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Endogenically sourced volatiles on Charon and other Kuiper belt objects. Nat Commun 2022; 13:4457. [PMID: 35945207 PMCID: PMC9363412 DOI: 10.1038/s41467-022-31846-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 07/01/2022] [Indexed: 11/18/2022] Open
Abstract
Kuiper belt objects (KBOs) have diverse surface compositions, and the New Horizons mission to the Pluto-Charon system allows us to test hypotheses on the origin and evolution of these KBO surfaces. Previous work proposed that Charon’s organic-rich north pole formed from radiolytically processed volatiles sourced from Pluto’s escaping atmosphere. Here, we show an endogenic source of volatiles from Charon’s interior is plausible. We calculate that cryovolcanic resurfacing released 1.29 × 1015–3.47 × 1015 kg of methane to Charon’s surface from its interior. We modeled volatile transport and found the vast majority of this volcanically released methane migrates to Charon’s poles, with deposition rates sufficient to be processed into the observed organic compounds. Irradiated methane products appear on similarly sized KBOs that do not orbit a Pluto-sized object to draw an escaping atmosphere from, so interior-sourced volatiles could be a common and important process across the Kuiper belt. We show cryovolcanic eruptions released sufficient methane to source volatile products on Charon. Irradiated methane products are found on other Kuiper belt objects, so endogenically sourced volatiles could be important across the Kuiper belt.
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Raut U, Teolis BD, Kammer JA, Gimar CJ, Brody JS, Gladstone GR, Howett CJA, Protopapa S, Retherford KD. Charon's refractory factory. SCIENCE ADVANCES 2022; 8:eabq5701. [PMID: 35714189 PMCID: PMC9205591 DOI: 10.1126/sciadv.abq5701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 04/16/2022] [Accepted: 04/29/2022] [Indexed: 06/15/2023]
Abstract
We combine novel laboratory experiments and exospheric modeling to reveal that "dynamic" Ly-α photolysis of Plutonian methane generates a photolytic refractory distribution on Charon that increases with latitude, consistent with poleward darkening observed in the New Horizons images. The flux ratio of the condensing methane to the interplanetary medium Ly-α photons, φ, controls the distribution and composition of Charon's photoproducts. Mid-latitude regions are likely to host complex refractories emerging from low-φ photolysis, while high-φ photolysis at the polar zones primarily generate ethane. However, ethane being colorless does not contribute to the reddish polar hue. Solar wind radiolysis of Ly-α-cooked polar frost past spring sunrise may synthesize increasingly complex, redder refractories responsible for the unique albedo on this enigmatic moon.
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Affiliation(s)
- Ujjwal Raut
- Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Benjamin D. Teolis
- Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Joshua A. Kammer
- Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
| | - Caleb J. Gimar
- Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Joshua S. Brody
- Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
| | - G. Randall Gladstone
- Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Carly J. A. Howett
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
- Department of Physics, University of Oxford, Oxfordshire, UK
| | - Silvia Protopapa
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
| | - Kurt D. Retherford
- Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249, USA
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Schenk PM, Moore JM. Topography and geology of Uranian mid-sized icy satellites in comparison with Saturnian and Plutonian satellites. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20200102. [PMID: 33161858 DOI: 10.1098/rsta.2020.0102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/03/2020] [Indexed: 05/20/2023]
Abstract
Newly processed global imaging and topographic mapping of Uranus's five major satellites reveal differences and similarities to mid-sized satellites at Saturn and Pluto. Three modes of internal heat redistribution are recognized. The broad similarity of Miranda's three oval resurfacing zones to those mapped on Enceladus and (subtly) on Dione are likely due to antipodal diapiric upwelling. Conversely, break-up and foundering of crustal blocks accompanied by extensive (cryo)volcanism is the dominant mode on both Charon and Ariel. Titania's fault network finds parallels on Rhea, Dione, Tethys and possibly Oberon. Differences in the geologic style of resurfacing in the satellite systems (e.g. plains on Charon, Dione, Tethys and perhaps Titania versus ridges on Miranda and Ariel) may be driven by differences in ice composition. Surface processes such as volatile transport may also be indicated by bright and dark materials on Oberon, Umbriel and Charon. The more complete and higher quality observations of the Saturnian and Plutonian mid-sized icy satellites by Cassini and New Horizons reveal a wealth of features and phenomena that cannot be perceived in the more limited Voyager coverage of the Uranian satellites, harbingers of many discoveries awaiting us on a return to Uranus. This article is part of a discussion meeting issue 'Future exploration of ice giant systems'.
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Affiliation(s)
- Paul M Schenk
- Lunar and Planteray Institute/USRA, Houston, TX, USA
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Singer KN, McKinnon WB, Gladman B, Greenstreet S, Bierhaus EB, Stern SA, Parker AH, Robbins SJ, Schenk PM, Grundy WM, Bray VJ, Beyer RA, Binzel RP, Weaver HA, Young LA, Spencer JR, Kavelaars JJ, Moore JM, Zangari AM, Olkin CB, Lauer TR, Lisse CM, Ennico K. Impact craters on Pluto and Charon indicate a deficit of small Kuiper belt objects. Science 2019; 363:955-959. [PMID: 30819958 DOI: 10.1126/science.aap8628] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 02/05/2019] [Indexed: 11/02/2022]
Abstract
The flyby of Pluto and Charon by the New Horizons spacecraft provided high-resolution images of cratered surfaces embedded in the Kuiper belt, an extensive region of bodies orbiting beyond Neptune. Impact craters on Pluto and Charon were formed by collisions with other Kuiper belt objects (KBOs) with diameters from ~40 kilometers to ~300 meters, smaller than most KBOs observed directly by telescopes. We find a relative paucity of small craters ≲13 kilometers in diameter, which cannot be explained solely by geological resurfacing. This implies a deficit of small KBOs (≲1 to 2 kilometers in diameter). Some surfaces on Pluto and Charon are likely ≳4 billion years old, thus their crater records provide information on the size-frequency distribution of KBOs in the early Solar System.
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