Abstract
The development of space technology makes the exposure of organisms and molecules to the space environment possible by using the ESA Biopan and Expose facilities and NASA nanosatellites; the aim is to decipher the origin, evolution and distribution of life on Earth and in the Universe. The study of microbial communities thriving in lithic habitats in cold and hot deserts is gathering appreciation when dealing with the limits of life as we know it, the identification of biosignatures for searching life beyond Earth and the validation of the (litho)-Panspermia theory. Cyanobacteria of the genus Chroococcidiopsis dominate rock-dwelling communities in extreme deserts that are considered terrestrial analogues of Mars, like the Dry Valleys in Antarctica, the Atacama Desert in Chile or the Mojave Desert in California. The extraordinary tolerance of these cyanobacteria towards desiccation, ionizing and UV radiation makes them suitable experimental strains which have been already used in astrobiological experiments and already selected for future space missions. Evidence gained so far supports the use of desert cyanobacteria to develop life support systems and in-situ resource utilization for the human space exploration and settlement on the Moon or Mars.
Highlights
Astrobiology is a rather young field of research gathering scientists from different backgrounds around the questions of the origin, evolution, distribution and future of life on Earth and in the Universe
Desiccation, radiation-resistant desert strains of Chroococcidiopsis have been employed in several experimentations in Low Earth Orbit (LEO) and ground-based simulations of space and Martian conditions in order to investigate the tenancy of life as we know it, to detect biosignatures to search for life on Mars and test thePanspermia theory [4,5]
The major effect caused by space vacuum is desiccation, while concerning solar and galactic cosmic radiation, desiccation-tolerant organisms exhibit a resistance towards UV and ionizing radiation; evidences suggested that such a resistance might be enhanced when cells are irradiated in the dried status, as reported for Deinococcus radiodurans [34]
Summary
Astrobiology is a rather young field of research gathering scientists from different backgrounds around the questions of the origin, evolution, distribution and future of life on Earth and in the Universe. Five short-duration missions (two weeks) were performed using the Russian Foton spacecraft carrying the European Space Agency (ESA) BIOPAN facility [3] More recently another ESA facility, called EXPOSE, has provided a long-duration exposure platform (1.5 years) on the International Space Station (ISS), which provides a complete laboratory orbiting Earth at about 400 km [4,5]. The record of survival in space remains that of 6 years of Bacillus subtilis spores [11] In this context, desiccation-, radiation-resistant desert strains of Chroococcidiopsis have been employed in several experimentations in LEO and ground-based simulations of space and Martian conditions in order to investigate the tenancy of life as we know it, to detect biosignatures to search for life on Mars and test the (litho)Panspermia theory [4,5]. Since cyanobacteria started to introduce oxygen into the Earth atmosphere 2.5 billion years ago, the spectroscopic detection of oxygen in a planet’s atmosphere has been suggested as an indicator of the presence of life, exploiting its star as its primary energy source [12]
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