SMuK 2023 – wissenschaftliches Programm

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GR: Fachverband Gravitation und Relativitätstheorie

GR 5: Classical Relativity

GR 5.2: Vortrag

Dienstag, 21. März 2023, 17:20–17:40, ZEU/0255

Gravitational field recovery via inter-satellite redshift measurements — •Jan P. Hackstein, Eva Hackmann, Dennis Philipp, and Claus Lämmerzahl — Center of Applied Space Technology and Microgravity, Bremen, Germany

Satellite gravimetry is a common technique to monitor global changes in the Earth system. High-precision atomic clocks are currently used in first experiments in terrestrial gravimetry to measure physical heights. In relativistic gravity, a clock comparison is sensitive to their positions in the gravity field and relative velocity. This makes clocks ideal tools to investigate the Earth's gravity field. Equipping Earth-orbiting satellites with clocks and comparing them to terrestrial ground stations allows for global and continuous measurements. However, one important obstacle for Earth-satellite chronometry is the low measurement accuracy of satellite velocity, which enters into the redshift via the Doppler effect. We present an alternative approach based on the framework of general relativity without velocity measurements from ground stations. Considering an idealised satellite setup in the Schwarzschild spacetime, pairwise redshift measurements between satellites equipped with clocks are used to recover the gravitational field's monopole moment. We investigate whether or not only relative observables between satellites suffice to recover the complete information about the gravitational field. This method promises higher accuracy for gravity field recovery by improving control of the Doppler effect. We compare the results and error estimates of this setup with conventional Earth-satellite measurements and conclude with future steps to generalise this approach.