抄録
There are several planets and satellites such as Venus, . Mars and the Moon which probably show rotational fluctuations and tidal deformations whose amplitudes are larger than 0.01 arc sec or 0.lm. The inverse VLBI method, which receives synchronous radio waves from two or more transmitters on the planet and measures delays between the radio waves within a precision of 0.05 us, can observe the angular velocity of the planets with an accuracy of 10-4 if the amplitudes is about 1 arc sec like the nutations of Mars. Tidal deformation is also possible phenomena which the inverse VLBI method can detect. It can expand targets of geodetic research to the solar system. Observations of rotational fluctuations and tidal deformations by the inverse VLBI will give us a new information of structure and property of the interior of the planets.
