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Breakthroughs in the study of the Earth's magnetic field

Japan's Akebono satellite
(Photo: JAXA)



Aurora borealis
(Photo: NASA)



How solar winds affect Earth's magnetosphere.
(Illustration: NASA)

The Japanese satellite Akebono, launched in 1989, has been at the centre of major discoveries about energy patterns and solar particles in the Earth's magnetosphere. For over 10 years, the instruments carried on the satellite, including the Canadian-built suprathermal ion mass spectrometer (SMS), have measured magnetic and electrical fields, plasma, and waves.

Together, the SMS and seven other instruments on Akebono gather data in four research areas: source mechanisms of the aurora borealis, causes and effects of magnetic storms, energy processes in the atmosphere, and physics of high-latitude space phenomena. These data have been used in conjunction with data from other satellites to analyze and predict the effects of solar variability on the space environment.

The Akebono mission has revealed how the shape of an aurora relates to the flow of plasma through the magnetic field and how the magnetosphere is controlled by the magnetic field in interplanetary space. The SMS has increased our understanding of how the positive ions—tiny electrically charged particles—escape from the Earth's atmosphere.

Akebono was the fourth in a series of Japanese scientific satellites dedicated to the study of space plasma physics. The SMS was the first foreign instrument to be included in a Japanese space mission. It was developed jointly by the National Research Council of Canada and the Institute of Space and Astronautical Science (ISAS) of Japan, then built by SED Systems of Saskatoon. The mission data were gathered by Earth-based stations in Japan, Sweden, Antarctica, and Canada.