  NASA's New Horizons spacecraft observed (15810) 1994 JR$_1$, a 3:2 resonant
Kupier Belt Object (KBO), using the LOng Range Reconnaissance Imager (LORRI) on
November 2, 2015 from a distance of 1.85 AU, and again on April 7, 2016 from a
distance of 0.71 AU. These were the first close observations of any KBO other
than Pluto. Combining ground-based and Hubble Space Telecope (HST) observations
at small phase angles and the LORRI observations at higher phase angles, we
produced the first disk-integrated solar phase curve of a typical KBO from
$\alpha$=0.6-58$^\circ$. Observations at these geometries, attainable only from
a spacecraft in the outer Solar System, constrain surface properties such as
macroscopic roughness and the single particle phase function. 1994 JR$_1$ has a
rough surface with a 37$\pm$5$^\circ$ mean topographic slope angle and has a
relatively rapid rotation period of 5.47$\pm$0.33 hours. 1994 JR$_1$ is
currently 2.7 AU from Pluto; our astrometric points enable high-precision orbit
determination and integrations which show that it comes this close to Pluto
every 2.4 million years (10$^4$ heliocentric orbits), causing Pluto to perturb
1994 JR$_1$. During the November spacecraft observation, the KBO was
simultaneously observed using HST in two colors, confirming its very red
spectral slope. These observations have laid the groundwork for numerous
potential future distant KBO observations in the New Horizons-Kuiper Belt
Extended Mission.
