Summary of interplanetary and interstellar dust observation by Mars Dust Counter on board NOZOMI

Mars Dust Counter (MDC) is a light-weight dust detector of impact ionization type on board Japanese Mars mission NOZOMI. NOZOMI was launched on July 4th (3rd at UT) 1998. From December 1998 to December 2003 for five years, NOZOMI took eccentric orbits between the Earth's and Mars' orbits. Until April 2002, MDC continuously observed interplanetary dust. MDC has detected nearly 100 doubtless dust impacts. There were observed several high-velocity particles, which are apparently different from Keplerian dust particles gravitationally bound to the sun. Directional analysis showed that MDC has detected several particles of interstellar origin during the cruising phase of NOZOMI.