Satellites and Spacecraft Magnetospheric Observation Satellite (GEOTAIL)

In Operation

About Magnetospheric Observation Satellite (GEOTAIL)

Explores the magnetotail to understand the flow of energy from the sun.

GEOTAIL is a satellite whose primary objective is to study the structure and dynamics of Earth’s magnetotail. The satellite was named "GEOTAIL" because it explores that magnetotail. ("Geo" is a prefix for words relating to the Earth.)
The nightside magnetosphere, compressed and confined by the solar wind, is stretched out into a long "magnetotail." This part of the magnetosphere is quite dynamic, as it continually absorbs energy from the sun. The magnetotail is also the main source of the polar aurora and the radiation belt. Exploration of the magnetotail has a great significance in astrophysics and space science.
The GEOTAIL mission is a collaborative project between Japan and the United States. The satellite was developed and is operated by Japan’s Institute of Space and Astronautical Science (ISAS), one of the predecessor bodies of JAXA. It was launched by the National Aeronautics and Space Administration (NASA) in 1992, using the Delta II launch vehicle.
GEOTAIL carries five sets of instruments provided by NASA and ISAS: a magnetic-field experiment, an electric-field experiment, two sets of plasma instruments, two sets of high-energy particle instruments, and a plasma-wave instrument. The satellite’s orbit has been designed to cover the magnetosphere over a wide range of distances, from 8 Earth radii (Re) to 220 Re.

Constructing an information-sharing network with other countries is also an important part of the mission.
GEOTAIL plays a key role in international cooperation.

GEOTAIL, in pursuit of its goal of understanding of the flow of energy and substances from the Sun into the magnetosphere, is part of a collaboration with Russia and other European nations. GEOTAIL plays a major role in the International Solar-Terrestrial Physics (ISTP) program, a network of observation consisting of ten participating satellites orbiting in the geospace. Those participating satellites include WIND (a solar wind-observation satellite from NASA), INTERBALL-Tail (a magnetotail high-latitude measurement satellite from IKI), SOHO (the solar and heliospheric observatory from ESA), POLAR (a high-latitude magnetopause-observation satellite from NASA), and Cluster (a satellite from ESA observing the microstructure of the magnetosphere).
Along with AKEBONO, which has already been playing an active role, GEOTAIL also participates in research in collaboration with other satellites of the Inter-Agency Consultative Group for Space Science (IACG).

Lauch date: July 24, 19992

Characteristics of Magnetospheric Observation Satellite (GEOTAIL)

Major Characteristics

International Designation Code 1992-044A
Launch Date July 24, 1992
Launch Vehicle Delta 2
Location Cape Canaveral (Florida, U.S.A.)
Shape Cylinder of 2.2m diameter and 1.6m height
Equipped with two 6m-long extendable masts for magnetic sensor and four 50m-long antennas
Weight 1,009 kg (at launch)
Orbiter Double lunar swing-by
Altitude Perigee 57,000 km, Apogee 200,000 km
Inclination 29 degrees

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