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Mission Profile

Name (pre-launch in parentheses) AKEBONO (EXOS-D)
International Designation Code 1989-016A
Objectives Elucidation of physical phenomena of the magnetosphere in relation to aurora (observation of acceleration mechanism of aurora particles and aurora luminous event)
Launch Date 08:30, February 22, 1989 (JST)
Location Kagoshima Space Center (Uchinoura)
Launch Vehicle
Configuration Weight Approx. 295 kg
Shape 100cm high, 126cm long from face to face
Octagonal cylinder with four solar-array paddles
Equipped with 30m-long antenna and two (5m and 3m) extendable masts

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Orbit Altitude Perigee 275 km, Apogee 10,500 km
Inclination 75°
Type of Orbit Highly elliptical
Period 211 min
Scientific Instruments
  1. Three-axis fluxgate magnetometer
  2. Electric field detector
  3. Low energy ion detector
  4. Suprathermal ion spectrometer
  5. Thermal electron detector
  6. VLF wave detector
  7. HF wave detector and topside sounder
  8. Visible and UV auroral imager
Results Apart from the auroral imager whose CCDs were degraded by the harsh radiation environment, all onboard instruments are still healthy and operable, achieving observation over an entire cycle (11 years) of solar activity. Scientific results obtained until now include: demonstration of particle acceleration by electric field parallel to magnetic field lines; quantitative research on ions flowing out from the polar ionosphere: detailed research on reinforcement of UHR waves on the equator: thermal structure of low-altitude plasmasphere; discovery of partial dropping phenomenon in density of the plasmasphere when magnetic storms occur; and observation of long-term variation of particles in the radiation belt.