Experimental Geodetic Satellite "Ajisai"(EGS)

In Operation

Project Topics

May 26, 2011 Updated

AJISAI received the Tsuboi Prize of the Geodetic Society of Japan (Group Prize)

The 25-year operation and precious observation data of the Experimental Geodetic Satellite "AJISAI" (EGS) was highly evaluated by the Geodetic Society of Japan, and, on May 23, 2011, the Tsuboi Prize (Group Prize) was awarded to a group led by former space verification team project manager Eiichi Hashimoto. The group consists of JAXA, the National Institute of Information and Communications Technology (NICT), the Japan Coast Guard (JCG), Geospatial Information Authority of Japan (GSI), and Hitotsubashi University. The AJISAI was launched on August 13, 1986, to establish the Japan's geodetic datum. The Tsuboi Prize of the Geodetic Society of Japan (Group Prize) is awarded to a group that has made outstanding contributions to geodetic studies as organizational activities are particularly important for geodetic research.

AJISAI's major achievements
  • Contributions to updating a nautical chart of Japan's neighboring waters and determining locations of islets (JCG's original objectives)
  • Communications and positioning experiments and technological developments (NICT, Hitotsubashi Univ.)
  • Research on satellite rotation (GSI)
  • Acquired technology for accurate orbit determination by laser ranging (JAXA)
  • Decided the 36th to 50th gravity field model (world research institutes, such as Jet Propulsion Laboratory, JPL, and Deutsches Zentrum f?r Luft- und Raumfahrt, DLR)
  • Contributed to construct the International Terrestrial Reference Frames (ITRF)
  • Determined the absolute value of the velocity field for plate tectonics motion thanks to the long-term motion analysis of 25 years by the AJISAI
  • Recently verified that the core inside the Earth is vibrating through the analysis combined with the LAGIOS1/2 . The result of the verified fact was incorporated into the new earth rotation model (IERS2010.)



The primary short-range objective for AJISAI (EGS) was testing of NASDA's H-I'(2-stage) launch vehicle. Long-range applications included a survery aimed at rectifying Japan's demestic geodetic triangular net - determining the exact position of many isolated Japanese islands and establishing Japan's geodetic point of origin.
The survey was conducted by the Geographical Survey Institute of the Ministry of Construction and the Hydrography Department of the Maritime Safety Agency, Ministry of Transport.

Major Characteristics

International Designation Code 1986-061A
Launch Date 05:45, August 13, 1986 (JST)
Launch Vehicle H-I Launch Vehicle No.1(H15F)
Location Tanegashima Space Center
Shape 215cm(D) sphere with solar ray and laser beam reflectors.
Weight Approx. 685kg
Orbiter circular
Altitude Approx. 1500km
Inclination Approx. 50 deg
Period Approx. 116 minutes
Attitude Control Spin-stabilization