Coherent lidar is useful for many applications including navigation, imaging, ranging and Doppler velocimetry during spacecraft landing, proximity operations, hazard avoidance, and docking. A reliable source of coherent modulated optical waveforms is required for simultaneous ranging and velocimetry. Existing sources are bulky since they require large electronic bandwidth, fragile fiber-based lasers and other discrete components, modulators, or long optical delay lines. This makes coherent lidar systems difficult to miniaturize for small platforms such as cubeSats, smallSats, and autonomous aerial and land vehicles. We propose to develop a low power, mass and size photonic integrated circuit (PIC) that implements a high data rate coherent lidar transceiver operating at the 1550 nm wavelength. The innovation is based on a new method to generate frequency modulated continuous wave (FMCW) laser radiation that relies on optical components present on a PIC only and does not use optical phase locked loops or modulators. This new architecture enables extremely compact and low cost coherent lidar engine for navigation, imaging and object detection. Potential NASA Applications (Limit 1500 characters, approximately 150 words): - Automated landing, hazard avoidance and docking. - Object detection and imaging. - Position, and navigation in GNSS/GPS denied/degraded environments. - Terrain relative navigation and odometry for GN&C of lunar and other small vehicles, - Small body proximity operations, including to augment machine vision techniques in low or variable light conditions and to reduce errors in proximity planning algorithms. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): In urban environments where usage of UAVs is expected to dramatically raise, the GNSS signals are not always reliable. IMUs and computer vision techniques are not accurate enough for robust localization. Compact navigation Doppler lidar will help reduce drift and improve loop closure in visual SLAM, odometry and exploration of unknown environments. Duration: 6