2011 HM102, also written 2011 HM102, is the ninth Neptune trojan discovered. It was first observed on April 29, 2011, by the New Horizons KBO Search Survey. It has the same orbital period as Neptune and orbits at the L5Lagrangian point about 60 degrees west of Neptune.
2011 HM102 follows a low-eccentricity (0.08) orbit and its semi-major axis (30.05 AU) is very similar to Neptune's (30.10 AU), orbiting in a 1:1 mean-motion resonance with it. It has a high orbital inclination of 29.42°. This large value makes 2011 HM102, as of July 2013, the highest-inclination Neptune trojan known.2011 HM102 has been observed 145 times over 2 oppositions.
As of October 2012, 2011 HM102 is the closest known object of any kind to the New Horizons spacecraft. In mid- to late-2013, New Horizons will pass within 1.2 au of 2011 HM102, where it may be detectable with one of the onboard instruments. An observation from New Horizons would measure the phase curve of 2011 HM102 at phase angles unobtainable from the Earth.