The successful landing of the large Mars rover Curiosity on August 5, 2012 outlined the increasing complexity of safely landing large rovers on the planet. A precise knowledge of the spacecraft speed is required in order to initiate the landing sequence near 900 mph; the present method uses IMUs to determine the position and speed of the craft, which is prone to drift and highly sensitive to initial conditions. The proposed MArs VelocitY sensor (MARVY) is a short range air data sensor based on direct, or incoherent, detection of light scattered by both molecules and aerosols. The instrument operates in the presence or absence of aerosols, thus enabling operation in completely clear atmosphere. The MARVY design will be based on micro-fabricated optical components to provide an instrument that affords all requirements for planetary exploration. This Phase I will entail modeling and design of the instrument. Critical components will be tested in Phase II.