Previous Mars landers have been able to land only within tens to hundreds of km of a target site. Principal sources of uncertainty are approach navigation, atmospheric modeling, and vehicle aerodynamics; additional (lesser) uncertainty sources are map-tie error and wind drift. The Mars Science Laboratory mission scheduled for 2009 launch will use guidance during hypersonic entry to improve this to /spl sim/10 km. To achieve "pinpoint landing" (within 100m) for future missions, ways of addressing the remaining error sources (approach navigation, wind drift and map-tie error) must be found. This work defines a "reference system design" for guidance, navigation, and control in future pinpoint landing missions, and assesses uncertainties and performance penalties associated with pinpoint landing using this reference system design.