Jaroslav Klokočník works at the Astronomical Institute of the Czech Academy of Sciences. He has co-authored about 260 research papers and five books. His specialisation is orbital resonances of artificial satellites, satellite altimetry and gradiometry, and geo-applications of Earth’s gravity field models. Jan Kostelecký works at the Research Institute of Geodesy, Topography and Cartography, Czech Republic. He has published over 260 articles and several books. His research concerns applications of the gravity field of Earth, geodynamics, and the establishment of geodetic networks.Václav Cílek works at the Institute of Geology of the Czech Academy of Sciences. His recent scientific activities focus on environmental and quaternary geology, as well as paleoclimatology. He has co-authored 200 scientific papers and about 30 books dealing with landscape and environmental aspects of contemporary society.Aleš Bezděk works at the Astronomical Institute of the Czech Academy of Sciences. His research interests include the orbital dynamics of Earth’s artificial satellites, time-variable gravity fields, and applied time series analysis. He has co authored 40 research articles and three books.