ABSTRACT
In this work we investigated the ability of four extremophilic bacteria from Archaea and Bacteria domains to resist to space environment by exposing them to extreme conditions of temperature, UV radiation, desiccation coupled to low pressure generated in a Mars' conditions simulator. All the investigated extremophilic strains (namely Sulfolobus solfataricus, Haloterrigena hispanica, Thermotoga neapolitana and Geobacillus thermantarcticus) showed a good resistance to the simulation of the temperature variation in the space; on the other hand irradiation with UV at 254 nm affected only slightly the growth of H. hispanica, G. thermantarcticus and S. solfataricus; finally exposition to Mars simulated condition showed that H. hispanica and G. thermantarcticus were resistant to desiccation and low pressure.
Subject(s)
Euryarchaeota/radiation effects , Geobacillus/radiation effects , Space Simulation , Sulfolobus solfataricus/radiation effects , Thermotoga neapolitana/radiation effects , Cold Temperature , Desiccation , Euryarchaeota/growth & development , Exobiology , Extraterrestrial Environment , Geobacillus/growth & development , Hot Temperature , Mars , Microbial Viability/radiation effects , Sulfolobus solfataricus/growth & development , Thermotoga neapolitana/growth & development , Ultraviolet Rays , VacuumABSTRACT
We have studied the effects of the substrate, namely amorphous olivine (MgFeSiO(4)) cosmic dust analogues (CDAs), in synthesis of molecules obtained after 200 keV proton irradiation of formamide (NH(2)COH). Formamide has been deposited on the olivine substrate at 20 K. The abundances of new molecular species formed after an irradiation dose of 12 eV/16 amu in formamide pure (i.e. deposited on an inert silicon substrate) and deposited on CDAs have been compared. Specifically, MgFeSiO(4) amorphous olivine is a selective catalyst preventing formation of NH(3) and CN(-) molecules and changing the relative abundances of NH4(+)OCN(-), CO(2), HNCO, CO. We have shown that the role of CDAs has to be taken into account in experiments simulating processes occurring in astronomical environments.
Subject(s)
Cosmic Dust/analysis , Extraterrestrial Environment/chemistry , Inorganic Chemicals/chemistry , Ammonia/chemistry , Astronomical Phenomena , Astronomy , Catalysis , Cyanides/chemistry , Evolution, Chemical , Formamides/chemistry , Iron Compounds/chemistry , Magnesium Compounds/chemistry , Silicates/chemistry , Spectrophotometry, InfraredABSTRACT
Laboratory simulations of carbonaceous grain processing which occurs in space are fundamental to outline an evolutionary pathway for these particles. We consider the UV spectral changes induced in hydrogenated carbon grains by thermal annealing, UV irradiation and ion bombardment. The results give the opportunity to interpret observations in different space environments. In particular, modelling of the optical properties, based on a description of the electronic structure of carbons, indicates small hydrogenated amorphous carbon grains, with different degrees of UV irradiation, as the carrier of the ubiquitous UV interstellar extinction bump.
