Launch: February 22, 1989
Status: Inactive


Breakthroughs in the study of the Earth's magnetic field

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 the mobile-satellite service (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 (NRC) 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.

Though the aurora imager camera has degraded due to long-term exposure to space radiation, the remaining instruments are functioning well. Since the Sun’s activity increases in one 11-year cycle and decreases in another 11-year cycle, Akebono has been scheduled to collect data for at least 22 years to capture the full scope of solar activity. As of 2012, it is still active.

Larger image of Japan's Akebono satellite.

Japan's Akebono satellite.
Credit: JAXA

Larger image of Aurora borealis.

Aurora borealis.
Credit: NASA

Larger image of magnetosphere.

How solar winds affect Earth's magnetosphere.
Credit: NASA