CETACEAN is Starfish Spaces onboard relative navigation software for satellite proximity operations and docking that will reliably determine the relative state between two spacecraft. There are two areas of development needed to advance relative navigation towards onboard autonomous viability: 1) Improvement in machine vision image processing and 2) Development of navigation filter structure to blend machine vision measurements with a combination of sensor types to enable flight software and hardware modularity. CETACEAN embodies these development areas, and will offer accurate relative position, velocity, attitude, and pose. CETACEAN generates relative estimates using rapid image processing and several, new, and Commercial-Off-The-Shelf onboard sensorsincluding various cameras, LiDAR, RADAR, GPS, star trackers, and Inertial Measurement Units. CETACEAN is designed as a plug-and-play solution that can run on multiple software stacks and has been successfully integrated with existing software platforms, including NASAs core flight system (cFS). CETACEAN further advances rapid image processing capabilities and machine vision to autonomously conduct optical relative navigation and Rendezvous, Proximity Operations, and Docking (RPOD) in low and variable lighting conditions and without the need for target spacecraft fiducials or human decision-making. CETACEANs autonomy and modularity will help realize a low Size, Weight, Power, and Cost (SWaP-C) spacecraft. The ability to easily swap out different sensors and update sensor processing filters, will allow organizations to more rapidly design spacecraft to meet mission needs. For spacecraft RPOD to be done in a safe and reliable manner, a robust relative navigation software like CETACEAN is required, for without it, autonomous on-orbit approach and docking would not be possible. Potential NASA Applications (Limit 1500 characters, approximately 150 words): CETACEAN enables a variety of NASA missions: 1) Proximity operations and docking in Earth orbit, cislunar space, lunar orbit, and Mars orbit (including Mars Sample Return), which require increased autonomy and reduced human involvement, 2) Servicing, upgrading, and extending the life of multibillion-dollar NASA science satellites, and 3) Removal of defunct satellites and orbital debris that endanger NASA spacecraft and critical space infrastructure such as the International Space Station. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): Starfish recently raised $7.25M from top VCs, won a $1.7M Space Force contract, and is building relationships with major satellite operators, who are interested in CETACEAN to enable commercial missions such as satellite life extension and defunct satellite removal. Customers have also indicated interest in on-orbit: satellite relocation, assembly, materials transport, and inspection. Duration: 6