THE OBJECTIVE OF THIS PROPOSAL IS TO DEVELOP AN ANMBR SUITABLE FOR ZERO-G SETTINGS. THE MAJOR BARRIER IN THE TRANSITION OF THE ANMBR FROM GRAVITY-BASED GROUND SYSTEM TO CLOSED-SYSTEM ZERO- G SYSTEM IS RELATED TO THE REDESIGN OF 1) BIOREACTOR GEOMETRY AND 2) SOLID/LIQUID/GAS SEPARATION MECHANISMS FACILITATED BY ULTRAFILTRATION (SEPARATION OF GAS/LIQUID FROM SOLID) AND GAS-PERMEABLE (SEPARATION OF GAS FROM LIQUID) MEMBRANES. THE BIOREACTOR GEOMETRY WILL NEED TO ACCOMMODATE THE REDISTRIBUTION OF POSITIVE DENSITY GRADIENTS FROM TOP TO BOTTOM (EARTH-BASED SYSTEMS) TO CENTER TO PERIMETER (ZERO G). ACCORDINGLY THE MEMBRANE SEPARATION SYSTEMS WILL NEED REDESIGN/REALIGNMENT THROUGH THE COMBINED USE OF TUBULAR AND HOLLOW FIBER FORM FACTORS.