Astronomers using the Hubble Space Telescope have located at least one and possibly three Kuiper Belt objects that NASA's New Horizons spacecraft can reach after its flyby Pluto next year.
"After years of searching, my team and I have found a world in the Kuiper Belt for New Horizons to visit after Pluto!," astronomer Alex Parker, with the Southwest Research Institute in Boulder, Colo., posted on Twitter.
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"In fact, we may have up to three Kuiper Belt Objects to choose from, but the other two require further follow-up to confirm," he wrote.
The best target, known as "Potential Target 1," is in a near-circular orbit around the sun and flying 44 times as far from the sun as Earth. The object is "several tens of kilometers," in diameter, Parker noted.
"The two other (potential targets) are brighter (hence, larger) objects, so if they are confirmed targetable, they may beat PT1 in the final selection," he wrote.
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New Horizons is expected to become the first spacecraft to fly past Pluto, which was still considered a planet when the spacecraft launched in 2006. Pluto is now referred to as a "dwarf planet" and the largest of thousands of frozen bodies located in the Kuiper Belt region beyond Neptune's orbit.
KBOs are believed to be pristine remnants dating back to the birth of the solar system and the building blocks of dwarf planets like Pluto.
The KBOs Hubble found are each about 10 times larger than typical comets, but only about 1-2 percent of the size of Pluto, NASA noted in a press release.
Finding an object beyond Pluto that New Horizons could reach required a dedicated search with Hubble.
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"We started to get worried that we could not find anything suitable, even with Hubble, but in the end the space telescope came to the rescue," astronomer John Spencer, also with the Southwest Research Institute, said in a statement. "There was a huge sigh of relief when we found suitable KBOs."
One sobering note, added Parker: "Even though New Horizons can reach this Kuiper Belt Object, there is no guarantee of an extended mission ... Until that approval happens, the in-situ exploration of a pristine classical Kuiper Belt object is still not a sure thing."