ASI - Agenzia Spaziale Italiana - Mission and Projects ASI - Agenzia Spaziale Italiana - Mission and Projects


Testing of General Relativity

Main Theme Testing of General Relativity
Mission Responsibility ASI
Launch Date 2009
End of Mission 2016
Current phase Phase C/D


LARES (LAser Relativity Satellite) is a low-cost all-Italian mission with a short development time that will enable achieving important scientific goals in gravitational physics, fundamental physics and Earth sciences fields. The completely passive satellite is a tungsten sphere that has retroreflectors that allow the satellite's motion to be followed via laser from the Earth. LARES will go into orbit in february 2012 from the Kourou base with Vega's test launch and will be inserted into orbit at about 1,400 km at perigee with an inclination between 60° to 86° and reduced eccentricity. Data will be acquired through the "International Laser Ranging Service" (ILRS), a network of various laser ranging stations in the world, which offers services for free on the basis of precise international agreements and makes all data immediately available. Data analysis will be performed in a specially created centre.

Scientific Objectives
Albert Einstein's theory of General Relativity on which most of our understanding of the Universe is based, even though it has already been confirmed by other experiments, continues to be put to the test by scientists. Present-day efforts are focused on two threads which are the detecting of gravitational waves and the always more accurate measurement of the Lense-Thirring effect. The Lense-Thirring effect describes the distortion of space-time caused by the rotation of a body with mass and has been measured with a precision of 10% through the evaluation of the variation of the orbit of the Italian-American satellites LAGEOS and LAGEOS 2, by means of laser ranging. The putting into orbit of the LARES satellite and scientific analysis of the data obtained will allow obtaining accuracy in the order of 1% in the measurement of the Lense-Thirring effect. In addition to this primary objective, the mission will allow: the measurement of several PPN (Parameterized Post-Newtonian) parameters, the testing of gravitational laws, the equivalence principle and the alternative theories of General Relativity, as well as important measurements in Geodynamics and space Geodesics for the definition of the International Terrestrial Reference System (ITRF).

Italian Contribution
LARES is an all-Italian small mission. The principal investigator is Ignazio Ciufolini of the Università di Lecce (University of Lecce); the satellite will be produced at Carlo Gavazzi Space with the support of numerous SMEs located on the national territory:. Rheinmetall of Rome (RHI) for the separation mechanism, SAB (Società Aerospaziale Benevento) of Benevento for the support structure, TEMIS of Milan for the telemetric system.

International Agreements
The LARES satellite will be the payload of the first qualification flight of the VEGA launcher whose development is in finalization phase. This has involved the need to define with ESA various documents for managing the agreements, both those of strictly technical nature (Interface Control Document VEGA-LARES) and programme-management (Joint Development Plan VEGA-LARES).