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Volume 46 (2000)
- Issue 4 Pages 239-
- Issue 3 Pages 177-
- Issue 2 Pages 89-
- Issue 1 Pages 1-
Volume 46, Issue 3
Displaying 1-4 of 4 articles from this issue
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Shuhei Okubo, Yasutaka Ikeda, Takashi Kumamoto, Gaku Seta, Nobuhisa Ma ...2000 Volume 46 Issue 3 Pages 177-186
Published: September 25, 2000
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSWe carried out gravity surveying along a profile of the reflection seismological prospecting in the northern part of the Itoigawa-Shizuoka Tectonic Line (ISTL). Combined use of gravity and seismic data enables us to construct a 2-D subsurface density model. We also pre sent a 3-D model which is consistent with the previous works on gravity and reflection/refraction prospecting. Both 2-D and 3-D models show a reverse fault structure dipping toward the east. We do not find any thrusting structure dipping toward the west as implied from the up lifting of the Hida range.View full abstractDownload PDF (5787K) -
Jinsong Ping, Yusuke Kong, Atsushi Tsuchiya, Nobuyuki Kawano2000 Volume 46 Issue 3 Pages 187-202
Published: September 25, 2000
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSIntegrated Doppler measurement is one of the major methods for tracking a planetary space vehicle. To study the lunar gravity field precisely, the SELENE project is to measure the Doppler frequency of the spacecraft (s/c) radio signal with an accuracy of 1 mHz, or of 0.1 mm/s of range rate. Also, the Doppler measurement should be done with a data rate of everyfew tens seconds. Nonlinear phase pattern of the s/c antenna together with s/c spin will make erroneous Doppler measurements. Two types of antennas i.e. crossed-dipole and micro-strip are assumed for the spacecraft-borne antenna and the effects on Doppler measurements were investigated. Due to the s/c spin and antenna phase characteristics, three kinds of errors, i.e., a constant component, a periodical component with spin rate and higher order harmonic components will appear in Doppler measurement. Methods to remove those errors have been mentioned.View full abstractDownload PDF (3787K) -
Manabu Yatabe2000 Volume 46 Issue 3 Pages 203-222
Published: September 25, 2000
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe gravity fields containing the self-gravitation have been considered for studying shapes of celestial bodies. However, assuming the hydrostatic equilibrium, the self-gravitation does not deform the shape to deviate from the sphere . Therefore, it is not necessary to con sider the self-gravitation when we discuss deviations from spherical shapes for celestial bodies.This study introduced the concept of the residual gravity field to exclude the self -gravitation from the gravity field, and discussed the lunar shape and history . Employing the lunar grav ity model (GLGM-2) and the topography model (GLTM-2B), following results were obtained. (a) There is a strong positive correlation between the residual gravity and the lunar geoid. The present lunar geoid is explained by two interpretations: The Moon was asynchronously rotating. The angular velocity was 2.1 times as fast as the present one . By the other interpretation, the present geoid is fitting the equilibrium state when the distance from the Earth was 1.81 x 105 km. (b) Correlations between the residual gravity and the topography have regionaldifferences. The correlation on the far side is strong . On the contrary, the correlation on the near side is weak. This difference can be explained as follows: When the magma ocean solidified, the lunar topography must have been an equilibrium shape fitting the residual gravity of the synchronous rotation at the time. After that, the mare formation has erased the topogra phy affected by the residual gravity on the near side. From the correlation on the far side, it is inferred that the Moon had been synchronously rotating when the lunar surface were covered by the magma ocean. (c) Assuming that both the geoid and the topography have somecorrelations with the residual gravity, the lunar center of gravity is located in the position of1.96 km toward the Earth from its center of figure.View full abstractDownload PDF (1797K) -
Jiro Segawa, Shigekazu Kusumoto, E. John Joseph, Hiroshi Hasegawa, Sei ...2000 Volume 46 Issue 3 Pages 223-229
Published: September 25, 2000
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSWe have developed an airborne-gravity measurement system using a helicopter as a plat form for the first time in Japan and carried out test measurements around Kawagoe, Saitama Prefecture, Japan. Our airborne-gravity measurement system showed the repeatability of better than 2 meal root-mean-square residuals estimated by comparison between the data on forward and return tracks. We believe our system will contribute much to the gravimetric study over land-sea boundaries as well as in remote areas.View full abstractDownload PDF (2708K)
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