The acoustic sounding and receiving system of CASSE has two principal operation modes:
Listen passively, like a seismometer, into the comet nucleus and locate noise sources, caused by thermal stress, seismic effects, particle impacts or Lander instruments.
Perform actively, like a sonar, a sounding of the surface layers. One can calculate the elastic constants of the cometary surface from the measured sound velocities cP and cS. It is intended to conduct a deep sounding in order to detect layering and other inhomogeneities, like holes. This requires a complex analysis of the acoustic signals.