Scientists at the Southwest Research Institute combined data from NASA’s New Horizons mission with new laboratory experiments and exospheric modeling to reveal the possible composition of Pluto’s moon Charon’s red cap and how it formed. This very first description of Charon’s dynamic methane atmosphere using new experimental data provides an interesting look at the beginning of the red phase this month as described in two new papers.
“Before New Horizons, the very best Hubble images of Pluto only revealed a fuzzy blob of reflected light,” said Randy Gladstone of SwRI, a member of the New Horizons science team. “In addition to all the interesting features discovered on Pluto’s surface, the flyby reveals a unique feature of Charon, a shocking red hat centered on his. north pole. “
Shortly after the 2015 encounter, scientists at New Horizons suggested that a reddish “tholin-like” material in Charon’s pole could be synthesized in ultraviolet light WRECKAGE methane molecules. It was obtained after escaping from Pluto and then frozen into the polar regions of the moon during their long winter nights. Tholins are sticky organic residues formed by chemical reactions powered by light, in this case the Lyman-alpha ultraviolet glow scatters the interplanetary hydrogen molecule.
“Our findings show that the severe seasonal surge in Charon’s thin atmosphere as well as the light breaking condensing methane frost is key to understanding the origin of Charon’s red polar zone,” said Dr. . Ujjwal Raut of SwRI, lead author of a paper titled “Charon’s. Refractory Factory” in the journal Scientific Advances. “This is one of the most descriptive and vivid examples of surface-atmospheric interactions observed in a planetary body.”
The team realistically simulated the situation above Charon at SwRI’s new Center for Laboratory Astrophysics and Space Science Experiments (CLASSE) to measure the composition and color of hydrocarbons produced in Charon’s winter hemisphere as methane freezes. under the Lyman-alpha glow. The team fed the measurements to a new model of Charon’s atmosphere to show the methane depleting the rest of Charon’s north polar area.
“Our team’s novel‘ dynamic photolysis ’experiments present new limits to the contribution of interplanetary Lyman-alpha to Charon’s red material synthesis,” Raut said. “Our experiment condensed methane in a ultra-high vacuum chamber under exposure to Lyman-alpha photons to replicate with high fidelity to the conditions of Charon’s poles. “
SwRI scientists also created a new computer simulation to model Charon’s thin methane atmosphere.
“The model focuses on‘ explosive ’seasonal pulsations in Charon’s atmosphere due to drastic changes in conditions during Pluto’s long journey around the Sun,” Drs. Ben Teolis, lead author of a related paper titled “Extreme Exospheric Dynamics and Charon: Implications for the Red Spot” in Geophysical Research Letters.
The team inputs results from ultra-realistic SwRI experiments into the atmospheric model to estimate the distribution of hydrocarbon complexes arising from methane decomposition under the influence of ultraviolet light. The model has polar zones that primarily produce ethane, a colorless material that does not contribute a red color.
“We are thinking of ionizing radiation from solar-wind decomposes Lyman-alpha-cooked polar frost to synthesize the more complex, redder materials responsible for this mysterious moon’s unusual albedo, ”Raut said.“ Ethane is less volatile than methane and stays frozen over Charon long after the rising of the spring sun. Exposure to solar wind can convert ethane into persistent red surface deposits that contribute to Charon’s red hat. “
“The team is set to investigate the role of the solar wind in the formation of the red pole,” said Drs. Josh Kammer of SwRI, who has received ongoing support from NASA’s New Frontier Data Analysis Program.
Ben Teolis et al, Extreme Exospheric Dynamics of Charon: Implications for the Red Spot, Geophysical Research Letters (2022). DOI: 10.1029/2021GL097580
Ujjwal Raut et al, Charon’s refractory factory, Scientific Advances (2022). DOI: 10.1126/sciadv.abq5701
Southwest Research Institute
quotation: Scientists identify possible source of Charon’s red cap (2022, June 21) obtained on June 22, 2022 from
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