James Webb Space Telescope Reveals New Clues About Pluto’s Icy Moon Charon

The James Webb Space Telescope (JWST) has made a groundbreaking discovery on Pluto’s largest moon, Charon, detecting carbon dioxide and hydrogen peroxide on its frozen surface. These findings offer new insights into Charon’s composition and provide a window into how icy bodies at the edge of the solar system have evolved over billions of years.

Uncovering Carbon Dioxide and Hydrogen Peroxide on Charon

Charon, discovered in 1978, orbits in the distant Kuiper Belt and has been studied extensively over the decades. While earlier missions, such as NASA's New Horizons, revealed that Charon’s surface contains water ice, ammonia, and organic materials, key compounds like carbon dioxide had remained elusive—until now. The JWST, using its powerful Near-Infrared Spectrograph (NIRSpec), was able to detect carbon dioxide on the moon’s surface, a discovery that confirmed long-held theories. As lead researcher Silvia Protopapa explained, “The detection of carbon dioxide was a satisfying confirmation of our expectations.”

The carbon dioxide likely originates from Charon's subsurface and was exposed during impact events, providing a glimpse into the moon’s deeper layers. The discovery of this compound, which had been missed by previous missions, adds a crucial piece to the puzzle of how Charon and other icy bodies in the outer solar system formed and evolved.

Even more surprising was the detection of hydrogen peroxide, a compound that Protopapa did not expect to find on Charon. “The detection of hydrogen peroxide on Charon came as a surprise. I honestly did not expect to find evidence of it on the surface,” she said. Hydrogen peroxide typically forms on icy surfaces when cosmic radiation or ultraviolet light breaks down water molecules, and its presence on Charon suggests that the moon’s surface has been significantly altered by exposure to the Sun’s ultraviolet radiation and cosmic rays over time. This marks the first time hydrogen peroxide has been detected on Charon, offering new clues about the chemical processes that shape the surfaces of distant moons and planets.

Implications for Kuiper Belt Research

The detection of carbon dioxide and hydrogen peroxide on Charon doesn’t just provide insights into this one moon but also has broader implications for understanding the Kuiper Belt, a region beyond Neptune filled with icy objects. Unlike many other trans-Neptunian objects (TNOs), Charon’s surface is not obscured by methane or other volatile ices, making it a valuable subject for studying the long-term effects of radiation and impact cratering.

Charon’s surface composition offers a clearer view of how these distant, icy bodies evolve. Protopapa emphasized the importance of Charon as a study object: “These objects serve as time capsules, offering scientists a glimpse into the early solar system.” The moon’s surface reflects a history of cratering events and cosmic exposure, revealing how such processes alter the chemical makeup of icy worlds at the edge of our solar system.

The discoveries on Charon could also help scientists better understand other objects in the Kuiper Belt, many of which remain mysterious due to their distance from Earth. By studying Charon, researchers can make inferences about the composition and evolution of the wider population of TNOs, many of which are thought to be remnants from the early solar system.

Continuing Exploration with the James Webb Space Telescope

The exploration of Charon is far from complete. The James Webb Space Telescope will continue to observe the moon, and scientists are already planning additional studies to fill in gaps in the current data. Future observations will target spectral ranges not covered by the current data, which could lead to the detection of more compounds and provide an even deeper understanding of Charon’s surface and subsurface composition.

Protopapa and her team believe that these continued studies will unlock further secrets of this distant moon and its Kuiper Belt neighbors. She explained, “Future JWST observations targeting the spectral gaps not covered in the current data could lead to new Charon discoveries and further expand its chemical inventory.” The ability to detect even more complex compounds on Charon’s surface could offer fresh insights into the processes that shaped not only this moon but also the broader Kuiper Belt and the early solar system.

These new discoveries, published in the journal Nature Communications, highlight the JWST's transformative role in deepening our understanding of the outer solar system. By identifying key chemical compounds like carbon dioxide and hydrogen peroxide on Charon, scientists are piecing together the evolutionary history of one of Pluto's most intriguing moons and, by extension, the ancient history of our solar system.