The New Horizons spacecraft is about the size of a baby grand piano. (NASA/Johns Hopkins Univ. Applied Physics Laboratory/Southwest Research Institute/AP)

The spacecraft team that brought us close-ups of Pluto will ring in the new year by exploring an even more distant and mysterious world.

NASA’s New Horizons spacecraft will zip past the scrawny, icy object nicknamed Ultima Thule (pronounced TOO-lee) soon after the stroke of midnight.

Ultima Thule will be the farthest world ever explored by humankind. It is 1 billion miles beyond Pluto and an astounding 4 billion miles from Earth, at the edge of the solar system. Its nickname means “beyond the known world.” No spacecraft has visited anything so primitive.

New Horizons, which launched in January 2006, flew past Pluto in 2015, providing the first close-up views of the dwarf planet.

As dramatic and illuminating as the Pluto flyby was, scientists know even less about what to expect from Ultima Thule. Because it’s so far away and so dim, they aren’t even sure if it’s a single mass. They suspect it is made up of two lobes, but it also could be two separate objects orbiting around each other.

“We were already getting hints of what Pluto was going to be looking like well in advance of the day of closest approach,” said Hal Weaver, the mission’s project scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “This time, everything is going to be pretty much a mystery, we think, until the last hour or so.”

This image from NASA shows Ultima Thule in the crosshairs, surrounded by stars, in the Kuiper belt. (NASA/Johns Hopkins Univ. Applied Physics Laboratory/Southwest Research Institute/AP)

The scientists hope to fly the spacecraft within about 2,200 miles of Ultima Thule, four times closer than its encounter with Pluto, to capture images and other data with as much resolution as possible. But that could depend on what, if anything, New Horizons spots in its path as Ultima Thule gets closer and brighter.

Mission engineers were preparing for the possibility they would have to steer the speeding spacecraft as far as 6,200 miles from its target, if that means avoiding any bits of debris in space.

“A rice-sized pellet hitting the spacecraft in the wrong place could destroy it,” Weaver said.

The first signal back from New Horizons is expected about 10 a.m. New Year’s Day, with the best images and data from Ultima Thule expected to come down later Tuesday and also on Wednesday, the scientists said.

Any good data would be the first collected from a planetary object so far from Earth.

The dwarf planet Pluto, seen in 2015. (NASA/Johns Hopkins Univ. Applied Physics Laboratory/Southwest Research Institute/AP)

Only the Voyager and Pioneer missions have traveled farther than New Horizons will, but they were taking relatively more crude observations of plasma and particles in space. When they launched in the 1970s, Weaver said, scientists “didn’t even know what existed out there.”

— From news services