# On the Integration of VLBI Observations to GENESIS into Global VGOS Operations
## 5 Discussion  
This study investigates the integration of VLBI observations with the upcoming ESA mission GENESIS into VGOS operations. The results demonstrate that the negative impact of GENESIS on the precision of geodetic parameter estimates is minimal. These findings are consistent with those of previous simulation studies that incorporated additional artificial radio sources into VLBI experiments [18; 34]. The results presented herein provide further enhancement to the findings of previous studies by implementing the planned GENESIS orbit parameters, utilizing both the current and projected VGOS antenna networks, and conducting comprehensive scheduling. In contrast to prior studies, this investigation addresses the trade-off between the negative impact of GENESIS on geodetic parameter  
Figure 14: Station position repeatabilities with mixed schedules following the GENESIS processing. The repeatabilities are given for the three networks A, B, and C with orbit errors at the level of 0 cm (no orbit errors), 1 cm, 3 cm, and 5 cm. The results are shown for the cadence 2 (2 experiments per week) and cadence 3 (3 experiments per week) after 3, 6, 9, and 12 months, respectively. Additionally, the number of performed experiments is given in brackets. estimates and the estimated frame tie accuracy between the VLBI and GENESIS frames. The findings suggest integrating GENESIS into VGOS schedules with MRTs of at least 5 min. As a result, the degradation of the station position and dUT1 repeetabilities are less than 0.09 mm and 0.06 us, respectively. Furthermore, the number of observations is reduced by less than 5%. A comparison is presented between the degradation of the parameters due to GENESIS and the variation within the VGOS schedule optimization. It was demonstrated that no single schedule provides the best estimates for all geodetic parameters. Rather, each schedule shows strengths in the estimation of different parameters. It was found that the geodetic parameter estimates exhibited a variation of between 7% and 10% among the best-tested schedules. In comparison, the change in the station position and dUT1 estimation due to GENESIS is less than 3.2% and 7%, respectively, while the impact of GENESIS on VGOS schedules is not negligible, especially considering the decrease in the number of observations; the results suggest that GENESIS can be included into regular VGOS experiments. A significant aspect of this work is the application of comprehensive scheduling. We utilized the well-established scheduling software VieSched++. The software assesses the anticipated orbit of GENESIS and creates realistic observability with the global antenna network. With an MRT of 5 min, the mixed schedules comprise about 150 to 200 scans and about 1000 to 5000 observations of GENESIS, depending on the VGOS network. In this study, we present the first numbers of scans and observations of GENESIS with current and projected VGOS networks that are based on profound scheduling. The given numbers in this work can contribute to further studies by other groups within the geodetic community in preparation for the GENESIS mission. We employed a two-step approach to establish the frame tie between the VLBI and GENESIS frames. In the first step, the GENESIS orbit is determined with satellite-based techniques. In the second step, VLBI observations with VGOS networks serve to establish a tie between the two frames. The results indicate that the frame tie can be achieved with an accuracy of several millimeters after a few months of observations. After 12 months of experiments with GENESIS for all three networks, a frame tie can be achieved with an accuracy of 2-4 mm, assuming orbit errors of 5 cm and a session cadence of three experiments per week. A cadence of two experiments per week results in a decrease in frame tie accuracy to approximately 3-5 mm. As expected, the results improve further when assuming smaller orbit errors of 3 cm or 1 cm. However, these values warrant cautious interpretation.