Moon meteorites

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... 

Solid bodies of extraterrestrial material that penetrate the atmosphere and reach the Earth s surface are called meteorites. Other extraterrestrial materials include micrometer-sized interplanetary dust particles (IDEs) collected in the lower stratosphere and polar ices. Most meteorites and IDEs are fragments of asteroids, but some IDEs may represent cometary material and some meteorites are fragments of the planets Mars and Earth s moon. Meteorites recovered following observed falls are called/a// those which cannot definitely be associated with observed falls are called finds. Meteorites are given names based on the location where they were recovered (e.g., the Allende meteorite fell in Allende, Mexico). Meteorites recovered in Antarctica and the deserts of Australia and northern Africa are given names and numbers, because numerous samples are found in the same locations. Fragments thought to be of the same meteorite fall, which, in Antarctica or hot deserts, may have different numbers or even names because they were found in different locations, are called... 

Korotev R. L. (2002) Lunar meteorites. Website, http //epsc. wustl.edu/admin/resources/moon meteorites.html. 

Notes The petrographic discriptions are from ht //epsc.wustl.edu/admin/resources/meteorites/moon meteorites list.htiiil... 

Eugster O., Polnau E., Salerno E., and Terribilini D. (2000) Lunar surface exposure models for meteorites Elephant Moraine 96008 and Dar al Gani 262 from the Moon. Meteorit. Planet. Sci. 35, 1177-1181. 

Warren P. H. (2003) New lunar meteorites II. Implications for composition of the global lunar surface, of the lunar crust, and of the bulk Moon. Meteorit. Planet. Sci. 38 (submitted). 

Wiechert UH, Halliday AN, Lee DC, Snyder GA, Taylor LA, Rumble D (2000) Oxygen- and tungsten-isotopic constraints on the early development of the moon. Meteoritics Planetary Sci 35 A169 Woodhead JD, Greenwood P, Harmon RS, Staffers P (1993) Oxygen isotope evidence for recycled crust in the source of EM-type ocean island basalts. Nature 362 809-813 Woodhead JD, Harmon RS, Fraser DG (1987) O, S, Sr, and Pb isotope variations in volcanic rocks from the northern Mariana islands implications for crastal recycling in intra-oceanic ares. Earth Planet Sci Letters 83 39-52... 

Zirconium is found in abundance in S-type stars, and has been identified in the sun and meteorites. Analysis of lunar rock samples obtained during the various Apollo missions to the moon show a surprisingly high zirconium oxide content, compared with terrestrial rocks. 

The emphasis of the present work is science and technology in the laboratory. The natural shock-compression laboratory of meteoritic impact should not be overlooked. In these environments unique solid state materials have been synthesized for the first time. Perhaps the most common features of our Earth, Moon, and other planets and moons are the craters produced by such high velocity impacts [67C01, 87A03]. 

The nuclei of iron are especially stable, giving it a comparatively high cosmic abundance (Chap. 1, p. 11), and it is thought to be the main constituent of the earth s core (which has a radius of approximately 3500 km, i.e. 2150 miles) as well as being the major component of siderite meteorites. About 0.5% of the lunar soil is now known to be metallic iron and, since on average this soil is 10 m deep, there must be 10 tonnes of iron on the moon s surface. In the earth s crustal rocks (6.2%, i.e. 62000ppm) it is the fourth most abundant element (after oxygen, silicon and aluminium) and the second most abundant metal. It is also widely distributed. 

Our solar system consists of the Sun, the planets and their moon satellites, asteroids (small planets), comets, and meteorites. The planets are generally divided into two categories Earth-like (terrestrial) planets—Mercury, Venus, Earth, and Mars and Giant planets—Jupiter, Saturn, Uranus, and Neptune. Little is known about Pluto, the most remote planet from Earth. 

Water and carbon play critical roles in many of the Earth s chemical and physical cycles and yet their origin on the Earth is somewhat mysterious. Carbon and water could easily form solid compounds in the outer regions of the solar nebula, and accordingly the outer planets and many of their satellites contain abundant water and carbon. The type I carbonaceous chondrites, meteorites that presumably formed in the asteroid belt between the terrestrial and outer planets, contain up to 5% (m/m) carbon and up to 20% (m/m) water of hydration. Comets may contain up to 50% water ice and 25% carbon. The terrestrial planets are comparatively depleted in carbon and water by orders of magnitude. The concentration of water for the whole Earth is less that 0.1 wt% and carbon is less than 500 ppm. Actually, it is remarkable that the Earth contains any of these compounds at all. As an example of how depleted in carbon and water the Earth could have been, consider the moon, where indigenous carbon and water are undetectable. Looking at Fig. 2-4 it can be seen that no water- or carbon-bearing solids should have condensed by equilibrium processes at the temperatures and pressures that probably were typical in the zone of fhe solar... 

Samples that are 4.6 X 10 years old have been found in meteorites. This is the best present estimate for the age of the solar system. Example illustrates this type of calculation for rock from the Earth s moon. 

The purine base guanine is also formed in concentrated solutions of ammonium cyanide, i.e., the same substance which became known from Or6 s adenine synthesis. Or6, as well as Stanley Miller, was involved in a new series of experiments (Levi et al., 1999). The yield of guanine is, however, 10 10 times lower than that of adenine surprisingly, the synthesis is just as effective at 253 K as at 353 K. Low temperatures seem conceivable in certain parts of Earth as well as on the Jovian moon Europa (see Sect. 3.1.5) or in the Murchison meteorite. 

Now, apart from the planets, many meteorites were formed, moving in quite different orbits and of quite different chemical composition. In particular, the so-called C-l meteorites composed of carbonaceous chondrites have a composition of elements much closer to that of the Sun. It is proposed (see for example Harder and also Robert in Further Reading) that many of these meteorites collided with very early Earth and became incorporated in it, so that eventually some 15% of Earth came from this material (see Section 1.11). Other planets such as Mars and the Moon could have had similar histories, but the remote planets and Venus are very different. 

The noble gas elements act as a record of the deposited material because they are essentially chemically inert and are also trapped within the ice of comets and meteorites. The late-heavy bombardment era must have affected both the Earth and the Moon similarly so an estimate of the collision frequency may be obtained by using the record of impacts on the Moon s surface. The collision rate calculated... 

The delivery of volatiles to Earth and Mars must have been similar but where has the early Martian atmosphere gone The atmosphere of the inner planets can be seen in Table 7.3. Cometary and meteorite impacts can deliver material to a planet but are also responsible for a process called impact erosion where the atmosphere could be lost due to an impact such as the Earth-Moon capture event. Current estimates suggest that impact erosion may be responsible for the loss of 100 times the current mass of the Martian atmosphere. 

Nuclear dating has been most helpful in establishing the history of the earth and of the moon and of the meteorites. The fact is, there is no other way of measuring their ages. Prior to the discovery of natural radioactivity in the late 19th century, indirect methods were used to estimate the age of the earth, but there were no real answers until the radioactivity of thorium, uranium, and potassium were discovered and we began to understand atomic structure and to realize that nuclear transformation was essentially independent of the chemical form. 

Interaction of Cosmic Rays with Meteorites, The Moon and The Earth s Surface... 

The penetration depth of cosmic radiation is of the order of 1 m and therefore isotopes are produced by spallation only in the surface layers of meteorites and the moon. After collisions of meteorites with each other or with the moon, newly formed surfaces get exposed to cosmic radiation and production of stable and radioactive isotopes starts. If P is the production rate of a... 

The basic idea in radioactive age-dating of rocks (from the Earth, Moon and meteorites) is to find the ratio of daughter to parent in an isolated system. Thus the age inferred is usually the solidification age which is the time since the last occasion when chemical fractionation was halted by solidification. (K-Ar dating gives a gas-retention age which can be slightly shorter.)... 

A few meteorites have significantly younger ages these are believed to come from the Moon and in some cases from Mars, rather than from asteroids. 

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