Scientists at the Southwest Research Institute combined data from NASA’s New Horizons mission with new laboratory experiments and exospheric modeling to reveal the likely composition of the red layer of Pluto’s moon Charon and how it might have formed. New findings suggest that drastic seasonal rises in Charon’s fine atmosphere, combined with light breaking the condensed methane frost, may be key to understanding the origins of Charon’s red polar zones. Credit: NASA / Johns Hopkins APL / SwRI
Scientists at the Southwest Research Institute combined data from NASA’s New Horizons mission with new laboratory experiments and exospheric modeling to reveal the likely composition of the red layer of Pluto’s moon Charon and how it might have formed. This first description of Charon’s dynamic methane atmosphere using new experimental data provides a fascinating insight into the origins of this moon’s red spot as described in two recent articles.
“Before New Horizons, the best images of Pluto’s Hubble only revealed a diffuse spot of reflected light,” said Randy Gladstone of SwRI, a member of the New Horizons scientific team. “In addition to all the fascinating features discovered on Pluto’s surface, the overflight revealed an unusual feature to Charon, a striking red cap centered at its north pole.”
Shortly after the 2015 meeting, New Horizons scientists proposed that a “toline-like” reddish material at Charon’s pole could be synthesized by ultraviolet light that shattered methane molecules. These are captured after escaping from Pluto and then frozen in the polar regions of the Moon during their long winter nights. Tolins are sticky organic wastes formed by light-driven chemical reactions, in this case the ultraviolet glow Lyman-alpha dispersed by interplanetary hydrogen molecules.
“Our results indicate that drastic seasonal increases in Charon’s fine atmosphere, as well as light breaking the condensed methane frost, are key to understanding the origins of Charon’s red polar zone,” said Dr. Ujjwal. Raut of SwRI, lead author of an article entitled “Charon’s”. Refractory Factory “in the magazine Advances in Science. “This is one of the most illustrative and clear examples of surface-atmospheric interactions observed to date in a planetary body.”
The team realistically replicated Charon’s surface conditions at SwRI’s new Center for Astrophysics and Space Science Experiments (CLASS) to measure the composition and color of hydrocarbons produced in the winter hemisphere. Charon when methane freezes under the Lyman-alpha glow. The team introduced the measurements into a new atmospheric Charon model to show that methane decomposes into waste at the north polar point of Charon.
“Our team’s new‘ dynamic photolysis ’experiments provided new limits to the contribution of interplanetary Lyman-alpha to the synthesis of Charon’s red material,” Raut said. “Our experiment condensed methane in an ultra-high vacuum chamber under exposure to Lyman-alpha photons to faithfully replicate conditions at Charon’s poles.”
SwRI scientists also developed a new computer simulation to model Charon’s thin methane atmosphere.
“The model points to ‘explosive’ seasonal pulses in Charon’s atmosphere due to extreme changes in conditions along Pluto’s long journey around the Sun,” said Dr. Ben Teolis, lead author of an article. related article entitled “Extreme exosphere dynamics in Charon: Implications for the red spot” in Geophysical research letters.
The team introduced the results of SwRI’s ultra-realistic experiments into the atmospheric model to estimate the distribution of complex hydrocarbons arising from the decomposition of methane under the influence of ultraviolet light. The model has polar zones generating mainly ethane, a colorless material that does not contribute to a reddish color.
“We believe that ionizing radiation from the solar wind breaks down polar ice cooked with Lyman-alpha to synthesize increasingly complex, red materials responsible for the unique albedo on this enigmatic moon,” Raut said. “Ethane is less volatile than methane and stays frozen on the surface of Charon long after the spring sun rises. Exposure to solar wind can turn ethane into persistent reddish surface deposits that contribute to the layer. Charon’s Red. “
“The team is ready to investigate the role of the solar wind in the formation of the red pole,” said Dr. Josh Kammer of SwRI, who secured continued support from NASA’s New Frontier data analysis program.
Pluto “paints” its largest moon Charon in red. More information: Ben Teolis et al, Extreme exospheric dynamics in Charon: Implications for red spot, Geophysical research letters (2022). DOI: 10.1029 / 2021GL097580
Ujjwal Raut et al, Charon Refractory Factory, Advances in Science (2022). DOI: 10.1126 / sciadv.abq5701
Provided by Southwest Research Institute
Citation: Scientists identify a possible source of Charon’s red cap (2022, June 21) recovered on June 22, 2022
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