The constellation of LARES and LAGEOS satellites for testing General Relativity

LARES was developed under the support of the Italian Space Agency. It has been successfully put in orbit on the 13th February 2012 with the VEGA launcher. The main objective of the LARES mission is to test frame-dragging, with the unprecedented accuracy of about 1%. Frame-dragging is that phenomenon, theorized by General Relativity, such that the currents of mass-energy drag spacetime, in the sense that they drag the inertial frames of reference. It is an intriguing effect that together with gravitational waves and other relativistic predictions is not present in classical Galilei-Newton mechanics. By determining very accurately the orbit of the constellation constituted by LARES and the two LAGEOS satellites, it is possible to achieve such an objective. In fact one of the key issues of the experiment is to have three independent observables that are provided by the three satellites. In the paper it will be shown that the use of the constellation is not the only ingredient required, and in particular LARES needed to be designed at the limit of current technology. Also the most updated and accurate determinations of the gravitational field of Earth are of paramount importance in the test. The paper will describe the main LARES mission components and will show why it is so important the use of a constellation to reach the goal.