Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Solar X-ray Flare Hazards on the Surface of Mars   Putative organisms on the Martian surface would be exposed to potentially
high doses of ionizing radiation during strong solar X-ray flares. We
extrapolate the observed flare frequency-energy release scaling relation to
releases much larger than seen so far for the sun, an assumption supported by
observations of flares on other solar- and subsolar-mass main sequence stars.
We calculate the surficial reprocessed X-ray spectra using a Monte Carlo code
we have developed. Biological doses from indirect genome damage are calculated
for each parameterized flare spectrum by integration over the X-ray opacity of
water. We estimate the mean waiting time for solar flares producing a given
biological dose of ionizing radiation on Mars and compare with lethal dose data
for a wide range of terrestrial organisms. These timescales range from decades
for significant human health risk to 0.5 Myr for D. radiodurans lethality. Such
doses require total flare energies of 10^33--10^38 erg, the lower range of
which has been observed for other stars. Flares are intermittent bursts, so
acute lethality will only occur on the sunward hemisphere during a sufficiently
energetic flare, unlike low-dose-rate, extended damage by cosmic rays. We
estimate the soil and CO_2 ice columns required to provide 1/e shielding as
4--9 g cm^-2, depending on flare mean energy and atmospheric column density.
Topographic altitude variations give a factor of two variation in dose for a
given flare. Life in ice layers that may exist ~ 100 g cm^-2 below the surface
would be well protected.

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The categories of this paper are: nucl-th
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: stat
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: q-alg
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg