Periodic Reporting for period 3 - SPACE TIE (Unifying the three pillars of Geodesy using space ties)
Período documentado: 2022-05-01 hasta 2023-10-31
The aim of the SPACE TIE project is to use two satellite geodetic techniques, namely Global Navigation Satellite Systems (GNSS) and Satellite Laser Ranging (SLR), to connect the three pillars of Geodesy (“Earth’s space”, “Earth rotation”, “Earth’s gravity field”) by co-location sites in space. These so-called space ties shall be realized on satellites of the currently existing space infrastructure. This includes the Medium Earth Orbits (MEO) of the GNSS satellites and, in particular, satellites in Low Earth Orbits (LEO) with GNSS and SLR co-located on-board. To maximize the sensitivity to the Earth’s gravity field, the ultra-precise inter-satellite ranging between LEO satellites of dedicated gravity missions shall be added as a third satellite geodetic technique in the final phase of the SPACE TIE project.
During the period covered by this report we focused on tasks covering all four Work Packages. Major achievements were
• the set-up of a full processing chain for the operational provision of GNSS phase bias products needed for undifferenced ambiguity resolution
• studies about the GNSS-based determination of the terrestrial scale via Galileo satellites
• a significant upgrade of the dynamic LEO orbit determination capabilities by using sophisticated non-gravitational force models
• first orbit determinations based on the multi-GNSS data (GPS and GLONASS) of the COSMIC-2 mission launched in 2019 and (GPS and Galileo) of the Sentinel-6A mission launched in 2020
• studies about systematic errors in Jason-3 orbit solutions
• the generation of multi-satellite SLR solutions including data of the LARES satellite
• the set-up of a new normal point generator to analyze full-rate SLR data from spherical satellites
• the study of annual range biases and station coordinate corrections derived from SLR LEO data
• first steps towards a simultaneous estimation of orbit correction parameters from a multitude of LEO satellites tracked by SLR, and the exploitation of GPS-tracked LEO satellites to recover mass variations in the system Earth.
In addition, significant efforts have been performed to work towards unifying the two branches of the Bernese GNSS Software related to GNSS analyses and SLR analyses, and to develop a new tool of the Bernese GNSS Software for numerically integrating satellite orbits that will allow for a flexible handling of orbit and gravity field parameters as it will be needed for the SPACE TIE project.
• the set-up of a full processing chain for the operational provision of GNSS phase bias products needed for undifferenced ambiguity resolution
• studies about the GNSS-based determination of the terrestrial scale via Galileo satellites
• a significant upgrade of the dynamic LEO orbit determination capabilities by using sophisticated non-gravitational force models
• first orbit determinations based on the multi-GNSS data (GPS and GLONASS) of the COSMIC-2 mission launched in 2019 and (GPS and Galileo) of the Sentinel-6A mission launched in 2020
• studies about systematic errors in Jason-3 orbit solutions
• the generation of multi-satellite SLR solutions including data of the LARES satellite
• the set-up of a new normal point generator to analyze full-rate SLR data from spherical satellites
• the study of annual range biases and station coordinate corrections derived from SLR LEO data
• first steps towards a simultaneous estimation of orbit correction parameters from a multitude of LEO satellites tracked by SLR, and the exploitation of GPS-tracked LEO satellites to recover mass variations in the system Earth.
In addition, significant efforts have been performed to work towards unifying the two branches of the Bernese GNSS Software related to GNSS analyses and SLR analyses, and to develop a new tool of the Bernese GNSS Software for numerically integrating satellite orbits that will allow for a flexible handling of orbit and gravity field parameters as it will be needed for the SPACE TIE project.
The progress beyond the state of the art is
• the development of GNSS clock products which on the one hand allow single-receiver ambiguity resolution and on the other hand also show best possible consistency to pseudo-range measurements
• the analysis of the GNSS contribution to the determination of the terrestrial scale
• the exploitation of LEO SLR data beyond the usual LEO orbit validation applications towards core geodetic analyses
• recovered mass trends and variations in Greenland and the Amazon River basin from a combination of several LEO satellites tracked by GPS.
The expected results until the end of the project to fulfill the SPACE TIE objectives are
• a rigorous multi-GNSS zero-difference processing including ambiguity resolution
• a rigorously combined multi-GNSS processing (including ambiguity resolution) to determine parameters from both terrestrial and spaceborne GNSS data in one and the same parameter estimation process
• the simultaneous calibration of the GNSS transmitter and the LEO receiver GNSS antennas using minimum constraints
• the exploitation of homogenously generated SLR normal points from SLR full-rate data to further reduce systematic errors in the SLR data analysis
• the exploitation of GNSS co-location platforms offered by the GLONASS and the Galileo constellations in a combined GNSS-SLR processing
• the exploitation of LEO co-location platforms in a combined GNSS-SLR processing
• a flexible technical handling of orbit and gravity field parameters in the Bernese GNSS Software.
• the generation of combined solutions of various complexity including gravity field modeling in the above mentioned solutions to eventually cover all three pillars of Geodesy.
• the development of GNSS clock products which on the one hand allow single-receiver ambiguity resolution and on the other hand also show best possible consistency to pseudo-range measurements
• the analysis of the GNSS contribution to the determination of the terrestrial scale
• the exploitation of LEO SLR data beyond the usual LEO orbit validation applications towards core geodetic analyses
• recovered mass trends and variations in Greenland and the Amazon River basin from a combination of several LEO satellites tracked by GPS.
The expected results until the end of the project to fulfill the SPACE TIE objectives are
• a rigorous multi-GNSS zero-difference processing including ambiguity resolution
• a rigorously combined multi-GNSS processing (including ambiguity resolution) to determine parameters from both terrestrial and spaceborne GNSS data in one and the same parameter estimation process
• the simultaneous calibration of the GNSS transmitter and the LEO receiver GNSS antennas using minimum constraints
• the exploitation of homogenously generated SLR normal points from SLR full-rate data to further reduce systematic errors in the SLR data analysis
• the exploitation of GNSS co-location platforms offered by the GLONASS and the Galileo constellations in a combined GNSS-SLR processing
• the exploitation of LEO co-location platforms in a combined GNSS-SLR processing
• a flexible technical handling of orbit and gravity field parameters in the Bernese GNSS Software.
• the generation of combined solutions of various complexity including gravity field modeling in the above mentioned solutions to eventually cover all three pillars of Geodesy.