After its pioneering exploration of Pluto and its five moons in July 2015, NASA’s New Horizons spacecraft is outward bound from the solar system on a voyage to infinity. Directly ahead of it in the void, however, is an object in the Kuiper Belt called 2014 MU69, an ancient dark reddish aggregate of rock and ice only a few dozen kilometers in diameter, discovered just a year before the Pluto encounter. MU69 has orbited the far reaches of the solar system since it, our sun, our own world condensed out of a cloud of dust and gas nearly five billion years ago.

We think, hope—guess, maybe—that it’s a raw, leftover lump of the ingredients that formed the solar system, a fossil witness to the creation of the planets and their moons. Regardless, MU69 provides the first in situ sampling of the Kuiper Belt, a diffuse torus of thousands of icy planetoids that circle the outer solar system. The voyage to MU69 marks the most distant destination in the history of civilization. It is the last speck of land New Horizons will pass before sailing on to deep interstellar space.

New Horizons reaches this last port of call on New Year’s Day, 2019, a year that will mark the 50th anniversary of the first steps of humans on another world. There’s so much to prepare for, investigations to be sketched out, studies to be drawn up, so many decisions to be made that even now the New Horizons team of scientists and engineers is working full time to get ready. It’s been my pleasure to have a tiny part in this.

An email comes in near the end of the day, asking how we might best use one of the cameras on the spacecraft for this or that. I start typing my thoughts into my laptop, day dreaming a little perhaps, looking out my office window at the jagged Catalina mountains that rise out of the desert north of Tucson. Above them a crystal clear cerulean sky extends forever in all directions. It’s a great arena for an astronomer. Watching a full moon clear the rocky skyline, it hangs just above the distant peaks as an amber, delicately shaded globe. You can feel the distance to the moon. There’s no question that it’s a real world to explore.

Looking over the sky, I know that New Horizons is out there somewhere. It’s hurtling off into the galaxy at 14 km/s, or more than 31,000 m.p.h., far, far, far out in the outer solar system on a course we set it on after its flight past Pluto. From Earth it would take only eight hours to get out to the moon at this clip, not the three days it took the old Apollo astronauts. Yet we have two years before the mast until we make landfall at MU69, and this on top of a total journey that started 11 years ago.

We won’t have much time there. We can’t slow down in the slightest, let alone go into orbit around it. The best data will come from the single tightly packed hour of closest approach. What should we measure? What’s the cleverest use of our instruments? Right now we’re busy using email exploders, conference calls, meetings to pool all our ideas and then slice them ever, ever finer into a precise second by second mission timeline.

Long before the MU69 encounter we will speak across the solar system with the NASA’s Deep Space Network to the robotic mind of New Horizons. We will send it endless packets of commands, a painstaking and demanding distillation of our ideas, thoughts, wishes, guesses, contingencies, rules—a complete philosophy—to tell it exactly how to explore an unknown world. It now takes over five hours for the microwave signals traveling at the speed of light to reach New Horizons, but the spacecraft listens still, a beautiful ship ever responsive to the right touch at the helm. We call ourselves scientists, but we are sailors, too.

In the background on my laptop I’m streaming KUAT, the local Tucson classical music station. Smetana’s “Ma Vlast” is playing, a deeply romantic epic with energy that seems to fill the immense space stretching out in front of me. I know that it comes across the net as a long string of numbers—data converted by software into sounds. Likewise, the treasures returned by New Horizons from distant lands are just other numbers—pixels to be recorded, processed, analyzed, modeled by cool, logical, mathematical algorithms. But like the music, their impact is profoundly emotional—strange visions of places never imagined—startling discoveries that will shine a bright light into the darkness. We don’t know what awaits us at 2014 MU69, but it will touch our hearts as much as our minds.