Project Details
Projekt
Accurate long distance optical time transfer from ground to ground via a satellite link
Applicants
Professor Dr.-Ing. Frank Flechtner, since 5/2023; Dr. Thomas Klügel; Dr. Anja Schlicht; Professor Dr.-Ing. Ulrich Schreiber
Subject Area
Geophysics
Term
since 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 490990195
In this research unit we explore a novel concept of geodetic ties, derived from a clock. These clock ties allow us to measure and remove the detrimental effect of variable system delays, which are not accessible otherwise. Therefore, this project has two main goals. Firstly, it connects two remote clocks via optical time transfer over a satellite link, utilizing the Atomic Clock Ensemble in Space (ACES) in order to transport a stable phase relationship (phase coherence) of a clock frequency from one observatory to the next over several hundred kilometers. This demonstrates the general feasibility of spreading time coherence adequately over larger networks, a prerequisite for the application of clocks as a viable novel tie in space geodesy. Secondly, it explores highly accurate delay-compensated clock comparisons via an optical free space link in common-view, so that the physical properties of the respective clock transitions can be exploited for the determination of the physical height difference between the two clocks. It literally ties two distant geometrical geodetic markers to the same timescale to demonstrate that time coherence can be used as a valuable strong tie in space geodesy. Furthermore, it allows us to accurately link time to space, a prerequisite for the path towards a relativistic geodesy. Physically, we realize an Einstein Synchronization process between ground and space. The validity of this approach is demonstrated by a direct comparison of the optical clocks over the ACES microwave link. In addition, we can closely study the properties of the ACES composite clock, in order to extract relativistic corrections with high accuracy.
DFG Programme
Research Units
Ehemaliger Antragsteller
Dr.-Ing. Sven Bauer, until 5/2023
