[G01-P] Poster

[G01-P-05] Investigating the performance of the GNSS-SLR co-location on-board GNSS satellites for reference frame determination

^○Sara Bruni¹, Paul Rebischung², Susanna Zerbini¹, Zuheir Altamimi², Maddalena Errico¹, Efisio Santi¹ (1.University of Bologna, Department of Physics and Astronomy, Bologna, Italy, 2.Institut National de l'Information Geographique et Forestiere (IGN), Laboratoire de Recherche en Geodesie (LAREG), Paris, France)

The International Terrestrial Reference Frame (ITRF) is realized by combining data provided by four space geodetic techniques, namely the GNSS, SLR, VLBI and DORIS. Since the technique-specific ground networks do not share any common point, the combination requires some additional information establishing their reciprocal spatial distribution. In the current computation strategy, the inter-technique connection is provided by the so-called terrestrial ties which result from topometric surveys performed at those ITRF sites where the instruments of at least two different techniques are co-located. A possible alternative is provided by satellites equipped with the positioning payloads of different techniques. In principle, the co-location in space could overcome major limitations, such as, poor spatial distribution of ground local ties, their infrequent updates and their discrepancies with space geodesy estimates due to technique systematic errors. However, actual operational conditions are likely to impact the performance of the co-location in space and should be carefully assessed. In this study, we investigate the potential of the space ties on-board GNSS satellites for the realization of a homogeneous GNSS-SLR frame. We analyzed four years (2011-2014) of data collected by a ground network of about 100 GNSS receivers and 40 SLR stations. The computations were operated to determine long-term and quasi-instantaneous (9 days) reference frames. The resulting fully combined frames were compared to the GNSS-only and LAGEOS-only solutions in order to test the efficiency of the selected space ties in transferring frame information between the different subnetworks. The effect of possible future improvements in SLR tracking performances was also investigated by means of simulations. According to our results, the space ties on-board GNSS satellites do not realize, at present, a homogeneous GNSS-SLR frame.