Using data from the Near-Infrared Spectrograph (NIRSpec) onboard the NASA/ESA/CSA James Webb Space Telescope, astronomers have detected carbon dioxide (CO2) and hydrogen peroxide (H2O2) on the frozen surface of Pluto’s moon Charon. Their findings provide new insights into the chemical processes and surface composition of Charon, which could help us understand the origin and evolution of icy bodies in the outer Solar System.
Protopapa et al. detected carbon dioxide and hydrogen peroxide spectral signatures on Charon using Webb telescope observations (white), which extend the wavelength coverage of previous New Horizons flyby measurements (pink). Image credit: S. Protopapa / SwRI / NASA / ESA / CSA / STScI / JHUAPL.
Beyond Neptune, a fascinating collection of small bodies called trans-Neptunian objects (TNOs) orbit the Sun.
These objects serve as time capsules, offering planetary scientists a glimpse into the early Solar System.
“Charon stands unique as the only mid-sized TNO — i.e., with a diameter between 500 and 1700 km — for which geological mapping is available, thanks to measurements returned by NASA’s New Horizons mission,” said Dr. Silvia Protopapa of Southwest Research Institute and her colleagues.
“Unlike larger TNOs (e.g., Pluto, Eris, and Makemake), Charon’s surface is not obscured by hyper-volatile ices, such as methane, with the possible exception toward the poles.”
“As a result, Charon serves as an excellent candidate for retrieving valuable insights into processes such as differentiation, radiation exposure, and cratering within the Kuiper Belt.”
“Charon has been extensively studied since its discovery in 1978, but previous spectral data were limited to wavelengths below 2.5 µm, leaving gaps in our understanding of its surface composition.”
“The presence of water ice, ammonia-bearing species, and organic compounds has previously been noted, but the spectral range used was insufficient to detect other compounds.”
Dr. Protopapa and co-authors used Webb’s Near-Infrared Spectrograph to observe Charon at wavelengths from 1.0 to 5.2 µm.
They conducted four observations at different longitudes and, together with laboratory experiments and spectral modeling, confirmed the presence of crystalline water ice and ammonia, and also identified carbon dioxide and hydrogen peroxide.
“The advanced observational capabilities of Webb enabled our team to explore the light scattered from Charon’s surface at longer wavelengths than what was previously possible, expanding our understanding of the complexity of this fascinating object,” said Dr. Ian Wong, a staff scientist at the Space Telescope Science Institute.
The presence of hydrogen peroxide suggests active processing of water ice by irradiation and light on Charon’s surface, while carbon dioxide likely originates from subsurface carbon dioxide reservoirs present since formation and exposed on the surface by impact events.
The detection of carbon dioxide and hydrogen peroxide on Charon represents a step forward in planetary science, offering insights into the moon’s surface chemistry.
This research may lay the groundwork for future studies to explore the dynamics of outer solar system bodies, their surface compositions, and the effects of solar radiation.
“Our preferred interpretation is that the upper layer of carbon dioxide originates from the interior and has been exposed to the surface through cratering events,” Dr. Protopapa said.
“Carbon dioxide is known to be present in regions of the protoplanetary disk from which the Pluto system formed.”
“The new insights were made possible by the synergy between Webb observations, spectral modeling and laboratory experiments and are possibly applicable to other similar midsized objects beyond Neptune.”
The results appear today in the journal Nature Communications.
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S. Protopapa et al. 2024. Detection of carbon dioxide and hydrogen peroxide on the stratified surface of Charon with JWST. Nat Commun 15, 8247; doi: 10.1038/s41467-024-51826-4
Source : Breaking Science News