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A: Fachverband Atomphysik
A 13: Quantum meets gravity and metrology I
A 13.2: Hauptvortrag
Dienstag, 19. März 2013, 11:30–12:00, E 415
How Attractive is the Moon for Relativity? — •Jürgen Müller1,2, Liliane Biskupek1, Enrico Mai1, and Franz Hofmann1 — 1Institut für Erdmessung (IfE), Leibniz Universität Hannover, Schneiderberg 50, 30167 Hannover, Germany — 2QUEST -- Centre for Quantum Engineering and Space-Time Research, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
In 1969, a new era for studying relativity has started. With the first returns of laser pulses sent from observatories on Earth to reflector arrays on the Moon, a new space technique -- Lunar Laser Ranging (LLR) -- has been providing an ongoing time series of highly accurate Earth-Moon distance measurements. To enable data analysis at the mm level of accuracy, all elements of the tracking process have to be modeled at appropriate (relativistic) approximation, i.e. the orbits of the major bodies of the solar system, the rotation of Earth and Moon, the signal propagation, but also the involved reference and time systems.
We will show where relativity enters the LLR analysis and how the whole measurement process is modeled, including the major classical (Newtonian) effects like gravity field of Earth and Moon, tidal effects, ocean loading, lunar tidal acceleration (that causes the increase of the Earth-Moon distance by about 3.8 cm/year), etc.
By analysing the 43-year record of range data, LLR is one of the best tools to test General Relativity in the solar system. It allows for constraining gravitational physics parameters related to the strong equivalence principle, geodetic precession, preferred-frame effects, or the time variability of the gravitational constant. We will present recent results for the various relativistic parameters.
[1] Hofmann, F., Müller, J., Biskupek, L.: Lunar laser ranging test of the Nordtvedt parameter and a possible variation of the gravitational constant. Astronomy and Astrophysics, Vol. 522, No. L5, 2010, doi: 10.1051/0004-6361/201015659.
[2] Müller, J., Hofmann, F., Biskupek, L.: Testing various facets of the equivalence principle using Lunar Laser Ranging. Classical and quantum gravity, Vol. 29, 184006 (9pp), 2012, doi:10.1088/0264-9381/29/18/184006.
[3] Müller, J., Murphy, T., Schreiber, U., Shelus, P., Torre, J., Williams, J., Boggs, D., Bouquillon, S. Francou, G.: Lunar Laser Ranging -- A Tool for General Relativity, Lunar Geophysics and Earth Science. ILRS JoG special issue, submitted 2012.