Lunar surface

Its importance depends on the nuclear property of being readily fissionable with neutrons and its availability in quantity. The world s nuclear-power reactors are now producing about 20,000 kg of plutonium/yr. By 1982 it was estimated that about 300,000 kg had accumulated. The various nuclear applications of plutonium are well known. 238Pu has been used in the Apollo lunar missions to power seismic and other equipment on the lunar surface. As with neptunium and uranium, plutonium metal can be prepared by reduction of the trifluoride with alkaline-earth metals. 

RBS is based on collisions between atomic nuclei, and it involves measuring the number and energy of ions in a beam which backscatter after colliding with atoms in the near-surface region of a sample. The use of scattering as an analysis tool led to the first in situ chemical analysis of the lunar surface during the landing of Surveyor V. The use of particle accelerators as an a-source was the next powerful step made in Chalk River (Canada) and Arus (Denmark). 

Vacuum may be natural or artificially produced. Natural vacuum, for example, occurs on the lunar surface or in the interstellar space where one should however speak of numerical density of particles ( 1 particle/cm3) instead of pressure. In the intergalactic space, the density is around 1 particle/m3. Natural vacuum laboratories in use are, for example, the Space Shuttle or Space Stations, but we will deal only with artificial vacuum, produced by pumps inside a container. 

Whereas isotopes produced in the solid matter of meteorites or the lunar surface material remain at their production sites, isotopes produced mainly in the earth s atmosphere are separated according to the geochemical properties of the different elements. 

Studies Based on Isotope Production in Meteorites and on the Lunar Surface... 

C. E., "Cosmic-ray exposure history at the Apollo 16 and other lunar sites lunar surface dynamics", Geochim... 

The abundance of niobium in the earth s crust is estimated to be in the range 20 mg/kg and its average concentration in sea water is 0.01 mg/L. The metal also is found in the solar system including the lunar surface. Radionucleides niobium-94 and -95 occur in the fission products of uranium-235. 

Plutonium is the most important transuranium element. Its two isotopes Pu-238 and Pu-239 have the widest applications among all plutonium isotopes. Plutonium-239 is the fuel for nuclear weapons. The detonation power of 1 kg of plutonium-239 is about 20,000 tons of chemical explosive. The critical mass for its fission is only a few pounds for a solid block depending on the shape of the mass and its proximity to neutron absorbing or reflecting substances. This critical mass is much lower for plutonium in aqueous solution. Also, it is used in nuclear power reactors to generate electricity. The energy output of 1 kg of plutonium is about 22 million kilowatt hours. Plutonium-238 has been used to generate power to run seismic and other lunar surface equipment. It also is used in radionuclide batteries for pacemakers and in various thermoelectric devices. 

The literature suggests that thermally stable explosives such as HNS were employed for seismic experiments on the moon [61]. This is probably due to safety considerations while handling explosives for such applications on the lunar surface. 

In order to understand it, knowledge of some facts about the lunar surface and its atmosphere is considered necessary which is given in the next paragraph. 

Lunar surface materials (Apollo and Luna returned samples and lunar meteorites) are classified into three geochemical end members - anorthosite, mare basalt, and KREEP. These components are clearly associated with the various geochemically mapped terrains of different age on the lunar surface. The composition of the lunar interior is inferred from the geochemical characteristics of basalts that formed by mantle melting, and geochemistry provides constraints on the Moon s impact origin and differentiation via a magma ocean. 

A gross subdivision of the Moon s surface is based on albedo. The bright regions are the highlands, which are clearly ancient because of their high densities of impact craters. The dark regions are younger maria, basaltic lavas that flooded the impact basins on the nearside of the Moon. Mare basalts are exposed over 17% of the lunar surface and probably comprise only 1% of the crustal volume. 

Distribution of iron on the lunar surface, as measured by the Clementine spacecraft, compared with the average iron contents (arrows) of Apollo highlands crustal rocks and lunar highlands meteorites. The meteorites, which presumably come from the nearside and farside, more closely match the global iron peak. The compositional ranges for various lunar rock types are shown as horizontal bars. 

Korotev, R. L., Jolliff, B. L., Zeigler, R. A., Gillis, J. J. and Haskin, L. A. (2003) Feldspathic lunar meteorites and their imphcations for compositional remote sensing of the lunar surface and the composition of the lunar crust. Geochimica et Cosmochimica Acta, 67, 4895—4923. 

Lucey, P. G., Blewett, D. T. and Hawke, B. R. (1998) Mapping the FeO and 2 content of the lunar surface with multispectral imagery. Journal of Geophysical Research, 103, 3679-3699. 

Lucey, P. G., plus 17 coauthors (2006) Understanding the lunar surface and space-Moon interactions. In New Views of the Moon, Reviews in Mineralogy and Geochemistry 60, eds. Jolliff, B. L., Wieczorek, M. A., Shearer, . K. and Neal, C. R. Washington, D.C. Mineralogical Society of America and Geochemical Society, 83-219. 

Prettyman, T. H., Hagerty, J. J., Elphic, R. C. et al. (2006) Elemental composition of the lunar surface analysis of gamma ray spectroscopy data from Lunar Prospector. Journal of Geophysical Research, 111, E12007, doi 10.1029/2005JE002656. 

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