Interplanetary dust particles composition

Fig. 7. A 10-)J.m interplanetary dust particle that is not porous and contains hydrated siUcates. The particle s elemental composition is a good match to solar...

These resnlts snggest that the interplanetary dust particles are among the most primitive samples available for laboratory stndies. Isotopically anomalous material constitutes only a small fraction of the investigated particles. Thus, it appears that the isotopic composition of these anomalons particles is not different from those observed in minor components of primitive meteorites. 

Cosmochemistry is the study of the chemical composition of the universe and the processes that produced those compositions. This is a tall order, to be sure. Understandably, cosmochemistry focuses primarily on the objects in our own solar system, because that is where we have direct access to the most chemical information. That part of cosmochemistry encompasses the compositions of the Sun, its retinue of planets and their satellites, the almost innumerable asteroids and comets, and the smaller samples (meteorites, interplanetary dust particles or IDPs, returned lunar samples) derived from them. From their chemistry, determined by laboratory measurements of samples or by various remote-sensing techniques, cosmochemists try to unravel the processes that formed or affected them and to fix the chronology of these events. Meteorites offer a unique window on the solar nebula - the disk-shaped cocoon of gas and dust that enveloped the early Sun some 4.57 billion years ago, and from which planetesimals and planets accreted (Fig. 1.1). 

Many of the micron-sized interplanetary dust particles (IDPs) have approximately chondritic bulk composition (see Chapter 1.26 for details). Porous IDPs match the Cl composition better than nonporous (smooth) IDPs. On an average, IDPs show some enhancement of moderately volatile and volatile elements (see Palme, 2000). Arndt et al. (1996) found similar enrichments in their suite of 44 chondritic particles (average size 17.2 1.2 p.m). The elements chlorine, copper, zinc, gallium, selenium, and rubidium were enriched by factors of 2.2-2.7. In addition, these... 

Figure 13 A 5 jjim interplanetary dust particle. This is a carbon-rich particle with chondritic elemental composition. It is porous and entirely composed of anhydrous phases. This 10 ° g particle is an aggregate of >10 umelated and unequilibrated grains. The smooth grains are t5fpically single mineral grains such as Fo, En, or pyrrhotite or carbonaceous material, and the <0.5 p,m lumpy grains are usually GEMSs. This is a relatively t5fpical example of the particles that have entry speeds consistent with cometary origin.

Esat T. M., Brownlee D. E., Papanastassiou D. A., and Wasserburg G. J. (1979) Magnesium isotopic composition of interplanetary dust particles. Science 206, 190-197. 

Flynn G. J. (1994a) Changes in the composition and mineralogy of interplanetary dust particles be terrestrial encounters. In Analysis of Interplanetary Dust, AIP Conf. Proc. 310 (eds. M. E. Zolensky, T. L. Wilson, E. J. M. Rietmeiier, and G. J. Flynn). Am. Inst. Phys., New York, pp. 127-143. 

The bulk SoS isotopic composition shows a high level of homogeneity. This is why it is mostly based on the terrestrial data. For H and the noble gases, as well as for Sr, Nd, Hf, Os, and Pb, some adjustments are required [30]. There are exceptions, however, to this high bulk isotopic homogeneity. One is due to the decay of relatively short-lived radionuclides that existed in the early SoS, and decayed in early formed solids in the solar nebula. Also interplanetary dust particles contain isotopic signatures apparently caused by chemical processes. Additional isotopic anomalies are observed in some meteoritic inclusions or grains (see Sect. 6.3). 

Below we will see that meteorites, smaller rocks from asteroidal objects delivered to Earth, provide important information for solar system abundances of non-volatile elements. Other sources to refine solar system abundances are analysis of other solar system objects such as the gas-giant planets, comets and the interplanetary dust particles from comets. Outside the solar system, the compositions of hot B stars, planetary nebulae, Galactic cosmic rays (GCR), the nearby interstellar medium (ISM) and H II regions have been employed to amend the solar system abundances of some elements. 

Figure 3. High energy region of the (J.XRF spectrum for a 3 pm interplanetary dust particle showing peaks due to trace elements at the 10 ag level. Shown are the raw spectrum, background fit, individual fitted peaks (labeled) and the overall fitted spectrum. The fluorescence spectra for elements with atomic number near 40 are complicated by the overlap between the peak of element Z and the Kp peak of element Z-2. The odd-even abundance effect in the chondritic (solar) composition is apparent. Krypton derives from air in the analysis environment.

Boroughs TJ, Faure G, Buchanan D (1992) Chemical compositions of minerals of the ordinary (H6) chondrite, RKP 86701, from the Reckling Moraine. Antarctic J US 27 (5) 30-31 Bradley JP (2005) Interplanetary dust particles. In Davis AM (ed) Meteorites, comets, and planets. Elsevier, Amsterdam, The Netherlands, pp 698-713... 

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