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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]

In this article, the novel type of dielectric elastomer made of polydimethylsiloxane, multi-walled carbon nanotubes, and carbon grease is presented. The aim of the study was the development of compliant electrodes with ability for large deformation under applied voltage. The largest deformation of 47% was obtained for electrodes made of 2 wt% of multi-walled carbon nanotubes and 20 wt% of carbon grease. Electrical conductivity achieved for this material was 4.8 S/m. Good dispersion of conductive fillers within silicone matrix was obtained by calendaring technique. It was found that electrical percolation threshold for the compound was below 0.05 wt%. The structure of the material and its mechanical properties were determined. It was described that both properties, electrical conductivity and stiffness of the nanocomposite, have a significant influence on the extent of the electrode deformation. Two actuator designs are presented as the examples of application of developed material. [ABSTRACT FROM AUTHOR]

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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]

MUPUS, the multi purpose sensor package onboard the Rosetta lander Philae, will measure the energy balance and the physical parameters in the near-surface layers – up to about 30 cm depth- of the nucleus of Rosetta’s target comet Churyumov-Gerasimenko. Moreover it will monitor changes in these parameters over time as the comet approaches the sun. Among the parameters studied are the density, the porosity, cohesion, the thermal diffusivity and conductivity, and temperature. The data should increase our knowledge of how comets work, and how the coma gases form. The data may also be used to constrain the microstructure of the nucleus material. Changes with time of physical properties will reveal timescales and possibly the nature of processes that modify the material close to the surface. Thereby, the data will indicate how pristine cometary matter sampled and analysed by other experiments on Philae really is. [ABSTRACT FROM AUTHOR]