James Webb Space Telescope Discovers Carbon Dioxide and Hydrogen Peroxide on Charon

James Webb Space Telescope's Groundbreaking Discoveries

Observations by the James Webb Space Telescope are giving scientists a fuller understanding of the composition and evolution of Pluto's moon Charon, the largest moon orbiting any of our solar system's dwarf planets.

• First Detection: Webb has, for the first time, detected carbon dioxide and hydrogen peroxide—both frozen as solids—on the surface of Charon, a spherical body about 750 miles (1,200 km) in diameter.
• Surface Composition: These findings add to the previously documented water ice, ammonia-bearing compounds, and organic materials on Charon's surface.
• Significance of Discoveries: The presence of hydrogen peroxide indicates the irradiation processes Charon has experienced over time. The carbon dioxide is likely an original component from Charon's formation around 4.5 billion years ago.

Insights from the New Horizons Mission

Charon, discovered in 1978, is notable as the largest moon relative in size to the planet it orbits, being about half the diameter and an eighth the mass of Pluto, residing in the frigid Kuiper Belt.

The distance between Charon and Pluto is approximately 12,200 miles (19,640 km). Most of Charon's surface is gray, with reddish-brown regions around its poles composed of organic materials.

The Webb observations build on data obtained from NASA's New Horizons spacecraft, which flew by Charon during its visit to the Pluto system in 2015. Webb, launched in 2021, allows for observations across a broader range of wavelengths than previously accessible.

Researchers explained that hydrogen peroxide resulted from the chemical alteration of water ice on Charon's surface due to the persistent exposure to ultraviolet radiation from the sun and energetic particles from the solar wind and galactic cosmic rays.

The observed carbon dioxide was probably buried under the surface and revealed by impacts on Charon. This material likely formed part of the primordial substance from which both Charon and Pluto originated, a fact that surprised scientists due to the previous absence of detected carbon dioxide.