We congratulate Torsten on his 25th anniversary of service at the GFZ. He began his work in the section on November 15, 1999 as part of the CHAMP project. At that time, he was responsible for the development and operation of the automated processing system for the GPS radio occultation data (GPS-RO). His most reliable work was very important for the success of the innovative atmospheric measurements. The long-term data set from CHAMP is still used today by many scientific analysis centers, especially for climate studies, and is also part of the IPCC report. The CHAMP data were also assimilated into global weather models in 2006 as the world's first GPS-RO measurements. Today, as head of the GPS radio occultation working group, Torsten is responsible for the operational analysis of the TerraSAR-X/TanDEM-X and GRACE-FO data and their scientific applications as part of the activities in POF4-Topic 1. In addition, he takes care of the water vapor radiometer on building A17.