New Horizons 2



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. 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).

Description
New Horizons 2 was included in the tentative budget for the New Horizons missions. In 2004 the United States Senate Appropriations Committee provided additional funding for New Horizons 2, a new Kuiper belt mission. As early as 2004 there was a conference on how to make the most use of New Horizons 2's Uranus flyby.

Candidate targets included, a system that, like Pluto–Charon, contains multiple bodies. The mission plan for also included flybys of Jupiter and Uranus, and perhaps four Kuiper belt objects (KBO). There was a lot of flexibility: even without a gravity assist any KBO within 50 AU and a 20-year flight time was possible. A flyby of Neptune's Triton was also considered, with 66652 Borasisi as a potential follow on. was also considered to be visited, having a similar flight plan as.