The New Horizons spacecraft launched on January 19, 2006 – beginning its odyssey to Pluto and the Kuiper Belt. New Horizons was the first mission to Pluto, completing the space-age reconnaissance of the planets that started 50 years earlier. It was also the first mission to explore the solar system's recently-discovered "third zone," the region beyond the giant planets called the Kuiper Belt.

But New Horizons began long before launch, starting with many years of work to design and propose the mission, build the spacecraft and its array of instruments, and plan the operations and scientific observations that would bring these new worlds into focus for the first time. The flyby of Pluto on July 14, 2015, was a resounding success, and New Horizons sent home data that resulted in profound new insights about Pluto and its moons. These data will continue to be analyzed for many years to come.

New Horizons continued on its unparalleled journey of exploration with the close flyby of a Kuiper Belt object called 2014 MU69 – officially named Arrokoth (Powhatan/Algonquian for "sky") – on January 1, 2019.

The Kuiper Belt is a scientifically rich frontier. Its exploration has important implications for better understanding comets, small planets, the solar system as a whole, the solar nebula, and disks around other stars. It's a laboratory for studying well-preserved primitive material from the planet formation era 4.5 billion years ago.

New Horizons approached Arrokoth (nicknamed "Ultima Thule" at the time) three times closer than it came to Pluto, resulting in even more detailed pictures and other kinds of data. The spacecraft obtained the first high-resolution geological and compositional maps of a small Kuiper Belt object (KBO), while conducting sensitive searches for atmospheric activity, satellites and rings.

The New Horizons Kuiper Belt Extended Mission, however, is much more than the close flyby of Arrokoth. The mission also takes advantage of the unique capabilities of New Horizons as an observation platform in the Kuiper Belt to study dozens of other KBOs in multiple ways that can't be done from Earth. New Horizons is also making groundbreaking measurements of dust and the heliospheric plasma environment across the Kuiper Belt.