Spectral reflectance properties of carbonaceous chondrites: 7. CK chondrites

Cloutis, E. A.; Hudon, Pierre; Hiroi, T.; Gaffey, M. J.

doi:10.1016/j.icarus.2012.09.017

Cited by 33 publications

(38 citation statements)

References 48 publications

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“…Carbonaceous chondrite meteorites can be linked to various asteroids surfaces based on spectral reflectance parameters such as visible albedo, VNIR spectral slopes, and silicate VNIR absorption band depths (e.g., DeMeo et al, , ). It has long been known that these parameters vary with grain size for powdered samples (e.g., Cloutis, Hiroi, et al, ; Cloutis, Hudon, et al, ; Cloutis, et al , ; Cloutis, Hudon, Hiroi, Gaffey, & Mann, ; Cloutis, Hudon, Hiroi, Gaffey, Mann, & Bell, ; Cloutis, Hudon, Hiroi, & Gaffey, ; T. V. Johnson & Fanale, ). Disc resolved imagery of asteroids, such as Itokawa, shows that their surfaces vary from boulder fields to powdered regoliths with grain sizes below the resolution of imaging systems and likely include materials lying along such a continuum, including shallow powder coatings on solid slab surfaces (e.g., Saito et al, ).…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…Spectra of the 500-to 2,000-μm size fraction were more blue sloped than those of the 0-to 2,000-μm size fraction, and reflectance in the visible region was generally similar. Other CVs and CKs (Cloutis, Hudon, Hiroi, & Gaffey, 2012c), ungrouped CC Kaidun (Cloutis, Hudon, Hiroi, Gaffey, & Mann, 2012b), and CC-bearing howardite PRA 04401 (Cloutis, Hudon, Hiroi, Gaffey, & Mann, 2012b), for which multiple grain size powder spectra were available, all show a brightening and reddening of spectral slope with decreasing grain size.…”

Section: Carbonaceous Chondrite Meteoritesmentioning

confidence: 99%

“…This is due, in part, to the fact that (1) spectral reflectance measurements across the ~400‐ to 2,500‐nm region are achievable from Earth‐based telescopes (and spacecraft‐based detectors); (2) a number of minerals that are indicative of petrogenesis have absorption features in this wavelength region (e.g., Clark et al, ); and (3) solar flux is high in this wavelength region. The ability of reflectance spectroscopy to provide mineralogically diagnostic information has been demonstrated for multiple CC groups (e.g., Cloutis, Hiroi, et al, ; Cloutis, Hudon, et al, ; Cloutis et al, ; Cloutis et al, ; Cloutis, Hudon, Hiroi, Gaffey, & Mann, ; Cloutis, Hudon, Hiroi, Gaffey, Mann, & Bell, ; Cloutis, Hudon, Hiroi, & Gaffey, ; Vernazza et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Spectral Reflectance of Powder Coatings on Carbonaceous Chondrite Slabs: Implications for Asteroid Regolith Observations

et al. 2018

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Carbonaceous chondrite meteorites (CCs) are among the most primitive materials in the solar system and provide important insights into solar system history and evolution. A number of planetary spacecraft missions will visit asteroids that are thought to compositionally resemble these meteorites. To better assist sample acquisition in terms of how the physical properties of CCs affect their reflectance spectra, we investigated the spectral reflectance properties of solid and powdered CCs and powder coatings on slabs of a number of CCs, including CB, CH, CK, CM, CO, CR, and CV classes. We found that decreasing grain size leads to increasing reflectance across the ~500‐ to 2,500‐nm range and steeper spectral slope, regardless of CC type. Powdered CC reflectance spectra are brighter beyond ~500 nm and redder than bare roughened slabs. For powders sprinkled on slabs, as the powder coating gets thicker, spectral slopes get redder. Optically thick fine‐grained powders are brighter beyond ~500 nm and are as red or redder than slabs covered with airfall dust (for dust thicknesses up to a few hundred microns). Diagnostic absorption features of CC minerals, particularly those in the 1,000‐nm region attributable to Fe‐bearing silicates, are ubiquitous regardless of physical properties. Reflectance spectra of terrestrially weathered (i.e., rusty) CCs are strongly modified below ~700 nm and in the 900‐ and 1,900‐nm regions by these Fe oxyhydroxides. Their effects can be mitigated through chemical treatment, but this may also affect preterrestrial ferric iron‐bearing phases. Some spectral characteristics, such as hydrous and anhydrous silicate absorption bands in CC spectra, are present regardless of physical properties (fine‐grained dust, powders, slabs, and dust on slabs). Other spectral characteristics (such as albedo and spectral slope) vary as a function of physical properties, indicating that reflectance spectroscopy could be used to ascribe spectral variations across an asteroid's surface to either physical or compositional causes. This information can, in turn, be used to inform site selection for asteroid sample return missions, where both composition and physical properties are important drivers. When searching for fine‐grained areas on an asteroid to sample, the best indication would be the brightest‐ and reddest‐sloped spectra.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Carbonaceous Chondrite Meteoritesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spectral Reflectance of Powder Coatings on Carbonaceous Chondrite Slabs: Implications for Asteroid Regolith Observations

et al. 2018

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“…The Eleonora spectrum drops off steeply shortwards of $0.70 lm, while the CK6 spectrum does not roll over until $0.55 lm. Cloutis et al (2012b) explored the spectral systematics of CK chondrites, all of which show this similar short wavelength roll over. While this possibility cannot be ruled out entirely, this spectral mismatch would mitigate against a CK6 interpretation for (354) Eleonora.…”

Section: Questionsmentioning

confidence: 95%

Asteroid (354) Eleonora: Plucking an odd duck

Gaffey

Reddy

Fieber-Beyer

et al. 2015

Icarus

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a b s t r a c t During a survey of the S-type asteroids, Gaffey et al. (Gaffey, M.J., Bell, J.F., Brown, R.H., Burbine, T.H.,Piatek, J., Reed, K.L., Chaky, D.A. [1993]. Icarus 106, 573-602) identified Asteroid (354) Eleonora as anomalous with a 1 lm absorption feature $2.5 times stronger than any S-asteroid of comparable size. Subsequent investigation revealed significant differences in the 1 lm absorption feature between the visible & very near-infrared CCD spectra (k < $1.0 lm) and other spectral data sets for this asteroid. There were also significant spectral differences among the several CCD survey spectra (SMASS-I, SMASS-II & S 3 OS 2 ) of Eleonora. These differences could potentially arise from spectral variations across the asteroid surface, from observational phase angle differences, from surface temperature differences, from viewing geometry for a nonspherical body, or from the use of standard stars with deviated to different degrees from a true solar standard.In June 2011 Asteroid (354) Eleonora was observed over two nights using the NASA Infrared Telescope Facility (IRTF) at Mauna Kea Observatory in order to test these possible scenarios and to better understand the nature and history of Eleonora and its relationships to other asteroids and to the meteorites. Analysis of this data set has eliminated the following options as the cause of the differences in the 1 lm absorption feature within the CCD data sets and between the CCD data sets and the other spectral data: (1) rotational spectral variations; (2) variation in surface composition with latitude; (3) observation phase; (4) surface temperature variations with differing heliocentric distance in the asteroid's elliptical orbit; (5) spectral effects of viewing geometry for a nonspherical body; and (6) differences in spectral standard stars. We conclude that none of the CCD spectra of (354) Eleonora are reliable, and that within the limits of their spectral coverage, analyses of the three CCD spectra would produce significantly different -and generally unreliable -indications of surface mineralogy. An effort needs to be made to determine whether ''bad'' CCD spectra are rare with the case of (354) Eleonora being an uncommon occurrence or whether there is a broader problem with the CCD asteroid survey data sets, and if so, how to identify the ''bad'' spectra.While CCD survey spectra show apparently irreconcilable differences, the near-infrared spectra of (354) Eleonora from various observers show only minor differences, primarily in the overall spectral slope, most of which can be attributed to slight differences in the standard stars used to calibrate the data.In June 2011, 226 near-infrared ($0.76-2.5 lm) spectra of (354) Eleonora were obtained using the SpeX instrument on the NASA Infrared Telescope Facility at Mauna Kea Observatory. These spectra were consistent with the six sets of NIR spectra obtained for Eleonora by previous observers. The primary variation observed in this new data set was an approximately 10% variation in spectral slope between...

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Water Reservoirs in Small Planetary Bodies: Meteorites, Asteroids, and Comets

Alexander¹,

McKeegan²,

Altwegg³

2018

Space Sciences Series of ISSI

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Asteroids and comets are the remnants of the swarm of planetesimals from which the planets ultimately formed, and they retain records of processes that operated prior to and during planet formation. They are also likely the sources of most of the water and other volatiles accreted by Earth. In this review, we discuss the nature and probable origins of asteroids and comets based on data from remote observations, in situ measurements by spacecraft, and laboratory analyses of meteorites derived from asteroids. The asteroidal parent bodies of meteorites formed ≤4 Ma after Solar System formation while there was still a gas disk present. It seems increasingly likely that the parent bodies of meteorites spectroscopically linked with the E-, S-, M-and V-type asteroids formed sunward of Jupiter's orbit, while those associated with C-and, possibly, D-type asteroids formed further out, beyond Jupiter but probably not beyond Saturn's orbit. Comets formed further from the Sun than any of the meteorite parent bodies, and retain much higher abundances of interstellar material. CI and CM group meteorites are probably related to the most common C-type asteroids, and based on isotopic evidence they, rather than comets, are the most likely sources of the H and N accreted by the terrestrial planets. However, comets may have been major sources of the noble gases accreted by Earth and Venus. Possible constraints that these observations can place on models of giant planet formation and migration are explored.

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Spectral reflectance properties of carbonaceous chondrites: 7. CK chondrites

Cited by 33 publications

References 48 publications

Spectral Reflectance of Powder Coatings on Carbonaceous Chondrite Slabs: Implications for Asteroid Regolith Observations

Spectral Reflectance of Powder Coatings on Carbonaceous Chondrite Slabs: Implications for Asteroid Regolith Observations

Asteroid (354) Eleonora: Plucking an odd duck

Water Reservoirs in Small Planetary Bodies: Meteorites, Asteroids, and Comets

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