We propose to build and launch a fleet of thousands of autonomous ten-gram spacecraft to navigate the inner solar system. Example missions of these low-cost spacecraft will be to return visual images of near-earth objects (NEOs), create an interplanetary mesh network for data communications, deploy micro robots on NEOs, drop phosphine sensors into the atmosphere of Venus, and return samples from comets. Each spacecraft will weigh roughly ten grams, and navigate using a solar sail of one square meter. Three-axis control of the orientation of the spacecraft will be achieved with MEMS inchworm motor control of the shroud lines on the solar sail.