  To support scientific visualization of multiple-mission data from Mars, the
Virtual Astronaut (VA) creates an interactive virtual 3D environment built on
the Unity3D Game Engine. A prototype study was conducted based on orbital and
Opportunity Rover data covering Santa Maria Crater in Meridiani Planum on Mars.
The VA at Santa Maria provides dynamic visual representations of the imaging,
compositional, and mineralogical information. The VA lets one navigate through
the scene and provides geomorphic and geologic contexts for the rover
operations. User interactions include in-situ observations visualization,
feature measurement, and an animation control of rover drives. This paper
covers our approach and implementation of the VA system. A brief summary of the
prototype system functions and user feedback is also covered. Based on external
review and comments by the science community, the prototype at Santa Maria has
proven the VA to be an effective tool for virtual geovisual analysis.
