The experiments to detect microwave emission due to hypervelocity impacts have been carried out with significant improvements of time resolution. We can investigate waveforms up to 1 n sec so that the energy of the emitted microwave can be estimated. The emission is a random sequence of pulses which lasts more than 10 mu sec depending on the target destruction. The projectile is a nylon sphere of 0.21 gram, and is accelerated by a light-gas gun up to the velocity of 4 km/sec. The timing and duration of the emission are strongly dependent on the material and thickness of a target. Especially, large delay of the emission was observed in the cases a projectile penetrates a target. Therefore, those informations seem to include key suggestions to destruction process as well as the emission amplitude. This phenomena can be applied to the impact detection on a large space structure like a space station. The generated microwave propagate in vacuum and may be diffracted so that impacts can be detected more easily and at more flexible locations than by a vibration sensor or an accelerometer.