Solar X-ray flare hazards on the surface of Mars

摘要: Abstract Putative organisms on the Martian surface would be exposed to potentially high doses of ionizing radiation during strong solar X-ray flares. We extrapolate observed flare frequency-energy release scaling relation total energies much larger than seen so far for Sun, an assumption supported by observations flares other solar- and subsolar-mass main sequence stars. Flare spectra are taken as power laws, with logarithmic slope a parameter based statistics most energetic hard spectra. calculate using Monte Carlo code we developed transport X-rays gamma rays, including photoabsorption detailed Compton scattering. Biological from indirect genome damage calculated each parameterized spectrum integration over opacity water. The resulting depend sensitively spectral slope, which varies greatly unsystematically Using roughly uniform distribution slopes, estimate mean waiting time producing given biological dose Mars compare lethal data wide range terrestrial organisms. These timescales decades significant human health risk 0.5 Myr D. radiodurans lethality. Such require 10 33 – 38 erg, lower has been Flares intermittent bursts, acute lethality will only occur sunward hemisphere sufficiently flare, unlike low-dose-rate, extended cosmic rays. soil CO 2 ice columns required provide 1 / e shielding 4 9 g cm - , depending energy atmospheric column density. Topographic altitude variations give factor two variation in flare. Life layers that may exist ∼ 100 below well protected. Finally, point out designing spacesuits block this missions difficult, conflict between solutions lightweight protection particles those X-rays.