SCIENCE GOALS AND OBJECTIVES: THE SCIENCE QUESTIONS WE PROPOSE ARE MOTIVATED BY RECENT SPACECRAFT DATA ANALYSIS AND EXPERIMENTAL RESULTS. WE SEEK TO ANSWER: 1) WHAT IS THE TEMPORAL AND SPATIAL DISTRIBUTION OF SUBSURFACE LIQUID WATER ENVIRONMENTS ON PRESENT-DAY MARS? 2) WHEN DO SUBSURFACE LIQUID WATER ENVIRONMENTS MEET THE CONDITIONS THAT PERMIT BIOLOGICAL ACTIVITY SUCH AS METABOLISM AND REPLICATION? 3) HOW DO SUBSURFACE LIQUID WATER ENVIRONMENTS CHANGE WITH LOCAL-SCALE GEOLOGY SUCH AS TOPOGRAPHIC EFFECTS? 4) HOW MUCH WATER IS AVAILABLE FOR POTENTIAL BIOLOGICAL PROCESSES?