Development of Mercury Dust Monitor (MDM) using piezoelectric ceramics on board BepiColombo space craft.

Abstract

The Mercury Dust Monitor (MDM) will be onboard the BepiColombo MMO spacecraft which will be launched in 2013. The MDM is an array of lightweight and heat resistant piezoelectric (lead-zirconate-titanate; PZT) detector in order to measure momentum and incoming direction of hypervelocity micro-particles around Mercury. Two major scientific interests are flux and origin variations on interplanetary meteoroid complex inside 1 AU, and the in-situ investigation of the near-Mercury dust environment.The MDM consists of 4 flat PZT plates whose size is 4cm x 4cm and 1mm thick for each PZT. The calibration experiments of this system are made using micro-particle accelerators at HIT, Univ. Tokyo in Japan and at MPI-K in Germany. By analyzing impact signal, rough momentum and velocity of impact particles can be determined. Only the output signal within a few hundred nanoseconds immediately after impact is analyzed, which is free from interference with reflected waves and could contain an impact hysteresis. The following results are obtained; 1. Output amplitude is proportional to the momentum of particles below 6 km/s, 2. rise-time is related to the particle velocity above 10km/s, 3. there exists a transition region in between, and 4. the sensitivity is confirmed to be independent of the element thickness.