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We briefly present preliminary results of our study of the radioresistant bacteria in a low temperature and pressure and high-radiation environment and hypothesize the ability of microorganisms to survive extraterrestrial high-radiation environments, such as the icy surface of Jupiter’s moon, Europa. In this study, samples containing a strain of Deinococcus radiodurans VKM B-1422T embedded into a simulated version of Europa’s ice were put under extreme environmental (−130 °C, 0.01 mbar) and radiation conditions using a specially designed experimental vacuum chamber. The samples were irradiated with 5, 10, 50, and 100 kGy doses and subsequently studied for residual viable cells. We estimate the limit of the accumulated dose that viable cells in those conditions could withstand at 50 kGy. Combining our numerical modelling of the accumulated dose in ice with observations of water eruption events on Europa, we hypothesize that in the case of such events, it is possible that putative extraterrestrial organisms might retain viability in a dormant state for up to 10,000 years, and could be sampled and studied by future probe missions.

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During the solar flares protons and heavier ions are accelerated up to GeV energies. Accelerated ions can escape the Sun and be registered directly on spacecraft or penetrate into the solar atmosphere and then produce gamma-ray lines as the result of nuclear reactions. Previous studies revealed very poor correlation between fluxes of interplanetary ions and gamma-ray line emission. In this work we focus on joint observations of interplanetary solar energetic particles registered by PAMELA experiment and gamma-ray emission registered by Konus-Wind instrument in hard X-ray and soft gamma-ray ranges. This study confirmed the previous results: during the period from 2006 to 2014 there were only two solar flares registered both by PAMELA and Konus-Wind at energies above 1 MeV. We analyze gamma-ray spectrum for one of these flares and make suggestions about the reasons for the low correlation between interplanetary solar accelerated ions and accelerated ions interacted in the solar atmosphere.

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