PROTECTIVE EFFECTS OF HALITE TO VACUUM AND VUV: A POTENTIAL SCENARIO DURING A YOUNG SUN SUPERFLARE

ABREVAYA X.C.; GALANTE, D.; TRIBELLI, P.; OPPEZZO, O.J.; NOBREGA, F.; ARAUJO, G.; RODRIGUES, F.; ODERT, P.; LEITZINGER, M.; RICARDI, M. ; VARELA, M.E.; GALLO, T.; SANZ FORCADA, J.; RIBAS, I.; PORTO DE MELLO, G.F.; RODLER, F.; CERINI, M. F.; HANSLMEIER, A.; HORVATH, J. E.

ASTROBIOLOGY

MARY ANN LIEBERT INC

Lugar: New York; Año: 2022

1531-1074

Halites (NaCl minerals) have shown the potential to preserve microorganisms for millions of years on Earth. These minerals were also identified on Mars and in meteorites. In this study, we investigate the potential of halites to protect microbial life forms on the surface of an airless body (e.g. meteorite), for instance during a lithopanspermia process (interplanetary travel step) in the early Solar System. To study the effect of the radiation of the young Sun on microorganisms, we performed extensive simulation experiments by employing a synchrotron facility. In particular, we focused on two regimes: vacuum (low Earth orbit, 10-5 Pa, and vacuum UV radiation (VUV range 57.6 - 124 nm, fluence rate 7.14 Wm-2), the latter representing an extreme scenario with high VUV fluxes, comparable to the amount of a stellar superflare from the young Sun. The stellar VUV parameters were estimated using the very well-studied solar analog of the young Sun, κ1 Cet. To evaluate the protective effects of halite, we entrapped halophilic archaea (Haloferax volcanii) and non-halophilic bacteria (Deinococcus radiodurans) in laboratory-grown halites. Control groups were cells entrapped in salt crystals (salt mixtures) and naked cells, respectively. All groups were exposed to either vacuum alone or vacuum plus VUV. Our results demonstrate that halite can serve as protection against vacuum and VUV radiation, regardless of the type of microorganism. In addition, we have found that the protection is higher than the one provided by crystals obtained from salt mixtures (which ones? specify). This extends the protective effects of halites documented in previous studies and reinforces the possibility to consider these minerals as potential preservation structures in airless bodies or as vehicles for the interplanetary transfer of microorganisms.