for increasing bandwidth in the satellite radio communication domain is moving the communication channels to the higher frequency bands. Hence for both research and commercial purposes is especially important to effectively explore the Q band that is affected by attenuation, depolarization and scintillation due to different atmospheric effects. In 2014 the Department of Broadband Infocommunications and Electromagnetic Theory at Budapest University of Technology and Economics joined the ASAPE (AlphaSat Aldo Paraboni Experimenters) group and developed a ground station to be installed in Budapest. This work was supported by the European Space Agency under its Plan for European Cooperating States program. Our paper gives the background of the Alphasat Scientific Experiment and overviews the design phases of the receiver station in Budapest. We present also the processing and validation of data recorded so far and our future experimenting plans.

scholarly journals Earth Rotation Parameters Estimation Using GPS and SLR Measurements to Multiple LEO Satellites

2021 ◽  
Vol 13 (15) ◽  
pp. 3046
Author(s):  
Xingxing Li ◽  
Hongmin Zhang ◽  
Keke Zhang ◽  
Yongqiang Yuan ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Earth Rotation ◽  
Laser Ranging ◽  
Accuracy Improvement ◽  
Station Coordinates ◽  
Earth Rotation Parameters ◽  
Leo Satellites ◽  
One Step ◽  
Rotation Parameters ◽  
Gps Observations

Earth rotation parameters (ERP) are one of the key parameters in realization of the International Terrestrial Reference Frames (ITRF). At present, the International Laser Ranging Service (ILRS) generates the satellite laser ranging (SLR)-based ERP products only using SLR observations to Laser Geodynamics Satellite (LAGEOS) and Etalon satellites. Apart from these geodetic satellites, many low Earth orbit (LEO) satellites of Earth observation missions are also equipped with laser retroreflector arrays, and produce a large number of SLR observations, which are only used for orbit validation. In this study, we focus on the contribution of multiple LEO satellites to ERP estimation. The SLR and Global Positioning System (GPS) observations of the current seven LEO satellites (Swarm-A/B/C, Gravity Recovery and Climate Experiment (GRACE)-C/D, and Sentinel-3A/B) are used. Several schemes are designed to investigate the impact of LEO orbit improvement, the ERP quality of the single-LEO solutions, and the contribution of multiple LEO combinations. We find that ERP estimation using an ambiguity-fixed orbit can attain a better result than that using ambiguity-float orbit. The introduction of an ambiguity-fixed orbit contributes to an accuracy improvement of 0.5%, 1.1% and 15% for X pole, Y pole and station coordinates, respectively. In the multiple LEO satellite solutions, the quality of ERP and station coordinates can be improved gradually with the increase in the involved LEO satellites. The accuracy of X pole, Y pole and length-of-day (LOD) is improved by 57.5%, 57.6% and 43.8%, respectively, when the LEO number increases from three to seven. Moreover, the combination of multiple LEO satellites is able to weaken the orbit-related signal existing in the single-LEO solution. We also investigate the combination of LEO satellites and LAGEOS satellites in the ERP estimation. Compared to the LAGEOS solution, the combination leads to an accuracy improvement of 0.6445 ms, 0.6288 ms and 0.0276 ms for X pole, Y pole and LOD, respectively. In addition, we explore the feasibility of a one-step method, in which ERP and the orbit parameters are jointly determined, based on SLR and GPS observations, and present a detailed comparison between the one-step solution and two-step solution.

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