This project will continue an ongoing program of astrometric (positional) observations of Near-Earth asteroids (NEAs). Astrometric follow-up of new observations is essential in order to determine orbits and recover the objects at future observing opportunities; over 60% of NEAs newly discovered in 2008 and 2009 were subsequently lost due to the lack of adequate follow-up. The Principal Investigator and students supported by this project will perform astrometric measurements using the University of Hawaii 2.24-meter telescope and other telescopes on Mauna Kea. The telescopes and specialized techniques used enable this team to observe fainter objects, with greater positional accuracy, and with better access to the south celestial hemisphere than other groups. They will adapt the newest and most accurate astrometric reference catalog, the PPMXL catalog, for use in NEA astrometry and provide this customized catalog to the community. Improvements will be made to their data processing pipeline to speed the process and enable more positional measurements per object. Finally, the group will plan and carry out measurements of physical characteristics, including shapes, albedos and colors, of selected objects that are possible candidates for human exploration. Accurate NEA astrometry is most critical for the tracking of potentially hazardous asteroids that could collide with Earth; the project thus has broad impacts on impacts. This has implications for Earth-science questions, such as how Earth acquired its water, as well on strategies for mitigating the impact hazard. The project will educate graduate students in observational techniques and in Solar System dynamics; these students, in turn, will have the opportunity to mentor high school students in using the Falukes educational telescope on Haleakala for asteroid research.