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Naponiello L, Mancini L, Sozzetti A, Bonomo AS, Morbidelli A, Dou J, Zeng L, Leinhardt ZM, Biazzo K, Cubillos PE, Pinamonti M, Locci D, Maggio A, Damasso M, Lanza AF, Lissauer JJ, Collins KA, Carter PJ, Jensen ELN, Bignamini A, Boschin W, Bouma LG, Ciardi DR, Cosentino R, Crossfield I, Desidera S, Dumusque X, Fiorenzano AFM, Fukui A, Giacobbe P, Gnilka CL, Ghedina A, Guilluy G, Harutyunyan A, Howell SB, Jenkins JM, Lund MB, Kielkopf JF, Lester KV, Malavolta L, Mann AW, Matson RA, Matthews EC, Nardiello D, Narita N, Pace E, Pagano I, Palle E, Pedani M, Seager S, Schlieder JE, Schwarz RP, Shporer A, Twicken JD, Winn JN, Ziegler C, Zingales T. A super-massive Neptune-sized planet. Nature 2023; 622:255-260. [PMID: 37648866 DOI: 10.1038/s41586-023-06499-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/28/2023] [Indexed: 09/01/2023]
Abstract
Neptune-sized planets exhibit a wide range of compositions and densities, depending on factors related to their formation and evolution history, such as the distance from their host stars and atmospheric escape processes. They can vary from relatively low-density planets with thick hydrogen-helium atmospheres1,2 to higher-density planets with a substantial amount of water or a rocky interior with a thinner atmosphere, such as HD 95338 b (ref. 3), TOI-849 b (ref. 4) and TOI-2196 b (ref. 5). The discovery of exoplanets in the hot-Neptune desert6, a region close to the host stars with a deficit of Neptune-sized planets, provides insights into the formation and evolution of planetary systems, including the existence of this region itself. Here we show observations of the transiting planet TOI-1853 b, which has a radius of 3.46 ± 0.08 Earth radii and orbits a dwarf star every 1.24 days. This planet has a mass of 73.2 ± 2.7 Earth masses, almost twice that of any other Neptune-sized planet known so far, and a density of 9.7 ± 0.8 grams per cubic centimetre. These values place TOI-1853 b in the middle of the Neptunian desert and imply that heavy elements dominate its mass. The properties of TOI-1853 b present a puzzle for conventional theories of planetary formation and evolution, and could be the result of several proto-planet collisions or the final state of an initially high-eccentricity planet that migrated closer to its parent star.
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Affiliation(s)
- Luca Naponiello
- Department of Physics, University of Rome "Tor Vergata", Rome, Italy.
- Department of Physics and Astronomy, University of Florence, Florence, Italy.
- Department of Physics, Sapienza University of Rome, Rome, Italy.
- INAF - Turin Astrophysical Observatory, Pino Torinese, Italy.
| | - Luigi Mancini
- Department of Physics, University of Rome "Tor Vergata", Rome, Italy
- INAF - Turin Astrophysical Observatory, Pino Torinese, Italy
- Max Planck Institute for Astronomy, Heidelberg, Germany
| | | | - Aldo S Bonomo
- INAF - Turin Astrophysical Observatory, Pino Torinese, Italy
| | - Alessandro Morbidelli
- Laboratoire Lagrange, Université Cote d'Azur, CNRS, Observatoire de la Côte d'Azur, Nice, France
| | - Jingyao Dou
- School of Physics, H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK
| | - Li Zeng
- Center for Astrophysics, Harvard & Smithsonian, Cambridge, MA, USA
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
| | - Zoe M Leinhardt
- School of Physics, H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK
| | - Katia Biazzo
- INAF - Rome Astronomical Observatory, Monte Porzio Catone, Italy
| | - Patricio E Cubillos
- INAF - Turin Astrophysical Observatory, Pino Torinese, Italy
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | | | - Daniele Locci
- INAF - Palermo Astronomical Observatory, Palermo, Italy
| | | | - Mario Damasso
- INAF - Turin Astrophysical Observatory, Pino Torinese, Italy
| | | | - Jack J Lissauer
- NASA Ames Research Center, Moffett Field, CA, USA
- Department of Earth and Planetary Sciences, Stanford University, Stanford, CA, USA
| | - Karen A Collins
- Center for Astrophysics, Harvard & Smithsonian, Cambridge, MA, USA
| | - Philip J Carter
- School of Physics, H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK
| | - Eric L N Jensen
- Department of Physics & Astronomy, Swarthmore College, Swarthmore, PA, USA
| | | | - Walter Boschin
- Fundación Galileo Galilei - INAF, Tenerife, Spain
- Instituto de Astrofísica de Canarias (IAC), Tenerife, Spain
- Departamento de Astrofísica, Universidad de La Laguna (ULL), Tenerife, Spain
| | - Luke G Bouma
- NASA Exoplanet Science Institute - Caltech/IPAC, Pasadena, CA, USA
| | - David R Ciardi
- NASA Exoplanet Science Institute - Caltech/IPAC, Pasadena, CA, USA
| | | | - Ian Crossfield
- Department of Physics and Astronomy, University of Kansas, Lawrence, KS, USA
| | | | - Xavier Dumusque
- Observatoire de Genève, Université de Genève, Versoix, Switzerland
| | | | - Akihiko Fukui
- Instituto de Astrofísica de Canarias (IAC), Tenerife, Spain
- Komaba Institute for Science, The University of Tokyo, Tokyo, Japan
| | - Paolo Giacobbe
- INAF - Turin Astrophysical Observatory, Pino Torinese, Italy
| | - Crystal L Gnilka
- NASA Ames Research Center, Moffett Field, CA, USA
- NASA Exoplanet Science Institute - Caltech/IPAC, Pasadena, CA, USA
| | | | - Gloria Guilluy
- INAF - Turin Astrophysical Observatory, Pino Torinese, Italy
| | | | | | | | - Michael B Lund
- NASA Exoplanet Science Institute - Caltech/IPAC, Pasadena, CA, USA
| | - John F Kielkopf
- Department of Physics and Astronomy, University of Louisville, Louisville, KY, USA
| | | | - Luca Malavolta
- INAF - Padova Astronomical Observatory, Padova, Italy
- Department of Physics and Astronomy, University of Padova, Padova, Italy
| | - Andrew W Mann
- Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | | | | | - Norio Narita
- Instituto de Astrofísica de Canarias (IAC), Tenerife, Spain
- Komaba Institute for Science, The University of Tokyo, Tokyo, Japan
- Astrobiology Center, Osawa, Mitaka, Japan
| | - Emanuele Pace
- Department of Physics and Astronomy, University of Florence, Florence, Italy
| | | | - Enric Palle
- Instituto de Astrofísica de Canarias (IAC), Tenerife, Spain
- Departamento de Astrofísica, Universidad de La Laguna (ULL), Tenerife, Spain
| | - Marco Pedani
- Fundación Galileo Galilei - INAF, Tenerife, Spain
| | - Sara Seager
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | - Avi Shporer
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Joseph D Twicken
- NASA Ames Research Center, Moffett Field, CA, USA
- SETI Institute, Mountain View, CA, USA
| | - Joshua N Winn
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA
| | - Carl Ziegler
- Department of Physics, Engineering & Astronomy, Stephen F. Austin State University, Nacogdoches, TX, USA
| | - Tiziano Zingales
- INAF - Padova Astronomical Observatory, Padova, Italy
- Department of Physics and Astronomy, University of Padova, Padova, Italy
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Broadley MW, Bekaert DV, Piani L, Füri E, Marty B. Origin of life-forming volatile elements in the inner Solar System. Nature 2022; 611:245-255. [DOI: 10.1038/s41586-022-05276-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 08/25/2022] [Indexed: 11/11/2022]
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Sossi PA, Stotz IL, Jacobson SA, Morbidelli A, O’Neill HS. Stochastic accretion of the Earth. NATURE ASTRONOMY 2022; 6:951-960. [PMID: 35971330 PMCID: PMC7613298 DOI: 10.1038/s41550-022-01702-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
Chondritic meteorites are thought to be representative of the material that formed the Earth. However, the Earth is depleted in volatile elements in a manner unlike that in any chondrite, and yet these elements retain chondritic isotope ratios. Here we use N-body simulations to show that the Earth did not form from chondrites, but rather by stochastic accretion of many precursor bodies whose variable compositions reflect the temperatures at which they formed. Earth's composition is reproduced when initial temperatures of planetesimal- to embryo-sized bodies are set by disk accretion rates of (1.08±0.17)×10-7 solar masses/yr, although they may be perturbed by 26Al heating on bodies formed at different times. Our model implies that a heliocentric gradient in composition was present in the protoplanetary disc and that planetesimals formed rapidly within ~1 Myr, in accord with radiometric volatile depletion ages of the Earth.
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Affiliation(s)
- Paolo A. Sossi
- Institute of Geochemistry and Petrology, ETH Zürich, CH-8092, Zürich, Switzerland
| | - Ingo L. Stotz
- Institut für Geophysik, Ludwig-Maximilians Universität Münich, Münich, Germany
| | - Seth A. Jacobson
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI 48824, USA
| | - Alessandro Morbidelli
- Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d'Azur, Boulevard de l'Observatoire, 06304 Nice Cedex 4, France
| | - Hugh St.C. O’Neill
- School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC 3800, Australia
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Sakuraba H, Kurokawa H, Genda H, Ohta K. Numerous chondritic impactors and oxidized magma ocean set Earth's volatile depletion. Sci Rep 2021; 11:20894. [PMID: 34686749 PMCID: PMC8536732 DOI: 10.1038/s41598-021-99240-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 09/22/2021] [Indexed: 11/22/2022] Open
Abstract
Earth’s surface environment is largely influenced by its budget of major volatile elements: carbon (C), nitrogen (N), and hydrogen (H). Although the volatiles on Earth are thought to have been delivered by chondritic materials, the elemental composition of the bulk silicate Earth (BSE) shows depletion in the order of N, C, and H. Previous studies have concluded that non-chondritic materials are needed for this depletion pattern. Here, we model the evolution of the volatile abundances in the atmosphere, oceans, crust, mantle, and core through the accretion history by considering elemental partitioning and impact erosion. We show that the BSE depletion pattern can be reproduced from continuous accretion of chondritic bodies by the partitioning of C into the core and H storage in the magma ocean in the main accretion stage and atmospheric erosion of N in the late accretion stage. This scenario requires a relatively oxidized magma ocean (\documentclass[12pt]{minimal}
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\begin{document}$$f_{{\mathrm{O}}_2}$$\end{document}fO2 at the iron-wüstite buffer), the dominance of small impactors in the late accretion, and the storage of H and C in oceanic water and carbonate rocks in the late accretion stage, all of which are naturally expected from the formation of an Earth-sized planet in the habitable zone.
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Affiliation(s)
- Haruka Sakuraba
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8551, Japan.
| | - Hiroyuki Kurokawa
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
| | - Hidenori Genda
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
| | - Kenji Ohta
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8551, Japan
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Hirschmann MM, Bergin EA, Blake GA, Ciesla FJ, Li J. Early volatile depletion on planetesimals inferred from C-S systematics of iron meteorite parent bodies. Proc Natl Acad Sci U S A 2021; 118:e2026779118. [PMID: 33753516 PMCID: PMC8020667 DOI: 10.1073/pnas.2026779118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During the formation of terrestrial planets, volatile loss may occur through nebular processing, planetesimal differentiation, and planetary accretion. We investigate iron meteorites as an archive of volatile loss during planetesimal processing. The carbon contents of the parent bodies of magmatic iron meteorites are reconstructed by thermodynamic modeling. Calculated solid/molten alloy partitioning of C increases greatly with liquid S concentration, and inferred parent body C concentrations range from 0.0004 to 0.11 wt%. Parent bodies fall into two compositional clusters characterized by cores with medium and low C/S. Both of these require significant planetesimal degassing, as metamorphic devolatilization on chondrite-like precursors is insufficient to account for their C depletions. Planetesimal core formation models, ranging from closed-system extraction to degassing of a wholly molten body, show that significant open-system silicate melting and volatile loss are required to match medium and low C/S parent body core compositions. Greater depletion in C relative to S is the hallmark of silicate degassing, indicating that parent body core compositions record processes that affect composite silicate/iron planetesimals. Degassing of bare cores stripped of their silicate mantles would deplete S with negligible C loss and could not account for inferred parent body core compositions. Devolatilization during small-body differentiation is thus a key process in shaping the volatile inventory of terrestrial planets derived from planetesimals and planetary embryos.
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Affiliation(s)
- Marc M Hirschmann
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455;
| | - Edwin A Bergin
- Department of Astronomy, University of Michigan, Ann Arbor, MI 48109
| | - Geoff A Blake
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
| | - Fred J Ciesla
- Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637
- Chicago Center for Cosmochemistry, University of Chicago, Chicago, IL 60637
| | - Jie Li
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109
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Piani L, Marrocchi Y, Rigaudier T, Vacher LG, Thomassin D, Marty B. Earth’s water may have been inherited from material similar to enstatite chondrite meteorites. Science 2020; 369:1110-1113. [DOI: 10.1126/science.aba1948] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 07/15/2020] [Indexed: 11/02/2022]
Abstract
The origin of Earth’s water remains unknown. Enstatite chondrite (EC) meteorites have similar isotopic composition to terrestrial rocks and thus may be representative of the material that formed Earth. ECs are presumed to be devoid of water because they formed in the inner Solar System. Earth’s water is therefore generally attributed to the late addition of a small fraction of hydrated materials, such as carbonaceous chondrite meteorites, which originated in the outer Solar System where water was more abundant. We show that EC meteorites contain sufficient hydrogen to have delivered to Earth at least three times the mass of water in its oceans. EC hydrogen and nitrogen isotopic compositions match those of Earth’s mantle, so EC-like asteroids might have contributed these volatile elements to Earth’s crust and mantle.
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Affiliation(s)
- Laurette Piani
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), Centre National de Recherche Scientifique (CNRS)–Université de Lorraine, Vandoeuvre-les-Nancy, F-54500, France
| | - Yves Marrocchi
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), Centre National de Recherche Scientifique (CNRS)–Université de Lorraine, Vandoeuvre-les-Nancy, F-54500, France
| | - Thomas Rigaudier
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), Centre National de Recherche Scientifique (CNRS)–Université de Lorraine, Vandoeuvre-les-Nancy, F-54500, France
| | - Lionel G. Vacher
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), Centre National de Recherche Scientifique (CNRS)–Université de Lorraine, Vandoeuvre-les-Nancy, F-54500, France
- Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Dorian Thomassin
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), Centre National de Recherche Scientifique (CNRS)–Université de Lorraine, Vandoeuvre-les-Nancy, F-54500, France
| | - Bernard Marty
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), Centre National de Recherche Scientifique (CNRS)–Université de Lorraine, Vandoeuvre-les-Nancy, F-54500, France
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Abstract
The next step on the path toward another Earth is to find atmospheres similar to those of Earth and Venus-high-molecular-weight (secondary) atmospheres-on rocky exoplanets. Many rocky exoplanets are born with thick (>10 kbar) H2-dominated atmospheres but subsequently lose their H2; this process has no known Solar System analog. We study the consequences of early loss of a thick H2 atmosphere for subsequent occurrence of a high-molecular-weight atmosphere using a simple model of atmosphere evolution (including atmosphere loss to space, magma ocean crystallization, and volcanic outgassing). We also calculate atmosphere survival for rocky worlds that start with no H2 Our results imply that most rocky exoplanets orbiting closer to their star than the habitable zone that were formed with thick H2-dominated atmospheres lack high-molecular-weight atmospheres today. During early magma ocean crystallization, high-molecular-weight species usually do not form long-lived high-molecular-weight atmospheres; instead, they are lost to space alongside H2 This early volatile depletion also makes it more difficult for later volcanic outgassing to revive the atmosphere. However, atmospheres should persist on worlds that start with abundant volatiles (for example, water worlds). Our results imply that in order to find high-molecular-weight atmospheres on warm exoplanets orbiting M-stars, we should target worlds that formed H2-poor, that have anomalously large radii, or that orbit less active stars.
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Affiliation(s)
- Edwin S Kite
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637
| | - Megan N Barnett
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637
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9
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Bekaert DV, Broadley MW, Marty B. The origin and fate of volatile elements on Earth revisited in light of noble gas data obtained from comet 67P/Churyumov-Gerasimenko. Sci Rep 2020; 10:5796. [PMID: 32242104 PMCID: PMC7118078 DOI: 10.1038/s41598-020-62650-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 03/17/2020] [Indexed: 11/25/2022] Open
Abstract
The origin of terrestrial volatiles remains one of the most puzzling questions in planetary sciences. The timing and composition of chondritic and cometary deliveries to Earth has remained enigmatic due to the paucity of reliable measurements of cometary material. This work uses recently measured volatile elemental ratios and noble gas isotope data from comet 67P/Churyumov-Gerasimenko (67P/C-G), in combination with chondritic data from the literature, to reconstruct the composition of Earth’s ancient atmosphere. Comets are found to have contributed ~20% of atmospheric heavy noble gases (i.e., Kr and Xe) but limited amounts of other volatile elements (water, halogens and likely organic materials) to Earth. These cometary noble gases were likely mixed with chondritic - and not solar - sources to form the atmosphere. We show that an ancient atmosphere composed of chondritic and cometary volatiles is more enriched in Xe relative to the modern atmosphere, requiring that 8–12 times the present-day inventory of Xe was lost to space. This potentially resolves the long-standing mystery of Earth’s “missing xenon”, with regards to both Xe elemental depletion and isotopic fractionation in the atmosphere. The inferred Kr/H2O and Xe/H2O of the initial atmosphere suggest that Earth’s surface volatiles might not have been fully delivered by the late accretion of volatile-rich carbonaceous chondrites. Instead, “dry” materials akin to enstatite chondrites potentially constituted a significant source of chondritic volatiles now residing on the Earth’s surface. We outline the working hypotheses, implications and limitations of this model in the last section of this contribution.
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Affiliation(s)
- David V Bekaert
- Centre de Recherches Pétrographiques et Géochimiques, UMR 7358 CNRS - Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501, Vandoeuvre-lès-Nancy, France.
| | - Michael W Broadley
- Centre de Recherches Pétrographiques et Géochimiques, UMR 7358 CNRS - Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501, Vandoeuvre-lès-Nancy, France.
| | - Bernard Marty
- Centre de Recherches Pétrographiques et Géochimiques, UMR 7358 CNRS - Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501, Vandoeuvre-lès-Nancy, France
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Armstrong K, Frost DJ, McCammon CA, Rubie DC, Boffa Ballaran T. Deep magma ocean formation set the oxidation state of Earth's mantle. Science 2020; 365:903-906. [PMID: 31467218 DOI: 10.1126/science.aax8376] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 08/02/2019] [Indexed: 11/02/2022]
Abstract
The composition of Earth's atmosphere depends on the redox state of the mantle, which became more oxidizing at some stage after Earth's core started to form. Through high-pressure experiments, we found that Fe2+ in a deep magma ocean would disproportionate to Fe3+ plus metallic iron at high pressures. The separation of this metallic iron to the core raised the oxidation state of the upper mantle, changing the chemistry of degassing volatiles that formed the atmosphere to more oxidized species. Additionally, the resulting gradient in redox state of the magma ocean allowed dissolved CO2 from the atmosphere to precipitate as diamond at depth. This explains Earth's carbon-rich interior and suggests that redox evolution during accretion was an important variable in determining the composition of the terrestrial atmosphere.
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Affiliation(s)
| | - Daniel J Frost
- Bayerisches Geoinstitut, University of Bayreuth, D-95447 Bayreuth, Germany.
| | | | - David C Rubie
- Bayerisches Geoinstitut, University of Bayreuth, D-95447 Bayreuth, Germany
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Greenwood RC, Barrat JA, Miller MF, Anand M, Dauphas N, Franchi IA, Sillard P, Starkey NA. Oxygen isotopic evidence for accretion of Earth's water before a high-energy Moon-forming giant impact. SCIENCE ADVANCES 2018; 4:eaao5928. [PMID: 29600271 PMCID: PMC5873841 DOI: 10.1126/sciadv.aao5928] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 02/14/2018] [Indexed: 05/26/2023]
Abstract
The Earth-Moon system likely formed as a result of a collision between two large planetary objects. Debate about their relative masses, the impact energy involved, and the extent of isotopic homogenization continues. We present the results of a high-precision oxygen isotope study of an extensive suite of lunar and terrestrial samples. We demonstrate that lunar rocks and terrestrial basalts show a 3 to 4 ppm (parts per million), statistically resolvable, difference in Δ17O. Taking aubrite meteorites as a candidate impactor material, we show that the giant impact scenario involved nearly complete mixing between the target and impactor. Alternatively, the degree of similarity between the Δ17O values of the impactor and the proto-Earth must have been significantly closer than that between Earth and aubrites. If the Earth-Moon system evolved from an initially highly vaporized and isotopically homogenized state, as indicated by recent dynamical models, then the terrestrial basalt-lunar oxygen isotope difference detected by our study may be a reflection of post-giant impact additions to Earth. On the basis of this assumption, our data indicate that post-giant impact additions to Earth could have contributed between 5 and 30% of Earth's water, depending on global water estimates. Consequently, our data indicate that the bulk of Earth's water was accreted before the giant impact and not later, as often proposed.
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Affiliation(s)
- Richard C. Greenwood
- Planetary and Space Sciences, School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
| | - Jean-Alix Barrat
- Université de Bretagne Occidentale, Institut Universitaire Européen de la Mer, Laboratoire Géosciences Océan (CNRS UMR 6538), Plouzané, France
| | - Martin F. Miller
- Planetary and Space Sciences, School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - Mahesh Anand
- Planetary and Space Sciences, School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
- Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Nicolas Dauphas
- Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA
| | - Ian A. Franchi
- Planetary and Space Sciences, School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
| | - Patrick Sillard
- Centre de recherche en économie et statistique, 5 avenue Henry Le Chatelier, 91120 Palaiseau, France
| | - Natalie A. Starkey
- Planetary and Space Sciences, School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
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Ni H, Zheng YF, Mao Z, Wang Q, Chen RX, Zhang L. Distribution, cycling and impact of water in the Earth's interior. Natl Sci Rev 2017. [DOI: 10.1093/nsr/nwx130] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
The Earth's deep interior is a hidden water reservoir on a par with the hydrosphere that is crucial for keeping the Earth as a habitable planet. In particular, nominally anhydrous minerals (NAMs) in the silicate Earth host a significant amount of water by accommodating H point defects in their crystal lattices. Water distribution in the silicate Earth is highly heterogeneous, and the mantle transition zone may contain more water than the upper and lower mantles. Plate subduction transports surface water to various depths, with a series of hydrous minerals and NAMs serving as water carriers. Dehydration of the subducting slab produces liquid phases such as aqueous solutions and hydrous melts as a metasomatic agent of the mantle. Partial melting of the metasomatic mantle domains sparks off arc volcanism, which, along with the volcanism at mid-ocean ridges and hotspots, returns water to the surface and completes the deep water cycle. There appears to have been a steady balance between hydration and dehydration of the mantle at least since the Phanerozoic. Earth's water probably originates from a primordial portion that survived the Moon-forming giant impact, with later delivery by asteroids and comets. Water could play a critical role in initiating plate tectonics. In the modern Earth, the storage and cycling of water profoundly modulates a variety of properties and processes of the Earth's interior, with impacts on surface environments. Notable examples include the hydrolytic weakening effect on mantle convection and plate motion, influences on phase transitions (on the solidus of mantle peridotite in particular) and dehydration embrittlement triggering intermediate- to deep-focus earthquakes. Water can reduce seismic velocity and enhance electrical conductivity, providing remote sensing methods for water distribution in the Earth's interior. Many unresolved issues around the deep water cycle require an integrated approach and concerted efforts from multiple disciplines.
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Affiliation(s)
- Huaiwei Ni
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Yong-Fei Zheng
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Zhu Mao
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Qin Wang
- School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
| | - Ren-Xu Chen
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Li Zhang
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
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The Cosmic Shoreline: The Evidence that Escape Determines which Planets Have Atmospheres, and what this May Mean for Proxima Centauri B. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-4357/aa7846] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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18
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Genda H, Kobayashi H, Kokubo E. WARM DEBRIS DISKS PRODUCED BY GIANT IMPACTS DURING TERRESTRIAL PLANET FORMATION. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/810/2/136] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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19
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Balsiger H, Altwegg K, Bar-Nun A, Berthelier JJ, Bieler A, Bochsler P, Briois C, Calmonte U, Combi M, De Keyser J, Eberhardt P, Fiethe B, Fuselier SA, Gasc S, Gombosi TI, Hansen KC, Hässig M, Jäckel A, Kopp E, Korth A, Le Roy L, Mall U, Marty B, Mousis O, Owen T, Rème H, Rubin M, Sémon T, Tzou CY, Waite JH, Wurz P. Detection of argon in the coma of comet 67P/Churyumov-Gerasimenko. SCIENCE ADVANCES 2015; 1:e1500377. [PMID: 26601264 PMCID: PMC4643765 DOI: 10.1126/sciadv.1500377] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 06/22/2015] [Indexed: 05/15/2023]
Abstract
Comets have been considered to be representative of icy planetesimals that may have contributed a significant fraction of the volatile inventory of the terrestrial planets. For example, comets must have brought some water to Earth. However, the magnitude of their contribution is still debated. We report the detection of argon and its relation to the water abundance in the Jupiter family comet 67P/Churyumov-Gerasimenko by in situ measurement of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) mass spectrometer aboard the Rosetta spacecraft. Despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope (36)Ar and by the (36)Ar/(38)Ar ratio. Because of time variability and spatial heterogeneity of the coma, only a range of the relative abundance of argon to water can be given. Nevertheless, this range confirms that comets of the type 67P/Churyumov-Gerasimenko cannot be the major source of Earth's major volatiles.
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Affiliation(s)
- Hans Balsiger
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
- Corresponding author:
| | - Kathrin Altwegg
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
- Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Akiva Bar-Nun
- Department of Geoscience, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Jean-Jacques Berthelier
- LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales)/IPSL (Institut Pierre Simon Laplace)–CNRS–UPMC (University Pierre et Marie Curie)–UVSQ (Université de Versailles Saint-Quentin-en-Yvelines), 4 Avenue de Neptune, F-94100 Saint-Maur, France
| | - Andre Bieler
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA
| | - Peter Bochsler
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Christelle Briois
- Laboratoire de Physique et Chimie de l’Environnement et de l’Espace (LPC2E), UMR 6115 CNRS–Université d’Orléans, 45071 Orléans, France
| | - Ursina Calmonte
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Michael Combi
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA
| | - Johan De Keyser
- Belgian Institute for Space Aeronomy (BIRA-IASB), Ringlaan 3, B-1180 Brussels, Belgium
| | - Peter Eberhardt
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Björn Fiethe
- Institute of Computer and Network Engineering (IDA), Technische Universität (TU) Braunschweig, Hans-Sommer-Straße 66, D-38106 Braunschweig, Germany
| | - Stephen A. Fuselier
- Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA
| | - Sébastien Gasc
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Tamas I. Gombosi
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA
| | - Kenneth C. Hansen
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA
| | - Myrtha Hässig
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
- Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA
| | - Annette Jäckel
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Ernest Kopp
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Axel Korth
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Lena Le Roy
- Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Urs Mall
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Bernard Marty
- CRPG (Centre de Recherches Pétrographiques et Géochimiques)–CNRS, Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre lès Nancy, France
| | - Olivier Mousis
- Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
| | - Tobias Owen
- Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA
| | - Henri Rème
- Université de Toulouse; UPS (Université Paul Sabatier)–OMP (L’Observatoire Midi-Pyrénées); IRAP (L’Institut de Recherche en Astrophysique et Planétologie), 31400 Toulouse, France
| | - Martin Rubin
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Thierry Sémon
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Chia-Yu Tzou
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - J. Hunter Waite
- Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA
| | - Peter Wurz
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
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Tracing the ingredients for a habitable earth from interstellar space through planet formation. Proc Natl Acad Sci U S A 2015; 112:8965-70. [PMID: 26150527 DOI: 10.1073/pnas.1500954112] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We use the C/N ratio as a monitor of the delivery of key ingredients of life to nascent terrestrial worlds. Total elemental C and N contents, and their ratio, are examined for the interstellar medium, comets, chondritic meteorites, and terrestrial planets; we include an updated estimate for the bulk silicate Earth (C/N = 49.0 ± 9.3). Using a kinetic model of disk chemistry, and the sublimation/condensation temperatures of primitive molecules, we suggest that organic ices and macromolecular (refractory or carbonaceous dust) organic material are the likely initial C and N carriers. Chemical reactions in the disk can produce nebular C/N ratios of ∼1-12, comparable to those of comets and the low end estimated for planetesimals. An increase of the C/N ratio is traced between volatile-rich pristine bodies and larger volatile-depleted objects subjected to thermal/accretional metamorphism. The C/N ratios of the dominant materials accreted to terrestrial planets should therefore be higher than those seen in carbonaceous chondrites or comets. During planetary formation, we explore scenarios leading to further volatile loss and associated C/N variations owing to core formation and atmospheric escape. Key processes include relative enrichment of nitrogen in the atmosphere and preferential sequestration of carbon by the core. The high C/N bulk silicate Earth ratio therefore is best satisfied by accretion of thermally processed objects followed by large-scale atmospheric loss. These two effects must be more profound if volatile sequestration in the core is effective. The stochastic nature of these processes hints that the surface/atmospheric abundances of biosphere-essential materials will likely be variable.
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Day JMD, Moynier F. Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2014; 372:20130259. [PMID: 25114311 PMCID: PMC4128272 DOI: 10.1098/rsta.2013.0259] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The Moon is depleted in volatile elements relative to the Earth and Mars. Low abundances of volatile elements, fractionated stable isotope ratios of S, Cl, K and Zn, high μ ((238)U/(204)Pb) and long-term Rb/Sr depletion are distinguishing features of the Moon, relative to the Earth. These geochemical characteristics indicate both inheritance of volatile-depleted materials that formed the Moon and planets and subsequent evaporative loss of volatile elements that occurred during lunar formation and differentiation. Models of volatile loss through localized eruptive degassing are not consistent with the available S, Cl, Zn and K isotopes and abundance data for the Moon. The most probable cause of volatile depletion is global-scale evaporation resulting from a giant impact or a magma ocean phase where inefficient volatile loss during magmatic convection led to the present distribution of volatile elements within mantle and crustal reservoirs. Problems exist for models of planetary volatile depletion following giant impact. Most critically, in this model, the volatile loss requires preferential delivery and retention of late-accreted volatiles to the Earth compared with the Moon. Different proportions of late-accreted mass are computed to explain present-day distributions of volatile and moderately volatile elements (e.g. Pb, Zn; 5 to >10%) relative to highly siderophile elements (approx. 0.5%) for the Earth. Models of early magma ocean phases may be more effective in explaining the volatile loss. Basaltic materials (e.g. eucrites and angrites) from highly differentiated airless asteroids are volatile-depleted, like the Moon, whereas the Earth and Mars have proportionally greater volatile contents. Parent-body size and the existence of early atmospheres are therefore likely to represent fundamental controls on planetary volatile retention or loss.
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Affiliation(s)
- James M D Day
- Scripps Isotope Geochemistry Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0244, USA
| | - Frederic Moynier
- Institut de Physique du Globe de Paris, Université Paris Diderot, Sorbonne Paris Cité, 1 rue Jussieu, 75005 Paris, France
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22
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Avice G, Marty B. The iodine-plutonium-xenon age of the Moon-Earth system revisited. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2014; 372:20130260. [PMID: 25114317 PMCID: PMC4128273 DOI: 10.1098/rsta.2013.0260] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Iodine-plutonium-xenon isotope systematics have been used to re-evaluate time constraints on the early evolution of the Earth-atmosphere system and, by inference, on the Moon-forming event. Two extinct radionuclides ((129)I, T1/2=15.6 Ma and (244)Pu, T1/2=80 Ma) have produced radiogenic (129)Xe and fissiogenic (131-136)Xe, respectively, within the Earth, the related isotope fingerprints of which are seen in the compositions of mantle and atmospheric Xe. Recent studies of Archaean rocks suggest that xenon atoms have been lost from the Earth's atmosphere and isotopically fractionated during long periods of geological time, until at least the end of the Archaean eon. Here, we build a model that takes into account these results. Correction for Xe loss permits the computation of new closure ages for the Earth's atmosphere that are in agreement with those computed for mantle Xe. The corrected Xe formation interval for the Earth-atmosphere system is [Formula: see text] Ma after the beginning of Solar System formation. This time interval may represent a lower limit for the age of the Moon-forming impact.
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Affiliation(s)
- G Avice
- CRPG-CNRS, Université de Lorraine, 15 rue Notre-Dame des Pauvres, BP 20, 54501 Vandoeuvre-lès-Nancy Cedex, France
| | - B Marty
- CRPG-CNRS, Université de Lorraine, 15 rue Notre-Dame des Pauvres, BP 20, 54501 Vandoeuvre-lès-Nancy Cedex, France
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23
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Erkaev N, Lammer H, Elkins-Tanton L, Stökl A, Odert P, Marcq E, Dorfi E, Kislyakova K, Kulikov Y, Leitzinger M, Güdel M. Escape of the martian protoatmosphere and initial water inventory. PLANETARY AND SPACE SCIENCE 2014; 98:106-119. [PMID: 25843981 PMCID: PMC4375622 DOI: 10.1016/j.pss.2013.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 07/20/2013] [Accepted: 09/06/2013] [Indexed: 05/15/2023]
Abstract
Latest research in planet formation indicates that Mars formed within a few million years (Myr) and remained as a planetary embryo that never grew to a more massive planet. It can also be expected from dynamical models that most of Mars' building blocks consisted of material that formed in orbital locations just beyond the ice line which could have contained [Formula: see text] of H2O. By using these constraints, we estimate the nebula-captured and catastrophically outgassed volatile contents during the solidification of Mars' magma ocean and apply a hydrodynamic upper atmosphere model for the study of the soft X-ray and extreme ultraviolet (XUV) driven thermal escape of the martian protoatmosphere during the early active epoch of the young Sun. The amount of gas that has been captured from the protoplanetary disk into the planetary atmosphere is calculated by solving the hydrostatic structure equations in the protoplanetary nebula. Depending on nebular properties such as the dust grain depletion factor, planetesimal accretion rates and luminosities, hydrogen envelopes with masses [Formula: see text] to [Formula: see text] could have been captured from the nebula around early Mars. Depending on the before mentioned parameters, due to the planets low gravity and a solar XUV flux that was [Formula: see text] times stronger compared to the present value, our results indicate that early Mars would have lost its nebular captured hydrogen envelope after the nebula gas evaporated, during a fast period of [Formula: see text]. After the solidification of early Mars' magma ocean, catastrophically outgassed volatiles with the amount of [Formula: see text] H2O and [Formula: see text] CO2 could have been lost during [Formula: see text], if the impact related energy flux of large planetesimals and small embryos to the planet's surface lasted long enough, that the steam atmosphere could have been prevented from condensing. If this was not the case, then our results suggest that the timescales for H2O condensation and ocean formation may have been shorter compared to the atmosphere evaporation timescale, so that one can speculate that sporadically periods, where some amount of liquid water may have been present on the planet's surface. However, depending on the amount of the outgassed volatiles, because of impacts and the high XUV-driven atmospheric escape rates, such sporadically wet surface conditions may have also not lasted much longer than [Formula: see text]. After the loss of the captured hydrogen envelope and outgassed volatiles during the first 100 Myr period of the young Sun, a warmer and probably wetter period may have evolved by a combination of volcanic outgassing and impact delivered volatiles [Formula: see text] ago, when the solar XUV flux decreased to values that have been [Formula: see text] times that of today's Sun.
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Affiliation(s)
- N.V. Erkaev
- Institute for Computational Modelling, 660041 Krasnoyarsk 36, Russian Academy of Sciences, Russian Federation
- Siberian Federal University, 660041 Krasnoyarsk, Russian Federation
| | - H. Lammer
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, A-8042 Graz, Austria
- Corresponding author. Tel.: +43 31 6412 0641; fax: +43 31 6412 0690.
| | - L.T. Elkins-Tanton
- Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington DC 20015, USA
| | - A. Stökl
- Institute for Astronomy, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria
| | - P. Odert
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, A-8042 Graz, Austria
- Institute of Physics, IGAM, University of Graz, Universitätsplatz 5, A-8010 Graz, Austria
| | - E. Marcq
- LATMOS, Université de Versailles Saint-Quentin-en-Yvelines, Guyancourt, France
| | - E.A. Dorfi
- Institute for Astronomy, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria
| | - K.G. Kislyakova
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, A-8042 Graz, Austria
| | - Yu.N. Kulikov
- Polar Geophysical Institute, Russian Academy of Sciences, Khalturina 15, 183010 Murmansk, Russian Federation
| | - M. Leitzinger
- Institute of Physics, IGAM, University of Graz, Universitätsplatz 5, A-8010 Graz, Austria
| | - M. Güdel
- Institute for Astronomy, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria
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Saal AE, Hauri EH, Van Orman JA, Rutherford MJ. Hydrogen isotopes in lunar volcanic glasses and melt inclusions reveal a carbonaceous chondrite heritage. Science 2013; 340:1317-20. [PMID: 23661641 DOI: 10.1126/science.1235142] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Water is perhaps the most important molecule in the solar system, and determining its origin and distribution in planetary interiors has important implications for understanding the evolution of planetary bodies. Here we report in situ measurements of the isotopic composition of hydrogen dissolved in primitive volcanic glass and olivine-hosted melt inclusions recovered from the Moon by the Apollo 15 and 17 missions. After consideration of cosmic-ray spallation and degassing processes, our results demonstrate that lunar magmatic water has an isotopic composition that is indistinguishable from that of the bulk water in carbonaceous chondrites and similar to that of terrestrial water, implying a common origin for the water contained in the interiors of Earth and the Moon.
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Affiliation(s)
- Alberto E Saal
- Department of Geological Sciences, Brown University, Providence, RI 02912, USA.
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Abstract
Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth's atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth's subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials. One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fell out in a kind of condensation sequence. This ensures that the volatiles were concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost without exception strongly reducing and volatile-rich. A consequence is that, although CO- or methane-rich atmospheres are not necessarily stable as steady states, they are quite likely to have existed as long-lived transients, many times. With CO comes abundant chemical energy in a metastable package, and with methane comes hydrogen cyanide and ammonia as important albeit less abundant gases.
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Affiliation(s)
- Kevin Zahnle
- Space Science Division, NASA Ames Research Center, MS 245-3, Moffett Field, California 94035, USA.
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Holland G, Cassidy M, Ballentine CJ. Meteorite Kr in Earth’s Mantle Suggests a Late Accretionary Source for the Atmosphere. Science 2009; 326:1522-5. [DOI: 10.1126/science.1179518] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Greg Holland
- School of Earth, Atmospheric, and Environmental Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Martin Cassidy
- Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77204–5007, USA
| | - Chris J. Ballentine
- School of Earth, Atmospheric, and Environmental Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
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Abstract
AbstractTerrestrial planets form in a series of dynamical steps from the solid component of circumstellar disks. First, km-sized planetesimals form likely via a combination of sticky collisions, turbulent concentration of solids, and gravitational collapse from micron-sized dust grains in the thin disk midplane. Second, planetesimals coalesce to form Moon- to Mars-sized protoplanets, also called “planetary embryos”. Finally, full-sized terrestrial planets accrete from protoplanets and planetesimals. This final stage of accretion lasts about 10-100 Myr and is strongly affected by gravitational perturbations from any gas giant planets, which are constrained to form more quickly, during the 1-10 Myr lifetime of the gaseous component of the disk. It is during this final stage that the bulk compositions and volatile (e.g., water) contents of terrestrial planets are set, depending on their feeding zones and the amount of radial mixing that occurs. The main factors that influence terrestrial planet formation are the mass and surface density profile of the disk, and the perturbations from giant planets and binary companions if they exist. Simple accretion models predicts that low-mass stars should form small, dry planets in their habitable zones. The migration of a giant planet through a disk of rocky bodies does not completely impede terrestrial planet growth. Rather, “hot Jupiter” systems are likely to also contain exterior, very water-rich Earth-like planets, and also “hot Earths”, very close-in rocky planets. Roughly one third of the known systems of extra-solar (giant) planets could allow a terrestrial planet to form in the habitable zone.
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Hashimoto GL, Abe Y, Sugita S. The chemical composition of the early terrestrial atmosphere: Formation of a reducing atmosphere from CI-like material. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006je002844] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Raymond SN, Quinn T, Lunine JI. High-resolution simulations of the final assembly of Earth-like planets. 2. Water delivery and planetary habitability. ASTROBIOLOGY 2007; 7:66-84. [PMID: 17407404 DOI: 10.1089/ast.2006.06-0126] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The water content and habitability of terrestrial planets are determined during their final assembly, from perhaps 100 1,000-km "planetary embryos " and a swarm of billions of 1-10-km "planetesimals. " During this process, we assume that water-rich material is accreted by terrestrial planets via impacts of water-rich bodies that originate in the outer asteroid region. We present analysis of water delivery and planetary habitability in five high-resolution simulations containing about 10 times more particles than in previous simulations. These simulations formed 15 terrestrial planets from 0.4 to 2.6 Earth masses, including five planets in the habitable zone. Every planet from each simulation accreted at least the Earth's current water budget; most accreted several times that amount (assuming no impact depletion). Each planet accreted at least five water-rich embryos and planetesimals from the past 2.5 astronomical units; most accreted 10-20 water-rich bodies. We present a new model for water delivery to terrestrial planets in dynamically calm systems, with low-eccentricity or low-mass giant planets-such systems may be very common in the Galaxy. We suggest that water is accreted in comparable amounts from a few planetary embryos in a " hit or miss " way and from millions of planetesimals in a statistically robust process. Variations in water content are likely to be caused by fluctuations in the number of water-rich embryos accreted, as well as from systematic effects, such as planetary mass and location, and giant planet properties.
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Affiliation(s)
- Sean N Raymond
- NASA Postdoctoral Program Fellow, Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, Colorado 80309-0389, USA.
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Scalo J, Kaltenegger L, Segura A, Segura AG, Fridlund M, Ribas I, Kulikov YN, Grenfell JL, Rauer H, Odert P, Leitzinger M, Selsis F, Khodachenko ML, Eiroa C, Kasting J, Lammer H. M stars as targets for terrestrial exoplanet searches and biosignature detection. ASTROBIOLOGY 2007; 7:85-166. [PMID: 17407405 DOI: 10.1089/ast.2006.0125] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The changing view of planets orbiting low mass stars, M stars, as potentially hospitable worlds for life and its remote detection was motivated by several factors, including the demonstration of viable atmospheres and oceans on tidally locked planets, normal incidence of dust disks, including debris disks, detection of planets with masses in the 5-20 M() range, and predictions of unusually strong spectral biosignatures. We present a critical discussion of M star properties that are relevant for the long- and short-term thermal, dynamical, geological, and environmental stability of conventional liquid water habitable zone (HZ) M star planets, and the advantages and disadvantages of M stars as targets in searches for terrestrial HZ planets using various detection techniques. Biological viability seems supported by unmatched very long-term stability conferred by tidal locking, small HZ size, an apparent short-fall of gas giant planet perturbers, immunity to large astrosphere compressions, and several other factors, assuming incidence and evolutionary rate of life benefit from lack of variability. Tectonic regulation of climate and dynamo generation of a protective magnetic field, especially for a planet in synchronous rotation, are important unresolved questions that must await improved geodynamic models, though they both probably impose constraints on the planet mass. M star HZ terrestrial planets must survive a number of early trials in order to enjoy their many Gyr of stability. Their formation may be jeopardized by an insufficient initial disk supply of solids, resulting in the formation of objects too small and/or dry for habitability. The small empirical gas giant fraction for M stars reduces the risk of formation suppression or orbit disruption from either migrating or nonmigrating giant planets, but effects of perturbations from lower mass planets in these systems are uncertain. During the first approximately 1 Gyr, atmospheric retention is at peril because of intense and frequent stellar flares and sporadic energetic particle events, and impact erosion, both enhanced, the former dramatically, for M star HZ semimajor axes. Loss of atmosphere by interactions with energetic particles is likely unless the planetary magnetic moment is sufficiently large. For the smallest stellar masses a period of high planetary surface temperature, while the parent star approaches the main sequence, must be endured. The formation and retention of a thick atmosphere and a strong magnetic field as buffers for a sufficiently massive planet emerge as prerequisites for an M star planet to enter a long period of stability with its habitability intact. However, the star will then be subjected to short-term fluctuations with consequences including frequent unpredictable variation in atmospheric chemistry and surficial radiation field. After a review of evidence concerning disks and planets associated with M stars, we evaluate M stars as targets for future HZ planet search programs. Strong advantages of M stars for most approaches to HZ detection are offset by their faintness, leading to severe constraints due to accessible sample size, stellar crowding (transits), or angular size of the HZ (direct imaging). Gravitational lensing is unlikely to detect HZ M star planets because the HZ size decreases with mass faster than the Einstein ring size to which the method is sensitive. M star Earth-twin planets are predicted to exhibit surprisingly strong bands of nitrous oxide, methyl chloride, and methane, and work on signatures for other climate categories is summarized. The rest of the paper is devoted to an examination of evidence and implications of the unusual radiation and particle environments for atmospheric chemistry and surface radiation doses, and is summarized in the Synopsis. We conclude that attempts at remote sensing of biosignatures and nonbiological markers from M star planets are important, not as tests of any quantitative theories or rational arguments, but instead because they offer an inspection of the residues from a Gyr-long biochemistry experiment in the presence of extreme environmental fluctuations. A detection or repeated nondetections could provide a unique opportunity to partially answer a fundamental and recurrent question about the relation between stability and complexity, one that is not addressed by remote detection from a planet orbiting a solar-like star, and can only be studied on Earth using restricted microbial systems in serial evolution experiments or in artificial life simulations. This proposal requires a planet that has retained its atmosphere and a water supply. The discussion given here suggests that observations of M star exoplanets can decide this latter question with only slight modifications to plans already in place for direct imaging terrestrial exoplanet missions.
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Affiliation(s)
- John Scalo
- Department of Astronomy, University of Texas at Austin, Austin, Texas 78712, USA.
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Billings L, Cameron V, Claire M, Dick GJ, Domagal-Goldman SD, Javaux EJ, Johnson OJ, Laws C, Race MS, Rask J, Rummel JD, Schelble RT, Vance S. The astrobiology primer: an outline of general knowledge--version 1, 2006. ASTROBIOLOGY 2006; 6:735-813. [PMID: 17067259 DOI: 10.1089/ast.2006.6.735] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The Astrobiology Primer has been created as a reference tool for those who are interested in the interdisciplinary field of astrobiology. The field incorporates many diverse research endeavors, but it is our hope that this slim volume will present the reader with all he or she needs to know to become involved and to understand, at least at a fundamental level, the state of the art. Each section includes a brief overview of a topic and a short list of readable and important literature for those interested in deeper knowledge. Because of the great diversity of material, each section was written by a different author with a different expertise. Contributors, authors, and editors are listed at the beginning, along with a list of those chapters and sections for which they were responsible. We are deeply indebted to the NASA Astrobiology Institute (NAI), in particular to Estelle Dodson, David Morrison, Ed Goolish, Krisstina Wilmoth, and Rose Grymes for their continued enthusiasm and support. The Primer came about in large part because of NAI support for graduate student research, collaboration, and inclusion as well as direct funding. We have entitled the Primer version 1 in hope that it will be only the first in a series, whose future volumes will be produced every 3-5 years. This way we can insure that the Primer keeps up with the current state of research. We hope that it will be a great resource for anyone trying to stay abreast of an ever-changing field.
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