With the aid of the Hubble Space Telescope, scientists have identified three potential destinations that NASA's New Horizons probe could observe after next July's Pluto flyby. The primary target is known as PT1. Two other targets, called PT2 and PT3, are potentially reachable as alternatives, scientists said. NASA says all of the objects are roughly 1 billion miles (1.6 billion kilometers) beyond Pluto, and their estimated sizes range from 15 to 34 miles (25 to 55 kilometers) across.
The targets are in the Kuiper Belt, a broad ring of icy mini-worlds beyond Neptune, and were identified after a months-long Hubble search. "This has been a very challenging search, and it's great that in the end Hubble could accomplish a detection — one NASA mission helping another," the Southwest Research Institute's Alan Stern, principal investigator of the New Horizons mission, said Wednesday in a news release announcing the detections. The New Horizons team is expected to submit a proposal in late 2016 for an extended mission to fly past one of the Kuiper Belt objects. NASA said the encounter could take place three or four years after the Pluto flyby.
— Alan Boyle