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, 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]

Design of the first New Horizons spacecraft

Description

New Horizons 2 was included in the tentative budget for the New Frontiers program missions.^[5] In 2004, the United States Senate on 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).^[2] There was a lot of flexibility: even without a gravity assist, any KBO within 50 AU and a 20-year flight time was possible.^[3] A flyby of Neptune's largest moon Triton was also considered, with 66652 Borasisi as a potential follow-on.^[3] 55637 Uni was also considered for a visit, as it had a similar orbit to Lempo.^[8]

See also

• Innovative Interstellar Explorer (2003 concept study for RTG powered ion-engined probe to 200 AU by 2030)
• List of New Horizons topics