Berlin 2005 – scientific programme
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GR: Gravitation und Relativitätstheorie
GR 18: Postersitzung
GR 18.4: Poster
Friday, March 4, 2005, 14:00–19:00, Poster TU BH
Laser Astrometric Test of Relativity — •Hansjörg Dittus1, Claus Lämmerzahl1, Slava G. Turyshev2, Michael Shao2, Yekta Gursel2, and Kenneth L. Nordtvedt, Jr.3 — 1ZARM, Universität Bremen — 2Jet Propulsion Laboratory, Pasadena CA, U.S.A. — 3Nortwest Analysis, Bozeman MT, U.S.A.
The Laser Astrometric Test of Relativity (LATOR) is a large scale European – U.S. Michelson–Morley–type experiment designed to considerably improve tests of General Relativity. The primary objective of the LATOR experiment will be to measure differential deflection of laser light by solar gravity to an accuracy of 0.1 pico-radians. The mission architecture uses a light triangle formed by laser ranging between two small spacecrafts placed on heliocentric orbits and a laser transceiver station built on the International Space Station (ISS). Using independent time-series of highly accurate measurements of the Shapiro time-delay, LATOR will perform a variety of precision tests of gravity. With target precision at the level of the effects of the 2.5 post-Newtonian order, e.g. (beside many other tests) a measurement of the Eddington parameter γ with an accuracy of 1 part in 109 (ca. 30,000 better than obtained with the Cassini spacecraft) will be available. The key element of the experiment is a redundant geometry optical truss provided by the long-baseline (ca. 100 m) fibre-coupled optical interferometer on the ISS. The interferometer will perform differential astrometric measurements of the laser light sources on the two spacecrafts as their line-of-sight pass behind the sun. We will discuss the mission concept and improvements of accuracy expected for different tests.