Carbon dioxide discovered on Pluto's moon Charon

Researchers studying Pluto’s small moon, Charon, found something remarkable: carbon dioxide and hydrogen peroxide. This is the first time these chemicals have been discovered on the frozen surface of that particular moon.

A team of astronomers at the Southwest Research Institute, using the James Webb Space Telescope, recently confirmed this unexpected discovery.

Charon: A very special moon

For a moon that’s just floating around in the Kuiper Belt orbiting a dwarf planet, Charon is unique. How so? Well, it’s the only object of its kind that we’ve managed to map geologically.

“Charon is the only midsized Kuiper Belt object, in the range of 300 to 1,000 miles in diameter, that has been geologically mapped, thanks to the SwRI-led New Horizons mission, which flew by the Pluto system in 2015,” said SwRI’s Dr. Silvia Protopapa, lead author of a new Nature Communications paper and co-investigator of the New Horizons mission.

“Unlike many of the larger objects in the Kuiper Belt, the surface of Charon is not obscured by highly volatile ices such as methane and therefore provides valuable insights into how processes like sunlight exposure and cratering affect these distant bodies.”

Webb, Charon, and carbon dioxide

The Webb telescope is a fantastic tool for inspecting Charon and other frosty bodies beyond Neptune’s orbit.

In 2022 and 2023, the research team was able to get four different observations of the Pluto-Charon system, and that gave them a complete view of Charon’s northern hemisphere.

It’s a bit like changing your angle of view to get a better look, and boy, did they see some fascinating stuff.

The extended observations made with Webb revealed the signatures of carbon dioxide on Charon.

By comparing these observations with lab measurements and detailed spectral models of the surface, the team concluded that carbon dioxide primarily exists as a veneer on a subsurface rich in water ice.

Charon’s carbon past and future

This carbon dioxide layer likely comes from Charon’s interior, exposed through cratering events. It is potentially a remnant from the protoplanetary disk that gave birth to the whole Pluto system.

It doesn’t stop at carbon dioxide, though.

The detection of hydrogen peroxide is particularly intriguing because it shows that Charon’s water ice-rich surface undergoes change due to the UV light from the Sun and particles from the solar wind and galactic cosmic rays.

Hydrogen peroxide comes from oxygen and hydrogen atoms, which are products of water ice breaking up due to incoming ions, electrons, or photons.

Chemistry of Charon’s surface

The discovery of carbon dioxide and hydrogen peroxide on Charon invites us to explore the complex chemistry occurring on its surface.

The interactions between solar radiation, cosmic particles, and the moon’s icy terrain create a dynamic environment.

Understanding these chemical processes helps scientists infer the evolution and composition of Charon over time.

The presence of hydrogen peroxide, for instance, indicates oxidative stresses that involve radical reactions, significantly affecting the stability of surface compounds.

This detailed chemical portrait enhances our comprehension of similar celestial bodies in the Kuiper Belt and beyond.

Implications for astrobiology

The detection of these chemicals on Charon introduces intriguing astrobiological questions.

While neither carbon dioxide nor hydrogen peroxide by themselves suggest life, they are components of the broader chemical processes that could impact any biological precursors.

Scientists speculate that the mechanisms observed on Charon might exist on other icy bodies, opening potential research avenues in the quest to understand the habitability of distant worlds.

These findings underscore the importance of Charon as a natural laboratory for examining prebiotic chemistry, further amplified by the pristine conditions of the outer solar system where it resides.

Art of synergy

None of this discovery would be possible without the combination of Webb’s observations, spectral modeling, and lab experiments.

It’s the triplet of these processes that allowed for new insights into the composition of Charon. And the same approach could work for other similar-sized objects beyond Neptune.

In conclusion, we’re just scratching the surface of what we can learn from our outer solar system.

With tools like the Webb telescope and the brilliant minds working on this research, who knows what we’ll uncover next?

The study is published in the journal Nature.

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