MUPUS insertion device for the Rosetta mission.

An original mechanical device designed to insert a penetrator into a cometary nucleus in an almost gravity-free environment is described. The device comprises a hammer and a power supply system that stores electrical energy in a capacitor. The accumulated energy is discharged through a coil forming a part of electromagnetic circuit that accelerates the hammer. The efficiency of converting the electrical energy to kinetic energy of the hammer is not very high (amounts to about 25%), but the system is very reliable. Additionally, the hammer energy can be chosen from four power settings, hence adjustment of the stroke's strength to nucleus hardness is possible. The device passed many mechanical, functional, thermal and vibration tests and was improved from one model to another. The final, flight model was integrated with the lander Philae and started its space journey to comet Churyumov-Gerasimenko in March 2004. [ABSTRACT FROM AUTHOR]