Influence of Irradiation With Gamma - Quanta and Beam of Accelerated Electrons on the Sorption Parameters of Clay Minerals of the Montmorillonite Group

Spitsyn, V.I.; Balukova, B. D.; Savushkina, M. K.

doi:10.1557/proc-6-703

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“…Much of this research was directed toward understanding the interactions of nuclear waste with various containers, packing materials and geologic environments. Spitsyn et al [1981] subjected feldspars and quartz to 6øCo gamma radiation. They reported color changes in the feldspars, minor loss of crystallinity and shifts in some infrared spectral peaks.…”

Section: Effects On Rocks and Mineralsmentioning

confidence: 99%

Effects of sterilizing doses of gamma radiation on Mars analog rocks and minerals

Allen¹,

Albert²,

Combie³

et al. 1999

J. Geophys. Res.

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Abstract. Rock and soil samples from the planet Mars are due to be returned to Earth within a decade. Martian samples initially will be tested for evidence of life and biological hazard under strict biological containment. Wider distribution of samples for organic and inorganic analysis may occur only if neither evidence of life nor hazard is detected, or if the samples are first sterilized. We subjected a range of Mars analog rocks and minerals to high doses of gamma radiation in order to determine the effects of gamma sterilization on the samples' isotopic, chemical, and physical properties. Gamma photons from 6øCo (1.17 and 1.33 MeV) in doses as high as 3 x 107 rads did not induce radioactivity in the samples and produced no measurable changes in their isotopic and chemical compositions. This level of irradiation also produced no measurable changes in the crystallographic structure of any sample, the surface areas of soil analogs, or the fluid inclusion homogenization temperature of quartz. The only detectable effects of irradiation were dose-dependent changes in the visible and near-infrared spectral region (e.g., discoloration and darkening of quartz and halite and an increase in albedo of carbonates) and increases in the thermoluminescence of quartz and plagioclase. If samples returned from Mars require biological sterilization, gamma irradiation provides a feasible option. BackgroundMartian rock and soil, collected by robotic spacecraft, will be returned to terrestrial laboratories early in the next century. The return of documented samples, carefully collected and preserved, will be a major step in the search for evidence of Martian life. Martian conditions, including the lack of organic matehal, subfreezing temperatures, high flux of solar ultraviolet radiation, and strongly oxidizing chemical species in the soil, severely limit the survival of organisms at or near the surface [Klein, 1998] inCenters for Disease Control and Prevention, Atlanta, Georgia.•University of Portsmouth, Portsmouth, England.Copyright 1999 by the American Geophysical Union. Paper number 1999JE001064.0148-0227/99/1999JE001064509.00 specialized organisms at low concentrations in the returned samples is conceivable [Clark, 1998].Current planetary protection strategies call for the samples to be immediately placed into biological containment and tested for signs of present or past life and biological hazard [DeVincenzi et al., 1998]. It is recommended that "Controlled distribution of unsterilized materials from Mars should occur only if rigorous analyses determine that the materials do not constitute a biological hazard. If any portion of the sample is removed from containment prior to completion of these analyses it should first be sterilized" [Space Studies Board, 1997]. While sterilization of Mars samples may not be required, an acceptable method must be available before the samples are returned to Earth.A variety of sterilization techniques have been used or proposed for spacecraft missions to Mars. These include dry heating to t...

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Section: Effects On Rocks and Mineralsmentioning

confidence: 99%