The ion acoustic beam instability is suggested as a mechanism to produce wave turbulence observed in the Venus mantle at frequencies 100 Hz and 730 Hz. The plasma is assumed to consist of a stationary, cold O+ ion plasma and a flowing, shocked solar wind plasma. The O+ ions appear as a beam relative to the flowing ionosheath plasma which provides the free energy to drive the instability. The plasma is driven unstable by inverse electron Landau damping of an ion acoustic wave associated with the cold, ionospheric O+ ions. The instability can directly generate the observed 100 Hz waves in the Venus mantle, as well as the observed 730 Hz waves through the Doppler shift of the frequency caused by the satellite motion. ¿ American Geophysical Union 1993