Geotail satellite (artist's concept)
Mission type Earth observation
Operator ISAS
COSPAR ID 1992-044A
SATCAT № 22049
Website //
Spacecraft properties
Launch mass 980 kg (2,160 lb)
Power 273.0 watts
Start of mission
Launch date 24 July 1992, 14:26:00 (1992-07-24T14:26Z) UTC
Rocket Delta II 6925
Launch site Cape Canaveral LC-17A
Orbital parameters
Reference system Geocentric
Regime Highly elliptical
Semi-major axis 127,367.75 km (79,142.65 mi)[1]
Eccentricity 0.5469845[1]
Perigee 51,328 km (31,894 mi)[1]
Apogee 190,664 km (118,473 mi)[1]
Inclination 10.51 degrees[1]
Period 7539.86 minutes[1]
Epoch 15 January 2015, 13:40:53 UTC[1]

Geotail is a satellite observing the Earth's magnetosphere. It was developed by Japan's ISAS in association with the United States' NASA, and was launched by a Delta II rocket on July 24, 1992.

From the Geotail website (listed below): "The Geotail satellite was launched on July 24, 1992, by a Delta II launch vehicle from Cape Canaveral Air Force Station, Florida, United States. The primary purpose of this mission is to study the structure and dynamics of the tail region of the magnetosphere with a comprehensive set of scientific instruments. For this purpose, the orbit has been designed to cover the magnetotail over a wide range of distances: 8 R to 210 R from the earth. This orbit also allows us to study the boundary region of the magnetosphere as it skims the magnetopause at perigees. In the first two years the double lunar swing-by technique was used to keep apogees in the distant magnetotail. The apogee was lowered down to 50 R in mid November 1994 and then to 30 R in February 1995 in order to study substorm processes in the near-Earth tail region. The present orbit is 9 R × 30 R with inclination of -7° to the ecliptic plane."

Geotail instruments studied electric fields, magnetic fields, plasmas, energetic particles, and plasma waves.[2]

In 1994 the principal investigator of the Plasma Wave Instrument (PWI), the experiment complement, was Professor Hiroshi Matsumoto of Kyoto University, with co-investigators from NASA, the University of Iowa, and STX Corporation.[3] Geotail is an active mission as of 2015.[4] Geotail, WIND, Polar, SOHO, and Cluster were all part of the International Solar-Terrestrial Physics Science Initiative (ISTP) project.[4]


  • Discoveries 1
  • See also 2
  • References 3
  • External links 4


Geotail data has been used to show that flux transfer events move faster than the ambient medium through the Magnetosphere.[5] Those within the Magnetosheath were shown to move both faster and slower than the ambient medium.[5]

See also


  1. ^ a b c d e f g "GEOTAIL Satellite details 1992-044A NORAD 22049". N2YO. 15 January 2015. Retrieved 25 January 2015. 
  2. ^ Instruments of the Geotail Spacecraft
  3. ^ "The Geotail Plasma Wave Instrument". Retrieved 2014-10-19. 
  4. ^ a b NASA - Geotail
  5. ^ a b Korotova, G.I.; Sibeck, D.G.; Rosenberg, T. (2009). "Geotail observations of FTE velocities" (PDF). Annales Geophysicae (Copernicus Publications) 27 (1): 83–92. Retrieved 26 April 2015. 

External links