On New Year’s Day, a spacecraft will zoom by the most distant object humanity has ever visited Just after midnight on January 1st, a NASA spacecraft will whiz past the most distant space rock that’s ever been visited in our Solar System. This remote interplanetary flyby will be over in a blink. But if successful, the event could tell us a whole lot about the objects that dominate the far reaches of our cosmic neighborhood. The robotic spacecraft making this daring visit is called New Horizons, and it’s been traveling through space for the last 13 years. You may remember this famous bot: it was the first human-made object to ever visit Pluto in the summer of 2015. Ever since that flyby, New Horizons has been plunging farther into the Solar System. Three years later, it’s ready to meet up with another faraway target, a rock nicknamed Ultima Thule located 1 billion miles beyond Pluto. That’s 4.1 billion miles from Earth. ------------ Successfully passing by Ultima Thule is going to be an incredibly challenging task. Because it’s so small and so far away, the object is hard to see and track from Earth. And the New Horizons team only has one chance to get this flyby right. The spacecraft is currently traveling through space at 32,000 miles per hour. If something gets botched, there’s no way to turn New Horizons around and try again. “Like Pluto, it’s a one shot,” says Stern. “We don’t have a second spacecraft coming by a week later. And because it’s a very complex enterprise to do one of these flybys, there are literally hundreds of variables that all have to choreograph perfectly.” New Horizons wasn’t always guaranteed a visit to an object like Ultima Thule. The vehicle’s primary mission was to fly by Pluto, with the possibility of passing by a second Kuiper Belt object later. But when the spacecraft first launched from Earth in January 2006, astronomers didn’t even know if there was an object close enough to Pluto that New Horizons could target. All the objects we knew about at the time were out of reach. So while the New Horizons team prepped for Pluto, they also searched the sky for the spacecraft’s second destination. Finally in 2014, they found a target using NASA’s Hubble Space Telescope: a Kuiper Belt object named 2014 MU69. Ultima Thule, as seen by New Horizons’ onboard camera LORRI on Christmas Eve In 2017, New Horizons scientists were able to observe Ultima Thule as it passed in front of a background star. It was a momentary eclipse, known as an occultation, in which Ultima Thule briefly blocked out the star’s light. From that split-second crossing, the scientists were able to get a better understanding of the rock’s shape. All indications point to this rock being weird. In fact, it may not even be a single rock. The occultation revealed that Ultima Thule is either shaped like a rubber duck, looking a bit like two mounds squashed together. Or it could be two separate rocks orbiting super close to one another. We really won’t know for sure until just a day or two before New Horizons reaches Ultima Thule. The tiny object is 100 times smaller than Pluto, making it harder to see in advance with New Horizons’ onboard cameras. The best pictures won’t come until New Horizons is more or less on top of the object. (more to read on the link) .