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 out of the New Frontiers program, and was delivered to the U.S. Congress in June 2005.[4]
Description
New Horizons 2 was included in the tentative budget for the New Frontiers program missions.[5] In 2004 the United States Senate Appropriations Committee provided additional funding for New Horizons 2, a new Kuiper belt mission.[6] As early as 2004 there was a conference on how to make the most use of New Horizons 2's Uranus flyby.[7]
Candidate targets included 47171 Lempo, a system that, like Pluto–Charon, contains multiple bodies.[5] The mission plan for Lempo also included flybys of Jupiter and Uranus,[5] and perhaps four Kuiper belt objects (KBO).[8] There was a lot of flexibility: even without a gravity assist any KBO within 50 AU and a 20-year flight time was possible.[9] A flyby of Neptune's Triton was also considered, with 66652 Borasisi as a potential follow on.[9]2002 UX25 was also considered for a visit, as it had a similar orbit to Lempo.[10]
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