is returned to the pit 27 for recirculation the bottomhole assembly 100 may include a logging while drilling lwd module 120 a measuring while drilling mwd module 130 a rotary steerable system and motor and drill bit 105 the lwd module 120 may be housed in a special type of drill collar as is known in the art and can contain one or a plurality of known types of logging tools it will also be understood that more than one lwd and or mwd module can be employed e g as represented at 120 u2032 the lwd module may include capabilities for measuring processing and storing information as well as for communicating with the surface equipment the lwd module may include a fluid sampling device the mwd module 130 may also be housed in a special type of drill collar as is known in the art and can contain one or more devices for measuring characteristics of the drillstring and drill bit the mwd tool may further includes an apparatus not shown for generating electrical power to the downhole system this may typically include a mud turbine generator powered by the flow of the drilling fluid it being understood that other power and or battery systems may be employed the mwd module may include one or more of the following types of measuring devices a weight on bit measuring device a torque measuring device a.