Natural Transfer of Viable Microbes in Space from Planets in the Extra-Solar Systems to a Planet in our Solar System and Vice-Versa

We investigate whether it is possible that viable microbes could have been transported to Earth from the planets in extra-solar systems by means of natural vehicles such as ejecta expelled by comet or asteroid impacts on such planets. The probabilities of close encounters with other solar systems are taken into account as well as the limitations of bacterial survival times inside ejecta in space, caused by radiation and DNA decay. The conclusion is that no potentially DNA/RNA life-carrying ejecta from another solar system in the general Galactic star field landed on Earth before life already existed on Earth, not even if microbial survival time in space is as long as tens of millions of years. However, if the Sun formed initially as a part of a star cluster, as is commonly assumed, we cannot rule out the possibility of transfer of life from one of the sister systems to us. Likewise, there is a possibility that some extra-solar planets carry life that originated in our solar system. It will be of great interest to identify the members of the Sun's birth cluster of stars and study them for evidence for planets and life on the planets. The former step may be accomplished by the GAIA mission, the latter step by the SIM and DARWIN missions. Therefore it may not be too long until we have experimental knowledge on the question whether the natural transfer of life from one solar system to another has actually taken place.Comment: 25 pages, 1 table, accepted to Ap

ISS RADIATION ENVIRONMENT AS OBSERVED BY LIULIN TYPE-R3DR2 INSTRUMENT IN OCTOBER-NOVEMBER 2014

Space radiation was monitored using the R3DR2 spectrometer-dosimeter during the flight outside the Russian “Zvezda” module of ISS in October-November 2014. The instrument was mounted on the ESA EXPOSE-R2 platform. The R3DR2 instrument was first developed and used during the flight of ESA EXPOSE-R platform in 2009-2010 (Dachev et al, 2015a). It is a low mass, small dimension automated device that measures solar visible and ultraviolet (UV) radiation in four channels and ionizing radiation in 256 channels of a Liulin-type energy deposition spectrometer (Dachev et al, 2002). Ionizing radiation was measured and separated in 256 deposited energy spectra, which were further used for determination of the absorbed dose rate and flux. The main results obtained by the R3DR2 instrument are: (1) three different radiation sources were detected and quantified - galactic cosmic rays (GCR), energetic protons from the inner radiation belt (IRB) in the region of the South Atlantic anomaly and energetic electrons from the outer radiation belt (ORB); (2) for the first time in the history of using of the Liulin-type energy deposition spectrometers (Dachev et al, 2015b) an observable flux from solar energetic particles (SEP) was detected in the period 1-4 November 2014; (3) the obtained SEP energy deposition spectra were compared with other spectra to confirm their shape

Integrity of the DNA and Cellular Ultrastructure of Cryptoendolithic Fungi in Space or Mars Conditions: A 1.5-Year Study at the International Space Station

The black fungi Cryomyces antarcticus and Cryomyces minteri are highly melanized and are resilient to cold, ultra-violet, ionizing radiation and other extreme conditions. These microorganisms were isolated from cryptoendolithic microbial communities in the McMurdo Dry Valleys (Antarctica) and studied in Low Earth Orbit (LEO), using the EXPOSE-E facility on the International Space Station (ISS). Previously, it was demonstrated that C. antarcticus and C. minteri survive the hostile conditions of space (vacuum, temperature fluctuations, and the full spectrum of extraterrestrial solar electromagnetic radiation), as well as Mars conditions that were simulated in space for a 1.5-year period. Here, we qualitatively and quantitatively characterize damage to DNA and cellular ultrastructure in desiccated cells of these two species, within the frame of the same experiment. The DNA and cells of C. antarcticus exhibited a higher resistance than those of C. minteri. This is presumably attributable to the thicker (melanized) cell wall of the former. Generally, DNA was readily detected (by PCR) regardless of exposure conditions or fungal species, but the C. minteri DNA had been more-extensively mutated. We discuss the implications for using DNA, when properly shielded, as a biosignature of recently extinct or extant life

UV-radiation-induced formation of DNA bipyrimidine photoproducts in Bacillus subtilis endospores and their repair during germination

The spore photoproduct (SP) is the main DNA lesion after UV-C irradiation, and its repair is crucial for the resistance of spores to UV. The aims of the present study were to assess the formation and repair of bipyrimidine photoproducts in spore DNA of various Bacillus subtilis strains using a sensitive HPLC tandem mass spectrometry assay. Strains deficient in nucleotide excision repair, spore photoproduct lyase, homologous recombination (recA), and with wild-type repair capability were investigated. Additionally, one strain deficient in the formation of major small, acid-soluble spore proteins (SASPs) was tested. In all SASP wild-type strains, UV-C irradiation generated almost exclusively SP (>95 %) but also a few by-photoproducts. In the major SASP-deficient strain, SP and by-photoproducts were generated in equal quantities. The status of the UV-induced bipyrimidine photoproducts was determined at different stages of spore germination. After a germination time of 60 min, >75% of the SP was repaired in wild-type strains and in the SASP-deficient strain, while half of the photoinduced SP was removed in the recA-deficient strain. SP-lyase-deficient spores repaired < 20% of the SP produced. Thus, SP lyase, with respect to nucleotide excision repair, has a remarkable impact on the removal of SP upon spore germination. [Int Microbiol 2007; 10(1):39-46

Quantitative Proteomic Analysis of Bacillus pumilus from Spores that Survived in Outer Space Conditions

The hardy spores of Bacillus species are well known for their resistance to unfavorable conditions such as UV and gamma radiation, hydrogen peroxide desiccation, chemical disinfection, or starvation. In particular, Bacillus pumilus strain SAFR-032 that was originally recovered from the Jet Propulsion Lab Spacecraft Assembly Facility has shown to exhibit unusually high resistance to UV radiation and peroxide treatment compared to other Bacillus species. To further understand the resistance of bacterial endospores to relevant outer space environments, spores of B. pumilus SAFR-032 were exposed for 1.5 years to selected parameters of space on board of the International Space Station (ISS). Here we are using a quantitative proteomics approach to gain insights into the resistance mechanism of B. pumilus

К определению поверхностного натяжения, объема и площади криволинейной поверхности по форме сидячих пузырьков или висячих капель

The multi-user facility EXPOSE-E was designed by the European Space Agency to enable astrobiology research in space (low-Earth orbit). On 7 February 2008, EXPOSE-E was carried to the International Space Station (ISS) on the European Technology Exposure Facility (EuTEF) platform in the cargo bay of Space Shuttle STS-122 Atlantis. The facility was installed at the starboard cone of the Columbus module by extravehicular activity, where it remained in space for 1.5 years. EXPOSE-E was returned to Earth with STS-128 Discovery on 12 September 2009 for subsequent sample analysis. EXPOSE-E provided accommodation in three exposure trays for a variety of astrobiological test samples that were exposed to selected space conditions: either to space vacuum, solar electromagnetic radiation at > 110nm and cosmic radiation (trays 1 and 3) or to simulated martian surface conditions (tray 2). Data on UV radiation, cosmic radiation, and temperature were measured every 10 s and downlinked by telemetry. A parallel mission ground reference (MGR) experiment was performed on ground with a parallel set of hardware and samples under simulated space conditions. EXPOSE-E performed a successful 1.5-year mission in space

Survival of lichens and bacteria exposed to outer space conditions - Results of the Lithopanspermia experiments

n the space experiments Lithopanspermia, experimental support was provided to the likelihood of the lithopanspermia concept that considers a viable transport of microorganisms between the terrestrial planets by means of meteorites. The rock colonising lichens Rhizocarpon geographicum and Xanthoria elegans, the vagrant lichen Aspicilia fruticulosa, and endolithic and endoevaporitic communities of cyanobacteria and bacteria with their natural rock substrate were exposed to space for 10 days onboard the Biopan facility of the European Space Agency (ESA). Biopan was closed during launch and re-entry. In addition, in the Stone facility, one sample of R. geographicum on its natural granitic substrate was attached at the outer surface of the re-entry capsule close to the stagnation point, only protected by a thin cover of glass textolite. Post-flight analysis, which included determination of the photosynthetic activity, LIVE/DEAD staining, and germination capacity of the ascospores, demonstrated that all three lichen were quite resistant to outer space conditions, which include the full spectrum of solar extraterrestrial electromagnetic radiation or selected wavelength ranges. This high resistance of the lichens to space appears to be due to their symbiotic nature and protection by their upper pigmented layer, the cortex. In contrast, the rock- or halite-inhabiting bacteria were severely damaged by the same exposure. After atmospheric re-entry, the granite of the Stone sample was transformed into a glassy, nearly homogenous material, with several friction striae. None of the lichen cells survived this re-entry process. The data suggest that lichens are suitable candidates for testing the concept of lithopanspermia, because they are extremely resistant to the harsh environment of outer space. The more critical event is the atmospheric re-entry after being captured by a planet. Experiments simulating the re-entry process of a microbe-carrying meteoroid did not show any survivors

The astrobiological mission EXPOSE-R on board of the International Space Station

EXPOSE-R flew as the second of the European Space Agency (ESA) EXPOSE multi-user facilities on the International Space Station. During the mission on the external URM-D platform of the Zvezda service module, samples of eight international astrobiology experiments selected by ESA and one Russian guest experiment were exposed to low Earth orbit space parameters from March 10th, 2009 to January 21st, 2011. EXPOSE-R accommodated a total of 1220 samples for exposure to selected space conditions and combinations, including space vacuum, temperature cycles through 273K, cosmic radiation, solar electromagnetic radiation at >110, >170 or >200nm at various fluences up to GJm−2. Samples ranged from chemical compounds via unicellular organisms and multicellular mosquito larvae and seeds to passive radiation dosimeters. Additionally, one active radiation measurement instrument was accommodated on EXPOSE-R and commanded from ground in accordance with the facility itself. Data on ultraviolet radiation, cosmic radiation and temperature were measured every 10s and downlinked by telemetry and data carrier every few months. The EXPOSE-R trays and samples returned to Earth on March 9th, 2011 with Shuttle flight, Space Transportation System (STS)-133/ULF 5, Discovery, after successful total mission duration of 27 months in space. The samples were analysed in the individual investigators laboratories. A parallel Mission Ground Reference experiment was performed on ground with a parallel set of hardware and samples under simulated space conditions following to the data transmitted from the flight missio