Nozomi (spacecraft)

Nozomi was launched on July 3, 1998.

After launch on the third M-V launch vehicle, Nozomi was put into an elliptical geocentric parking orbit with a perigee of 340 km and an apogee of 400,000 km.

The spacecraft used a lunar swingby on September 24, 1998, and another on December 18, 1998, to increase the apogee of its orbit.[2]

This image of the Earth and Moon was the first picture taken by the Nozomi camera.

Animation of Nozomi's orbit around Sun
  Nozomi ·   Sun ·   Earth  ·   Mars

It flew by Earth on December 20, 1998, at a perigee of about 1000 km. The gravitational assist from the flyby coupled with a 7 minute burn of the bipropellant rocket put Nozomi into an escape trajectory towards Mars. It was scheduled to arrive at Mars on October 11, 1999, at 7:45:14 UT, but a malfunctioning valve during the Earth swingby resulted in a loss of fuel and left the spacecraft with insufficient acceleration to reach its planned trajectory. Two course correction burns on December 21 used more propellant than planned, leaving the spacecraft short of fuel.[2]

The new plan was for Nozomi to remain in heliocentric orbit for an additional four years, including two Earth flybys in December 2002 and June 2003, and encounter Mars at a slower relative velocity in December 2003, or January 1, 2004.[2]

On April 21, 2002, as Nozomi was approaching Earth for the gravity assist maneuver, powerful solar flares damaged the spacecraft's onboard communications and power systems. An electrical short occurred in a power cell used to control the attitude control heating system, allowing the hydrazine fuel to freeze. The fuel thawed out as the craft approached Earth and maneuvers to put the craft on the correct trajectory for its Earth flyby were successful.

Another Earth flyby within 11,000 km occurred on June 19, 2003. The fuel had completely thawed out for this maneuver because of the spacecraft's proximity to the Sun. However, on December 9, 2003, efforts to orient the craft to prepare it for a December 14, 2003, main thruster orbital insertion burn failed, and efforts to save the mission were abandoned. The small thrusters were fired on December 9, moving the closest approach distance to 1,000 km so that the probe would not inadvertently impact on Mars and possibly contaminate the planet with Earth bacteria, since the orbiter had not been intended to land and was therefore not properly sterilized.

The spacecraft flew by Mars on December 14, 2003, and went into a roughly 2-year heliocentric orbit.

Nozomi was to be inserted into a highly eccentric Mars orbit with a periareion 300 km above the surface, an apoareion of 15 Mars radii, and an inclination of 170 degrees with respect to the ecliptic plane. Shortly after insertion, the mast and antennas were to be deployed. The periareion would have been lowered to 150 km, the orbital period to about 38.5 hours. The spacecraft was to be spin stabilized at 7.5 rpm with its spin axis (and the dish antenna) pointed towards Earth. The periapsis portion of the orbit would have allowed in-situ measurements of the thermosphere and lower exosphere and remote sensing of the lower atmosphere and surface. The more distant parts of the orbit would be for study of the ions and neutral gas escaping from Mars and their interactions with the solar wind. The nominal mission was planned for one martian year (approximately two Earth years). An extended mission might have allowed operation of the mission for three to five years. The spacecraft was also to point its cameras at the martian moons Phobos and Deimos.