The Jet Propulsion Laboratory is developing the Lunar Surface Operations Simulator software package to support analyses for future NASA lunar missions. The package is built on and extended from previous simulation packages developed at JPL. It simulates mechanical motion, soil interaction, environmental, and physical processes. Physical process dynamics include environmental control and life support, thermal, radiation and power transients. An integrated architecture allows use of common models and enables interactions between components operating in different domains to be easily modeled. We describe recent developments and analyses performed to support lunar surface missions and analog field trials.