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In order to investigate the geomagnetic tail region of the magnetosphere, the Institute of Space and Astronautical Science of Japan (ISAS) and the United States National Aeronautics and Space Administration (NASA) agreed to undertake a joint project to develop, launch, and operate a scientific satellite designated the Geotail satellite. The Geotail mission measures global energy flow and transformation in the magnetotail to increase understanding of fundamental magnetospheric processes, including the physics of the magnetopause, the plasma sheet, and reconnection and neutral line formation. These objectives require spacecraft measurements in two orbits: a nightside double lunar swingby Geotail orbit to distances of 220 RE and a low inclination orbit at geocentric distances of about 8 to 30 RE. The Geotail satellite was designed and developed by ISAS, and it was launched by NASA by DELTA II expendable launch vehicle on 24 July 1992. It includes scientific instruments provided by ISAS and NASA. The satellite will be placed into the initial distant tail orbit for approximately two and a half years; thereafter, it will be maneuvered to a second orbit where it will operate for the remainder of it's lifetime.

Together with the Wind, Polar, SOHO and Cluster projects, Geotail constitutes a cooperative scientific satellite project of ISAS, NASA and the European Space Agency (ESA) designated the International Solar-Terrestrial Physics (ISTP). Program which aims at gaining improved understanding of the physics of the solar terrestrial relations. The Space Research Institute (IKI) of the former Soviet Union will also launch INTERBALL and RELICT-2 satellites in the same time frame, and the entire program is coordinated by the Inter Agency Consultative Group for Space Science (IACG).

The ISAS Geotail instrument was formally decommissioned and powered down on 28 Nov 2022. Over 30 years after its launch.

The 30th Anniversary of the Launch of the Geotail Mission was 24 July 2022

The 10,000th day Anniversary of the Launch of the Geotail Mission was 9 Dec 2019

The 10,000th day of Geotail CPI data (HP & SW) collection was on 21 Feb 2020

Check out the January 2012 CME observed by the CPI Solar Wind Analyzer: 5 Days Surrounding Arrival, Detailed Spectrogram, and Moments.  

Comprehensive Plasma Instrument (CPI)

CPI Instrument Documentation

HTML Documentation for the Geotail CPI and the Survey Spectrograms is available on-line. It can also be viewed as a PDF.

CPI Photo Gallery

CPI Survey Data

Individual 5 Day Survey plots for both the Solar Wind and Hot Plasma analyzers as well as a collection of monthly Geotail orbital position plots are available:

The ISTP project has made a variety of interesting data periods available by plotting "Key Parameter" data from several different instruments on the Geotail spacecraft, including components from the CPI. These are available for from the Space Physics Data Facility (SPDF).

High Time Resolution Data

Hot Plasma high time resolution distributions are available by direct contact with the managing scientist, Dr. Bill Paterson. High time resolution plasma moments and 6-hour survey spectrograms are currently available below.

Solar Wind high time resolution distributions are available by direct contact with the managing scientist, Dr. Kent Ackerson. High time resolution plasma moments are currently available below.

CPI Bibliography

Local Contact Information

Related Topics


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Last Modified: Wednesday, 02-Oct-2024 08:40:28 CDT