Geotail was a

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

that observed the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynam ...

. It was developed by Japan's ISAS in association with the United States'

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

, and was launched by a

Delta II Delta II was an expendable launch system, originally designed and built by McDonnell Douglas. Delta II was part of the Delta rocket family and entered service in 1989. Delta II vehicles included the Delta 6000, and the two later Delta 7000 va ...

rocket on 24 July 1992 from

Cape Canaveral Air Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the statio ...

. 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: to from the earth. This orbit also allowed it 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. This involved 14 lunar flybys. In 1993 the computer that controls the Low Energy Particles experiment locked up. Attempts to reset it failed. This problem was solved by changing the trajectory of the craft during a lunar flyby that took place on 26 September 1993 so that it passed through the shadow of the moon. Power from the batteries was cut while this took place. When the craft left the shadow of the moon, power returned and the computer started working again. The apogee was lowered down to in mid November 1994 and then to in February 1995 in order to study substorm processes in the near-Earth tail region. The present orbit is × with inclination of -7° to the ecliptic plane." Geotail instruments studied electric fields, magnetic fields, plasmas, energetic particles, and plasma waves. 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. Geotail is an active mission . Geotail,

WIND Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hou ...

Polar Polar may refer to: Geography Polar may refer to: * Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates * Polar climate, the c ...

SOHO Soho is an area of the City of Westminster, part of the West End of London. Originally a fashionable district for the aristocracy, it has been one of the main entertainment districts in the capital since the 19th century. The area was develop ...

, and

Cluster may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Asteroid cluster, a small asteroid family * Cluster II (spacecraft), a European Space Agency mission to study t ...

were all part of the

International Solar-Terrestrial Physics Science Initiative The International Solar-Terrestrial Physics Science Initiative (or ISTP for short) is an international research collaboration between NASA, the ESA, and ISAS. Its goal is to study physical phenomena related to the Sun, solar wind and its effects o ...

(ISTP) project. In June of 2022, the second and final of Geotails two data recorders failed, jeopardizing science observation. It was decided to terminate the operation, and the spacecraft was deactivated on 28 November 2022.

Discoveries

Geotail data has been used to show that

flux transfer event A flux transfer event (FTE) occurs when a magnetic portal opens in the Earth's magnetosphere through which high-energy particles flow from the Sun. This connection, while previously thought to be permanent, has been found to be brief and very dynam ...

s move faster than the ambient medium through the

Magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynam ...

. Those within the

Magnetosheath The magnetosheath is the region of space between the magnetopause and the bow shock of a planet's magnetosphere. The regularly organized magnetic field generated by the planet becomes weak and irregular in the magnetosheath due to interaction with ...

were shown to move both faster and slower than the ambient medium. During the lunar flybys Geotail identified oxygen, silicon, sodium and aluminium in the

lunar atmosphere The atmosphere of the Moon is a very scant presence of gases surrounding the Moon. For most practical purposes, the Moon is considered to be surrounded by vacuum. The elevated presence of atomic and molecular particles in its vicinity compared to ...

References

External links

JAXA , Magnetospheric Observation Satellite (GEOTAIL)GEOTAIL Magnetosphere Tail Observation Satellite , SpacecraftNASA Polar, Wind, and Geotail Projects
{{Moon spacecraft Geospace monitoring satellites Satellites of Japan Satellites of the United States Spacecraft launched by Delta II rockets Spacecraft launched in 1992

Discoveries

See also

References

External links