Depletion of sulfur on the surface of asteroids and the moon

Killen, R. M.

doi:10.1111/j.1945-5100.2003.tb00273.x

Cited by 17 publications

(11 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Sasaki et al (2006) have suggested that the resurfacing process on Itokawa may be caused by seismic destruction due to impacts or tidal stress as a result of planet encounters, and thus the portion of exposed material on the surface may be little altered materials by space weathering. Killen (2003) and Kracher and Sears (2005) have suggested that it is easy to remove the sulfur on the asteroid surface by space weathering in the uppermost layer of 10-100 μm per 10 6 years, and thus the sulfur abundance on the surface may vary between little and highly altered areas. Since our result did not indicate a global depletion of sulfur, in spite of large errors, the abundance of sulfur may be fresh in local areas due to the resurfacing process compared to highly altered materials by space weathering.…”

Section: Discussionmentioning

confidence: 99%

“…Nittler et al (2001) suggested that the reason for low S/Si is impact-induced volatilization and/or photoor ion-induced sputtering at the surface of the asteroid, or the loss of FeS-rich material due to partial melting. Also, a sulfur volatilization process due to space weathering, such as micro-meteorite impacts or/and energetic erosion due to solar wind sputtering, has been proposed by Killen (2003) and Kracher and Sears (2005). Their timescale estimation for sulfur depletion in the uppermost layer of 10-100 μm due to space weathering is the order of 10 6 years, so that sulfur on the surface can easily be taken away from the uppermost layer.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Sulfur abundance of asteroid 25143 Itokawa observed by X-ray fluorescence spectrometer onboard Hayabusa

et al. 2008

View full text Add to dashboard Cite

The Japanese Hayabusa spacecraft successfully carried out in situ observations of S-class asteroid 25143 Itokawa, including the surface major elemental analysis with the X-ray fluorescence spectrometer (XRSHayabusa). Our previous results for the X-ray experiments (Okada et al., 2006a) indicated that major elemental ratios of Mg/Si and Al/Si on the surface of Itokawa resemble ordinary LL-or L-chondrites more than any other meteorite analogues. In the NEAR Shoemaker observations of S-class asteroid 433 Eros, the results of X-ray fluorescence observations indicated the depletion of sulfur, probably reflecting impact-induced volatilization, photoor ion-induced sputtering at the surface, or the loss of FeS-rich materials due to partial melting. Here, we determined the elemental abundance of sulfur (S) on the surface of Itokawa, in addition to that of Mg, Al, and Si, and its regional variation using XRS-Hayabusa observations. In particular, we carefully corrected the fluctuation of solar X-rays, variation of surface geometry, and sensor response function in this analysis, and thus we believe that the results are more accurate than those of our previous report. In this study, the upper and lower limits for Mg/Si, Al/Si, and S/Si overlap those of meteorite analogues for ordinary chondrites or primitive achondrites. In terms of the major elemental composition, Itokawa is best classified as a ordinary chondrite or a primitive achondrite. Our models do not include the mineral mixing effects. With the effects, the abundance of sulfur is expected to be 30% lower than our results. Hence, we conclude that the abundance of sulfur on the surface of Itokawa is almost equal to or even lower than the average abundance in ordinary chondrites. Although the abundances for Mg and Si are globally homogeneous, best-fit or upper limits of mass fraction for Al and S vary in local areas. There is a negative correlation (−0.92) for Al/Si vs. S/Si in ten facets. In particular, the area with the lowest sulfur, accompanied with enriched aluminum, is found in Arcoona, close to a cratered area. Therefore, aluminum enrichment and sulfur depletion features may support events of partial melting on the parent body of Itokawa or aluminum-rich material impacts on the surface of Itokawa. In some areas, Itokawa has a brighter geometric albedo and color variation. Little altered, fresh material may be exposed in these portions of the surface. The sulfur abundance on the surface appears to vary between little and highly altered areas by space weathering. Thus, the sulfur regional variation in our result may reflect the heterogeneity of a surface altered by space weathering.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sulfur abundance of asteroid 25143 Itokawa observed by X-ray fluorescence spectrometer onboard Hayabusa

et al. 2008

View full text Add to dashboard Cite

show abstract

“…The processes hypothesized to destroy sulfides on Eros are much more vigorous on Mercury. Mean micrometeoroid impact velocities are much greater at Mercury (~20 km/s) [ Cintala , ] than at the location of Eros (~9 km/s) [ Killen , ]. The flux of micrometeoroids is also greater at Mercury.…”

Section: Formation Hypothesesmentioning

confidence: 99%

Mercury's hollows: Constraints on formation and composition from analysis of geological setting and spectral reflectance

et al. 2013

View full text Add to dashboard Cite

Landforms unique to Mercury, hollows are shallow, flat‐floored irregular depressions notable for their relatively high reflectance and characteristic color. Here we document the range of geological settings in which hollows occur. Most are associated with impact structures (simple bowl‐shaped craters to multiring basins, and ranging from Kuiperian to Calorian in age). Hollows are found in the low‐reflectance material global color unit and in low‐reflectance blue plains, but they appear to be absent from high‐reflectance red plains. Hollows may occur preferentially on equator‐ or hot‐pole‐facing slopes, implying that their formation is linked to solar heating. Evidence suggests that hollows form because of loss of volatile material. We describe hypotheses for the origin of the volatiles and for how such loss proceeds. Intense space weathering and solar heating are likely contributors to the loss of volatiles; contact heating by melts could promote the formation of hollows in some locations. Lunar Ina‐type depressions differ from hollows on Mercury in a number of characteristics, so it is unclear if they represent a good analog. We also use MESSENGER multispectral images to characterize a variety of surfaces on Mercury, including hollows, within a framework defined by laboratory spectra for analog minerals and lunar samples. Data from MESSENGER's X‐Ray Spectrometer indicate that the planet's surface contains up to 4% sulfur. We conclude that nanophase or microphase sulfide minerals could contribute to the low reflectance of the low‐reflectance material relative to average surface material. Hollows may owe their relatively high reflectance to destruction of the darkening agent (sulfides), the presence of alteration minerals, and/or physical differences in particle size, texture, or scattering behavior.

show abstract

“…This model for impact vaporization is based on the impedance matching method [ Melosh , 1989; Morgan and Killen , 1998; Killen , 2003] and the total influx is an input parameter.…”

Section: Lunar Atmospheric Modelmentioning

confidence: 99%

The effect on the lunar exosphere of a coronal mass ejection passage

2012

Self Cite

View full text Add to dashboard Cite

[1] Solar wind bombardment onto exposed surfaces in the solar system produces an energetic component to the exospheres about those bodies. The solar wind energy and composition are highly dependent on the origin of the plasma. Therefore, using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), we have estimated the total sputter yield for each type of solar wind. We show that the heavy ions, especially the He ++ and O +7 , can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. Folding in the flux with the yield of individual ions, we compute the source rate for several species during different types of solar wind. Finally, we use a Monte Carlo model developed to simulate the time-dependent evolution of the lunar exosphere to study the sputtering component of the exosphere under the influence of a CME passage. We simulate the background exosphere of Na, K, Ca, and Mg. Simulations indicate that sputtering increases the mass of those constituents in the exosphere more than ten times the background values. The escalation of atmospheric density occurs within an hour of onset. The decrease in atmospheric density after the CME passage is also rapid, although takes longer than the increase. Sputtered neutral particles have a high probability of escaping the Moon, by both leaving the Hill Sphere and photoionization. Density and spatial distribution of the exosphere can be tested with the LADEE mission.

show abstract

Depletion of sulfur on the surface of asteroids and the moon

Cited by 17 publications

References 24 publications

Sulfur abundance of asteroid 25143 Itokawa observed by X-ray fluorescence spectrometer onboard Hayabusa

Sulfur abundance of asteroid 25143 Itokawa observed by X-ray fluorescence spectrometer onboard Hayabusa

Mercury's hollows: Constraints on formation and composition from analysis of geological setting and spectral reflectance

The effect on the lunar exosphere of a coronal mass ejection passage

Contact Info

Product

Resources

About