The Role of Adhesion and Sub-Newton Pull-Off Forces on the Test Mass Release for the LISA Experiment

The present paper illustrates the problematic of precise release of objects in weightless conditions. Under these circumstances, the role of weak bonds (electrostatic and van der Waals attractive forces) is not obscured by the gravity force. A finite-element analysis approach has been presented with the aim to quantify the adhesion forces between smooth surfaces in vacuum. On the basis of the obtained results, some solutions aimed at reducing adhesion pull-off forces have been discussed. Special emphasis has been placed on the role of surface roughness in reducing adhesion. To this purpose, a fractal surface theory has been used to estimate interaction forces. The obtained results have been used to discuss the role of adhesion on the release of a gold test mass under zero gravity conditions for the scientific space mission LISA.