Contributions from geodesy in Germany to the scientific use of Genesis data (Genesis-D)
GENESIS-D is a collaboration between GFZ Potsdam, DGFI-TUM, BKG and further partners. The project aims to enable the participating institutions to make comprehensive scientific use of data from ESA's new Genesis mission. Background of the project is the central importance of the International Terrestrial Reference System (ITRS) for positioning, navigation and Earth observation. A highly accurate and long-term stable realization of the ITRS — the International Terrestrial Reference Frame (ITRF) — is required by a 2015 UN resolution. The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) requires an ITRF accuracy of 1 mm in position, and a long-term stability of 0.1 mm/year. As one of the three ITRS Combination Centers of the International Earth Rotation and Reference Service (IERS), DGFI-TUM is tasked with implementing the ITRS and regularly calculates its own ITRF solutions, known as DTRF.
Current ITRF solutions do not yet achieve the accuracy required by GGOS, primarily because systematic errors between the four relevant geodetic space techniques (GNSS, VLBI, SLR and DORIS) cannot be adequately detected. This is primarily due to the absence of a direct link between the space segments of the measurement systems. For the first time, the Genesis mission offers the possibility of implementing this so-called 'space tie combination' on board a satellite, thereby enabling systematic errors to be detected and quantified.
The project establishes a powerful scientific network of German research institutions to develop consistent processing, combination and validation strategies for Genesis data. This involves further developing established software packages, implementing realistic simulations of all four space techniques and developing new combination strategies for the ITRF, the ICRF (International Celestial Reference Frame) and EOP (Earth Orientation Parameters). Another key technical outcome will be extending the SINEX format to include satellite orbit parameters, making the existing distributed processing chain usable for space-tie combinations. The redundancy of various software solutions and comprehensive simulations are intended to produce robust, validated methods that can be directly incorporated into the future ITRS realization.
Contributions of DGFI-TUM:
DGFI-TUM plays a key role by combining geodetic space techniques and further developing innovative reference frame solutions. It contributes its expertise as an ITRS Combination Center and makes a central contribution to methodological innovation, quality assurance, and the sustainable use of the Genesis mission for high-precision global reference frames:
- Further development of the DOGS (DGFI Orbit and Geodetic Parameter Estimation) software to enable SLR and DORIS observations of LEO satellites and their combination at the observation and normal equation level.
- Development of new combination strategies that use both co-locations on the ground (local ties) and on board satellites (space ties)
- Development of evaluation and validation procedures to identify systematic errors between space techniques
- Development of concepts for how Genesis data can be consistently integrated into the routine ITRS realization.
Selected Publications
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