Experimental Gravitation: GAIA, Galileo-Galilei, CRONOS

This research programme is for participation in 3 experiments on space projects that test the predictions of General Relativity (GR) and test foundations of the theory. These are: 1. On GAIA: to determine the bending of light parameter, gamma (=1 in GR) to an accuracy of 1 part in 10^7, and to look for possible angular variations of gamma, which are not predicted by GR but could exist if the foundations of GR are incorrect. 2. Galileo-Galilei: To test the Equivalence Principle, that bodies fall together under gravity, which lies at the foundation of GR. This Italian mission, on which I am a co-investigator, should be able to detect possible violations at a level of 1 part in 10^17 3. CRONOS. Originally an ESA mission of opportunity to determine the gravitational redshift (the slowing down of clocks in a gravitational field) predicted by GR to 1 part in 1000,000 by comparing a high precision clock on board the Russian mission Radioastron with ground based clocks.