New Horizons 2 (also New Horizons II, NHII, or NH2) was a proposed mission to the trans-Neptunian objects by NASA. It was conceived as a planetary flyby mission in 2002, based on the New Horizons spacecraft, which was in development at the time.[1][2] In March 2005, the proposal was not selected for further development because of a shortage of plutonium-238 needed for the radioisotope thermoelectric generator (RTG).[3] The New Horizons 2 study was funded by the New Frontiers program, and delivered to the U.S. Congress in June 2005.[4]