COSPAR and its space agency partners are supporting a multi-year stepwise process to identify, prioritize and plan the research and technology developments needed to address planetary protection requirements for human missions beyond Earth orbit. The objective is to move incrementally from the current qualitative COSPAR planetary protection "Principles and Guidelines for Human Missions to Mars" towards development of quantitative planetary protection requirements for such future missions. The workshops and meetings in this series have involved participants from NASA, ESA, JAXA and other national space agencies, as well as the scientific/technical community, and commercial/private enterprise stakeholders. This presentation provides a summary of the findings of the four COSPAR Meetings on this topic. First, the identification and prioritization of knowledge gaps in three major topic areas will be described. Then, work done to identify the measurements needed to close the knowledge gaps (and instruments necessary to make those measurements) in each area will be described. The three topic areas are: Microbial and Human Health Monitoring; Spacecraft Technology and Operations, and; Natural Transport of Contamination at Mars. Finally, a look forward to how the findings of the study series can be integrated into COSPAR Planetary Protection Policy, and into future human mission architectures and designs, will be presented.