The G3ISTAR is a small GPS/Galileo dual-frequency GNSS receiver designed for use by micro-launchers, based on existing GNSS Receiver solution from DEIMOS and a flight-proven platform for CubeSats. The reliability and integrity of the receiver’s navigation solution will be ensured through the development of the Galileo Open Service Navigation Message Authentication (OSNMA) and Failure Detection Isolation and Recovery (FDIR) algorithms.  The specific challenges associated with tracking GNSS signals due to the demanding dynamics and vibration environment associated with micro-launch vehicles will be addressed.  The receiver’s role is to provide navigation data for the launcher’s GNC sub-system and, alternatively, for relaying to the ground flight termination system.  The output of the project will be an Engineering Qualification Model and a plan to produce immediately recurrent Flight Models, targeting to be on-board of a qualification flight by end of 2022.