The Science Data Buy (SDB), has been a success in supplying commercial remote sensing data that serves NASA science requirements, but plans for its continuation are uncertain. Although NASA has said that it will purchase science data when it is cost-effective to do so, rather than build new satellites, there is little guidance on determining cost effectiveness. This study was organized to examine public-private partnerships in remote sensing, metrics for evaluating such partnerships, the types of partnerships that might be most appropriate for NASA's Earth Science Enterprise, and options for the future of NASA's SDB. The authors caution that NASA needs to understand and choose what kind of buyer of private remote sensing data it wants to be before it develops specific cost-effectiveness metrics, and that it should clearly articulate the role of the SDB with respect to an overall strategy for Earth science research. Read Less