The PLANET-B mission

PLANET-B is the Japanese Mars orbiter program. The spacecraft will begin its journey to Mars in July 1998, and will be inserted into Mars orbit in October 1999. It will collect data for at least one Martian year (about two Earth years). The primary objective of the program is to study the Martian aeronomy, with emphasis on the interaction of the Martian upper atmosphere with the solar wind. The periapsis altitude and the apoapsis distance are 150 km and 15 Mars radii, respectively. The dry weight of the orbiter is 258 kg including 15 scientific instruments. Advanced technologies are employed in the design of the spacecraft in attempt to overcome the mass limitation. This paper describes the scientific objectives of the PLANET-B program and the outline of the observation scenario.