Toughness Evaluation of LARES Satellite Tungsten Alloy

LARES (LAser RElativity Satellite) is a passive satellite, it was launched on February 13, 2012 using the new European Space Agency (ESA) launcher VEGA, to measure with high accuracy the effect of the Earth angular momentum on the spacetime geometry that in turn affect the orbital motion of a satellite. This effect is called frame-dragging or Lense-Thirring effect. The reduction of the surface-to-mass ratio is the most important parameter in this respect. A tungsten alloy has been chosen as the best cost effective solution. The LARES 2 mission has been recently proposed aiming at the construction and launch of a second LARES satellite which, in one possible configuration, has a larger diameter and mass. During the LARES manufacturing some issues related to the low fracture toughness of tungsten alloys were evident, the most critical parts being the screws used in the retroreflectors mounting system. The aim of this work, on the basis of all these considerations, is to measure the fracture toughness of this alloy in order to evaluate, in a second stage, feasible thermomechanical treatments that should be able to increase safety margins.