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GipsyX/RTGx, a new tool set for space geodetic operations and research / Willy I. Bertiger in Advances in space research, vol 66 n° 3 (1 August 2020)  

Public [article]  inAdvances in space research > vol 66 n° 3 (1 August 2020) . - pp 469 - 489 Titre : GipsyX/RTGx, a new tool set for space geodetic operations and research Type de document : Article/Communication Auteurs : Willy I. Bertiger, Auteur ; Yoaz E. Bar-Sever, Auteur ; A. Dorsey, Auteur ; Bruce J. Haines, Auteur ; N.R. Harvey, Auteur ; Dan Hemberger, Auteur ; Michael B. Heflin, Auteur ; Wenwen Lu, Auteur ; Mark Miller, Auteur ; Angelyn Moore, Auteur ; Dave Murphy, Auteur ; Paul Ries, Auteur ; L.J. Romans, Auteur ; Aurore E. Sibois, Auteur ; Ant Sibthorpe, Auteur ; Bela Szilagyi, Auteur ; Michele Vallisneri, Auteur ; Pascal Willis , Auteur Année de publication : 2020 Projets : 3-projet - voir note / Article en page(s) : pp 469 - 489 Note générale : bibliographie The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données DORIS [Termes IGN] données GNSS [Termes IGN] données ITGB [Termes IGN] données TLS (télémétrie) [Termes IGN] filtre de Kalman [Termes IGN] horloge atomique [Termes IGN] horloge du satellite [Termes IGN] logiciel d'orbitographie [Termes IGN] positionnement ponctuel précis [Termes IGN] série temporelle [Termes IGN] temps réel [Termes IGN] traitement de données GNSS Résumé : (auteur) GipsyX/RTGx is the Jet Propulsion Laboratory’s (JPL) next generation software package for positioning, navigation, timing, and Earth science using measurements from three geodetic techniques: Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS); with Very Long Baseline Interferometry (VLBI) under development. The software facilitates combined estimation of geodetic and geophysical parameters using a Kalman filter approach on real or simulated data in both post-processing and in real-time. The estimated parameters include station coordinates and velocities, satellite orbits and clocks, Earth orientation, ionospheric and tropospheric delays. The software is also capable of full realization of a dynamic terrestrial reference through analysis and combination of time series of ground station coordinates. Applying lessons learned from its predecessors, GIPSY-OASIS and Real Time GIPSY (RTG), GipsyX/RTGx was re-designed from the ground up to offer improved precision, accuracy, usability, and operational flexibility. We present some key aspects of its new architecture, and describe some of its major applications, including Real-time orbit determination and ephemeris predictions in the U.S. Air Force Next Generation GPS Operational Control Segment (OCX), as well as in JPL’s Global Differential GPS (GDGPS) System, supporting User Range Error (URE) of 5 cm RMS; precision post-processing GNSS orbit determination, including JPL’s contributions to the International GNSS Service (IGS) with URE in the 2 cm RMS range; Precise point positioning (PPP) with ambiguity resolution, both statically and kinematically, for geodetic applications with 2 mm horizontal, and 6.5 mm vertical repeatability for static positioning; Operational orbit and clock determination for Low Earth Orbiting (LEO) satellites, such as NASA’s Gravity Recovery and Climate Experiment (GRACE) mission with GRACE relative clock alignment at the 20 ps level; calibration of radio occultation data from LEO satellites for weather forecasting and climate studies; Satellite Laser Ranging (SLR) to GNSS and LEO satellites, DORIS-based and multi-technique orbit determination for LEO; production of terrestrial reference frames and Earth rotation parameters in support of JPL’s contribution to the International Terrestrial Reference Frame (ITRF). Numéro de notice : A2020-575 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : INFORMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2020.04.015 Date de publication en ligne : 22/04/2020 En ligne : https://doi.org/10.1016/j.asr.2020.04.015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96369 [article]

Effects of thermosphere total density pertubations on LEO Orbits during severe geomagnetic conditions (Oct-Nov 2003) using Doris and SLR data / Florent Deleflie in Advances in space research, vol 36 n° 3 (March 2005)  

Public [article]  inAdvances in space research > vol 36 n° 3 (March 2005) . - pp 522 - 533 Titre : Effects of thermosphere total density pertubations on LEO Orbits during severe geomagnetic conditions (Oct-Nov 2003) using Doris and SLR data Type de document : Article/Communication Auteurs : Florent Deleflie, Auteur ; François Barlier, Auteur ; Yoaz E. Bar-Sever, Auteur ; L.J. Romans, Auteur ; Pascal Willis , Auteur Année de publication : 2005 Article en page(s) : pp 522 - 533 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] bruit blanc [Termes IGN] données DORIS [Termes IGN] filtrage du bruit [Termes IGN] géomagnétisme [Termes IGN] orbite basse [Termes IGN] orbitographie [Termes IGN] télémétrie laser sur satellite [Termes IGN] tempête magnétique [Termes IGN] thermosphère Résumé : (Auteur) An exceptional solar activity event occurred at the end of October 2003. On October 29th, seven groups of sunspots were visible on the Sun's surface and the geomagnetic index Kp reached the extreme value of 9, leading to beautiful auroras, among other effects. Similar events also occurred in November 2003. These events have been an exceptional opportunity to estimate effects of the thermosphere total density perturbations in extreme conditions on a Low Earth Orbit (LEO orbit corresponding in this study at altitudes ranging from 800 km up to 1400 km). Specifically, we study the best way to get reliable geodetic products even during such solar events, and how well the thermosphere models (DTM78, DTM94, DTM2000, and MSIS86 models) allow us to accomplish this and to predict the observed perturbations on the orbital elements. Thus our analysis is twofold. First, we have computed orbits of satellites equipped with the onboard DORIS tracking system, at an altitude ranging from 800 to 1330 km and for periods of time including these exceptional events (October 2931 and November 20, 2003). We have computed 30hour arc orbits, estimating the drag coefficient parameter very frequently (every minute) using a tight randomwalk constraint or using a white noise reset in the Gipsy/Oasis software. We show that significant errors are obtained for the considered thermosphere models, but can be greatly improved. using a more sophisticated data processing. We also investigated how these proposed processing strategies affect the quality of the DORIS geodetic products. Significant improvements were found for weekly stations coordinates estimations as well as for polar motion determination. In addition, we have investigated the global quality of the modeling of the variations of the mean orbital elements in using thermosphere models over long periods of time including such severe geomagnetic events. This original approach is based on averaging techniques implemented in the CODIOR software. We have analysed the continuous longterm evolution of the semimajor axis of the geodetic satellites Starlette, Stella and Ajisai tracked by the Satellite Laser Ranging (SLR) network. In this second part, we give: (i) a single global empirical coefficient per satellite, to validate the models over the whole duration of the orbital arc, including the exceptional solar activity events, and (ii) one coefficient per a period of about 2 months to quantify the seasonal differences between the models and the observations. As a result of both investigations, we compare the capability of recent models of thermosphere to allow us to get reliable geodetic products and mean orbital elements variations over short and long periods of time as well as for the recent exceptional geomagnetic events. Different altitudes are considered: around 800900 km for the Stella and Starlette satellites tracked by laser ranging systems and SPOT tracked by DORIS; around also 13001400 km for the Ajisai satellite tracked by laser techniques and TOPEX and Jason also tracked by DORIS. It appears in our study that laser and DORIS data are complementary to probe the thermosphere, and to test the quality of thermosphere models in specific conditions for getting accurate geodetic products. Numéro de notice : A2005-611 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2005.03.029 Date de publication en ligne : 13/04/2005 En ligne : https://doi.org/10.1016/j.asr.2005.03.029 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33947 [article]

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38017-01	30.82	Tiré à part	Centre de documentation	Géodésie	Disponible