Breakthrough Propulsion Study – Assessing Interstellar Challenges and Prospects Authors: Marc Millis and James Gilland Objective: A database of interstellar propulsion options is being created. The database aims to capture a span of concepts in the peer-reviewed literature and cover the evaluation factors devised in the 1st stage. The focus is on identifying which research paths have the most leverage for traveling farther, faster, and with more capability, rather than being a system to select pick an interstellar mission and its technology. The assessments will allow for varying assumptions and priorities. Though NASA is the sponsor, the results will be publicly accessible. Methods: To collect information, three database sets are planned, the first of which is underway; (1) Mission-Vehicle Concepts, (2) Propulsion and Power System Performance, (3) Research Plans and Roadmaps. In the process of collecting information, “dashboards” for accessing the information are being developed, including a publicly accessible version. Results: In March, 2021, an online questionnaire began collecting information for Mission-Vehicle concepts. By June, 2021, the following concepts were submitted: • Pulsed Fission Fusion Hybrid (PUFF) [Cassibry] • Firefly Icarus [Freeland] • Q-Drive to Alpha Centauri [Greason] • Project Hyperion [Hein] • Icarus Interstellar [Lamontagne] • Deep In, Starlight, Starship [Lubin] • Graphene Solar Photon Sail [Matloff] • Project Daedalus [Millis] • Forward’s Starwisp [Millis] • Forward’s Rendezvous Laser Sail to Alpha Centauri [Millis] • Forward’s Round-Trip Interstellar Sail [Millis] • Solar Sail with Thermal Desorption [Starinova] Conclusions: Techniques have been devised to equitably compare the disparate and unproven propulsion options, and in a way to accommodate the uncertainties. Collecting data has begun, but not all of the needed information is available. Examples include predictions on infrastructure growth, technology readiness rates, and having consistent performance specs for ancillary technologies (e.g. thermal radiators, magnetic nozzles, power storage). Developing user-interfaces for the database is a work in progress, adjusting to the submissions received.