In this paper it is explained how most of asteroids can avoid very close approach to Jupiter, to the earth for earth orbit crossing asteroids, and to Neptune for Kuiper-belt asteroids by mechanisms which work also for Neptune-Pluto system. In fact the mutual distance of the planets cannot become very small as the critical argument librates around 180° because of 2:3 mean motion resonance and the argument of perihelion of Pluto librates around 90°. And it is found that among nearly 40 Kuiper-belt asteroids discovered in recent years 40% have orbits similar to Pluto. For main-belt asteroids the distribution with respect to the semi-major axes has peculiar characteristics and the author tries to explain how their peaks and gaps are created. It is also found that 30% of 80 earth orbit crossing asteroids which have minimum perihelion distances less than 1.04AU have no chance to collide with the earth. Still 30% of them have a few probability to collide with the earth as they have dynamical characteristics of short-periodic comets.

This paper reports on the outline and the status of the TAMA-300 project, the 300 meter laser interferometer gravitational wave detector developed by a team of scientists of several research institutes and universities in Japan. In fact the project has been funded and its construction started at the National Astronomical Observatory, Mitaka, in spring 1995. And the constructions of the tunnels for the east-west and north-south arms and of the central building are completed and a half of pipes for laser beams were brought in. Very stable laser oscillator has been almost completed and mew techniques such as vibration isolations, recycling of laser power, and suspension of mirrors by double pendulums have been developed. In fact the purposes of the project are to establish techniques necessary for future km-class detectors and to operate the detector to catch possible gravitational wave events in nearby galaxies such as Andromeda, the target sensitivity being 3 × 10-21 at 300Hz.