The use of synchrotron radiation in Astrobiology: Lithopanspermia studies and the Biosun project

ABREVAYA XC; GALANTE D; NOBREGA F; TRIBELLI PM; RODRIGUEZ F; ARAUJO G; GALLO T; RIBAS I; SANZ FORCADA J; RODLER F; PORTO DE MELLO GF; LEITZINGER M; ODERT P; HANSLMEIER A; HORVATH J

Sao Paulo

Encuentro; 25 th RAU Annual Users meeting LNLS/CNPEM; 2015

Panspermia theory assumes that microscopic life forms (e.g.: microorganisms) could survivelong interplanetary travels (Arrhenius, 1903; Hoyle and Wickramasinghe, 1979). This hasbeen matter of debate since a long time ago, opening the possibility of an extraterrestrialorigin of life on the Earth. One of the open issues is that it is still not known if these lifeforms could survive these travels because they would be exposed to multiple extremeconditions (e.g.: radiation, vacuum). Abrevaya et al (2011) showed the capacity of somespecies of microorganisms to survive several doses of VUV radiation and vacuum as thoserelated to the conditions of low Earth orbit (L.E.O.). In a new round of experimentsperformed at the TGM beamline (LNLS, Campinas, Brazil) we tested the survival of themicroorganisms considering Lithopanspermia (interplanetary transfer of life throughmeteorites) in the context of the BioSun project (Abrevaya et al., 2013). The Martianmeteorite ?Nakhla? was chosen as model for these studies because it contains haliteinclusions (NaCl evaporitic minerals). This is connected to the fact that microorganismsknown as haloarchaea were found entrapped inside ancient halites (250 Mya) on Earth(e.g.:McGenity et al., 2000); therefore these organisms were proposed as possible inhabitantsof Mars and possible candidates for the interplanetary transfer of life (Stan-Lotter et al.,2004). As the project is focused in the radiation environment of the young Sun, for thesimulation experiments we selected as main parameters low pressure (vacuum) and VUVradiation as those we could found in L.E.O. around 3.8 Gyr ago. Two species of haloarchaeaand the radioresistant bacteria D. radiodurans were entrapped inside halites and irradiatedwith VUV (57.5 ?124 nm) with different doses up to 40000 J/m2 (eq. to 10 days in L.E.O.).We showed that the survival of of the microorganisms is strongly dependent on the specieand that halites could not offer enough protection.