Experimental investigation of the lunar seismic signals

Summary This study presents the experimental investigation of the propagation of ultrasonic signals with distance along the surfaces of steel spheres. The results give a good indication of the frequencies and the phase velocities contained in the observed signals. An improved laboratory signal as compared to an earlier experiment gives a better comparison with the lunar seismic signal. Also the effect of a dent on the surface of a steel sphere has been studied. The results obtained due to the presence of the dent may give an indication to the effect the craters on the surface of the moon will have on a propagating seismic signal. The presence of the dent definitely reduces the amplitude of the signal propagating across it. The craters may reduce rather than enhance the recorded signal. The recorded signals are constituted of frequencies of 100–500 kHz and the phase velocity varies from 1.0 km/sec to 3.0 kms/sec.