NASA's New Horizons Will Fly Much Closer to a Hunk of Rock and Ice Than It Did Past Pluto

During the summer of 2015, the New Horizons spacecraft stole Earth's heart by swooping over Pluto and sending home the best images we'd ever seen of the demoted planet. But after its big moment in the spotlight, NASA figured it might as well go on a new adventure—and the agency just announced how good a view they're planning to snag of the destination.

Its next target is what's called a Kuiper Belt Object, thanks to its location in what's similar to a second asteroid belt, a broad ring circling the solar system outside of Neptune's orbit. (Pluto is also a Kuiper Belt Object, but the rest of the region was only discovered in 1992.)

This particular Kuiper Belt Object, called 2014 MU69, landed in the spotlight mostly due to dumb luck. It's one of just a few objects we know of that New Horizons can reach on the fuel it has left—when the spacecraft finally reaches MU69, it will have travelled more than 4 billion miles since it left Earth.

An artist's representation of what New Horizons could look like approaching 2014 MU69. Carlos Hernandez

In fact, MU69 hadn't even been spotted when New Horizons first left Earth, and we still don't know all that much about it, same as other Kuiper Belt Objects. It probably formed at about the same time as the rest of the solar system, more than 4 billion years ago. Where asteroids are made of rock, Kuiper Belt Objects are likely in large part hunks of ice with rock mixed in.

When it comes to MU69 specifically, scientists aren't sure if it's one larger chunk or two smaller ones tagging along together. NASA has been passing its time before the flyby, running experiments from Earth to try to pin down its size, with current estimates topping out at just 20 miles long.

All that uncertainty is why scientists are so excited for this next phase of the New Horizons mission. And Wednesday NASA announced just how spectacular a view we can expect.

Ideally, New Horizons will fly just 2,175 miles above the surface of MU69, which would let its longest range camera spot features that are just 230 feet across—that's smaller than a football field. If it turns out there's lots of junk in MU69's neighborhood that could damage the spacecraft, it will fly farther away from the object, but within 6,000 miles. Either way, the spacecraft will get a better view of MU69 than it did of Pluto, which it stayed 7,800 miles above.

The flyby will happen on January 1, 2019. That's quite a New Year's celebration.