| 词条 | Nozomi (spacecraft) |
| 释义 |
| name = Nozomi | names_list = Planet B (before launch) | image = | image_caption = Artist's concept of Nozomi | image_alt = | image_size = | mission_type = Orbiter | operator = JAXA | Harvard_designation = | COSPAR_ID = 1998-041A | SATCAT = 25383 | website = | mission_duration = 5 years, 5 months, 5 days (launch to last contact) | distance_travelled = | orbits_completed = | suborbital_range = | suborbital_apogee = | spacecraft = | spacecraft_type = | spacecraft_bus = | manufacturer = | launch_mass = {{convert|258|kg}} | BOL_mass = | landing_mass = | dry_mass = | payload_mass = | dimensions = | power = | launch_date = {{start date|1998|07|03|18|12|7=Z}} | launch_rocket = M-V | launch_site = Uchinoura Space Center | launch_contractor = | deployment_from = | deployment_date = | entered_service = | disposal_type = | deactivated = | destroyed = | last_contact = {{end date|2003|12|9}} | recovery_by = | recovery_date = | decay_date = | landing_date = | landing_site =
| programme = | previous_mission = | next_mission = | insignia = | insignia_caption = | insignia_alt = | insignia_size = }}{{nihongo|Nozomi|のぞみ||lit. "Wish" or "Hope," and known before launch as Planet-B|lead=yes}} was a planned and launched Mars-orbiting aeronomy probe. It did not reach Mars orbit due to electrical failures. The mission was terminated on December 31, 2003.{{cn|date=February 2019}} It was constructed by the Institute of Space and Astronautical Science, University of Tokyo and launched on July 4, 1998, at 03:12 JST (July 3, 1998, at 18:12 UTC) with an on-orbit dry mass of 258 kg and 282 kg of propellant.{{cn|date=February 2019}} Nozomi was designed to study the upper Martian atmosphere and its interaction with the solar wind and to develop technologies for use in future planetary missions. Specifically, instruments on the spacecraft were to measure the structure, composition and dynamics of the ionosphere, aeronomy effects of the solar wind, the escape of atmospheric constituents, the intrinsic magnetic field, the penetration of the solar-wind magnetic field, the structure of the magnetosphere, and dust in the upper atmosphere and in orbit around Mars. The mission would have also returned images of Mars' surface.{{cn|date=February 2019}} Mission profileLaunchAfter 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.{{cn|date=February 2019}} Lunar swing-bysThe spacecraft used a lunar swingby on September 24, 1998, and another on December 18, 1998, to increase the apogee of its orbit.{{cn|date=February 2019}} Earth swing-by{{cn|date=February 2019}}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.{{cn|date=February 2019}} New mission planThe 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.{{cn|date=February 2019}} First Earth flybyOn 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.{{cn|date=February 2019}} Second Earth flybyAnother 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 1000 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.{{cn|date=February 2019}} Mars flybyThe spacecraft flew by Mars on December 14, 2003, and went into a roughly 2-year heliocentric orbit.{{cn|date=February 2019}} Intended Mars missionNozomi 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.{{cn|date=February 2019}} Spacecraft and subsystemsThe Nozomi orbiter is a 0.58 meter high, 1.6 meter square prism with truncated corners. Extending out from two opposite sides are solar panel wings containing silicon solar cells which provide power to the spacecraft directly or via NiMH (nickel metal hydride) batteries. On the top surface is a dish antenna, and a propulsion unit protrudes from the bottom. A 5 m deployable mast and a 1 m boom extend from the sides, along with two pairs of thin wire antennas which measure 50 m tip to tip. Other instruments are also arranged along the sides of the spacecraft. Spacecraft communications are via X-band at 8410.93 MHz and S-band at 2293.89 MHz. The 14 instruments carried on Nozomi are 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 of Nozomi at launch including 282 kg of propellant was 540 kg.{{cn|date=February 2019}} Canada provided a $5 million thermal plasma analyzer.[1] This was the Canadian Space Agency's first participation in an interplanetary mission.[2] (Previously, the National Research Council of Canada provided the High Flux Telescope (HFT) for the Ulysses interplanetary mission.[3]) Scientific InstrumentsThe spacecraft carried 14 scientific instruments to conduct scientific observations of Mars. They are[4][5][6]
Scientific ResultsNozomi transmitted useful data on measurement of Lyman-alpha light during the course of conducting various scientific observations in interplanetary space.[4] See also{{Portal|Spaceflight}}
References1. ^{{cite web |quote=The failure of Nozomi represents a $5-million loss for Canada. |agency=Canadian Press |newspaper=The Globe and Mail |title=Japan abandons Mars mission |url=https://www.theglobeandmail.com/news/national/japan-abandons-mars-mission/article20453161/ |date=9 December 2003 |accessdate=24 March 2016 }} 2. ^{{cite press release |archive-url=https://web.archive.org/web/19981202103455/http://www.space.gc.ca/ENG/News_Releases/980703.html |archive-date=2 December 1998 |date=3 July 1998 |url=http://www.space.gc.ca/ENG/News_Releases/980703.html |publisher=Canadian Space Agency |title=Canadian Probe Launched to Mars }} 3. ^{{cite web |quote=The Herzberg Institute of Astrophysics (HIA) of the National Research Council of Canada provided instrumentation and test equipment for the COsmic ray and Solar Particle INvestigation (COSPIN) on the Ulysses spacecraft. The COSPIN instrument consists of five sensors which measure energetic nucleons and electrons over a wide range of energies. This was the first participation by Canada in a deep-space interplanetary mission. |archive-url=https://web.archive.org/web/20110817205127/http://hiauly1.hia.nrc.ca/index.html |url=http://hiauly1.hia.nrc.ca/index.html |archive-date=17 August 2011 |title=Welcome to the HIA Ulysses Project |publisher=Herzberg Institute of Astrophysics}} 4. ^1 {{Cite web|url=http://www.isas.jaxa.jp/en/missions/spacecraft/past/nozomi.html|title=NOZOMI {{!}} Spacecraft|website=ISAS|language=en|access-date=2019-01-02}} 5. ^{{Cite web|url=https://solarsystem.nasa.gov/missions/nozomi/in-depth|title=In Depth {{!}} Nozomi|website=Solar System Exploration: NASA Science|access-date=2019-01-02}} 6. ^{{Cite web|url=https://solarsystem.nasa.gov/resources/298/deep-space-chronicle-a-chronology-of-deep-space-and-planetary-probes-1958-2000|title=Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000|website=Solar System Exploration: NASA Science|access-date=2019-01-02}} External links
6 : Missions to Mars|Japanese space probes|Artificial satellites orbiting the Sun|Spacecraft launched in 1998|1998 in Japan|Derelict space probes |
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