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GRAS NRT Precise Orbit Determination: Operational ExperienceEUMETSAT launched the meteorological satellite MetOp-A in October 2006; it is the first of the three satellites that constitute the EUMETSAT Polar System (EPS) space segment. This satellite carries a challenging and innovative instrument, the GNSS Receiver for Atmospheric Sounding (GRAS). The goal of the GRAS instrument is to support the production of atmospheric profiles of temperature and humidity with high accuracy, in an operational context, based on the bending of the GPS signals traversing the atmosphere during the so-called occultation periods. One of the key aspects associated to the data processing of the GRAS instrument is the necessity to describe the satellite motion and GPS receiver clock behaviour with high accuracy and within very strict timeliness limitations. In addition to these severe requirements, the GRAS Product Processing Facility (PPF) must be integrated in the EPS core ground segment, which introduces additional complexity from the data integration and operational procedure points of view. This paper sets out the rationale for algorithm selection and the conclusions from operational experience. It describes in detail the rationale and conclusions derived from the selection and implementation of the algorithms leading to the final orbit determination requirements (0.1 mm/s in velocity and 1 ns in receiver clock error at 1 Hz). Then it describes the operational approach and extracts the ideas and conclusions derived from the operational experience.
Document ID
Document Type
Conference Paper
MartinezFadrique, Francisco M.
(GMV Aerospace and Defense S.A. Madrid, Spain)
Mate, Alberto Agueda
(GMV Aerospace and Defense S.A. Madrid, Spain)
Rodriquez-Portugal, Francisco Sancho
(European Organization for the Exploitation of Meteorological Satellites Darmstadt, Germany)
Date Acquired
August 24, 2013
Publication Date
September 24, 2007
Publication Information
Publication: Proceedings of the 20th International Symposium on Space Flight Dynamics
Subject Category
Spacecraft Design, Testing And Performance
Distribution Limits
Public Use Permitted.
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