Meteorites on Mars

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... 

Schroder, C. et al. 2008. Meteorites on Mars observed with the Mars Exploration Rovers. Journal of Geophysical Research, 113, E06S22, doi 10.1029/2007JE002990. 

Schroder, C. et al. 2009. Santorini, Another Meteorite on Mars and Third of a Kind. Lunar and Planetary Science, 40, 1665. 

The photo below, taken by the Ttl/ng spacecraft, shows that the surface of Mars has been eroded, apparently by liquid water. More recent photos transmitted by Spirit and Opportunity convince scientists that this was the case. Apparently, Mars was once much warmer than it is today. Planetary scientists speculate that at one time the atmosphere of Mars may have contained large amounts of carbon dioxide, setting up a greenhouse effect that made the surface of that planet warmer and wetter. Might there, then, have been life on Mars at some earlier time Molecular stmctures found in meteorites thought to come from Mars have been interpreted to show that there was once life there, but these results are controversial. 

Recently, sulphur has also been found on the surface of Mars it was probably deposited from the atmosphere and originated in volcanic activity. Sulphur was also found in meteorites which probably originated on Mars (Farquhar et al., 2000). The mean surface temperature is 210 K (at night 150 K and during the day 270 K). 

Primarily iron and nickel and similar in composition to M-type asteroids iron, 91% nickel, 8.5% cobalt, 0.6%. A recent find of an iron meteorite on the surface of Mars is shown on p. 7 of the colour plate section... 

The desorption laser can be tracked across the surface of the meteorite so the plume of molecules can be associated directly with internal structures and morphology on the meteorite surface. The internal morphology of a meteorite is accessed by cleaving the sample in an ultraclean environment to prevent terrestrial contamination, followed by the laser desorption analysis. Nearly all meteorites have been studied in this way producing a mature field of research, however, the details of just two meteorites will be discussed in some detail. The Murchison and ALH84001 meteorites have provoked considerable interest, particularly the Antarctic meteorite ALH84001, which was the subject of a NASA announcement regarding life on Mars. 

Meteorite ALH84001 was found in the Allan Hills in Antarctica in 1984 and was the subject of an extraordinary NASA press announcement in 1996. It weighed 1.93 kg when it was collected (Figure 6.10) and is probably the most extensively studied lump of rock of all time. It is 95 per cent orthopyroxene, the volcanic rock mineral that accumulated in a molten-lava-reducing environment on Mars some... 

Gibson Jr E. K. et al. (2001). Fife on Mars evaluation of the evidence within Martian meteorites ALH84001, Nakhla and Shergotty, Precabrian Research 106 15-34. 

Several meteorites were identified on Mars on the basis of their Fe metal and troilite contents (Schroder et al. 2008,... 

Compared to the Moon, meteorites have a greater chance to survive impact on Mars because of its atmosphere. Compared to Earth, the current extremely arid climate on Mars lets meteorites... 

Landis, G.A. 2009. Meteoritic steel as a construction resource on Mars. Acta Astronautica, 64, 183-187. 

McKay DS, et al. (1996) Search for past life on Mars possible relic biogenic activity in martian meteorite ALH 84001. Science 273 924-930... 

Romanek CS, et al. (1994) Record of fluid-rock interaction on Mars from the meteorite ALH 84001. Nature 372 655-657... 

Watson LL, Hutcheon ID, Epstein S, Stolper EM (1994) Water on Mars clues from deu-terium/hydrogen and water contents of hydrous phases in SNC meteorites. Science 265 86-90 Weber IN, Raup DM (1966a) Eractionation of the stable isotopes of carbon and oxygen in marine calcareous organisms-the Echinoidea. 1. Variation of and content within individuals. Geochim Cosmochim Acta 30 681-703... 

Ion microprobe analyses of hydrous minerals in Martian meteorites reveal two different sources of hydrogen. One is interpreted as magmatic water, with 5D = 900 permil, and thought to reflect the mantle composition the other is thought to reflect the atmospheric composition, with 5D =4000 permil (Leshin, 2000). The incorporation of atmospheric water into these meteorites suggests some kind of cycling of water between the atmosphere and lithosphere on Mars. 

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. 

Borg, L. and Drake, M. J. (2005) A review of meteorite evidence for the timing of magmatism and of surface or near-surface liquid water on Mars. Journal of Geophysical Research, 110, E12S03. 

Analysis of a small meteorite that landed on Antarctica some 15 x 106 year s ago sparked what may be the greatest scientific discovery ever, possible evidence of life on Mars,... 

Gooding JL (1992) Soil mineralogy and chemistry on Mars Possible clues from salts and clays in SNC meteorites. Icarus 99 28-41 Gow AJ (1971) Relaxation of ice in deep drill cores from Antarctica. J Geo-phys Res 76 2533-2541... 

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