JAXA Japan Aerospace Exploration Agency

	AKEBONO observes the physical processes taking place in geospace and collects detailed data in collaboration with the ground stations. AKEBONO (EXOS-D) is an aurora observation satellite launched by the M-3SII-4 launch vehicle from Uchinoura Space Center (USC) on February 22, 1989. AKEBONO’s objective is to investigate the magnetospheric phenomena associated with the acceleration process of aurora particles. Aurora is a luminous phenomenon that occurs when solar-wind particles trapped in the magnetosphere collide with Earth’s atmospheric particles. A better understanding of this phenomenon will help us understand the physical processes taking place in the Sun and the reaction on Earth. The AKEBONO observed these physical processes to create a greater understanding of the structure of the magnetosphere and the flow and momentum of energy from the Sun through the geospace. It achieved various observation results including a finding that the Earth’s magnetosphere controls aurora phenomena. Its observation activities were terminated on April 23, 2015, due to deterioration of onboard instruments and reduced flight altitude after 26 years and two months of operation, which was amazingly longer than its target life of one year. Lauch date: February 22, 1989

AKEBONO observes the physical processes taking place in geospace and collects detailed data in collaboration with the ground stations.

AKEBONO (EXOS-D) is an aurora observation satellite launched by the M-3SII-4 launch vehicle from Uchinoura Space Center (USC) on February 22, 1989.

AKEBONO’s objective is to investigate the magnetospheric phenomena associated with the acceleration process of aurora particles. Aurora is a luminous phenomenon that occurs when solar-wind particles trapped in the magnetosphere collide with Earth’s atmospheric particles. A better understanding of this phenomenon will help us understand the physical processes taking place in the Sun and the reaction on Earth.
The AKEBONO observed these physical processes to create a greater understanding of the structure of the magnetosphere and the flow and momentum of energy from the Sun through the geospace. It achieved various observation results including a finding that the Earth’s magnetosphere controls aurora phenomena. Its observation activities were terminated on April 23, 2015, due to deterioration of onboard instruments and reduced flight altitude after 26 years and two months of operation, which was amazingly longer than its target life of one year.

Lauch date: February 22, 1989

Project Topics

Apr. 23, 2015 Updated

AKEBONO operation completed

	JAXA stopped sending and receiving radio waves to and from the Aurora Observation Satellite “AKEBONO” (EXOS-D) at 3:59 p.m. on April 23, 2015 to terminate its operation. The AKEBONO, launched on Feb. 22, 1989, continued its observation activities for 26 years and two months, amazingly longer than its target life of one year, and attained various important achievements including aurora phenomena in the polar region of the Earth and the long-term periodical changes of the Van Allen radiation belt. The achievements and knowledge obtained by the AKEBONO project will be utilized for observation planning and data analysis of a future explorer to the geospace (the Exploration of energization and Radiation in Geospace "ERG" project.) Message from AKEBONO Project Manager, Associate Professor Ayako Matsuoka Thank you very much for all of you who have supported the AKEBONO observation operations for such a long time. I would also like to renew and send my highest respects to my predecessor and former AKEBONO team members who sent the satellite into its orbit 26 years ago. We will keep generating new achievements by utilizing data acquired by the AKEBONO.

JAXA stopped sending and receiving radio waves to and from the Aurora Observation Satellite “AKEBONO” (EXOS-D) at 3:59 p.m. on April 23, 2015 to terminate its operation.
The AKEBONO, launched on Feb. 22, 1989, continued its observation activities for 26 years and two months, amazingly longer than its target life of one year, and attained various important achievements including aurora phenomena in the polar region of the Earth and the long-term periodical changes of the Van Allen radiation belt.
The achievements and knowledge obtained by the AKEBONO project will be utilized for observation planning and data analysis of a future explorer to the geospace (the Exploration of energization and Radiation in Geospace "ERG" project.)

Message from AKEBONO Project Manager, Associate Professor Ayako Matsuoka
Thank you very much for all of you who have supported the AKEBONO observation operations for such a long time. I would also like to renew and send my highest respects to my predecessor and former AKEBONO team members who sent the satellite into its orbit 26 years ago. We will keep generating new achievements by utilizing data acquired by the AKEBONO.

Characteristics of Aurora Observation Satellite "AKEBONO" (EXOS-D)

AKEBONO is an ambitious satellite carrying a number of "world-first" technologies.

AKEBONO carries eight sets of instruments for scientific observation. It also has a radiation monitor, and anti-radiation technology that has been applied to a satellite for the first time in the world. This technology provides protection against radiation, even in the near-Earth radiation belt, as it is designed to tolerate about ten times the intensity withstood by conventional satellites. Other world-first technology applied to AKEBONO includes an extension mast for antenna and surface electrical conduction processing, to gain better conductivity and protection from charged particles. The GEOTAIL and NOZOMI satellites have inherited these technologies. GEOTAIL operates in the world-best quiet environment, which has never before been possible without the electromagnetic compatibility test conducted by AKEBONO.

AKEBONO carries eight sets of instruments for scientific observation. It also has a radiation monitor, and anti-radiation technology that has been applied to a satellite for the first time in the world. This technology provides protection against radiation, even in the near-Earth radiation belt, as it is designed to tolerate about ten times the intensity withstood by conventional satellites.

Other world-first technology applied to AKEBONO includes an extension mast for antenna and surface electrical conduction processing, to gain better conductivity and protection from charged particles. The GEOTAIL and NOZOMI satellites have inherited these technologies. GEOTAIL operates in the world-best quiet environment, which has never before been possible without the electromagnetic compatibility test conducted by AKEBONO.

The AKEBONO has operated for more than 20 years. Although the aurora imager camera has deteriorated due to the severe radioactive environment, all the other instruments are in good order. The direction of the major magnetic field of the Sun is known to reverse in a 22-year cycle. The Sun’s activeness, which is typically measured by the number of sunspots, increases and decreases twice in this 22-year cycle. In other words, the Sun’s behavior is changing in an 11-year cycle.
The AKEBONO attained continued data acquisition for 26 years through its onboard radiation monitor and plasma monitor to clarify changes of the “Van Allen radiation belt” due to the Sun’s activities.

Major Characteristics

International Designation Code	1989-016A
Launch Date	08:30, February 22, 1989 (JST)
Launch Vehicle	M-3SII-4
Location	Kagoshima Space Center (Uchinoura)
Shape	100cm high, 126cm long from face to face Octagonal cylinder with four solar-array paddles Equipped with 30m-long antenna and two (5m and 3m) extendable masts
Weight	Approx. 295 kg
Orbiter	Highly elliptical
Altitude	Perigee 275 km, Apogee 10,500 km
Inclination	75 degrees
Period	211 minutes