A drilling module comprising: a rotary drill-bit; an oscillator configured to apply high frequency axial oscillatory loading to the rotary drill-bit, of up to 1 kHz; a vibro-transmission section connecting the rotary drill-bit and the oscillator, the vibro-transmission section configured to transmit the high frequency axial oscillatory loading from the oscillator to the rotary drill-bit; a vibrational isolation unit for connecting the drilling module to a drill-string, the vibrational isolation unit being configured to isolate the high frequency axial oscillatory loading from the drill-string; sensors for taking downhole measurements; and a closed loop real-time controller positioned downhole and configured to operate downhole under closed loop real-time control by utilizing the downhole measurements from the sensors to control the oscillator by varying the high frequency axial oscillatory loading responsive to conditions of material through which the rotary drill-bit is passing to establish and maintain oscillation system resonance between the oscillator, the rotary drill-bit and the material through which the rotary drill-bit is passing, whereby the high frequency axial oscillatory loading is sufficient to initiate cracks in the material through which the rotary drill-bit is passing. a rotary drill-bit; an oscillator configured to apply high frequency axial oscillatory loading to the rotary drill-bit, of up to 1 kHz; a vibro-transmission section connecting the rotary drill-bit and the oscillator, the vibro-transmission section configured to transmit the high frequency axial oscillatory loading from the oscillator to the rotary drill-bit; a vibrational isolation unit for connecting the drilling module to a drill-string, the vibrational isolation unit being configured to isolate the high frequency axial oscillatory loading from the drill-string; sensors for taking downhole measurements; and a closed loop real-time controller positioned downhole and configured to operate downhole under closed loop real-time control by utilizing the downhole measurements from the sensors to control the oscillator by varying the high frequency axial oscillatory loading responsive to conditions of material through which the rotary drill-bit is passing to establish and maintain oscillation system resonance between the oscillator, the rotary drill-bit and the material through which the rotary drill-bit is passing, whereby the high frequency axial oscillatory loading is sufficient to initiate cracks in the material through which the rotary drill-bit is passing. an oscillator configured to apply high frequency axial oscillatory loading to the rotary drill-bit, of up to 1 kHz; a vibro-transmission section connecting the rotary drill-bit and the oscillator, the vibro-transmission section configured to transmit the high frequency axial oscillatory loading from the oscillator to the rotary drill-bit; a vibrational isolation unit for connecting the drilling module to a drill-string, the vibrational isolation unit being configured to isolate the high frequency axial oscillatory loading from the drill-string; sensors for taking downhole measurements; and a closed loop real-time controller positioned downhole and configured to operate downhole under closed loop real-time control by utilizing the downhole measurements from the sensors to control the oscillator by varying the high frequency axial oscillatory loading responsive to conditions of material through which the rotary drill-bit is passing to establish and maintain oscillation system resonance between the oscillator, the rotary drill-bit and the material through which the rotary drill-bit is passing, whereby the high frequency axial oscillatory loading is sufficient to initiate cracks in the material through which the rotary drill-bit is passing.