On its way out from Pluto, New Horizons observed a red thing in space:
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| 1994 JR1. (c) NASA/JHUAPL/SwRI |
"The 3:2 resonant KBO (15810) 1994 JR1 was observed by NASA's New
Horizons spacecraft on November 2, 2015 from a distance of 1.85 AU, and
again on April 7, 2016 from a distance of 0.71 AU. Acquired using the
LOng Range Reconnaissance Imager (LORRI), these were the first close
observations of any KBO other than Pluto, and the first ever of a small
KBO. Combining ground-based and 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 degrees. 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 JR1 has a rough surface with a 37+/-5 degree mean
topographic slope angle and has a relatively rapid rotation period of
5.47+/-0.33 hours. 1994 JR1 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, causing Pluto to perturb 1994 JR1. During the November
spacecraft observation, the KBO was simultaneously observed using the
Hubble Space Telescope in two colors, confirming its very red spectral
slope. These observations have laid the groundwork for numerous
potential future distant KBO observations in the proposed New
Horizons-Kuiper Belt Extended Mission."
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