scholarly journals Martian sub-surface ionising radiation: biosignatures and geology

2007 ◽  
Vol 4 (1) ◽  
pp. 455-492 ◽  
Author(s):  
L. R. Dartnell ◽  
L. Desorgher ◽  
J. M. Ward ◽  
A. J. Coates
Keyword(s):  
Radiation Field ◽  
Surface Composition ◽  
Accumulation Rate ◽  
Galactic Cosmic Rays ◽  
Optically Stimulated Luminescence ◽  
Cellular Survival ◽  
Dose Accumulation ◽  
Global Magnetic Field ◽  
Absorbed Radiation Dose ◽  
Shielding Material

Abstract. The surface of Mars, unshielded by thick atmosphere or global magnetic field, is exposed to high levels of cosmic radiation. This ionizing radiation field is deleterious to the survival of dormant cells or spores and the persistence of molecular biomarkers in the subsurface, and so its characterisation is of prime astrobiological interest. Previous research has attempted to address the question of biomarker persistence by inappropriately using dose profiles weighted specifically for cellular survival. Here, we present modelling results of the unmodified physically absorbed radiation dose as a function of depth through the Martian subsurface. A second major implementation of this dose accumulation rate data is in application of the optically stimulated luminescence technique for dating Martian sediments. We present calculations of the dose-depth profile from galactic cosmic rays in the Martian subsurface for various scenarios: variations of surface composition (dry regolith, ice, layered permafrost), solar minimum and maximum conditions, locations of different elevation (Olympus Mons, Hellas basin, datum altitude), and increasing atmospheric thickness over geological history. We also model the changing composition of the subsurface radiation field with depth compared between Martian locations with different shielding material, determine the relative dose contributions from primaries of different energies, and briefly treat particle deflection by the crustal magnetic fields.

scholarly journals Martian sub-surface ionising radiation: biosignatures and geology

2007 ◽  
Vol 4 (4) ◽  
pp. 545-558 ◽  
Author(s):  
L. R. Dartnell ◽  
L. Desorgher ◽  
J. M. Ward ◽  
A. J. Coates
Keyword(s):  
Radiation Field ◽  
Surface Composition ◽  
Accumulation Rate ◽  
Optically Stimulated Luminescence ◽  
Ionising Radiation ◽  
Dose Accumulation ◽  
Dormant Cells ◽  
Global Magnetic Field ◽  
Absorbed Radiation Dose ◽  
Shielding Material

Abstract. The surface of Mars, unshielded by thick atmosphere or global magnetic field, is exposed to high levels of cosmic radiation. This ionising radiation field is deleterious to the survival of dormant cells or spores and the persistence of molecular biomarkers in the subsurface, and so its characterisation is of prime astrobiological interest. Here, we present modelling results of the absorbed radiation dose as a function of depth through the Martian subsurface, suitable for calculation of biomarker persistence. A second major implementation of this dose accumulation rate data is in application of the optically stimulated luminescence technique for dating Martian sediments. We present calculations of the dose-depth profile in the Martian subsurface for various scenarios: variations of surface composition (dry regolith, ice, layered permafrost), solar minimum and maximum conditions, locations of different elevation (Olympus Mons, Hellas basin, datum altitude), and increasing atmospheric thickness over geological history. We also model the changing composition of the subsurface radiation field with depth compared between Martian locations with different shielding material, determine the relative dose contributions from primaries of different energies, and discuss particle deflection by the crustal magnetic fields.

Global magnetic field of the Sun and long-term variations of galactic cosmic rays

2001 ◽  
Vol 63 (18) ◽  
pp. 1923-1929 ◽  
Author(s):  
A.V. Belov ◽  
B.D. Shelting ◽  
R.T. Gushchina ◽  
V.N. Obridko ◽  
A.F. Kharshiladze ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Galactic Cosmic Rays ◽  
The Sun ◽  
Global Magnetic Field ◽  
Long Term Variations

The Radiation Environment on the Surface of Mars: dMEREM predictions based on RAD data

2021 ◽  
Author(s):  
Patrícia Gonçalves ◽  
Luisa Arruda ◽  
Marco Pinto
Keyword(s):  
Radiation Field ◽  
Solar Energetic Particle ◽  
Cosmic Ray ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Field Of View ◽  
Radiation Environment ◽  
Soil Composition ◽  
Particle Radiation ◽  
Spectrometer Data

<p>The characterisation of the Martian radiation environment is essential to understand if the planet can sustain life and ultimately if its human exploration is feasible. The major components of the radiation environment in the Mars orbit, are Galactic Cosmic Rays (GCRs) and Solar Energetic Particle (SEP) events. Since Mars has a negligible magnetic field and a much thinner atmosphere compared to the Earth’s, its surface is exposed to GCR and eventual SEP events, as well as to secondary particles produced in the atmosphere and in the shallow layers of the planet. The Curiosity rover that has been exploring the surface of Mars since August 2012, carries in its Mars Science Laboratory (MSL), the Radiation Assessment Detector (RAD) which measures high-energy radiation, such as protons, energetic ions of various elements, neutrons, and gamma rays. That includes not only direct radiation from space, but also secondary radiation produced by the interaction of space radiation with the atmosphere and surface rocks and soil.</p> <p><br />The detailed Martian Energetic Radiation Environment Model (dMEREM) is a GEometry ANd Tracking (GEANT4) based model developed for ESA which enables to predict the radiation environment expected at different locations on the Martian orbit, atmosphere and surface, as a function of epoch, latitude and longitude, taking into account the specific atmospheric and soil composition. dMEREM can be interfaced to different Primary Particle Models, such as the ISO-15390 and the Badhwar - O'Neill (BON) 2014 or 2020 Galactic Cosmic Ray Flux Models, or the National Aeronautics and Space Administration (NASA) Emission of Solar Protons (ESP) model for solar energetic proton fluences. dMEREM is interfaced with the European Mars Climate Database from where it retrieves information on the atmosphere composition and density at specific locations and solar longitudes and Gamma Ray Spectrometer data aboard Mars Odyssey, for the description of Mars soil composition, although soil compositions for specific locations, including those locally sampled by Martian rovers can also be defined by the user. dMEREM provides the kinetic energy and directional spectra of all particle types produced in the interactions of energetic particles with the Martian Atmosphere and Soil.</p> <p>The dMEREM validation results using differential proton fluxes stopping in the RAD sensor head as measured by MSL/RAD in Gale crater from November 15, 2015 to January 15, 2016 and in the begin of September 2017 is presented. Although the RAD only measures a limited field-of-view in zenith angle of the Martian Particle Radiation Field, the good agreement between the RAD data and the dMEREM predictions for protons within the RAD field of-view, are used as the basis for the use of dMEREM in the assessment of the expected ionizing radiation field on the surface of Mars for particles coming from all directions, including albedo particles. This assessment is also used to make predictions of dosimetric quantities, such as Ambient Dose Equivalent and Effective Dose, relevant for Human Space Flight, for the considered data periods.  </p>

Abstract

2019 ◽  
Vol 19 (1) ◽  
pp. 11-11
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Neutron Activation ◽  
Radiation Field ◽  
Micronucleus Assay ◽  
Absorbed Dose ◽  
Optically Stimulated Luminescence ◽  
Paramagnetic Resonance ◽  
Field Mapping ◽  
Tissue Reactions ◽  
Electron Paramagnetic

Dosimetry methods for use in dose assessment for individuals following acute exposure to radiation are described. Primary methods include biodosimetry and physical dosimetry techniques, while additional supplementary methods are bioassays, neutron activation, and radiation field mapping. Biodosimetry methods include the established techniques of dicentric chromosome assay, cytokinesis-block micronucleus assay, translocation analysis by fluorescent in-situ hybridization, premature chromosome condensation, and the γ-H2AX assay. Emerging techniques include RNA expression-based, protein-based, and metabolomic-based assays. Physical dosimetry methods include electron paramagnetic resonance and the luminescence-based techniques of thermoluminescence and optically stimulated luminescence. Electron paramagnetic resonance methods are used to assess absorbed dose in biologically derived materials, such as bone, teeth, and keratinous tissue, as well as non-biologically derived materials such as sugars, glasses, and polymeric materials used in fabrics and other personal items. Thermoluminescence and optically stimulated luminescence techniques are used to assess absorbed dose in the components of personal electronics, along with other items such as plastic cards, fabrics, and clothing. There have also been similar efforts for teeth and dental repair ceramics. Since the above-listed techniques cannot distinguish between exposure to internal and external sources, bioassays may be used to assess exposure from internal contamination, including thyroid counting, chest counting, and excretion analysis methods. When a neutron exposure is expected, neutron activation analysis in blood, hair, or other non-biological items is useful. Radiation field mapping can be a useful method for determining locations where doses to individuals may be expected to be high and may complement radiation transport calculations performed for that purpose. Since immediate medical assessment is concerned with tissue reactions (deterministic effects), the quantity of interest for the above dosimetry methods is absorbed dose (expressed in gray). This Report concludes with a summary of the various methods and a brief discussion of the uses of such information in the aftermath of acute radiation exposure.

scholarly journals The Responses of the Black Fungus Cryomyces Antarcticus to High Doses of Accelerated Helium Ions Radiation within Martian Regolith Simulants and Their Relevance for Mars

Life ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 130
Author(s):  
Claudia Pacelli ◽  
Alessia Cassaro ◽  
Lorenzo Aureli ◽  
Ralf Moeller ◽  
Akira Fujimori ◽  
...  
Keyword(s):  
Natural Habitat ◽  
Galactic Cosmic Rays ◽  
High Dose ◽  
Geological Time ◽  
Geological Time Scale ◽  
Near Surface ◽  
Dose Accumulation ◽  
High Doses ◽  
Martian Regolith ◽  
The Impact

One of the primary current astrobiological goals is to understand the limits of microbial resistance to extraterrestrial conditions. Much attention is paid to ionizing radiation, since it can prevent the preservation and spread of life outside the Earth. The aim of this research was to study the impact of accelerated He ions (150 MeV/n, up to 1 kGy) as a component of the galactic cosmic rays on the black fungus C. antarcticus when mixed with Antarctic sandstones—the substratum of its natural habitat—and two Martian regolith simulants, which mimics two different evolutionary stages of Mars. The high dose of 1 kGy was used to assess the effect of dose accumulation in dormant cells within minerals, under long-term irradiation estimated on a geological time scale. The data obtained suggests that viable Earth-like microorganisms can be preserved in the dormant state in the near-surface scenario for approximately 322.000 and 110.000 Earth years within Martian regolith that mimic early and present Mars environmental conditions, respectively. In addition, the results of the study indicate the possibility of maintaining traces within regolith, as demonstrated by the identification of melanin pigments through UltraViolet-visible (UV-vis) spectrophotometric approach.

A Comparison of Conventional 60Co Testing and Low Dose-Accumulation-Rate Exposure of Metal-Gate CMOS IC's

1984 ◽  
Vol 31 (6) ◽  
pp. 1582-1584 ◽  
Author(s):  
Stanley B. Roeske ◽  
William H. Edwards ◽  
James W. Zipay ◽  
Jack W. Puariea ◽  
Paul E. Gammill
Keyword(s):  
Low Dose ◽  
Accumulation Rate ◽  
Metal Gate ◽  
Dose Accumulation

scholarly journals A sub-centennial-scale optically stimulated luminescence chronostratigraphy and late Holocene flood history from a temperate river confluence

Geology ◽  
2020 ◽  
Vol 48 (8) ◽  
pp. 819-825 ◽  
Author(s):  
Ben Pears ◽  
Antony G. Brown ◽  
Phillip S. Toms ◽  
Jamie Wood ◽  
David Sanderson ◽  
...  
Keyword(s):  
Land Use ◽  
Accumulation Rate ◽  
Optically Stimulated Luminescence ◽  
Ice Age ◽  
Flood Events ◽  
14C Dating ◽  
Flood Duration ◽  
Flood Magnitude ◽  
High Flood ◽  
Flood Intensity

Abstract River confluences can be metastable and contain valuable geological records of catchment response to decadal- to millennial-scale environmental change. However, in alluvial reaches, flood stratigraphies are particularly hard to date using 14C. In this paper, we use a novel combination of optically stimulated luminescence and multiproxy sedimentological analyses to provide a flood record for the confluence of the Rivers Severn and Teme (United Kingdom) over the past two millennia, which we compare with independent European climate records. The results show that by ca. 2000 yr B.P., the Severn-Teme confluence had stabilized and overbank alluviation had commenced. Initially, this occurred from moderately high flood magnitudes between ca. 2000 and 1800 yr B.P. (50 BCE–150 CE), but was followed from 1800 to 1600 yr B.P. (150–350 CE) by fine alluvial deposition and decreased flood intensity. From 1600 to 1400 yr B.P. (350–550 CE), the accumulation rate increased, with evidence of large flood events associated with the climatic deterioration of the Dark Age Cold Period. Following a period of reduced flood activity after ca. 1400 yr B.P. (ca. 550 CE), larger flood events and increase in accumulation rate once again became more prevalent from ca. 850 yr B.P. (ca. 1100 CE), coincident with the start of the Medieval Climate Anomaly, a period associated with warmer, wetter conditions and increased land-use intensity. This state persisted until ca. 450 yr B.P. (ca. 1500 CE), after which increased flood magnitudes can be associated with climatic variations during the Little Ice Age. We demonstrate that from the combination of high-resolution dating techniques and multiple analytical parameters, distinctive phases of relative flood magnitude versus flood duration can be determined to a detailed chronological precision beyond that possible from 14C dating. This permits the identification of the regional factors behind floodplain sedimentation, which we correlate with the intensification of land-use and climatic drivers over the last two millennia.

scholarly journals 16Cr-19Ni steel swelling at dose rates from 1×10-8 to 1.6×10-6 dpa/s

2020 ◽  
Vol 6 (4) ◽  
pp. 249-252
Author(s):  
Evgeny A. Kinev
Keyword(s):  
Nuclear Reactor ◽  
Accumulation Rate ◽  
Dose Accumulation ◽  
Dose Rates ◽  
Grain Sizes ◽  
Swelling Rate ◽  
Hydrostatic Weighing ◽  
Weighing Method ◽  
Material Swelling ◽  
Characteristic Maximum

The article presents the first data on EK-164ID steel swelling after operational irradiation in a fast nuclear reactor in the temperature range of 370–630 °C and maximum damaging doses of 66–77 dpa. The dose accumulation rate along the cladding tubes made of this material was 1×10-8–1.6×10-6 dpa/s. The swelling was determined by the hydrostatic weighing method with an error of no more than 0.5%. The results obtained were analyzed depending on the irradiation parameters and in comparison with the 16Cr-15Ni grade material. The objectives of the study were to estimate the characteristic values of the maximum swelling temperature and dose as well as to calculate the average material swelling rate at the working temperature of irradiation, the incubation period for the onset of swelling, and the stationary swelling rate. It was found that the tube samples, characterized with austenite grain sizes of 9–12 µm before irradiation, have an average swelling rate of 0.035–0.05 %/dpa after reaching the maximum damaging doses of 66–77 dpa (at a rate of (1–1.5)×10-6 dpa/s) and not more than 0.035%/dpa at doses less than 20 dpa (at a rate of 5×10-7 dpa/s). The characteristic maximum swelling temperature of the studied material is in the range of 430–500 °C. The characteristic maximum swelling dose is in the range of 61–72.5 dpa or 70–80% of the maximum accumulated dose. The incubation stationary swelling period for the material is 30 dpa. The stationary swelling rate is 0.1% /dpa. The radiation resistance characteristics of the studied material have an advantage over those for 16Cr-15Ni grade cladding materials under similar irradiation conditions and a similar structural state, which inherits grain sizes of 9–14 μm during the tube processing.

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