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Starts With A Bang

NASA’s New Horizons views first distant Kuiper belt object beyond Pluto

Combined with Hubble, it creates our longest-baseline view.

“It used to be that Pluto was a misfit. Now it turns out that Earth is the misfit. Most planets in the solar system look like Pluto, and not like the terrestrial planets.” –Alan Stern

NASA’s New Horizons flew by Pluto in July 2015, but continued to coast deeper into the Kuiper belt, away from the Sun.

Illustration of the Kuiper Belt from the New Horizons mission site at Johns Hopkins. Image credit: © 2016 The Johns Hopkins University Applied Physics Laboratory LLC.

In November 2015, its longest range camera imaged a Kuiper belt object (KBO) — (15810) 1994 JR1 — multiple times, independently, over the course of many hours.

New Horizons image of 1994 JR1, taken Nov. 2, was the then-closest-ever picture of a Kuiper Belt object. Image credit: NASA/JHUAPL/SwRI.

Back here in low-Earth orbit, the Hubble space telescope imaged the exact same KBO simultaneously, creating the longest-baseline parallax observations ever made.

New Horizons’ “deep” observations of JR1, from April 2016. Image credit: NASA/JHUAPL/SwRI; acknowledgment to Simon Porter.

In April of 2016, New Horizons made its closest approach to this object at just 66 million miles, taking a much longer and more complex series of images.

The lightcurve of JR1. Image credit: NASA/JHUAPL/SwRI, acknowledgment to Simon Porter.

An incredible amount of science was learned, including:

  • it rotates rapidly, with a period of just 5.5 hours,
  • it has no moons,
  • and is small and heavily cratered, with long evening and morning shadows.
Saturn’s moon Phoebe, thought to be a captured KBO, and perhaps analogous to 1994 JR1. Image credit: NASA/JPL/Space Science Institute, under catalog number PIA06117.

The most exciting find was to completely determine this new Kuiper belt object’s orbit: a 3-to-2 resonance with Neptune, much like Pluto.

The orbit of the KBO 1994 JR1, shown with other Solar System bodies, made with NASA’s JPL Small-Body Database Browser. Image credit: NASA and Wikimedia Commons user Tomruen.

But unlike Pluto, it never dips interior to Neptune’s orbit, making this Neptune-centered simulated view of the Solar System possible.

New Horizons seeks to extend its mission beyond this year, closely flying-by another KBO and characterizing dozens more.

Mostly Mute Monday tells the story of a single astronomical phenomenon or object primarily in visuals, with no more than 200 words of text.

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