Planet B (Nozomi)

Planet B (Nozomi) [ISAS]

The primary scientific objective of Nozomi program is to study the Martian upper atmosphere with emphasis on its interaction with the solar wind.

The orbit of the Nozomi spacecraft around Mars will be an elliptical one with periapsis altitude of 150 km and apoapsis distance of 15 Mars radii. The low periapsis altitude is chosen to probe the ionosphere as low as possible and relatively large apoapsis distance is to study the night side of Mars where detection of ionospheric ions is expected.

Nozomi observations are grouped into five categories:

• Magnetic field of Mars - We do not know yet if there is a magnetic field on Mars. NOZOMI is designed to precisely measure the Martian magnetic field for the first time.
• Atmosphere of Mars - Nozomi will investigate the composition and structure of the atmosphere by using ultraviolet remote-sensing detectors. Also by using a small mass-analyzer, Nozomi will be able to identify the composition of the ionosphere.
• Plasma in the Ionosphere of Mars
  Nozomi investigates the components, the structure, the temperature and plasma waves within the Martian ionosphere with its newly developed detectors. We expect to see a new face of Mars in these particular unobserved regions.
• Pictures - A very small onboard camera will take pictures of the Martian weather and the two satellites, Phobos and Deimos. We will be able to know how sandstorms and clouds are generated and also monitor the growth and retreat of the polar ice-caps.
• Dust - It is said that there could be a dust-ring along the orbit of Phobos. By using the dust counter, we will confirm whether or not it exists.

Nozomi was launched with M-5 [KM-V1] rocket at Kagoshima Space Center (KSC) on 4 July 1998. During orbiting the earth for 4 months, Nozomi made its first lunar swing-by on September 24. Then it made the second lunar swing-by on December 18, and executed a powered earth swing-by two days later. The earth swing-by was to send Nozomi onto a transfer orbit to Mars.

Due to malfunction of a thruster valve during the powered earth swing-by, however, the Nozomi flight control team had to send an uplink command again to get it back on the right trajectory to Mars. As a result of this second maneuver, the Nozomi team found that Nozomi no longer had enough fuel to inject itself into its scheduled orbit on arrival at Mars.

The mission analysis team managed to find an alternative trajectory to meet both fuel and observation conditions. Thus the orbit insertion that was scheduled in October 11, 1999, was abandoned, and a new trajectory strategy was established. For the moment, Nozomi's arrival at Mars is scheduled early in 2004 through two more earth swing-bys in Dec. 2002 and June 2003.

In Dec. 2003, when the probe was to insert itself into Mars orbit, all fuel was used up on this attempt, preventing the probe from entering orbit. Inspite of the failed Mars mission, Nozomi remains in an heliocentric orbit to continue monitoring solar activity.