The BioSun project: first results of an astrobiological approach involving Astrophysics, Biology and Geology

ABREVAYA, X.C.

Congreso; 59 reunion de la AAA; 2016

The BioSun project is an international collaborative project oriented to study the radiation envi-ronment of the early planetary bodies of the solar system, in particular those important form the astrobiologicalpoint of view. This international collaboration involves experts from dierent areas such as astrophysics, biologyand geology. Within this context, one of the goals of the project is to study the possibility of an extraterres-trial origin of life, commonly know as panspermia". One of the open issues of this hypothesis is that it is stillunknown whether these life forms could survive this long interplanetary travels, because they would be exposedto multiple extreme conditions (e.g.: radiation, vacuum, low temperatures). In previous studies we simulatedthe environment of the low Earth orbit (L.E.O.) in laboratory conditions and we showed that some species ofmicroorganisms are capable to survive several to doses of V-UV radiation and vacuum. In the context of thisproject we hypothesized an interplanetary travel of a Martian meteorite to the early Earth around 3.8 Gyr ago.Considering this hypothesis, in a new round of experiments we simulated an step of the interplanetary travel.We simulated the V-UV and vacuum conditions of the L.E.O. and we tested the survival of the microorganismsconsidering potential Martial-like life forms, in particular halophilic archaea. This microorganisms were foundentrapped inside ancient halites (NaCl minerals) on Earth in evaporitic deposits from Permic and Triassic (250My ago). Therefore these organisms were proposed as possible inhabitants of Mars and are considered as possiblecandidates for the interplanetary transfer of life by natural processes. The Martian meteorite Nakhla" whichcontains halite inclusions has been chosen as model for these studies. As the project is focused in the radiationenvironment of the young Sun, the astrophysical input for the simulation experiments considered the solar analogof the young Sun, 1 Cet (96 Ceti/HD 20630/HR 996). Microorganisms were entrapped inside halites under Mar-tian and Earth-like conditions and irradiated with VUV radiation (57.5{124.0 nm) at dierent doses (up to 40000Jm􀀀2). The results showed dierential survival and the halites could eectively oer some kind of protection tothe conditions evaluated in the experiments.