Busek, in partnership with Arizona State University (ASU), proposes to develop a robotic resource prospecting mission to a near-Earth asteroid using a 6U CubeSat, nicknamed "AstroCube". This ambitious mission is enabled by Busek's iodine-fueled BIT-3 RF ion propulsion system that can deliver ~1mN of thrust and ~2200sec of total Isp with 65W nominal input power. With 1.6kg of solid iodine propellant onboard, the BIT-3 thruster will provide AstroCube approximately 3.1km/s of delta-V maneuverability to rendezvous with the target, Asteroid 2001 GP2, during its next closest Earth approach in October 2020. The 6U CubeSat platform is chosen due to its low cost and ease of access to ride-share opportunity on GEO-bound upper stages, as well as on the upcoming NASA SLS demonstration missions. The AstroCube mission will leverage a unique deep-space 6U CubeSat bus with ion propulsion, currently being co-developed by Busek and Morehead State University (MSU) under NASA's Lunar IceCube flight program. The proposed mission will encompass several technology innovations, including compact science instruments and autonomous CONOPS, which are the focus of this Phase I development. A rad-tolerant, 1/4U sized camera-Lidar device will give AstroCube "eyes" to survey the asteroid and help with proximity navigation. Due to the asteroid?s weak gravitational field, the spacecraft will be required to use real-time depth image processing and its ion thruster to navigate around the asteroid during final approach to a low stationary altitude. Once such close proximity is reached, a 1U sized neutron spectrometer will be activated to characterize the abundance of hydrogen, which would indicate presence of water ice, by detecting slow-moving neutrons as they scatter off the asteroid's regolith from the bombardment of cosmic rays.