James Webb Telescope reveals details of Pluto’s moon – 10/02/2024 – Science

Observations made by the James Webb Telescope are providing scientists with a more complete understanding of the composition and evolution of Charon, Pluto’s moon and the largest orbiting of any of the dwarf planets in our Solar System.

For the first time, Webb detected carbon dioxide and hydrogen peroxide —both frozen as solids— on the surface of Charon, a spherical body about 1,200 kilometers in diameter, according to a study published this Tuesday (1st). These elements are in addition to water ice, ammonia-containing compounds and organic materials previously documented on the surface of the natural satellite.

Discovered in 1978, Charon is the largest moon in the Solar System in relation to the size of the planet it orbits. It is about half the diameter and one-eighth the mass of Pluto, a dwarf planet located in a cold region of the outer Solar System called the Kuiper Belt, beyond the most distant planet, Neptune.

The distance between Charon and Pluto is about 19,640 kilometers, compared to the average 384,400 kilometers that separate Earth from the Moon.

Most of Charon’s surface is gray, with reddish regions around its poles composed of organic materials.

Webb’s observations are based on data obtained when NASA’s New Horizons spacecraft flew over Charon during its visit to the Pluto system in 2015. The new study took advantage of the capabilities of the telescope, which launched in 2021 and began collecting data in next year to make observations across a wider range of wavelengths than previously available.

The presence of hydrogen peroxide indicates the irradiation processes that Charonte experienced over time, according to the researchers. Furthermore, carbon dioxide is suspected to be an original component dating back to the formation of the moon about 4.5 billion years ago.

The hydrogen peroxide, according to the researchers, formed as the water ice on the satellite’s surface was chemically altered by the constant bombardment of ultraviolet radiation from the Sun, as well as energetic particles from the solar wind and galactic cosmic rays that pass through the Earth. Universe.

The researchers said the carbon dioxide recorded by the telescope was likely buried beneath the surface but ended up exposed by impacts on the moon. It must be part of the primordial material from which both Charon and Pluto originally formed.

Scientists were surprised that carbon dioxide had not been spotted before.

“The detection of carbon dioxide was a satisfactory confirmation of our expectations,” said Silvia Protopapa, assistant director of the department of space studies at the Southwest Research Institute in Boulder, Colorado, co-investigator on the New Horizons mission and lead author of the study published in Nature Communications magazine.

“The detection of hydrogen peroxide on Charon was unexpected. I honestly didn’t expect to find evidence of it on the surface,” Protopapa added.

The new observations help tell a broader story about the celestial bodies that populate our Solar System.

“Each small body in the outer Solar System is a unique piece of a larger puzzle that scientists are trying to piece together,” Protopapa said.

Researchers used an instrument on Webb to conduct four observations in 2022 and 2023, obtaining full coverage of Charon’s northern hemisphere.

“These new Webb observations add carbon dioxide and hydrogen peroxide to the known inventory of Charon’s surface components. Both provide insights into the ongoing processes of impact-driven irradiation and resurfacing,” said study co-author Ian Wong, scientist of the Space Telescope Science Institute in Baltimore.