New Horizons 2

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).

[5] In 2004, the United States Senate on Appropriations Committee provided additional funding for New Horizons 2, a new Kuiper belt mission.

[5] The mission plan for Lempo also included flybys of Jupiter and Uranus,[5] and perhaps four Kuiper belt objects (KBO).

[3] A flyby of Neptune's largest moon Triton was also considered, with 66652 Borasisi as a potential follow-on.