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Mission record

Nozomi

Also known as Planet-B, Hope

Institute of Space and Aeronautical Science, U of Tokyo · Launched

Explore trajectory

Failed · Failure

Nozomi (Japanese for Hope and known before launch as Planet-B) was planned as a Mars orbiting aeronomy mission designed to study the martian upper atmosphere and its interaction with the solar wind and to develop technologies for use in future planetary missions. A malfunctioning valve during an Earth swingby resulted in a loss of fuel and left the spacecraft with insufficient acceleration to reach its planned trajectory, and solar flares later damaged its communications and power systems. Efforts to put the Nozomi spacecraft into martian orbit have been abandoned: an attempt to fire thrusters to orient the craft for a Mars orbit insertion burn failed on December 9, the smaller thrusters were successfully fired, and Nozomi flew past Mars at a distance of 1000 km on 14 December and went into a heliocentric orbit with a period of roughly two years.

Destinations
Launch vehicle
M-5
Launch site
Uchinoura Space Center, Japan
Countries
Japan
Mission types
Orbiter, Flyby

Chronology

Mission timeline

  1. Launch

    Launched into a highly elliptical geocentric orbit

    NSSDCA's launch/orbital information page gives the launch date and time as 1998-07-03T18:12:00Z and the resulting orbit as 340.00 x 400000.00 km, 10.80 days, 28.400 degrees. After launch Nozomi was put into an elliptical geocentric parking orbit with a perigee of 340 km and an apogee of 400,000 km. The one page disagrees with itself about the launch vehicle and the disagreement is recorded rather than resolved: its Facts in Brief and its launch/orbital information page both print M-5, while the master catalog text says the launch was on an M-V-3 launch vehicle.

    Earth

  2. Gravity assist

    First lunar swingby

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

    Moon

  3. Gravity assist

    Second lunar swingby

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

    Moon

  4. Gravity assist

    Earth swingby onto an escape trajectory towards Mars

    It swung by Earth on 20 December 1998 at a perigee of about 1000 km. The gravitational assist from the swingby coupled with a 7 minute burn of the bipropellant engine put Nozomi into an escape trajectory towards Mars. 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, and two course correction burns on 21 December used more propellant than planned.

    Earth

  5. Milestone

    Solar flares damaged the communications and power systems

    On 21 April 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 was caused in a power cell used to control the attitude control heating system which allowed 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.

    Earth

  6. Gravity assist

    Second Earth flyby, within 11000 km

    Another Earth flyby within 11000 km occurred on 19 June 2003. The fuel had completely thawed out for this manuever because of the spacecraft's proximity to the Sun.

    Earth

  7. Flyby

    Flew past Mars at 1000 km after orbit insertion was abandoned

    On 9 December 2003, efforts to orient the craft to prepare it for a 14 December 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 1000 km. The spacecraft flew by Mars on 14 December 2003 and went into a roughly 2-year heliocentric orbit. Nozomi was to be inserted into a highly eccentric Mars orbit with a periapsis 300 km above the surface, an apoapsis of 15 Mars radii, and an inclination of 170 degrees with respect to the ecliptic plane.

    Mars

Mission architecture

Vehicles

Trajectory record

Time-dependent navigation trajectory

Source states place the model at the selected time. Reconstructed flight, estimates, predictions and historical mission plans are identified by interval; gaps remain visible.

J2000 · Sun-centered display · positions interpolated between source states

Coverage: February 8, 1999 to December 13, 2003

Source records and sampling assumptions are retained with the repository data. Model attitude and surface appearance are illustrative.

  • Nozomi: Historical mission plan · actual flight not reconstructed · February 8, 1999 to December 13, 2003

Provenance

Sources

Each source is listed once and labeled with the mission, event, trajectory, or destination/body context it supports.

Data verified through October 11, 2026