CICERO is a planned array of 100 low-Earth Orbiting (LEO) micro-satellites for performing GPS and Galileo radio occultation (GNSS-RO) of Earth's atmosphere and surface remote sensing by GNSS reflection.  The system will deliver critical data on the state of the earth to scientists and decision makers worldwide. Products will include high-accuracy profiles of atmospheric pressure, temperature, and moisture; 3D maps of the electron distribution in the ionosphere; and a variety of ocean and ice properties (see GPS Earth Sensing). Principal applications will be weather forecasting, climate research, and space weather monitoring.