Pluto, Kuiper Belt Objects, and Comets

The Solar System’s Distant, Icy Frontier

The Kuiper Belt is home to dozens of dwarf planets like Pluto and multitudes of planetary building blocks called planetesimals, such as Arrokoth. Comets, small icy planetesimals that are older than Earth and occasionally fall close to our Sun, hail from the Kuiper Belt and even more distant Oort Cloud.

Stretching from the orbit of Neptune to 50 times the distance between Earth and the Sun, the Kuiper Belt is a remote, donut-shaped region of space that’s littered with icy worlds, including comets and the solar system’s famous small planet Pluto. It’s a scientifically rich frontier, replete with objects carrying details from the solar system’s formation. APL has been at the forefront of exploring this distant province, designing and operating NASA’s New Horizons spacecraft—the farthest planetary exploration mission to date—as well as several of its instruments, including the imager that brought us the first close-up views of Pluto’s surface.

Related Areas of Impact

Space Science and Engineering

Mission Area

Missions

APL has designed, built, and operated more than 70 innovative spacecraft over its six decades of spaceflight experience. Click below to learn about some of the missions that made revolutionary discoveries, and spacecraft that will push the boundaries of exploration and investigate outstanding scientific mysteries.

New Horizons Pluto, Kuiper Belt Objects, and Comets

New Horizons is the first mission to Pluto and the Kuiper Belt, the distant region of planetary building blocks that hold keys to our solar system’s formation.

Learn more about New Horizons

Balloon program engineers working outside

Balloon Programs Interstellar Medium

APL balloon missions and instruments observe planetary targets and the interstellar medium, and conduct other space science investigations.

Learn more about Balloon Programs

Instruments

Scientists and engineers at APL have designed, built, and operated more than 300 novel space instruments and methods to conduct cutting-edge research and make groundbreaking discoveries. Click below to learn about some of these instruments and their role in shaping our understanding of space and the solar system.

PEPSSI Pluto, Kuiper Belt Objects, and Comets

The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) is the most compact, lowest-power directional energetic-particle spectrometer flown in space.

Learn more about PEPSSI

Engineers working on the LORRI Instrument

LORRI Pluto, Kuiper Belt Objects, and Comets

The Long Range Reconnaissance Imager (LORRI) is a telescopic camera built to enable distant imaging of the farthest regions of the solar system.

Learn more about LORRI

The GUSTO telescope hangs from the hangar crane

GUSTO Mission Breaks NASA Record for Longest Flight by Heavy Lift Balloon Feb 24, 2024

NASA’s balloon mission GUSTO broke the record for the longest flight time by a heavy lift, long-duration balloon on Feb. 24, topping the previous record holder, which lasted for 55 days, 1 hour and 34 minutes. The new record is 57 days, 7 hours.

NASA’s Balloon Mission GUSTO Mapping the Space Between the Stars Dec 20, 2023

Amid the cacophony of penguins and seals, scientists from Johns Hopkins APL and the University of Arizona celebrated the new year with the launch of NASA’s newest balloon mission GUSTO. The airborne telescope will study molecular clouds of gas and dust between the stars.

Comet 67P/Churyumov-Gerasimenko as seen by the European Space Agency’s Rosetta spacecraft

Comet 67P’s Abundant Oxygen More of an Illusion, New Study Suggests Mar 10, 2022

Seven years ago, scientists made the surprising discovery of oxygen coming from comet 67P/Churyumov-Gerasimenko, throwing into question much of what they thought they knew about the early solar system. But a new study led by Johns Hopkins APL researchers reveals new details that suggest not everything about that discovery is as it seems.