Early Solar Nebula Grains – Interplanetary Dust Particles

Bradley, J. P.

doi:10.1016/b978-0-08-095975-7.00114-5

Cited by 35 publications

(43 citation statements)

References 111 publications

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“…, , ); the silicate features in infrared spectra obtained from CP IDPs in the laboratory are similar to those observed in the astronomical spectra of comets (Sandford and Walker ; Bradley et al. ; Molster and Waters ); and their unequilibrated, anhydrous mineralogies, combined with the high content of presolar grain and carbonaceous material, suggest they have not been subjected to significant processing on the parent body, which is consistent with our understanding of cometary evolution (Bradley , ). In contrast, the chondritic smooth (CS) IDPs are low‐porosity particles composed primarily of hydrated layer silicates, with lesser anhydrous crystalline and amorphous silicates; sulfides (predominantly Ni‐rich); and in some cases, carbonates (see Bradley , for reviews).…”

Section: Introductionsupporting

confidence: 81%

“…; Molster and Waters ); and their unequilibrated, anhydrous mineralogies, combined with the high content of presolar grain and carbonaceous material, suggest they have not been subjected to significant processing on the parent body, which is consistent with our understanding of cometary evolution (Bradley , ). In contrast, the chondritic smooth (CS) IDPs are low‐porosity particles composed primarily of hydrated layer silicates, with lesser anhydrous crystalline and amorphous silicates; sulfides (predominantly Ni‐rich); and in some cases, carbonates (see Bradley , for reviews). These CS IDPs share several mineralogical and petrographic similarities with fine‐grained matrices of some carbonaceous meteorites and they are generally believed to originate from asteroids.…”

Section: Introductionsupporting

confidence: 63%

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The survivability of phyllosilicates and carbonates impacting Stardust Al foils: Facilitating the search for cometary water

Wozniakiewicz

Ishii

Kearsley

et al. 2015

Meteorit & Planetary Scien

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Abstract-Comet 81P/Wild 2 samples returned by NASA's Stardust mission provide an unequalled opportunity to study the contents of, and hence conditions and processes operating on, comets. They can potentially validate contentious interpretations of cometary infrared spectra and in situ mass spectrometry data: specifically the identification of phyllosilicates and carbonates. However, Wild 2 dust was collected via impact into capture media at~6 km s À1 , leading to uncertainty as to whether these minerals were captured intact, and, if subjected to alteration, whether they remain recognizable. We simulated Stardust Al foil capture conditions using a two-stage light-gas gun, and directly compared transmission electron microscope analyses of pre-and postimpact samples to investigate survivability of lizardite and cronstedtite (phyllosilicates) and calcite (carbonate). We find the phyllosilicates do not survive impact as intact crystalline materials but as moderately to highly vesiculated amorphous residues lining resultant impact craters, whose bulk cation to Si ratios remain close to that of the impacting grain. Closer inspection reveals variation in these elements on a submicron scale, where impact-induced melting accompanied by reducing conditions (due to the production of oxygen scavenging molten Al from the target foils) has resulted in the production of native silicon and Fe-and Fe-Si-rich phases. In contrast, large areas of crystalline calcite are preserved within the calcite residue, with smaller regions of vesiculated, Al-bearing calcic glass. Unambiguous identification of calcite impactors on Stardust Al foil is therefore possible, while phyllosilicate impactors may be inferred from vesiculated residues with appropriate bulk cation to Si ratios. Finally, we demonstrate that the characteristic textures and elemental distributions identifying phyllosilicates and carbonates by transmission electron microscopy can also be observed by state-of-the-art scanning electron microscopy providing rapid, nondestructive initial mineral identifications in Stardust residues.

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Section: Introductionsupporting

confidence: 81%

Section: Introductionsupporting

confidence: 63%

The survivability of phyllosilicates and carbonates impacting Stardust Al foils: Facilitating the search for cometary water

Wozniakiewicz

Ishii

Kearsley

et al. 2015

Meteorit & Planetary Scien

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“…This restricts their formation to a window between roughly 2 Ma and 4 Ma after Solar System (CAI) formation, the upper limit being when there was just enough short-lived radioactivity to melt ice and enable some aqueous alteration. Unlithified bodies that formed after approximately 4 Ma could be one of the sources, along with comets, of the IDPs that are being continuously accreted by the Earth [71]. More detailed estimates of accretion times can be made using thermal models and estimates of the maximum temperatures experienced by any member of a chondrite group (figure 3).…”

Section: Meteorites In Briefmentioning

confidence: 99%

The origin of inner Solar System water

Alexander¹

2017

Phil. Trans. R. Soc. A.

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Of the potential volatile sources for the terrestrial planets, the CI and CM carbonaceous chondrites are closest to the planets' bulk H and N isotopic compositions. For the Earth, the addition of approximately 2–4 wt% of CI/CM material to a volatile-depleted proto-Earth can explain the abundances of many of the most volatile elements, although some solar-like material is also required. Two dynamical models of terrestrial planet formation predict that the carbonaceous chondrites formed either in the asteroid belt (‘classical’ model) or in the outer Solar System (5–15 AU in the Grand Tack model). To test these models, at present the H isotopes of water are the most promising indicators of formation location because they should have become increasingly D-rich with distance from the Sun. The estimated initial H isotopic compositions of water accreted by the CI, CM, CR and Tagish Lake carbonaceous chondrites were much more D-poor than measured outer Solar System objects. A similar pattern is seen for N isotopes. The D-poor compositions reflect incomplete re-equilibration with H 2 in the inner Solar System, which is also consistent with the O isotopes of chondritic water. On balance, it seems that the carbonaceous chondrites and their water did not form very far out in the disc, almost certainly not beyond the orbit of Saturn when its moons formed (approx. 3–7 AU in the Grand Tack model) and possibly close to where they are found today. This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.

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“…Typical CP IDPs, on the other hand, are from small frozen (cometary) parent bodies, and they can remain cold (≤10°C) during their 10 4 -to 10 5 -y exposures to the SW while in solar orbit. They are pulse-heated for several seconds during entry, but the survival of SF tracks, near-saturation levels of implanted solar noble gases (He, Ne, and Ar), and volatile organic compounds show that low-density, highly porous CP IDPs can enter the atmosphere with minimal heating (11,(28)(29)(30) (Fig. 1B).…”

Section: Discussionmentioning

confidence: 99%

“…We examine rims on surface grains in IDPs because they are solely due to SW irradiation, whereas rims on lunar soil grains are due to SW irradiation, impact vapor deposition, or a combination of both (9), and remote observations suggest that if water is indeed produced in rims on lunar soil grains, it is not efficiently retained (10). Typical 5-to 25-μm diameter chondritic porous (CP) IDPs are low-density aggregates of predominantly submicrometer-sized grains, and they are collected in the stratosphere (11) (Fig. 1 A-D and Origins of CP IDPs).…”

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confidence: 99%

Detection of solar wind-produced water in irradiated rims on silicate minerals

Bradley

Ishii

Gillis-Davis

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The solar wind (SW), composed of predominantly ∼1-keV H + ions, produces amorphous rims up to ∼150 nm thick on the surfaces of minerals exposed in space. Silicates with amorphous rims are observed on interplanetary dust particles and on lunar and asteroid soil regolith grains. Implanted H + may react with oxygen in the minerals to form trace amounts of hydroxyl (−OH) and/or water (H 2 O). Previous studies have detected hydroxyl in lunar soils, but its chemical state, physical location in the soils, and source(s) are debated. If −OH or H 2 O is generated in rims on silicate grains, there are important implications for the origins of water in the solar system and other astrophysical environments. By exploiting the high spatial resolution of transmission electron microscopy and valence electron energy-loss spectroscopy, we detect water sealed in vesicles within amorphous rims produced by SW irradiation of silicate mineral grains on the exterior surfaces of interplanetary dust particles. Our findings establish that water is a byproduct of SW space weathering. We conclude, on the basis of the pervasiveness of the SW and silicate materials, that the production of radiolytic SW water on airless bodies is a ubiquitous process throughout the solar system. solar wind radiolysis | prebiotic water | cosmic dust | astrobiology | aberration-corrected scanning transmission electron microscopy T here are two principal space weathering processes, solar wind (SW) ion irradiation and micrometeorite impacts, that produce rims on exposed mineral surfaces (1). Our focus here is on SW irradiation because of its possible connection to the production of water and hydroxyl radicals (2-5). Space-weathered rim thicknesses vary with the densities of implanted solar flare (SF) tracks, and track densities depend on the exposure ages of individual interplanetary dust particles (IDPs) in space. On lunar soil grains and grains on surfaces of IDPs, rims are typically 75-150 nm thick with SF track densities of 10 10 -10 11 cm −2 that are consistent with 10 4 -to 10 5 -y SW exposure ages (6, 7) ( Fig. 1 B-D). Rims on asteroid Itokawa regolith grains are 30-60 nm thick with SF track densities of 5 × 10 9 cm −2 that are consistent with ∼10 3 -y exposure ages (8) (Origins and Properties of Rims on IDPs, Asteroid Itokawa, and Lunar Soil Grains). This correlation between amorphous rim thicknesses and SF track densities indicates that SW irradiation is the primary mechanism for amorphous rim formation. We examine rims on surface grains in IDPs because they are solely due to SW irradiation, whereas rims on lunar soil grains are due to SW irradiation, impact vapor deposition, or a combination of both (9), and remote observations suggest that if water is indeed produced in rims on lunar soil grains, it is not efficiently retained (10). Typical 5-to 25-μm diameter chondritic porous (CP) IDPs are low-density aggregates of predominantly submicrometer-sized grains, and they are collected in the stratosphere (11) (Fig. 1 A-D and Origins of CP IDPs). Chemical ana...

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Early Solar Nebula Grains – Interplanetary Dust Particles

Cited by 35 publications

References 111 publications

The survivability of phyllosilicates and carbonates impacting Stardust Al foils: Facilitating the search for cometary water

The survivability of phyllosilicates and carbonates impacting Stardust Al foils: Facilitating the search for cometary water

The origin of inner Solar System water

Detection of solar wind-produced water in irradiated rims on silicate minerals

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