Lunar and Planetary Institute
Lunar and Planetary Institute



KAGUYA (“SELENE”) Subsatellite Separation

October 12, 2007
Source:  JAXA

The KAGUYA onboard camera has captured numerous images of the Moon's surface. Credit: JAXAToday, at 1:28 p.m. Japan Standard Time (JST), KAGUYA’s VRAD (Very Long Baseline Interferometer) subsatellite was released. The first subsatellite, the Relay Satellite, separated earlier this week and was placed in an elliptical orbit at an apogee of 2400 kilometers and will soon begin to relay communications between the main orbiter and the ground station.

The Relay satellite and the VRAD satellite are respectively nicknamed “Okina,” meaning “honorable elderly man,” and “Ouna,” meaning “honorable elderly woman.” These nicknames, selected from nominations by people related to the SELENE project, stem from the Japanese classic story “The Tale of the Bamboo Cutter” (“Taketori Monogatari”). [The name of the spacecraft, “KAGUYA,” also comes from the name of one of the characters in that tale, "Kaguya-hime (Princess Kaguya)."]

In the tale, Princess Kaguya was found by an old man (“Okina”) in a bamboo and was brought up by the man and his wife (“Ouna”) with great care. The nicknames are thought to be appropriate, because the Relay and VRAD satellites are flying in a higher orbit than KAGUYA, as if they are watching over KAGUYA as its guardians.

KAGUYA is Japan’s first large lunar explorer and was launch by the H-IIA rocket on September 14, 2007. This is the largest mission of its kind since the Apollo program, and has been greatly anticipated by many countries. The major objectives of the mission are to understand the Moon’s origin and evolution, and to observe the Moon for the purpose of potential future utilization studies.

KAGUYA will investigate the entire Moon in order to obtain information on its elemental and mineralogical composition, its geography, its surface and subsurface structure, the remnant of its magnetic field, and its gravity field. The results are expected to lead to a better overall understanding of the Moon’s evolution. At the same time, the observation equipment installed on the orbiting satellite will observe plasma, the electromagnetic field, and high-energy particles. The data obtained in this way will be of great scientific importance for exploring the possibility of using the Moon for human endeavors.

For more information, visit

SELenological and ENgineering Explorer "KAGUYA" (SELENE)

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Last updated January 30, 2008