Nozomi(spacecraft)

Nozomi

Artist's concept ofNozomiorbiter at Mars
Names	Planet B (before launch)
Mission type	Mars orbiter
Operator	JAXA
COSPAR ID	1998-041A
SATCATno.	25383
Mission duration	5 years, 5 months, 5 days (launch to last contact)
Spacecraft properties
Launch mass	540 kg
Start of mission
Launch date	18:12, July 3, 1998 (UTC)(1998-07-03T18:12Z)
Rocket	M-V
Launch site	Uchinoura Space Center
End of mission
Deactivated	December 31, 2003
Last contact	December 9, 2003(2003-12-09)
Orbital parameters
Reference system	Heliocentric

Nozomi(Japanese:の ぞみ,lit. "Wish" or "Hope", and known before launch asPlanet-B)was a JapaneseMars orbiterthat failed to reach Mars due to electrical failure. It was constructed by theInstitute of Space and Astronautical Science,University of Tokyoand launched on July 4, 1998, at 03:12JST(July 3, 1998, at 18:12UTC) with an on-orbit dry mass of 258kgand 282 kg of propellant.The Nozomi mission was terminated on December 31, 2003.

Nozomiwas designed to study the upperMartian atmosphereand its interaction with thesolar windand to develop technologies for use in future planetary missions. Specifically, instruments on the spacecraft were to measure the structure, composition and dynamics of theionosphere,aeronomy effects of the solar wind, the escape of atmospheric constituents, the intrinsicmagnetic field,the penetration of the solar-wind magnetic field, the structure of themagnetosphere,and dust in the upper atmosphere and in orbit around Mars. The mission would have also returned images of Mars' surface.

Mission profile

Launch

Nozomiwas launched on July 3, 1998.

After launch on the thirdM-Vlaunch vehicle,Nozomiwas put into an elliptical geocentricparking orbitwith aperigeeof 340 km and anapogeeof 400,000 km.

Lunar swing-bys

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

Earth swing-by

This image of theEarthandMoonwas the first picture taken by theNozomicamera.

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. Thegravitational assistfrom the flyby coupled with a 7minuteburn of thebipropellant rocketputNozomiinto 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.

New mission plan

The new plan was forNozomito 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.

First Earth flyby

On April 21, 2002, asNozomiwas approaching Earth for the gravity assist maneuver, powerfulsolar flaresdamaged 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 thehydrazinefuel 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.

Second Earth flyby

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 theSun.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.

Mars flyby

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

Intended Mars mission

Nozomiwas to be inserted into a highly eccentric Mars orbit with aperiareion300 km above the surface, an apoareion of 15 Mars radii, and aninclinationof 170degreeswith respect to theeclipticplane. 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 7.5rpmwith its spin axis (and the dish antenna) pointed towards Earth. The periapsis portion of the orbit would have allowed in-situ measurements of thethermosphereand lowerexosphereandremote sensingof the lower atmosphere and surface. The more distant parts of the orbit would be for study of theionsand neutralgasescaping 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 martianmoonsPhobosandDeimos.

Spacecraft and subsystems

TheNozomiorbiter was a 0.58 meter high, 1.6 meter squareprismwith truncated corners. Extending out from two opposite sides were solar panel wings containingsiliconsolar cellswhich provide power to the spacecraft directly or viaNiMH (nickel metal hydride) batteries.On the top surface was a dish antenna, and a propulsion unit protrudes from the bottom. A 5 m deployable mast and a 1 m boom extended from the sides, along with two pairs of thin wire antennas which measure 50 m tip to tip. Other instruments were also arranged along the sides of the spacecraft. Spacecraft communications were via X-band at 8410.93MHzand S-band at 2293.89 MHz.

The 14 instruments carried onNozomiwere an imaging camera, neutral mass spectrometer, dust counter, thermal plasma analyzer,magnetometer,electron and ion spectrum analyzers, ion mass spectrograph, high energy particles experiment, VUV imaging spectrometer, sounder and plasma wave detector, LF wave analyzer, electron temperature probe, and a UV scanner. The total mass budgeted for the science instruments was 33 kg. Radio science experiments were also possible using the existing radio equipment and an ultrastable oscillator.

The total mass ofNozomiat launch, including 282 kg of propellant, was 540 kg.

Canadaprovided a $5 million thermal plasma analyzer.This was theCanadian Space Agency's first participation in an interplanetary mission.(Previously, theNational Research Council of Canadaprovided the High Flux Telescope (HFT) for theUlyssesinterplanetary mission.)

Scientific instruments

The spacecraft carried 14 scientific instruments to conduct scientific observations of Mars. They were

• MarsImaging Camera
• Magnetic Field Measurement (MGF)
• Probe forElectronTemperature (PET)
• ElectronSpectrum Analyzer(ESA)
• Ion Spectrum Analyzer (ISA)
• Electron and Ion Spectrometer (EIS)
• Extra Ultraviolet Scanner (XUV)
• Ultraviolet Imaging Spectrometer (UVS)
• Plasma Waveand Sounder (PWS)
• Low FrequencyPlasma Wave Analyzer(LFA)
• Ion Mass Imager (IMI)
• Mars Dust Counter(MDC)
• Neutral MassSpectrometer(NMS)
• Thermal Plasma Analyzer (TPA)

Scientific results

Nozomi transmitted useful data on measurement ofLyman- Alpha lightduring the course of conducting various scientific observations ininterplanetary space.

See also

• List of missions to Mars
• MELOS– Proposed Mars rover by JAXA
• Mars flyby– Spacecraft maneuver

External links

• NozomiProfilebyNASA's Solar System Exploration
• NSSDC entry
• Image of the Moon's farside byNozomi