JUST AS NASA USED THE REMOTELY OPERATED VEHICLES (ROV) SPIRIT AND OPPORTUNITY TO GATHER AND RELAY INFORMATION THAT CONTINUES TO BROADEN UNDERSTANDING OF MARS, WE WILL DEVELOP ROVS THAT WILL TRANSFORM OUR KNOWLEDGE OF RUMEN BIOLOGY AND FERMENTATION CHEMISTRY, WITH BACKING FROM NSF. THE RUMEN IS ONE OF THE PRIMARY DIGESTIVE CHAMBERS IN THE STOMACH OF A RUMINANT ANIMAL, SUCH AS A COW. ALTHOUGH THE COW RUMEN IS A VERY SPECIFIC ENVIRONMENT, IMPROVING OUR ABILITY TO STUDY THIS ECOSYSTEM PROVIDES NOTABLE OPPORTUNITY TO ENHANCE UNDERSTANDING OF FERMENTATION, FOOD PRODUCTION, AND ENERGY GENERATION, NOT JUST WITHIN CATTLE BUT WITHIN ANAEROBIC FERMENTATION ENVIRONMENTS IN GENERAL. RUMEN MICROORGANISMS ARE SOME OF THE WORLD'S MOST EFFICIENT FERMENTERS OF FIBROUS MATERIALS HIGH IN CELLULOSE; HOWEVER, ONLY A FRACTION OF THE SPECIES IN THE RUMEN MICROBIOME HAVE BEEN SEQUENCED OR CULTURED. THE RUMEN ECOSYSTEM IS A COMPLEX HETEROGENEOUS ENVIRONMENT STRATIFIED VERTICALLY AND HORIZONTALLY THAT CONTAINS MYRIAD SPECIALIZED MICROCLIMATES CAUSED BY DIFFERING DENSITY OF FEED PARTICLES AND O2 CONCENTRATIONS, AMONG OTHER FACTORS. THESE MICROCLIMATES ARE BELIEVED TO CREATE OPTIMAL ENVIRONMENTS FOR UNIQUE MICROBIAL SPECIES THAT MAY HAVE DIFFERING FERMENTATION CAPACITY AND THE STRATIFICATION WITHIN THE RUMEN MAY BE ONE CAUSE FOR DIFFICULTY IN CULTURING MANY OF THESE MICROORGANISMS OUTSIDE THE ANIMAL.A CURRENT ROADBLOCK HAMPERING ADVANCEMENT IN RUMEN PHYSIOLOGY AND MICROBIOLOGY IS THAT CONTEMPORARY RESEARCH TOOLS AND METHODS LACK THE ABILITY TO ACHIEVE THE NECESSARY DETAIL IN MEASUREMENT AND SAMPLE COLLECTION. KEY LIMITATIONS OF CURRENT TECHNOLOGIES INCLUDE: 1) LACK OF MOTILITY; 2) FAILURE TO SELF-IDENTIFY LOCATION WITHIN THE ANIMAL; 3) INABILITY TO RETRIEVE SAMPLES FOR LATER ANALYSIS; AND 4) POOR PRECISION AND ACCURACY. FOR EXAMPLE, BOLUS-DELIVERED TEMPERATURE AND PH PROBES CAN GENERATE PRECISE REAL-TIME MEASUREMENTS BUT SINK TO ONE LOCATION (TYPICALLY IN THE RETICULUM, BUT ULTIMATELY UNKNOWN TO THE RESEARCHER) AND OUTPUT VALUES CAN DRIFT OVER TIME. A DYNAMIC, PRECISE AND ACCURATE "MAP" OF THE RUMEN ENVIRONMENT THROUGH RUMEN ROV WOULD PROVIDE AN UNPRECEDENTED UNDERSTANDING OF THIS COMPLEX ECOSYSTEM. TO ADDRESS THIS GAP, WE WILL CONSTRUCT A ROBOTIC RUMEN ROV CAPABLE OF NAGIVATING, SAMPLING, AND CHARACTERIZING THE RUMEN AND ITS CONTENTS.