Japanese lunar explorer SELENE (KAGUYA) was equipped with 14 instruments for various measurements of the Moon. Three of these instruments took geodetic measurements of the Moon. These were two sub-satellites and a laser altimeter. The main results obtained by the instruments are: (1) precise orbit determination with an accuracy of ten meters by Doppler and same-beam VLBI; (2) the first precise gravity fields on the lunar far side by 4-way Doppler measurements; (3) the first topography in latitudes higher than 86 degrees; (4) a global map of the gravity anomaly by using the global topography and the global gravity fields; (5) a global map of the lunar crustal thickness and (6) an illumination rate map in the north and south polar regions. SELENE, gravity field, lunar far side, topography, gravity anomaly, crustal thickness, illumination rate PACS: 96.12.Bc, 96.12.Qr, 95.10.Eg, 95.75.De
SELENE was successfully launched in September 2007together with two sub-satellites. The SELENE mission has been proposed primarily to study the origin and evolution of the Moon by means of the global characterization of the lunar surface and investigations of its interior. A wide variety of observations by 14 instruments was carried out for about one year in order to perform these aims. These observations can be classified into five fields. Figure 1 shows relations among the observations by SELENE, scientific knowledge of the Moon to be obtained from the observations and our aims (lunar origin and evolution) [1]. The geodetic instruments among the 14 ones are two sub-satellites and a laser altimeter. Geodetic observations by them played the roles that are shown in the hatched blocks in Figure 1.
Strategy in geodetic observations of SELENEThere are not so many methods to study the interior of a planet or the Moon. For example, observations of lunar rotation and moonquakes have revealed the Moon's internal structure. Lunar gravity fields enabled us to better under- Figure 1 Observations by SELENE and scientific knowledge to be obtained. The hatched blocks are items with relation to geodetic measurements.