Posted by: Paul A. Forsyth | October 22, 2014

Hubble Finds New Targets for New Horizons Past Pluto

Hubble Survey Finds Two Kuiper Belt Objects to Support New Horizons Mission

Time-lapse Hubble images of two new Kuiper Belt objects that are potential targets for the New Horizons spacecraft after it finishes its Pluto mission. They desperately need new names.

The NASA unmanned spacecraft New Horizons has been traveling towards Pluto since 2006. New Horizons should be making its flyby of Pluto and its moons in July 2015, becoming the first spacecraft to visit Pluto and providing the first detailed images of the dwarf planet.

After its Pluto encounter, New Horizons will continue on its journey away from the heart of the Solar System. Mission planners have always intended that New Horizons, if possible, should visit some other object beyond Pluto. The problem: at the time of launch, astronomers had not identified any potential targets within range. The Kuiper Belt contains thousands (perhaps millions) of small bodies of rock and ice — including some dwarf planets — but New Horizons can only be steered toward objects within a small cone of space extending out from Pluto.

Last week, NASA announced that Hubble has identified three new Kuiper Belt objects within that cone — three new post-Pluto potential targets for New Horizons. Two of those objects are shown above. All three are quite small, probably with diameters in the range of 20-50 km. (For comparison: the asteroid Eros, the site of a base in the novel Ender’s Game, has a mean diameter of about 16 km. The Moon’s diameter is about 3,460 km, and Pluto’s diameter is [we think] 2,368 ± 20 km. See also this list.)

From what NASA and the Hubble folks tell us so far, it sounds like the most likely post-Pluto target for New Horizons — potential target 1 or PT1 — is KBO 1110113Y (the object on the left above). From Emily Lakdawalla:

What do we know about PT1 so far? Its orbit is circular and close to the plane of the ecliptic, so it is a Cold Classical Kuiper belt object, meaning that it has had a very different history from Pluto. Pluto is a member of a population of objects in the Kuiper belt whose orbits were changed as Neptune migrated outward, scattering them. Pluto now has an inclined and elliptical orbit that is locked in a resonance with Neptune, such that Pluto orbits the Sun twice for every three times Neptune does. In contrast, Cold Classical objects were probably never tossed around in this way. So PT1 could be very pristine, a cold, never-heated relic of solar system formation. On the other hand, it’s very small, estimated to be 30 to 45 kilometers in diameter, and scientists think that most objects of that size are not primordial, but are actually fragments from collisions of larger objects, which would make it less pristine.

If KBO 1110113Y is chosen, then New Horizons should make a fly-by of the KBO around January 2019. Before that happens, I strongly suggest that the Hubble folks pick a new name for the object; “KBO 1110113Y” does not exactly roll off the tongue. Something mythological would seem appropriate, but I’m not sure what mythological names are still available.


Astronomers haven’t even bothered to give a proper name to 2007 OR10 yet, and that’s after seven years.

Image Credit: (1) NASA, ESA, SwRI, JHU/APL, and the New Horizons KBO Search Team. Source: HubbleSite. (2) Artistic representations of the eight largest Trans-Neptunian Objects. Image by Lexicon. Used under a CC BY-SA 3.0 license. Source: Wikimedia Commons.


  1. I had forgotten all about Eris, and been blissfully unaware of Orcus. When does Demogorgon get his own Trans-Neptunian?

    • I had to look up Demogorgon, but having done so, that sounds like an excellent name for KBO 1110113Y.

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