The nation of Japan launched its first interplanetary mission on July 4, 1998 (local time), a date which served as a tribute to the US Mars Pathfinder mission, which had landed exactly one year previous. The Japanese mission, known as Planet-B throughout the planning and building phases, was renamed "Nozomi" (the Japanese word for "Hope") immediately after launch.

The $80 million dollar probe is designed to study the atmosphere and ionosphere of Mars, and carries fourteen instruments from five nations, including a NASA Neutral Mass Spectrometer. It's hoped that the Nozomi's results from this instrument can be compared with the results of the NASA Pioneer Venus mission, which used a similar instrument in the 1960s. By comparison, its hoped that the results will help scientists better understand the interactions between planetary atmospheres and ionospheres and the solar wind.

Unfortunately, the spacecraft used up too much fuel during a trajectory correction maneuver and was never able to reach Mars orbit. After years of attempts to do so, the mission was finally declared lost in late 2003.