Solar-system bodies

Meteorites on Mars. Meridiani Planum is the first Iron meteorite discovered on the surface of another planet, at the landing site of the Mars Exploration rover Opportunity [359]. Its maximum dimension is 30 cm (Fig. 8.38). Meteorites on the surface of solar system bodies can provide natural experiments for monitoring weathering processes. On Mars, aqueous alteration processes and physical alteration by Aeolian abrasion, for example, may have shaped the surface of the meteorite, which therefore has been investigated intensively by the MER instruments. Observations at mid-infrared wavelengths with the Mini-TES... 

Khare B. N. et al. (2001). Solid Organic Matter in the Atmosphere and on the Surface of Outer Solar System Bodies. Adv. Space Res. 27(2) 299-307. 

Wilson, L. and Keil, K. (1991) Consequences of explosive eruptions on small solar-system bodies the case of the missing basalts on the aubrite parent body. Earth and Planetary Science Letters, 104, 505-512. 

In this chapter, we review what is known about the chronology of the solar system, based on the radioisotope systems described in Chapter 8. We start by discussing the age of materials that formed the solar system. Short-lived radionuclides also provide information about the galactic environment in which the solar system formed. We then consider how the age of the solar system is estimated from its oldest surviving materials - the refractory inclusions in chondrites. We discuss constraints on the accretion of chondritic asteroids and their subsequent metamorphism and alteration. Next, we discuss the chronology of differentiated asteroids, and of the Earth, Moon, and Mars. Finally, we consider the impact histories of the solar system bodies, the timescales for the transport of meteorites from their parent bodies to the Earth, and the residence time of meteorites on the Earth s surface before they disintegrate due to weathering. 

Anhydrous planetesimals, and especially the meteorites derived from them, provide crucial cosmochemical data. Spectroscopic studies of asteroids do not provide chemical analyses, but the spectral similarities of several asteroid classes to known meteorite types provide indirect evidence of their compositions. The few chemical analyses of asteroids by spacecraft are consistent with ordinary chondrite or primitive achondrite compositions. Laboratory analyses of anhydrous meteorites - chondrites, achondrites, irons, and stony irons - allow us to study important chemical fractionations in early solar system bodies. Fractionations among chondrites occur mostly in elements with higher volatility, reflecting the accretion of various components whose compositions were determined by high- and low-temperature processes such as condensation and evaporation. Fractionations among achondrites and irons are more complex and involve partitioning of elements between melts and crystals during differentiation. 

Hydrogen isotopic compositions, expressed as molar D/H ratios, of solar system bodies. The relatively low D/H values in the atmospheres of Jupiter and Saturn are similar to those in the early Sun, whereas D/H ratios for Uranus and Neptune are intermediate between the Jupiter-Saturn values and those of comets and chondrites. The Earth s oceans have D/H shown by the horizontal line. Mars values are from SNC meteorites. Modified from Righter et al. (2006) and Lunine (2004). 

EXTRATERRESTRIAL MATERIALS. Extraterrestrial materials arc samples from other bodies in the solar system that can he studied in earth-hound laboratories. Sensitive and ever-improving analytical techniques are used lo provide information at levels of detail and sophistication that cannot be matched by telescopic or spacecraft investigations. Much of the know ledge of early solar system bodies, processes, environments, and chronology has come from the study of these samples. Extraterrestrial materials that arc availahlc for laboratory study include metcoritic materials that fall naturally lo the earth, some meteorilic material that has been... 

The two Solar System bodies beyond Earth that have elicited the most interest as potential habitats for life are Mars and Europa because both have clearly been impacted by aqueous processes. Considering the expanse of time subsequent to the Solar System s origin, conditions conducive to the occur-... 

A plausibility scale for life beyond Earth was developed by Irwin and Schulze-Makuch (2001) (Table 6.2). Earth-like planetary bodies with liquid water, readily available energy, and organic compounds were listed as Plausibility of Life (POL) Category I (high). At the other extreme are solar system bodies such as the Sun and Moon with conditions or compositions so harsh that life is unrealistic, which is Category V (remote verging on utterly impossible). The previously discussed planetary bodies, Mars and Europa, are Category II (favorable), which is why so much attention has been placed on these two Solar System bodies. 

The original version of the model dealt with chloride and sulfate chemistries and was written when the senior author worked at the Cold Regions Research and Engineering Laboratory (U.S. Army Corps of Engineers) in Hanover, New Hampshire. Subsequent versions with new chemistries were largely funded by NASA for applications to cold Solar System bodies such as Mars and Europa. 

Huss, G. (1997) The survival of presolar grains in solar system bodies. In Astrophysical Implications of the Laboratory Study of Presolar Materials, T. J. Bematowicz E. K. Zinner, Eds., pp. 721-48. AIP Conf. Proc. 402. 

What kinds of polymeric structures (or monomer collections) might support catalysis and genetics in nonaqueous environments, particularly in solvents found on solar system bodies other than Earth ... 

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